ORCID Profile
0000-0001-9435-8043
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Materials Engineering | Nanotechnology | Nanotechnology | Nanoscale Characterisation | Functional Materials | Materials Engineering Not Elsewhere Classified | Compound Semiconductors | Optics And Opto-Electronic Physics | Biomaterials | Nanomaterials | Colloid And Surface Chemistry | Metals and Alloy Materials | Composite and Hybrid Materials | Nanomanufacturing | Condensed Matter Physics | Chemical Characterisation of Materials | Alloy Materials | Other Electronic Engineering | Manufacturing Processes and Technologies (excl. Textiles) | Ceramics | Solid State Chemistry | Physical Chemistry (Incl. Structural) | Interdisciplinary Engineering Not Elsewhere Classified | Condensed Matter Characterisation Technique Development | Optical Physics | Chemical Spectroscopy | Polymerisation Mechanisms | Ceramics | Characterisation Of Macromolecules | Manufacturing Engineering Not Elsewhere Classified | Polymers | Composite Materials | Condensed Matter Physics—Electronic And Magnetic Properties; | Condensed Matter Physics—Structural Properties | Condensed Matter Physics—Other | Biomaterials | Optical And Photonic Systems | Construction Materials | Civil Engineering | Inorganic Geochemistry | Cellular Interactions (incl. Adhesion, Matrix, Cell Wall) | Crop and Pasture Improvement (Selection and Breeding) | Technology not elsewhere classified | Surfaces and Structural Properties of Condensed Matter | Soft Condensed Matter | Environmental Nanotechnology | Electronic and Magnetic Properties of Condensed Matter; Superconductivity | Cell Development, Proliferation and Death | Physical Sciences Not Elsewhere Classified | Nanofabrication, Growth and Self Assembly
ANZSRC Socio-Economic Objective (SEO)
Physical sciences | Other | Expanding Knowledge in Technology | Expanding Knowledge in Engineering | Expanding Knowledge in the Physical Sciences | Communication equipment not elsewhere classified | Structural Metal Products | Manufactured products not elsewhere classified | Integrated circuits and devices | Communication services not elsewhere classified | Energy Conservation and Efficiency not elsewhere classified | Management of Greenhouse Gas Emissions from Electricity Generation | Environmentally Sustainable Energy Activities not elsewhere classified | Health not elsewhere classified | Metals (composites, coatings, bonding, etc.) | Scientific instrumentation | Polymeric materials (e.g. paints) | Scientific Instruments | Expanding Knowledge in the Biological Sciences | Other | Renewable Energy not elsewhere classified | Management of Greenhouse Gas Emissions from Energy Activities (excl. Electricity Generation) | Materials performance and processes | Biological sciences | Chemical sciences | Other | Electronic Information Storage and Retrieval Services | Metal Castings | Management of Solid Waste from Manufacturing Activities | Integrated Circuits and Devices | Management of Greenhouse Gas Emissions from Manufacturing Activities | Ceramics | Energy Transformation not elsewhere classified | Ceramics | Plastic products (incl. Construction materials) | Cement and Concrete Materials | Structural metal products | Energy transformation not elsewhere classified | Oil and Gas Exploration | Mineral Resources (excl. Energy Resources) not elsewhere classified | Energy not elsewhere classified | "Stone, ceramics and clay materials" | Expanding Knowledge in the Chemical Sciences | Machinery and equipment not elsewhere classified |
Related Links
Publications
Enhancing thermoelectric performance of (Cu1-xAgx)2Se via CuAgSe secondary phase and porous design
Publisher: Elsevier BV
Date: 09-2018
Epitaxial growth of high mobility Bi2Se3 thin films on CdS
Publisher: AIP Publishing
Date: 13-06-2011
DOI: 10.1063/1.3599540
Abstract: We report the experiment of high quality epitaxial growth of Bi2Se3 thin films on hexagonal CdS (0001) substrates using a solid source molecular-beam epitaxy system. Layer-by-layer growth of single crystal Bi2Se3 has been observed from the first quintuple layer. The size of surface triangular terraces has exceeded 1 μm. Angle-resolved photoemission spectroscopy clearly reveals the presence of Dirac-cone-shape surface states. Magneto-transport measurements demonstrate a high Hall mobility of ∼6000 cm2/V s for the as-grown Bi2Se3 thin films at temperatures below 30 K. These characteristics of Bi2Se3 thin films promise a variety of potential applications in ultrafast, low-power dissipation devices.
Shape preservation of self-assembled SiGe quantum rings during Si capping
Publisher: IOP Publishing
Date: 07-02-2007
Laser Engineered Graphene Paper for Mass Spectrometry Imaging
Publisher: Springer Science and Business Media LLC
Date: 11-03-2013
DOI: 10.1038/SREP01415
A General Single-Source Route for the Preparation of Hollow Nanoporous Metal Oxide Structures
Publisher: Wiley
Date: 09-2009
Self-Healing of Fractured GaAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 18-03-2011
DOI: 10.1021/NL104330H
Visible-light photoresponsive heterojunctions of (Nb-Ti-Si) and (Bi/Bi-o) nanoparticles
Publisher: Elsevier BV
Date: 03-2009
NITRIDATION OF SILICON WITH AMMONIA AND NITROGEN
Publisher: World Scientific Pub Co Pte Lt
Date: 06-2010
DOI: 10.1142/S0219581X10006582
Abstract: Silicon nitride and silicon oxynitride are materials used extensively in mechanical and electronic devices due to their outstanding properties. Thin films of silicon nitride and silicon oxynitride can be deposited on a silicon surface. In this study, nitridation of silicon wafers by a rapid thermal heating process with both nitrogen and ammonia as precursors was investigated by transmission electron microscopy, electron energy loss spectroscopy, and ellipsometry analyses. It was found that, under ammonia gas, the growth of nitride film was limited to 0.5 nm, whilst under the nitrogen atmosphere, a nitride film of 5–10 nm could be formed at 1200°C. The limited growth in ammonia suggests formation of high-quality passivating layer.
Understanding Micro and Atomic Structures of Secondary Phases in Cu‐Doped SnTe
Publisher: Wiley
Date: 18-09-2022
Abstract: Highly efficient thermoelectric materials require, including point defects within the host matrix, secondary phases generating positive effects on lowering lattice thermal conductivity (κ L ). Amongst effective dopants for a functional thermoelectric material, SnTe, Cu doping realizes the ultra‐low κ L approaching the SnTe amorphous limit. Such effective κ L reduction is first attributed to strong phonon scattering by substitutional Cu atoms at Sn sites and interstitial defects in the host SnTe. However, other crystallographic defects in secondary phases have been unfocused. Here, this work reports micro‐ to atomic‐scale characterization on secondary phases of Cu‐doped SnTe using advanced microscopes. It is found that Cu‐rich secondary phases begin precipitation ≈1.7 at% Cu ( x = 0.034 where Sn 1− x Cu x Te). The Cu‐rich secondary phases encapsulate two distinct solids: Cu 2 SnTe 3 () has semi‐coherent interfaces with SnTe () such that they minimize lattice mismatch to favor the thermoelectric transport the other resembles a stoichiometric Cu 2 Te model, yet is so meta‐stable that it demonstrates not only various defects such as dislocation cores and ordered/disordered Cu vacancies, but also dynamic grain‐boundary migration with heating and a subsequent phase transition ≈350 °C. The atomic‐scale analysis on the Cu‐rich secondary phases offers viable strategies for reducing κ L through Cu addition to SnTe.
Spatially resolved luminescence investigation of AlGaAs/GaAs single quantum wires modified by selective implantation and annealing
Publisher: AIP Publishing
Date: 22-11-1999
DOI: 10.1063/1.125344
Abstract: Single Al0.5Ga0.5As/GaAs V-groove quantum wires (QWR) modified by selective implantation and rapid thermally annealing were investigated by spatially resolved microphotoluminescence (micro-PL). The PL from the necking region was clearly observed at room temperature. Optical properties of QWR and the adjacent quantum well structures were strongly degraded by the implantation. The recovery properties of the PL signals from all the structures were dependent on the implantation dose. A critical dose of 1×1013 cm−2 was found for the selective implantation, over which the PL from the necking region could not be recovered. Also the blueshifts of QWR and the necking-region PL peaks were observed for all the annealed s les. This blueshift is caused by the interface intermixing, which is very useful to increase the confinement of carriers in QWR region for optoelectronic device applications.
Establishing the Golden Range of Seebeck Coefficient for Maximizing Thermoelectric Performance
Publisher: American Chemical Society (ACS)
Date: 15-01-2020
DOI: 10.1021/JACS.9B13272
Abstract: The coupling nature of thermoelectric properties determines that optimizing the Fermi level is the priority to achieve a net increase in thermoelectric performance. Conventionally, the carrier concentration is used as the reflection of the Fermi level in the band structure. However, carrier concentration strongly depends upon the material's effective mass, leading to that the optimal carrier concentration varies over a large scale for different materials. Herein, inspired by the big data survey, we develop a golden Seebeck coefficient range of 202-230 μV K
Elemental diffusion during the droplet epitaxy growth of In(Ga)As/GaAs(001) quantum dots by metal-organic chemical vapor deposition
Publisher: AIP Publishing
Date: 13-01-2014
DOI: 10.1063/1.4859915
Abstract: Droplet epitaxy is an important method to produce epitaxial semiconductor quantum dots (QDs). Droplet epitaxy of III-V QDs comprises group III elemental droplet deposition and the droplet crystallization through the introduction of group V elements. Here, we report that, in the droplet epitaxy of InAs/GaAs(001) QDs using metal-organic chemical vapor deposition, significant elemental diffusion from the substrate to In droplets occurs, resulting in the formation of In(Ga)As crystals, before As flux is provided. The supply of As flux suppresses the further elemental diffusion from the substrate and promotes surface migration, leading to large island formation with a low island density.
Catalyst size dependent growth of Pd-catalyzed one-dimensional InAs nanostructures
Publisher: AIP Publishing
Date: 20-05-2013
DOI: 10.1063/1.4807597
Abstract: In this study, Pd was used as catalyst to grow one-dimensional InAs nanostructures on GaAs (111)B substrates in order to explore the growth mechanism and the effect of non-gold catalysts in growing epitaxial III-V nanostructures. With detailed morphological, structural, and chemical characterizations using electron microscopy, coupled with analysis of the Pd-In binary phase diagram, it was found that size of Pd nanoparticles plays a key role in determining the growth mechanism of one-dimensional InAs nanostructures.
Na-Doped p-Type ZnO Microwires
Publisher: American Chemical Society (ACS)
Date: 08-02-2010
DOI: 10.1021/JA908521S
Abstract: p-Type ZnO microwires were first synthesized by a simple chemical vapor deposition method using Na as the dopant source. p-Type doping was confirmed by the electrical transport in single-wire field-effect transistors and low-temperature photoluminescence. The carrier mobility of the microwires was estimated to be approximately 2.1 cm(2) V(-1) S(-1).
Hollow Carbon Nanospheres with Extremely Small Size as Anode Material in Lithium-Ion Batteries with Outstanding Cycling Stability
Publisher: American Chemical Society (ACS)
Date: 08-02-2016
Formation of coupled three-dimensional GeSi quantum dot crystals
Publisher: AIP Publishing
Date: 09-04-2012
DOI: 10.1063/1.3702883
Abstract: Coupled three-dimensional GeSi quantum dot crystals (QDCs) are realized by multilayer growth of quantum dots (QDs) on patterned SOI (001) substrates. Photoluminescence spectra of these QDCs show non-phonon (NP) recombination and its transverse-optical (TO) phonon replica of excitons in QDs. With increasing excitation power, peak energies of both the NP and TO peaks remain nearly constant and the width of the TO peak decreases. These anomalous features of the PL peaks are attributed to miniband formation due to strong coupling of the holes and the emergence of quasioptical phonon modes due to periodic scatters in ordered GeSi QDs.
Ni3C-assisted growth of carbon nanofibres 300 °C by thermal CVD
Publisher: IOP Publishing
Date: 23-07-2014
DOI: 10.1088/0957-4484/25/32/325602
Abstract: Ni-assisted thermal chemical vapor deposition (TCVD) is one of the most common techniques for the growth of carbon nanofibres/nanotubes (CNFs/CNTs). However, some fundamental issues related to the catalytic growth of CNFs/CNTs, such as the low-limit growth temperature, the limiting steps and the state of Ni, are still controversial. Here, we report the growth of CNFs at 300 °C that is the lowest temperature for the growth of CNFs by TCVD using Ni as the catalyst so far. The results showed that the Ni existed in rhombohedral Ni3C, not in the normal form of face-centered cubic Ni, and the C atoms for building the CNFs were precipitated from the (001) planes of the faceted Ni3C nanoparticles. The CNFs are believed to be formed by the decomposition-formation cycle of metastable Ni3C that has a low-limit decomposition temperature of about 300 °C. Our results strongly suggest that TCVD is a valuable tool for the synthesis of CNFs/CNTs at temperatures below 400 °C, which is generally considered as the upper-limit temperature for fabricating complementary metal oxide semiconductor devices but is the low-limit temperature for growing CNFs/CNTs by TCVD at present.
Anisotropic Electrical Properties from Vapor–Solid–Solid Grown Bi2Se3 Nanoribbons and Nanowires
Publisher: American Chemical Society (ACS)
Date: 22-08-2014
DOI: 10.1021/JP505407J
High Porosity in Nanostructured n-Type Bi2Te3 Obtaining Ultralow Lattice Thermal Conductivity
Publisher: American Chemical Society (ACS)
Date: 09-08-2019
Abstract: Porous structure possesses full potentials to develop high-performance thermoelectric materials with low lattice thermal conductivity. In this study, the
Effect of the crystal structure on the optical properties of InP nanowires
Publisher: IEEE
Date: 10-2009
Wafer-scale two-dimensional ferromagnetic Fe3GeTe2 thin films grown by molecular beam epitaxy
Publisher: Springer Science and Business Media LLC
Date: 14-09-2017
DOI: 10.1038/S41699-017-0033-3
Abstract: Recently, layered two-dimensional ferromagnetic materials (2D FMs) have attracted a great deal of interest for developing low-dimensional magnetic and spintronic devices. Mechanically exfoliated 2D FMs were discovered to possess ferromagnetism down to monolayer. It is therefore of great importance to investigate the distinct magnetic properties at low dimensionality. Here, we report the wafer-scale growth of 2D ferromagnetic thin films of Fe 3 GeTe 2 via molecular beam epitaxy, and their exotic magnetic properties can be manipulated via the Fe composition and the interface coupling with antiferromagnetic MnTe. A 2D layer-by-layer growth mode has been achieved by in situ reflection high-energy electron diffraction oscillations, yielding a well-defined interlayer distance of 0.82 nm along {002} surface. The magnetic easy axis is oriented along c -axis with a Curie temperature of 216.4 K. Remarkably, the Curie temperature can be enhanced when raising the Fe composition. Upon coupling with MnTe, the coercive field dramatically increases 50% from 0.65 to 0.94 Tesla. The large-scale layer-by-layer growth and controllable magnetic properties make Fe 3 GeTe 2 a promising candidate for spintronic applications. It also opens up unprecedented opportunities to explore rich physics when coupled with other 2D superconductors and topological matters.
Inverted vortex fluidic exfoliation and scrolling of hexagonal-boron nitride
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9RA03970H
Abstract: Exfoliation or scrolling of h-BN occurs in a vortex fluidic device under downward continuous flow.
Flame‐Synthesized Ceria‐Supported Copper Dimers for Preferential Oxidation of CO
Publisher: Wiley
Date: 02-02-2009
Nanoscratch-induced phase transformation of monocrystalline Si
Publisher: Elsevier BV
Date: 10-2010
Free-Standing InAs Nanobelts Driven by Polarity in MBE.
Publisher: American Chemical Society (ACS)
Date: 05-11-2019
Abstract: In this study, we demonstrated the Au-catalyzed growth of free-standing defect-free zinc-blende structured InAs nanobelts on the GaAs {111}
Cr metal thin film memory
Publisher: AIP Publishing
Date: 09-2011
DOI: 10.1063/1.3626901
Abstract: As state of the art flash memory technologies scale down to sub 30 nm node, conventional floating gate flash memory approaches its physical scaling limit mainly because of the high gate coupling ratio (GCR) requirement to secure proper memory window. Here, we report a novel flash memory device called Cr metal thin film memory (MTFM) that can circumvent the GCR issue and extend flash memory scalability by employing Cr thin film as a storage layer. Cr metal thin film memory devices with simple and low temperature processes produced a wide memory window of 10 V at the ±18 V voltage sweep with GCR of only 0.3. Such a large window can be adopted for multi-level cell operations, which can further increase the memory density. Also, retention measurement shows more than 10 years retention time due to higher energy barrier between Cr metal and tunnel oxide than conventional poly silicon and tunnel oxide. Cross section transmission electron microscope (TEM) images showed the structure and accurate dimensions of the Cr MTFM device with continuous Cr film and sharp interfaces. As for material characterizations, an amorphous like Cr phase was observed through TEM and x-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) confirmed the Cr-Cr bond and Cr-O bond near the Cr surface after evaporation and rapid thermal annealing. This metal thin film memory may open a new route to achieve the terabit level flash memory.
Crystallographically driven Au catalyst movement during growth of InAs/GaAs axial nanowire heterostructures
Publisher: AIP Publishing
Date: 04-2009
DOI: 10.1063/1.3103265
Abstract: The movement of Au catalysts during growth of InAs on GaAs nanowires has been carefully investigated by transmission electron microscopy. It has been found that Au catalysts preferentially stay on {112}B GaAs sidewalls. Since a {112} surface is composed of a {111} facet and a {002} facet and since {111} facets are polar facets for the zinc-blende structure, this crystallographic preference is attributed to the different interface energies caused by the different polar facets. We anticipate that these observations will be useful for the design of nanowire heterostructure based devices.
An unexpected plasticization phenomenon and a constant of the change rate of viscoelastic properties for polymers during nanoindentation test
Publisher: Wiley
Date: 19-05-2011
DOI: 10.1002/APP.34032
Improvement of morphology, structure, and optical properties of GaAs nanowires grown on Si substrates
Publisher: IEEE
Date: 08-2010
In-doped Bi2Se3 hierarchical nanostructures as anode materials for Li-ion batteries
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4TA00045E
Rashba Effect Maximizes Thermoelectric Performance of GeTe Derivatives
Publisher: Elsevier BV
Date: 09-2020
Boron nitride nanotubes: Pronounced resistance to oxidation
Publisher: AIP Publishing
Date: 23-03-2004
DOI: 10.1063/1.1667278
Abstract: Boron nitride (BN) nanotubes have the same nanostructure as carbon nanotubes but are found to exhibit significant resistance to oxidation at high temperatures. Our systematic study has revealed that BN nanotubes are stable at 700 °C in air and that some thin nanotubes (diameter less than 20 nm) with perfect multiwalled cylindrical structure can survive up to 900 °C. Thermogravimetric analysis reveals an onset temperature for oxidation of BN nanotubes of 800 °C compared with only 400 °C for carbon nanotubes under the same conditions. This more pronounced resistance of BN nanotubes to oxidation is inherited from the hexagonal BN and also depends on the nanocrystalline structure. This high level of resistance to oxidation allows promising BN nanotube applications at high temperatures.
Eco-Friendly Higher Manganese Silicide Thermoelectric Materials: Progress and Future Challenges
Publisher: Wiley
Date: 06-04-2018
Quantum Capacitance in Topological Insulators
Publisher: Springer Science and Business Media LLC
Date: 18-09-2012
DOI: 10.1038/SREP00669
Unravelling Effective-Medium transport and interfacial resistance in (CaTe) (GeTe)100- thermoelectrics
Publisher: Elsevier BV
Date: 2023
Wurtzite P-Doped GaN Triangular Microtubes as Field Emitters
Publisher: American Chemical Society (ACS)
Date: 07-05-2010
DOI: 10.1021/JP100689S
Strong Phonon–Phonon Interactions Securing Extraordinary Thermoelectric Ge1–xSbxTe with Zn-Alloying-Induced Band Alignment
Publisher: American Chemical Society (ACS)
Date: 28-12-2018
DOI: 10.1021/JACS.8B12624
Abstract: The ability of substitution atoms to decrease thermal conductivity is usually ascribed to the enhanced phonon-impurity scattering by assuming the original phonon dispersion relations. In this study, we find that 10% Sb
Amorphous SiOx nanowires catalyzed by metallic Ge for optoelectronic applications
Publisher: Elsevier BV
Date: 03-2011
Long wavelength emissions of periodic yard-glass shaped boron nitride nanotubes
Publisher: AIP Publishing
Date: 12-01-2009
DOI: 10.1063/1.3069278
Abstract: Extraordinary and stable long wavelength emission (centered at ∼685 nm) from the yard-glass shaped boron nitride nanotubes (YG-BNNTs) was observed in their cathodoluminescence and photoluminescence spectroscopy. The mechanism for this near-red light emission at ∼685 nm is attributed to the periodical nature of the BNNT units with regular lattice defects. The visible-light emission from YG-BNNTs indicates that this material has great potential for applications as nano-optical and/or nano-optoelectronic devices in nanoscale surgery and spectroscopy.
Solvothermal synthesis of high-purity porous Cu1.7Se approaching low lattice thermal conductivity
Publisher: Elsevier BV
Date: 11-2019
Atomic disorders in layer structured topological insulator SnBi2Te4 nanoplates
Publisher: Springer Science and Business Media LLC
Date: 17-08-2018
ZnS Branched Architectures as Optoelectronic Devices and Field Emitters
Publisher: Wiley
Date: 31-05-2010
Toughening and reinforcement of poly(vinylidene fluoride) nanocomposites with “bud-branched” nanotubes
Publisher: Elsevier BV
Date: 2012
Correction: Computer-aided design of high-efficiency GeTe-based thermoelectric devices
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0EE90029J
Abstract: Correction for ‘Computer-aided design of high-efficiency GeTe-based thermoelectric devices’ by Min Hong et al. , Energy Environ. Sci. , 2020, DOI: 10.1039/d0ee01004a.
MnGe magnetic nanocolumns and nanowells
Publisher: IOP Publishing
Date: 28-05-2010
DOI: 10.1088/0957-4484/21/25/255602
Abstract: We report a 'superlattice' growth method to produce well-aligned magnetic MnGe nanocolumns and nanowells by using low-temperature molecular-beam epitaxy. Both structural and magnetic properties show strong evidence of Mn(5)Ge(3) precipitates and lattice-coherent nanostructures with different blocking temperatures. Magnetotransport measurements reveal positive and negative magnetoresistances for the nanowells and nanocolumns, respectively. This distinction can be explained by different spin scattering mechanisms under magnetic fields. Our results suggest a new growth strategy to achieve reproducible MnGe nanostructures, which facilitates the development of Ge-based spintronics and magnetoelectronics devices.
Co-doped Sb2Te3paramagnetic nanoplates
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5TC03767K
Abstract: Paramagnetic Co-doped Sb 2 Te 3 nanoplates are fabricated using a facile and green solvothermal method.
Formation Mechanism of Al2 O3 -Containing Inclusions in Al-Deoxidized Spring Steel
Publisher: Springer Science and Business Media LLC
Date: 30-07-2019
Axiotaxy driven growth of belt-shaped InAs nanowires in molecular beam epitaxy
Publisher: Springer Science and Business Media LLC
Date: 24-03-2021
Mechanically Driven Grain Boundary Formation in Nickel Nanowires
Publisher: American Chemical Society (ACS)
Date: 22-11-2017
Abstract: Metallic nanomaterials are widely used in micro/nanodevices. However, the mechanically driven microstructure evolution in these nanomaterials is not clearly understood, particularly when large stress and strain gradients are present. Here, we report the in situ bending experiment of Ni nanowires containing nanoscale twin lamellae using high-resolution transmission electron microscopy. We found that the large, localized bending deformation of Ni nanowires initially resulted in the formation of a low-angle tilt grain boundary (GB), consisting of randomly distributed dislocations in a diffuse GB layer. Further bending intensified the local plastic deformation and thus led to the severe distortion and collapse of local lattice domains in the GB region, thereby transforming a low-angle GB to a high-angle GB. Atomistic simulations, coupled with in situ atomic-scale imaging, unravelled the roles of bending-induced strain gradients and associated geometrically necessary dislocations in GB formation. These results offer a valuable understanding of the mechanically driven microstructure changes in metallic nanomaterials through GB formation. The work also has implications for refining the grains in bulk nanocrystalline materials.
BixSb2-xTe3 nanoplates with enhanced thermoelectric performance due to sufficiently decoupled electronic transport properties and strong wide-frequency phonon scatterings
Publisher: Elsevier BV
Date: 02-2016
Ion damage buildup and amorphization processes in GaAs–AlxGa1−xAs multilayers
Publisher: AIP Publishing
Date: 09-1996
DOI: 10.1063/1.363186
Abstract: The nature of ion damage buildup and amorphization in GaAs–AlxGa1−xAs multilayers at liquid-nitrogen temperature is investigated for a variety of compositions and structures using Rutherford backscattering-channeling and cross-sectional transmission electron microscopy techniques. In this multilayer system, damage accumulates preferentially in the GaAs layers however, the presence of AlGaAs enhances the dynamic annealing process in adjacent GaAs regions and thus amorphization is retarded close to the GaAs–AlGaAs interfaces even when such regions suffer maximum collisional displacements. This dynamic annealing in AlGaAs and at GaAs–AlGaAs interfaces is more efficient with increasing Al content however, the dynamic annealing process is not perfect and an amorphous phase may be formed at the interface above a critical defect level or ion dose. Once an amorphous phase is nucleated, amorphization proceeds rapidly into the adjacent AlGaAs. This is explained in terms of the interplay between defect migration and defect trapping at an amorphous–crystalline or GaAs–AlGaAs interface. In addition, enhanced recrystallization of the amorphous GaAs at the interface may occur during heating if an amorphous phase is not formed in the adjacent AlGaAs layer. This is most likely the result of mobile defects injected from the AlGaAs layer during heating.
Flexible Thermoelectric Materials and Generators: Challenges and Innovations
Publisher: Wiley
Date: 30-05-2019
Abstract: The urgent need for ecofriendly, stable, long-lifetime power sources is driving the booming market for miniaturized and integrated electronics, including wearable and medical implantable devices. Flexible thermoelectric materials and devices are receiving increasing attention, due to their capability to convert heat into electricity directly by conformably attaching them onto heat sources. Polymer-based flexible thermoelectric materials are particularly fascinating because of their intrinsic flexibility, affordability, and low toxicity. There are other promising alternatives including inorganic-based flexible thermoelectrics that have high energy-conversion efficiency, large power output, and stability at relatively high temperature. Herein, the state-of-the-art in the development of flexible thermoelectric materials and devices is summarized, including exploring the fundamentals behind the performance of flexible thermoelectric materials and devices by relating materials chemistry and physics to properties. By taking insights from carrier and phonon transport, the limitations of high-performance flexible thermoelectric materials and the underlying mechanisms associated with each optimization strategy are highlighted. Finally, the remaining challenges in flexible thermoelectric materials are discussed in conclusion, and suggestions and a framework to guide future development are provided, which may pave the way for a bright future for flexible thermoelectric devices in the energy market.
Lithium-Catalyzed Dehydrogenation of Ammonia Borane within Mesoporous Carbon Framework for Chemical Hydrogen Storage
Publisher: Wiley
Date: 08-01-2009
A Solvothermal Synthetic Environmental Design for High-Performance SnSe-Based Thermoelectric Materials
Publisher: Wiley
Date: 11-04-2022
Abstract: SnSe is challenging to use in thermoelectric devices due to difficulties in simultaneously optimizing its thermoelectric and mechanical properties. Here, the authors show a unique solvothermal synthetic environmental design to fabricate super‐large and micro/nanoporous Sn 0.965 Se microplates by using CrCl 3 . Cl − ions to trigger Sn‐vacancy formation and optimize the hole concentration to ≈3 × 10 19 cm −3 , while the as‐formed Cr(OH) 3 colloidal precipitations act as “templates” to achieve micro/nanoporous features, leading to low lattice thermal conductivity of ≈0.2 W m −1 K −1 in the as‐sintered polycrystal, contributing to a high ZT of ≈2.4 at 823 K and an average ZT of ≈1.1. Of particular note, the polycrystal exhibits high hardness (≈2.26 GPa) and compression strength (≈109 MPa), strengthened by grain refinement and vacancy‐induced lattice distortions and dislocations while a single‐leg device provides a stable output power ( mW) and conversion efficiency of ≈10% by a temperature difference of 425 K, indicating great potential for applying to practical thermoelectric devices.
Electron‐Tomography Determination of the Packing Structure of Macroporous Ordered Siliceous Foams Assembled From Vesicles
Publisher: Wiley
Date: 29-01-2009
Abstract: The packing structures of macroporous ordered siliceous foams (MOSFs) are systematically investigated by using a 3D electron tomography technique and the nanostructural characteristics for layered MOSFs are resolved. MOSF materials adopt an ordered 2D hexagonal arrangement in single-layered areas, regular honeycomb patterns in double-layered s les, and polyhedric cells similar to a Weaire-Phelan structure in multilayered areas, all following the principle of minimizing surface area, which is well understood in soap foams at the macroscopic scale. In surfactant-templated materials, liquid-crystal templating is generally applied, but here it is revealed that the surface-area-minimization principle can also be applied, which facilitates the design and synthesis of novel macroporous materials using surfactant molecules as templates.
Comments on “Characterization of the Fe-Al Interfacial Layer in a Commercial Hot-dip Galvanized Coating”
Publisher: Iron and Steel Institute of Japan
Date: 1998
Anelastic Behavior in GaAs Semiconductor Nanowires
Publisher: American Chemical Society (ACS)
Date: 13-06-2013
DOI: 10.1021/NL401175T
Abstract: The mechanical behavior of vertically aligned single-crystal GaAs nanowires grown on GaAs(111)B surface was investigated using in situ deformation transmission electron microscopy. Anelasticity was observed in nanowires with small diameters and the anelastic behavior was affected by the crystalline defects in the nanowires. The underlying mechanism for the observed anelasticity is discussed. The finding opens up the prospect of using nanowire materials for nanoscale d ing applications.
Polycrystalline SnSe with Extraordinary Thermoelectric Property via Nanoporous Design
Publisher: American Chemical Society (ACS)
Date: 15-10-2018
Abstract: Nanoporous materials possess low thermal conductivities derived from effective phonon scatterings at grain boundaries and interfaces. Thus nanoporous thermoelectric materials have full potential to improve their thermoelectric performance. Here we report a high ZT of 1.7 ± 0.2 at 823 K in p-type nanoporous polycrystalline SnSe fabricated via a facile solvothermal route. We successfully induce indium selenides (InSe
Growth of single-crystalline tungsten nanowires by an alloy-catalyzed method at 850 °C
Publisher: Springer Science and Business Media LLC
Date: 2008
Abstract: In this study, we report the growth of metallic tungsten nanowires induced by alloy catalysts (Fe–Ni) at a temperature of 850 °C. The synthesized tungsten nanowires have bottom diameters of 100 to 400 nm and tip diameters of nm, and show a well-defined single-crystalline structure. The formation of the (Fe,Ni)-catalyzed W nanowires should be controlled by the vapor–solid–solid mechanism, rather than the traditional vapor–liquid–solid mechanism, because the growth temperature is significantly below the lowest eutectic temperature (1455 °C) of the Fe–Ni–W ternary system. Our study demonstrates the feasibility of synthesizing metallic nanowires via metal-catalyzed methods, which may be extended to the synthesis of some other metallic nanowires.
The preparation, structures, and properties of poly(vinylidene fluoride)/multiwall carbon nanotubes nanocomposites
Publisher: Wiley
Date: 02-02-2012
DOI: 10.1002/APP.36671
alpha-MoO3 Nanobelts: A High Performance Cathode Material for Lithium Ion Batteries
Publisher: American Chemical Society (ACS)
Date: 15-11-2010
DOI: 10.1021/JP108778V
Influence of Nanowire Density on the Shape and Optical Properties of Ternary InGaAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 21-02-2006
DOI: 10.1021/NL052189O
Abstract: We have synthesized ternary InGaAs nanowires on (111)B GaAs surfaces by metal-organic chemical vapor deposition. Au colloidal nanoparticles were employed to catalyze nanowire growth. We observed the strong influence of nanowire density on nanowire height, tapering, and base shape specific to the nanowires with high In composition. This dependency was attributed to the large difference of diffusion length on (111)B surfaces between In and Ga reaction species, with In being the more mobile species. Energy dispersive X-ray spectroscopy analysis together with high-resolution electron microscopy study of in idual InGaAs nanowires shows large In/Ga compositional variation along the nanowire supporting the present diffusion model. Photoluminescence spectra exhibit a red shift with decreasing nanowire density due to the higher degree of In incorporation in more sparsely distributed InGaAs nanowires.
Ion-beam-induced reconstruction of amorphous GaN
Publisher: American Physical Society (APS)
Date: 28-02-2001
Electron Tomography: A Unique Tool Solving Intricate Hollow Nanostructures
Publisher: Wiley
Date: 30-08-2018
Abstract: Innovations in nanofabrication have expedited advances in hollow-structured nanomaterials with increasing complexity, which, at the same time, set challenges for the precise determination of their intriguing and complicated 3D configurations. Conventional transmission electron microscopy (TEM) analysis typically yields 2D projections of 3D objects, which in some cases is insufficient to reflect the genuine architectures of these 3D nano-objects, providing misleading information. Advanced analytical approaches such as focused ion beam (FIB) and ultramicrotomy enable the real slicing of nanomaterials, realizing the direct observation of inner structures but with limited spatial discrimination. Electron tomography (ET) is a technique that retrieves spatial information from a series of 2D electron projections at different tilt angles. As a unique and powerful tool kit, this technique has experienced great advances in its application in materials science, resolving the intricate 3D nanostructures. Here, the exceptional capability of the ET technique in the structural, chemical, and quantitative analysis of hollow-structured nanomaterials is discussed in detail. The distinct information derived from ET analysis is highlighted and compared with conventional analysis methods. Along with the advances in microscopy technologies, the state-of-the-art ET technique offers great opportunities and promise in the development of hollow nanomaterials.
Enhancing thermoelectric performance of Bi2Te3-based nanostructures through rational structure design
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6NR00719H
Abstract: Nanostructuring has been successfully employed to enhance the thermoelectric performance of Bi2Te3 due to its obtained low thermal conductivity. In order to further reduce the thermal conductivity, we designed a hierarchical nanostructure assembled with well-aligned Bi2Te3 nanoplates using Te nanotubes as templates by a facile microwave-assisted solvothermal synthesis. From the comparisons of their thermoelectric performance and theoretical calculations with simple Bi2Te3 nanostructures, we found that Te/Bi2Te3 hierarchical nanostructures exhibit a higher figure-of-merit due to the optimized reduced Fermi level and enhanced phonon scattering, as well as the suppressed bipolar conduction. This study provides an effective approach to enhance the thermoelectric performance of Bi2Te3-based nanostructures by rationally designing the nanostructures.
Capacity-controllable Li-rich cathode materials for lithium-ion batteries
Publisher: Elsevier BV
Date: 05-2014
Lattice bending in monocrystalline GaAs induced by nanoscratching
Publisher: Elsevier BV
Date: 08-2012
Fabrication of crystal α-Si3N4/Si–SiOxcore–shell/Au–SiOxpeapod-like axial double heterostructures for optoelectronic applications
Publisher: IOP Publishing
Date: 11-07-2012
DOI: 10.1088/0957-4484/23/30/305603
Abstract: Novel crystal α-Si(3)N(4)/Si-SiO(x) core-shell/Au-SiO(x) peapod-like axial double heterostructural nanowires were obtained by directly annealing a Au covered SiO(2) thin film on a Si substrate. Our extensive electron microscopic investigation revealed that the α-Si(3)N(4) sections with a mathematical left angle bracket 101 mathematical right angle bracket growth direction were grown first, followed by growth of the Si-SiO(x) core-shell sections and finally growth of the Au-SiO(x) peapod-like sections. Through a series of systematically comparative experiments, a temperature-dependent multi-step vapor-liquid-solid growth mechanism is proposed. Room temperature photoluminescence measurement of in idual nanowires reveals two emission peaks (410 and 515 nm), indicating their potential applications in light sources, laser or light emitting display devices.
Conducting polymer-based flexible thermoelectric materials and devices: From mechanisms to applications
Publisher: Elsevier BV
Date: 08-2021
Lattice distortion oriented angular self-assembly of monolayer titania sheets
Publisher: American Chemical Society (ACS)
Date: 23-12-2011
DOI: 10.1021/JA109314U
Abstract: Self-assembly of exfoliated monolayer titania sheets is investigated by detailed transmission electron microscopy and the force field calculations. It is demonstrated for the first time that slight but significant lattice distortions result in modified angular self-assembly of exfoliated monolayer Ti(0.87)O(2) sheets. These findings significantly broaden current knowledge of the self-assembly of exfoliated nanoscale layered sheets, which may render the potential manipulation of self-assembly of nanosheets.
Nanoparticles Mimicking Viral Surface Topography for Enhanced Cellular Delivery
Publisher: Wiley
Date: 15-08-2013
Abstract: Novel silica nanoparticles mimicking virus surface topography are prepared. It is demonstrated that increases in nanoscale surface roughness promote both binding of biomolecules and cellular uptake thus, the cellular delivery efficiency is significantly increased (scale bars 20 μm).
Super Large Sn1–xSe Single Crystals with Excellent Thermoelectric Performance
Publisher: American Chemical Society (ACS)
Date: 05-02-2019
Abstract: SnSe single crystals have drawn extensive attention for their ultralow thermal conductivity and outstanding thermoelectric performance. Here, we report super large Sn
Thin-walled B–C–N ternary microtubes: from synthesis to electrical, cathodoluminescence and field-emission properties
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM16844H
Dislocation-induced spatial ordering of InAs quantum dots: Effects on optical properties
Publisher: AIP Publishing
Date: 17-04-2002
DOI: 10.1063/1.1467963
Abstract: Misfit dislocations were used to modify the surface morphology and to attain spatial ordering of quantum dots (QDs) by molecular beam epitaxy. Effects of anneal time and temperature on strain-relaxed InxGa1−xAs/GaAs layers and subsequent spatial ordering of InAs QDs were investigated. Photoluminescence (PL) and time-resolved PL was used to study the effects of increased QD positional ordering, increased QD uniformity, and their proximity to dislocation arrays on their optical properties. Narrower inhomogeneous PL broadening from the QDs ordered on dislocation arrays were observed, and differences in PL dynamics were found.
Understanding the Effect of Catalyst Size on the Epitaxial Growth of Hierarchical Structured InGaP Nanowires
Publisher: American Chemical Society (ACS)
Date: 29-10-2019
DOI: 10.1021/ACS.NANOLETT.9B03835
Abstract: Understanding the effect of a catalyst on the growth of nanowires is crucial for their controllable synthesis. In this study, we report the growth of InGaP nanowires induced by different-sized Au catalysts by metal-organic chemical vapor deposition. Through electron microscopy characterization, two types of InGaP nanowires are identified, and the difference in catalyst size is shown to cause their different morphological, structural, and compositional characteristics. Furthermore, the influencing mechanism of catalyst size on the formation of hierarchical structures in nanowires is discussed. This study provides an insight for a better understanding of the growth of ternary nanowires, especially the effect of catalyst size, which can be a promising approach to control the ternary nanowire growth, and is therefore beneficial for the design of the corresponding nanowire-based device.
Palladium Catalyzed Defect-free <110> Zinc-Blende Structured InAs Nanowires
Publisher: Springer Science and Business Media LLC
Date: 2013
DOI: 10.1557/OPL.2013.990
Abstract: In this study, Pd thin film is used as catalyst to grow epitaxial InAs nanowires on GaAs(111) B substrate in a metal-organic chemical vapor deposition reactor to explore the growth mechanism and the effects of non-gold catalysts in the growth of III-V epitaxial nanowires. Through detailed morphological, structural and chemical characterization using scanning and transmission electron microscopy, it is found that defect-free zinc-blende structured epitaxial InAs nanowires are grown along the directions with four {111} sidewall facets forming a diamond shaped cross-section. Furthermore, the interface between the nanowire/catalyst is found to be the uncommon {113} planes. It is anticipated that these zinc-blende structured InAs nanowires are grown via the vapor-liquid-solid mechanism. The defect-free nature of these nanowires arises from the non- growth direction and non-{111} nanowire/catalyst interface.
Thickness dependence of magnetic and transport properties in organic-CoFe discontinuous multilayers
Publisher: AIP Publishing
Date: 05-2010
DOI: 10.1063/1.3359438
Abstract: Spin-dependent transport measurement in 3-hexadecyl pyrrole (3HDP) with a CoFe layer and the current-in-plane geometry is reported. Transport properties indicate the CoFe layers are discontinuous when their thicknesses are smaller than 6 nm. The temperature dependence of the conductance suggests that the transport mechanism is likely small polaron hopping. The observed positive magnetoresistance ratio at low temperature gives evidence of spin-conserving transport.
Ultrasensitive Mid-wavelength Infrared Photodetection Based on a Single InAs Nanowire
Publisher: American Chemical Society (ACS)
Date: 28-02-2019
Abstract: One-dimensional InAs nanowire (NW)-based photodetectors have been widely studied due to their potential application in mid-wavelength infrared (MWIR) photon detection. However, the limited performance and complicated photoresponse mechanism of InAs NW-based photodetectors have held back their true potential for real application. In this study, we developed ferroelectric polymer P(VDF-TrFE)-coated InAs NW-based photodetectors and demonstrated that the electrostatic field caused by polarized ferroelectric materials modifies the surface electron-hole distribution as well as the band structure of InAs NWs, resulting in ultrasensitive photoresponse and a wide photodetection spectral range. Our single InAs NW photodetectors exhibit a high responsivity ( R) of 1.6 × 10
Fiber-based thermoelectrics for solid, portable, and wearable electronics
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0EE03520C
Abstract: This review comprehensively summarizes the recent progress of fiber-based thermoelectric materials and devices for solid, portable, and wearable electronics.
Au-catalysed free-standing wurtzite structured InAs nanosheets grown by molecular beam epitaxy
Publisher: Springer Science and Business Media LLC
Date: 27-08-2019
High-performance SnSe thermoelectric materials: Progress and future challenge
Publisher: Elsevier BV
Date: 08-2018
Growth, Cathodoluminescence and Field Emission of ZnS Tetrapod Tree-like Heterostructures
Publisher: Wiley
Date: 06-10-2008
Trifold Tellurium One-Dimensional Nanostructures and Their Formation Mechanism
Publisher: American Chemical Society (ACS)
Date: 03-10-2013
DOI: 10.1021/CG4009569
Room temperature Si δ-growth on Ge incorporating high-K dielectric for metal oxide semiconductor applications
Publisher: AIP Publishing
Date: 14-07-2008
DOI: 10.1063/1.2957476
Abstract: A low temperature Al2O3∕4 monolayer amorphous Si gate stack process was demonstrated on p-type Ge wafers using atomic layer deposition and molecular beam epitaxy. Multifrequency capacitance-voltage (C-V) and current-voltage (I-V) characteristics showed excellent electrical properties of the Pt∕Al2O3∕4 ML Si∕Ge metal oxide semiconductor capacitor. No kinks from 1MHzto4kHz and a leakage current density of 2.6×10−6A∕cm2 at 1V with an equivalent oxide thickness of 2.5nm. The interface characterization using a conductance method showed that interface trap density at the near midgap was 8×1012eV−1cm−2 and a mean capture cross section of holes was extracted to be 10−16cm2.
Correlation between Multiple Growth Stages and Photocatalysis of SrTiO3 Nanocrystals
Publisher: American Chemical Society (ACS)
Date: 06-02-2015
DOI: 10.1021/JP512448P
Vapor-phase synthesis, growth mechanism and thickness-independent elastic modulus of single-crystal tungsten nanobelts
Publisher: IOP Publishing
Date: 22-11-2013
DOI: 10.1088/0957-4484/24/50/505705
Abstract: Single-crystal tungsten nanobelts with thicknesses from tens to hundreds of nanometers, widths of several micrometers and lengths of tens of micrometers were synthesized using chemical vapor deposition. Surface energy minimization was believed to have played a crucial role in the growth of the synthesized nanobelts enclosed by the low-energy {110} crystal planes of body-centered-cubic structure. The anisotropic growth of the crystallographically equivalent {110} crystal planes could be attributable to the asymmetric concentration distribution of the tungsten atom vapor around the nanobelts during the growth process. The elastic moduli of the synthesized tungsten nanobelts with thicknesses ranging from 65 to 306 nm were accurately measured using a newly developed thermal vibration method. The measured modulus values of the tungsten nanobelts were thickness-dependent. After eliminating the effect of surface oxidization using a core-shell model, the elastic modulus of tungsten nanobelts became constant, which is close to that of the bulk tungsten value of 410 GPa.
Landau level splitting in Cd3As2 under high magnetic fields
Publisher: Springer Science and Business Media LLC
Date: 13-07-2015
DOI: 10.1038/NCOMMS8779
Abstract: Three-dimensional topological Dirac semimetals (TDSs) are a new kind of Dirac materials that exhibit linear energy dispersion in the bulk and can be viewed as three-dimensional graphene. It has been proposed that TDSs can be driven to other exotic phases like Weyl semimetals, topological insulators and topological superconductors by breaking certain symmetries. Here we report the first transport experiment on Landau level splitting in TDS Cd 3 As 2 single crystals under high magnetic fields, suggesting the removal of spin degeneracy by breaking time reversal symmetry. The detected Berry phase develops an evident angular dependence and possesses a crossover from non-trivial to trivial state under high magnetic fields, a strong hint for a fierce competition between the orbit-coupled field strength and the field-generated mass term. Our results unveil the important role of symmetry breaking in TDSs and further demonstrate a feasible path to generate a Weyl semimetal phase by breaking time reversal symmetry.
Solving hierarchical helical mesostructures by electron tomography
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B917426E
Abstract: A direct method to determine the pitch and chirality of complicated hierarchical helical mesostructures is presented by using the state-of-the-art electron tomography technique.
Vapour-solid growth of MoxW1-xTe2 nanobelts by a facile chemical vapour deposition method
Publisher: Elsevier BV
Date: 03-2019
Novel Growth Phenomena Observed in Axial InAs/GaAs Nanowire Heterostructures
Publisher: Wiley
Date: 05-11-2007
Formation of planar defects over GeSi islands in Si capping layer grown at low temperature
Publisher: AIP Publishing
Date: 15-01-2009
DOI: 10.1063/1.3068192
Abstract: Coherently strained GeSi/Si(001) islands were overgrown with a Si capping layer of different thicknesses at temperature 300 °C. The structures of the islands and the Si capping layer were investigated by high resolution transmission electron microscopy. The shapes of the embedded islands were well preserved, whereas planar defects were observed exactly over the islands in the capping layers. The strain energy in regions over the islands accumulated with increasing thickness of the Si capping layer, resulting in the formation of the planar defects. By means of a two-step deposition in which 20-nm-thick Si capping layer was first deposited at a low temperature of 300 °C followed by 70-nm-thick Si capping layer deposition at a high temperature of 640 °C, the defect-free Si capping layer with flat surface can be obtained.
Structural Materials for NEMS/MEMS Devices
Publisher: IEEE
Date: 2006
Novel Boron Nitride Hollow Nanoribbons
Publisher: American Chemical Society (ACS)
Date: 02-10-2008
DOI: 10.1021/NN8004922
Abstract: Novel BN hollow nanoribbons (BNHNRs) were fabricated by a simple ZnS nanoribbon templating method. Such BNHNRs have a distinct structure and show unique optical properties, as demonstrated from Raman, Fourier transform infrared spectroscopy, UV-vis spectroscopy, and cathodoluminescence spectroscopy, when compared with other forms of BN nanostructures. With high crystallinity, the BNHNRs exhibit an extraordinary ultraviolet CL emission at 5.33 eV. Such a property is highly advantageous for optoelectronic applications, particularly in the ultraviolet region, such as blue lasing and light emitting diodes. This templating method has also been extended to synthesize other hollow nanostructures such as boron carbonitride. This study represents a new methodology for fabricating hollow nanostructures with defined crystallinity and unique optical properties.
Long wavelength emissions of Se4+-doped In2O3hierarchical nanostructures
Publisher: Royal Society of Chemistry (RSC)
Date: 08-07-2014
DOI: 10.1039/C4TC01025F
Realizing high thermoelectric properties of SnTe via synergistic band engineering and structure engineering
Publisher: Elsevier BV
Date: 11-2019
Wearable fiber-based thermoelectrics from materials to applications
Publisher: Elsevier BV
Date: 03-2021
High shear in situ exfoliation of 2D gallium oxide sheets from centrifugally derived thin films of liquid gallium
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1NA00598G
Abstract: Ultrathin gallium oxide sheets formed under continuous flow from gallium metal are highly insulating with electrocatalytic activity for hydrogen evolution.
Toward an indexing approach to evaluate fly ashes for geopolymer manufacture
Publisher: Elsevier BV
Date: 07-2016
Separation of top and bottom surface conduction in Bi2Te3thin films
Publisher: IOP Publishing
Date: 07-12-2012
DOI: 10.1088/0957-4484/24/1/015705
Abstract: Quantum spin Hall (QSH) systems are insulating in the bulk with gapless edges or surfaces that are topologically protected and immune to nonmagnetic impurities or geometric perturbations. Although the QSH effect has been realized in the HgTe/CdTe system, it has not been accomplished in normal 3D topological insulators. In this work, we demonstrate a separation of two surface conductions (top/bottom) in epitaxially grown Bi(2)Te(3) thin films through gate dependent Shubnikov-de Haas (SdH) oscillations. By sweeping the gate voltage, only the Fermi level of the top surface is tuned while that of the bottom surface remains unchanged due to strong electric field screening effects arising from the high dielectric constant of Bi(2)Te(3). In addition, the bulk conduction can be modulated from n- to p-type with a varying gate bias. Our results on the surface control hence pave a way for the realization of QSH effect in topological insulators which requires a selective control of spin transports on the top/bottom surfaces.
Epitaxial growth of Bi2Se3 topological insulator thin films on Si (111)
Publisher: AIP Publishing
Date: 15-05-2011
DOI: 10.1063/1.3585673
Abstract: In this paper, we report the epitaxial growth of Bi2Se3 thin films on Si (111) substrate, using molecular beam epitaxy (MBE). We show that the as-grown s les have good crystalline quality, and their surfaces exhibit terracelike quintuple layers. Angel-resolved photoemission experiments demonstrate single-Dirac-conelike surface states. These results combined with the temperature- and thickness-dependent magneto-transport measurements, suggest the presence of a shallow impurity band. Below a critical temperature of ∼100K, the surface states of a 7 nm thick film contribute up to 50% of the total conduction.
Two-Dimensional Nanostructures for Energy-Related Applications
Publisher: CRC Press
Date: 27-03-2017
Structural, electrical, and optical analysis of ion implanted semi-insulating InP
Publisher: AIP Publishing
Date: 29-12-2003
DOI: 10.1063/1.1633349
Abstract: Semi-insulating InP was implanted with MeV P, As, Ga, and In ions, and the resulting evolution of structural properties with increased annealing temperature was analyzed using double crystal x-ray diffractometry and cross sectional transmission electron microscopy. The types of damage identified are correlated with scanning spreading resistance and scanning capacitance measurements, as well as with previously measured Hall effect and time resolved photoluminescence results. We have identified multiple layers of conductivity in the s les which occur due to the nonuniform damage profile of a single implant. Our structural studies have shown that the amount and type of damage caused by implantation does not scale with implant ion atomic mass.
TiB reinforced lattice structures produced by laser powder bed fusion with high elastic admissible strain
Publisher: Elsevier BV
Date: 06-2022
High-quality Bi2Te3 thin films grown on mica substrates for potential optoelectronic applications
Publisher: AIP Publishing
Date: 15-07-2013
DOI: 10.1063/1.4813903
Abstract: We report high-quality topological insulator Bi2Te3 thin films grown on muscovite mica substrates by molecular beam epitaxy. The topographic and structural analysis revealed that the Bi2Te3 thin films exhibited atomically smooth terraces over a large area and a high crystalline quality. Both weak antilocalization effect and quantum oscillations were observed in the magnetotransport of the relatively thin s les. A phase coherence length of 277 nm for a 6 nm thin film and a high surface mobility of 0.58 m2 V−1 s−1 for a 4 nm thin film were achieved. These results confirm that the thin films grown on mica are of high quality.
Realizing zT of 2.3 in Ge 1− x − y Sb x In y Te via Reducing the Phase-Transition Temperature and Introducing Resonant Energy Doping
Publisher: Wiley
Date: 19-01-2018
Abstract: GeTe with rhombohedral-to-cubic phase transition is a promising lead-free thermoelectric candidate. Herein, theoretical studies reveal that cubic GeTe has superior thermoelectric behavior, which is linked to (1) the two valence bands to enhance the electronic transport coefficients and (2) stronger enharmonic phonon-phonon interactions to ensure a lower intrinsic thermal conductivity. Experimentally, based on Ge
Thermally oxidized formation of new Ge dots over as-grown Ge dots in the Si capping layer
Publisher: AIP Publishing
Date: 12-2011
DOI: 10.1063/1.3665398
Abstract: A Si-capped Ge quantum dot s le was self-assembly grown via Stranski-Krastanov mode in a molecular beam epitaxy system with the Si capping layer deposited at 300 °C. After annealing the s le in an oxygen atmosphere at 1000 °C, a structure, namely two layers of quantum dots, was formed with the newly formed Ge-rich quantum dots embedded in the oxidized matrix with the position accurately located upon the as-grown quantum dots. It has been found that the formation of such nanostructures strongly depends upon the growth temperature and oxygen atmosphere. A growth mechanism was proposed to explain the formation of the nanostructure based on the Ge diffusion from the as-grown quantum dots, Ge segregation from the growing oxide, and subsequent migration/agglomeration.
Formation mechanism of nanocrystalline high-pressure phases in silicon during nanogrinding
Publisher: IOP Publishing
Date: 12-10-2007
DOI: 10.1088/0957-4484/18/46/465705
Abstract: The phase transformations of Si under nanogrinding have been studied by transmission electron microscopy and Raman spectroscopy. Nanocrystalline high-pressure phases (Si-III/Si-XII) were found in the amorphous layer of the subsurface of heavily ground Si. The sequence of the phase transformation in nanogrinding has been found to be different to that in nanoindentation. The formation mechanism of the nanocrystalline high-pressure phases in nanogrinding is proposed based on experimental results.
Criterion to control self-propagation high temperature synthesis for porous Ti–Al intermetallics
Publisher: Informa UK Limited
Date: 07-2011
Site-specific growth of MOF-on-MOF heterostructures with controllable nano-architectures: beyond the combination of MOF analogues
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC00417K
Abstract: A site-specific epitaxial-growth strategy is developed to synthesize two types of MOF-on-MOF heterostructures with elaborately designed architectures, which are comprised of two MOFs with totally different compositions.
Direct Measure of Strain and Electronic Structure in GaAs/GaP Core−Shell Nanowires
Publisher: American Chemical Society (ACS)
Date: 04-02-2010
DOI: 10.1021/NL903547R
Abstract: Highly strained GaAs/GaP nanowires of excellent optical quality were grown with 50 nm diameter GaAs cores and 25 nm GaP shells. Photoluminescence from these nanowires is observed at energies dramatically shifted from the unstrained GaAs free exciton emission energy by 260 meV. Using Raman scattering, we show that it is possible to separately measure the degree of compressive and shear strain of the GaAs core and show that the Raman response of the GaP shell is consistent with tensile strain. The Raman and photoluminescence measurement are both on good agreement with 8 band k.p calculations. This result opens up new possibilities for engineering the electronic properties of the nanowires for optimal design of one-dimensional nanodevices by controlling the strain of the core and shell by varying the nanowire geometry.
Direct structural evidences of Mn11Ge8 and Mn5Ge2 clusters in Ge0.96Mn0.04 thin films
Publisher: AIP Publishing
Date: 10-03-2008
DOI: 10.1063/1.2884527
Abstract: Mn-rich clusters in Mn-doped Ge thin films epitaxially grown on Ge (001) have been investigated by various transmission electron microscopy techniques. Both the mysterious Mn11Ge8 and the hexagonal Mn5Ge2 (a=0.72nm and c=1.3nm) clusters were confirmed to coexist in the thicker Ge0.96Mn0.04 film (80nm). Their possible formation mechanism is attributed to the existence of ordered stacking faults. The fact that no Mn-rich clusters found in thinner films (& =40nm) suggests that, for a given Mn concentration and growth/annealing condition, a critical thickness exists for the formation of Mn-rich clusters.
Growth and properties of III–V compound semiconductor heterostructure nanowires
Publisher: IOP Publishing
Date: 15-12-2010
Mn distribution behaviors and magnetic properties of GeMn films grown on Si (001) substrates
Publisher: Elsevier BV
Date: 03-2009
Tailoring the magnetic exchange interaction in MnBi2Te4 superlattices via the intercalation of ferromagnetic layers
Publisher: Springer Science and Business Media LLC
Date: 05-07-1970
Laser irradiated vortex fluidic mediated synthesis of luminescent carbon nanodots under continuous flow
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7RE00197E
Abstract: High shear vortex fluidics coupled with NIR affords luminescent carbon dots as a scalable process.
Polarity-driven Nonuniform Composition in InGaAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 21-10-2013
DOI: 10.1021/NL402244P
Abstract: Manipulating the composition and morphology of semiconductor nanowires in a precisely controlled fashion is critical in developing nanowire devices. This is particularly true for ternary III-V nanowires. Many studies have shown the complexities within those nanowires. Here we report our findings of compositional irregularity in the shells of core-shell InGaAs nanowires with zinc-blende structure. Such an effect is caused by the crystal polarity within III-V zinc-blende lattice and the one-dimensional nature of nanowires that allows the formation of opposite polar surfaces simultaneously on the nanowire sidewalls. This polarity-driven effect in III-V nanowires may be utilized in manipulating the composition and morphology of III-V nanowires for device applications.
Optical transition in infrared photodetector based on V-groove Al0.5Ga0.5As/GaAs multiple quantum wire
Publisher: AIP Publishing
Date: 15-02-2001
DOI: 10.1063/1.1339857
Abstract: Photoconductors based on V-grooved Al0.5Ga0.5As/GaAs multiple quantum wires (QWR) were fabricated. The geometric structure of the QWR was carefully characterized by transmission electron microscopy and spatially resolved microphotoluminescence measurements. Infrared response at 9.2 μm is observed from the photocurrent spectrum measured at 80 K. It is attributed as the intersubband transition in the quantum wire region. Due to the effective quantum confinement from the two (111)-surfaces forming the V groove, the overlapping between the ground state in the QWR and the one in the vertical quantum well is very small. This explains the weak photocurrent signal from the QWR photodetector. Theoretical design for a better wave function overlapping and optical coupling is outlined from the analysis of two-dimensional spatial distributions of the wave functions.
Manipulating surface states in topological insulator nanoribbons
Publisher: Springer Science and Business Media LLC
Date: 13-02-2011
Abstract: Topological insulators display unique properties, such as the quantum spin Hall effect, because time-reversal symmetry allows charges and spins to propagate along the edge or surface of the topological insulator without scattering. However, the direct manipulation of these edge/surface states is difficult because they are significantly outnumbered by bulk carriers. Here, we report experimental evidence for the modulation of these surface states by using a gate voltage to control quantum oscillations in Bi(2)Te(3) nanoribbons. Surface conduction can be significantly enhanced by the gate voltage, with the mobility and Fermi velocity reaching values as high as ~5,800 cm(2) V(-1) s(-1) and ~3.7 × 10(5) m s(-1), respectively, with up to ~51% of the total conductance being due to the surface states. We also report the first observation of h/2e periodic oscillations, suggesting the presence of time-reversed paths with the same relative zero phase at the interference point. The high surface conduction and ability to manipulate the surface states demonstrated here could lead to new applications in nanoelectronics and spintronics.
Nanoscale pores plus precipitates rendering high-performance thermoelectric SnTe1-xSex with refined band structures
Publisher: Elsevier BV
Date: 06-2019
A game-changing design of low-cost, large-size porous cocatalysts decorated by ultra-small photocatalysts for highly efficient hydrogen evolution
Publisher: Elsevier BV
Date: 06-2021
Mn behaviors in Mn-implanted ZnO
Publisher: Elsevier BV
Date: 04-2009
Ge/Si interdiffusion in the GeSi dots and wetting layers
Publisher: AIP Publishing
Date: 15-10-2001
DOI: 10.1063/1.1403667
Abstract: The Ge/Si interdiffusion in GeSi dots grown on Si (001) substrate by gas-source molecular beam epitaxy is investigated. Transmission electron microscopy images show that, after annealing, the aspect ratio of the height to base diameter increases. Raman spectra show that the Si–Ge mode redshifts and the intensity of the local Si–Si mode increases with the increase of annealing temperature, which suggests the Ge/Si interdiffusion during annealing. The photoluminescence peaks from the dots and the wetting layers show blueshift due to the atomic intermixing during annealing. The interdiffusion thermal activation energies of GeSi dots and the wetting layers are 2.16 and 2.28 eV, respectively. The interdiffusion coefficient of the dots is about 40 times higher than that of wetting layers and the reasons were discussed.
Hydrogenation/dehydrogenation in MgH2-activated carbon composites prepared by ball milling
Publisher: Elsevier BV
Date: 05-2012
Ultrahigh Aspect Ratio TiB Nanowhisker-Reinforced Titanium Matrix Composites as Lightweight and Low-Cost Replacements for Superalloys
Publisher: American Chemical Society (ACS)
Date: 10-08-2020
[001] zone-axis bright-field diffraction contrast from coherent Ge(Si) islands on Si(001)
Publisher: Elsevier BV
Date: 2004
Temperature influence on sintering with concurrent crystallization behavior in Ti-based metallic glassy powders
Publisher: Elsevier BV
Date: 04-2010
New Insight into Ordered Cage-Type Mesostructures and Their Pore Size Determination by Electron Tomography
Publisher: American Chemical Society (ACS)
Date: 18-02-2015
DOI: 10.1021/LA504474Z
Abstract: In this work, a new approach based on electron tomography (ET) has been developed to measure the pore size, through which new insight into cage-type ordered mesostructures and their pore size determination has been obtained. It is demonstrated that the accurate pore diameter, especially for cage-type cubic mesoporous materials, can be determined only through our ET approach by considering that the pore geometry is a real 3D space. We use the established ET method to revisit the applicability of different models for the pore size calculation in nitrogen adsorption analysis. Different from the overwhelming understanding that the nonlocal density functional theory (NLDFT) and Derjaguin-Broekhoff-de Boer (BdB) model are recommended to calculate the pore size of cage-type cubic mesoporous materials while the Barret-Joyner-Halenda (BJH) model should not be used, a new understanding is gained through this study. The choice of a suitable model for pore size determination depends on the precise pore structure. For a cage-type cubic mesoporous material with fcc symmetry and a large entrance connecting the cages, the BJH model is more accurate while the other two methods overestimate the pore size (by up to 40%). The DFT model is more appropriate when the pore shape is a perfect sphere than the BJH model, which underestimates the pore size, and the BdB model, which overestimates the pore size. It is our opinion that the unique ET approach should be used to revisit a vast number of large-pore cubic mesoporous materials to provide genuine structural information.
Controlled synthesis and optical properties of Cu/C core/shell nanoparticles
Publisher: Springer Science and Business Media LLC
Date: 15-07-2014
Fabrication of uniform anatase TiO2 particles exposed by {001} facets
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CC01473G
Abstract: Uniform anatase TiO(2) particles exposed by {001} facets were successfully synthesized by using EDTA together with F as morphology controlling agents. The crystallographic structure as well as the growth mechanism of anatase TiO(2) particles was investigated systematically by XRD, SEM, TEM and XPS, respectively.
Effects of interdiffusion on the band alignment of GeSi dots
Publisher: AIP Publishing
Date: 24-09-2001
DOI: 10.1063/1.1405152
Abstract: The interdiffusion effects on the band alignment of the GeSi dots embedded in Si matrix were studied by temperature- and excitation-power-dependent photoluminescence measurements. A different power-dependent behavior of the photoluminescence for the as-grown and the annealed s les was observed. It was suggested that the band alignments of the dots changed from type II to type I after annealing due to the Ge/Si interdiffusion. The decrease of the valence band offset, which was also induced by the Ge/Si interdiffusion, was observed from the temperature-dependent photoluminescence measurements.
Metallic and Carbon Nanotube-Catalyzed Coupling of Hydrogenation in Magnesium
Publisher: American Chemical Society (ACS)
Date: 23-11-2007
DOI: 10.1021/JA0751431
Abstract: Synergistic effect of metallic couple and carbon nanotubes on Mg results in an ultrafast kinetics of hydrogenation that overcome a critical barrier of practical use of Mg as hydrogen storage materials. The ultrafast kinetics is attributed to the metal-H atomic interaction at the Mg surface and in the bulk (energy for bonding and releasing) and atomic hydrogen diffusion along the grain boundaries (aggregation of carbon nanotubes) and inside the grains. Hence, a hydrogenation mechanism is presented.
Au impact on GaAs epitaxial growth on GaAs (111)B substrates in molecular beam epitaxy
Publisher: AIP Publishing
Date: 11-02-2013
DOI: 10.1063/1.4792053
Abstract: GaAs growth behaviour under the presence of Au nanoparticles on GaAs {111}B substrate is investigated using electron microscopy. It has been found that, during annealing, enhanced Ga surface diffusion towards Au nanoparticles leads to the GaAs epitaxial growth into {113}B faceted triangular pyramids under Au nanoparticles, governed by the thermodynamic growth, while during conventional GaAs growth, growth kinetics dominates, resulting in the flatted triangular pyramids at high temperature and the epitaxial nanowires growth at relatively low temperature. This study provides an insight of Au nanoparticle impact on GaAs growth, which is critical for understanding the formation mechanisms of semiconductor nanowires.
Novel C/Cu sheath/core nanostructures synthesized via low-temperature MOCVD
Publisher: IOP Publishing
Date: 13-09-2011
DOI: 10.1088/0957-4484/22/40/405704
Abstract: C/Cu sheath/core nanocable arrays were mass-produced on various substructures, such as Si, SiO(2), Cu or glass, by using a one-step low-temperature metal-organic chemical vapor deposition. The novel nanostructures consist of a faceted Cu nanowire core with six side surfaces and four top surfaces, and a sheath of carbon. The as-synthesized nanocables are demonstrated excellent oxidization resistance and field emission properties, and are expected to be excellent candidates as nano-interconnectors, or nanocables, in electronic devices and nano-emitters for field emissions.
Antiphotocorrosive photocatalysts containing CdS nanoparticles and exfoliated TiO2 nanosheets
Publisher: Springer Science and Business Media LLC
Date: 2010
Abstract: Aimed at designing an efficient visible light active photocatalyst and suppressing the self-corrosion tendency of CdS nanoparticles, a novel composite consisting of CdS nanoparticles and exfoliated two-dimensional (2D) TiO 2 nanosheets was successfully fabricated using a simple self-assembly process. The prepared s les were characterized using various techniques including x-ray diffraction, ultraviolet–visible absorption spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. It was found that the exfoliated 2D nanosheets played an important role as an ultrathin coating to suppress the photocorrosion of CdS nanoparticles, evidenced by inductively coupled plasma-atomic emission spectrometer analysis. The resultant CdS/TiO 2 composites exhibited enhanced photocatalytic activity in the oxidation of Rhodamine B in water under visible light irradiation ( λ 420 nm).
Optical properties of arsenic ions implanted GaAs/AlGaAs V-grooved quantum wires
Publisher: AIP Publishing
Date: 09-2000
DOI: 10.1063/1.1287119
Abstract: Asymmetric double GaAs/AlGaAs V-grooved quantum wires, grown by low pressure metalorganic chemical vapor deposition, are studied using photoluminescence (PL) spectroscopy. The structure was selectively treated by ion implantation at different arsenic (As) doses after growth. The ion implantation strongly reduces the efficiency of the emissions from the implanted well regions or even quenches the PL emissions from certain well regions due to irradiation damage. Wire emission is clearly resolved in the s les after treatment by low dose implantation. The temperature dependence of the wire emission intensity shows an enhancement at a temperature of around 45 K. The wire emission peak with a shoulder at its high energy side at low temperatures develops into double peaks in a temperature region between 20 and 140 K, and the high energy transition component dominates the PL spectra at temperatures above 140 K. The deduced energy separation between two peaks is about 10 meV. With further increasing temperatures the wire emission related to the light hole state can be observed at temperatures above 150 K. Deduced splitting between the heavy and light states is about 35 meV in our structures.
Enhanced optical properties of the GaAsN/GaAs quantum-well structure by the insertion of InAs monolayers
Publisher: AIP Publishing
Date: 04-2004
DOI: 10.1063/1.1697628
Abstract: Microstructural and optical properties of InAs-inserted and reference single GaAsN/GaAs quantum-well (QW) structures grown by metalorganic chemical vapor deposition were investigated using cross-sectional transmission electron microscopy and photoluminescence (PL). Significant enhancement of PL intensity and a blueshift of PL emission were observed from the InAs-inserted GaAsN/GaAs QW structure, compared with the single GaAsN/GaAs QW structure. Strain compensation and In-induced reduction of N incorporation are suggested to be two major factors affecting the optical properties.
Two-probe electrical measurements in transmission electron microscopes-Behavioral control of tungsten microwires
Publisher: Wiley
Date: 02-2009
DOI: 10.1002/JEMT.20648
Abstract: Tungsten microwires have been manipulated and electrically probed inside a transmission electron microscope. Using Au electrodes, the current-voltage characteristics of the W structures were extracted. These showed highly variable behaviors dependent on various factors, the most important of these being orientation and stiffness of the contact. Careful control of loading force and Au-W contact angle enabled a considerable degree of behavior tailoring from nonlinear to Ohmic responses.
Annealing of ion implanted gallium nitride
Publisher: AIP Publishing
Date: 09-03-1998
DOI: 10.1063/1.121030
Abstract: In this paper, we examine Si and Te ion implant damage removal in GaN as a function of implantation dose, and implantation and annealing temperature. Transmission electron microscopy shows that amorphous layers, which can result from high-dose implantation, recrystallize between 800 and 1100 °C to very defective polycrystalline material. Lower-dose implants (down to 5×1013 cm−2), which are not amorphous but defective after implantation, also anneal poorly up to 1100 °C, leaving a coarse network of extended defects. Despite such disorder, a high fraction of Te is found to be substitutional in GaN both following implantation and after annealing. Furthermore, although elevated-temperature implants result in less disorder after implantation, this damage is also impossible to anneal out completely by 1100 °C. The implications of this study are that considerably higher annealing temperatures will be needed to remove damage for optimum electrical properties.
Enhancing the thermoelectric performance of SnSe1-xTex nanoplates through band engineering
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7TA02677C
Abstract: Owing to the convergence of multivalence bands, the thermoelectric performance of polycrystalline SnSe was significantly enhanced.
Enhanced thermoelectric properties of nanostructured n-type Bi2Te3 by suppressing Te vacancy through non-equilibrium fast reaction
Publisher: Elsevier BV
Date: 07-2020
III–V semiconductor nanowires for optoelectronic device applications
Publisher: Elsevier BV
Date: 03-2011
Atomic-scale observation of parallel development of super elasticity and reversible plasticity in GaAs nanowires
Publisher: AIP Publishing
Date: 13-01-2014
DOI: 10.1063/1.4861846
Abstract: We report the atomic-scale observation of parallel development of super elasticity and reversible dislocation-based plasticity from an early stage of bending deformation until fracture in GaAs nanowires. While this phenomenon is in sharp contrast to the textbook knowledge, it is expected to occur widely in nanostructures. This work indicates that the super recoverable deformation in nanomaterials is not simple elastic or reversible plastic deformation in nature, but the coupling of both.
Zinc sulfide nanowire arrays on silicon wafers for field emitters
Publisher: IOP Publishing
Date: 08-01-2010
DOI: 10.1088/0957-4484/21/6/065701
Abstract: Wurtzite structured zinc sulfide (ZnS) nanowire arrays are synthesized on silicon (111) wafers by a facile evaporation-condensation approach. These ZnS nanowire arrays possess predominant field emission properties with a low turn-on field of 2.9 V microm(-1), a low threshold field of 4.25 V microm(-1), a high field-enhancement factor (over 2700), and a high stability with a low fluctuation (approximately 0.8%). The improved field emission performance of these ZnS nanowire arrays is attributed to their specific crystallographic feature-array structures with nanotips and high single crystallinity. These results suggest that such ZnS nanowire arrays can be used as building blocks for field emitters.
Influence of nitriding gases on the growth of boron nitride nanotubes
Publisher: Springer Science and Business Media LLC
Date: 06-2007
A synergy of strain loading and laser radiation in determining the high-performing electrical transports in the single Cu-doped SnSe microbelt
Publisher: Elsevier BV
Date: 06-2020
Te-Doped Cu2Se nanoplates with a high average thermoelectric figure of merit
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TA02998A
Abstract: Te-doped Cu 2 Se nanostructures with a high average ZT value for Cu 2 Se 0.98 Te 0.02 .
Effect of grain growth on densification and conductivity of ca-doped CeO2 electrolyte
Publisher: Wiley
Date: 26-10-2009
Au-catalyzed and catalyst-free growth of one-dimensional Bi<inf>2</inf>Se<inf>3</inf> nanostructures
Publisher: IEEE
Date: 12-2014
Two-dimensional flexible thermoelectric devices: Using modeling to deliver optimal capability
Publisher: AIP Publishing
Date: 15-10-2021
DOI: 10.1063/5.0067930
Abstract: Two-dimensional flexible thermoelectric devices (2D FTEDs) are a promising candidate for powering wearable electronics by harvesting low-grade energy from human body and other ubiquitous energy sources. However, immature device designs in the parametric geometries of FTEDs cannot provide an optimized output power density because of either insufficient temperature difference or unnecessarily large internal resistance. Here, we theoretically design optimal parametric geometries of 2D FTEDs by systematically considering applied temperature difference, temperature-dependent thermoelectric properties of materials, leg thickness, and thermodynamic conditions. The obtained analytical solution determines the optimal leg length for 2D FTEDs when these parameters are given and, therefore, minimizes the internal device resistance and simultaneously maintains the high temperature difference across the TE legs to maximize the device output power density. According to this design, we use flexible Ag2Se films as thermoelectric legs to assemble a 2D FTED, which displays a maximum power output of 11.2 mW and a normalized output power density of 1.43 μW cm−2 K−1 at a temperature difference of 150 K, outnumbering other 2D FTEDs by threefolds. Our 2D FTED can power up four light-emitting diodes, which shows great potential for harvesting electricity from low-grade heat. The exotic and reliable device design concept of 2D FTEDs reported here can be extended to other thermoelectric systems to boost the practical applications of FTEDs.
Effects of dopant concentration and calcination temperature on the microstructure of Ca-doped ceria nanopowders
Publisher: Elsevier BV
Date: 10-2008
Metal Nanodot Memory by Self-Assembled Block Copolymer Lift-Off
Publisher: American Chemical Society (ACS)
Date: 03-12-2009
DOI: 10.1021/NL903340A
Abstract: As information technology demands for larger capability in data storage continue, ultrahigh bit density memory devices have been extensively investigated. To produce an ultrahigh bit density memory device, multilevel cell operations that require several states in one cell have been proposed as one solution, which can also alleviate the scaling issues in the current state-of-the-art complementary metal oxide semiconductor technology. Here, we report the first demonstration of metal nanodot memory using a self-assembled block copolymer lift-off. This metal nanodot memory with simple low temperature processes produced an ultrawide memory window of 15 V at the +/-18 V voltage sweep. Such a large window can be adopted for multilevel cell operations. Scanning electron microscopy and transmission electron microscopy studies showed a periodic metal nanodot array with uniform distribution defined by the block copolymer pattern. Consequently, this metal nanodot memory has high potential to reduce the variability issues that metal nanocrystal memories previously had and multilevel cells with ultrawide memory windows can be fabricated with high reliability and manufacturability.
Transmission-electron microscopy study of the shape of buried quantum dots
Publisher: American Physical Society (APS)
Date: 15-08-1998
Self-Assembly Growth of In-Rich InGaAs Core–Shell Structured Nanowires with Remarkable Near-Infrared Photoresponsivity
Publisher: American Chemical Society (ACS)
Date: 10-11-2017
DOI: 10.1021/ACS.NANOLETT.7B04039
Abstract: Understanding the compositional distribution of ternary nanowires is essential to build the connection between nanowire structures and their potential applications. In this study, we grew epitaxial ternary InGaAs nanowires with high In concentration on GaAs {111}
Helical Growth of Aluminum Nitride: New Insights into Its Growth Habit from Nanostructures to Single Crystals
Publisher: Springer Science and Business Media LLC
Date: 15-05-2015
DOI: 10.1038/SREP10087
Abstract: By understanding the growth mechanism of nanomaterials, the morphological features of nanostructures can be rationally controlled, thereby achieving the desired physical properties for specific applications. Herein, the growth habits of aluminum nitride (AlN) nanostructures and single crystals synthesized by an ultrahigh-temperature, catalyst-free, physical vapor transport process were investigated by transmission electron microscopy. The detailed structural characterizations strongly suggested that the growth of AlN nanostructures including AlN nanowires and nanohelixes follow a sequential and periodic rotation in the growth direction, which is independent of the size and shape of the material. Based on these experimental observations, an helical growth mechanism that may originate from the coeffect of the polar-surface and dislocation-driven growth is proposed, which offers a new insight into the related growth kinetics of low-dimensional AlN structures and will enable the rational design and synthesis of novel AlN nanostructures. Further, with the increase of temperature, the growth process of AlN grains followed the helical growth model.
Nanomechanical Properties and Nanostructure of CMG and CMP Machined Si Substrates
Publisher: Trans Tech Publications, Ltd.
Date: 06-2008
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.381-382.525
Abstract: Silicon (100) substrates machined by chemo-mechanical-grinding (CMG) and chemicalmechanical- polishing (CMP) were investigated using atomic force microscopy, cross-sectional transmission electron microscopy and nanoindentation. It was found that the substrate surface after CMG was slightly better than machined by CMP in terms of roughness. The transmission electron microscopy analysis showed that the CMG-generated subsurface was defect-free, but the CMP specimen had a crystalline layer of about 4 nm in thickness on the top of the silicon lattice as evidenced by the extra diffraction spots. Nanoindentation results indicated that there exists a slight difference in mechanical properties between the CMG and CMP machined substrates.
Cooling rate effects on the microstructure and phase formation in Zr51Cu20.7Ni12Al16.3bulk metallic glass
Publisher: Informa UK Limited
Date: 2006
Growth and properties of III–V compound semiconductor heterostructure nanowires
Publisher: IOP Publishing
Date: 27-03-2012
TEM and XPS analysis of Cax Ce1-x O2-y (x = 0.05-0.5) as electrolyte materials for solid oxide fuel cells
Publisher: Elsevier BV
Date: 02-2009
Nanoscratch-induced deformation of single crystal silicon
Publisher: American Vacuum Society
Date: 05-2009
DOI: 10.1116/1.3049517
Abstract: The nanoscratching-induced deformation of monocrystalline Si has been investigated using transmission electron microscopy (TEM). The results indicate that amorphization and formation of crystalline defects are two dominant phenomena associated with the scratching processes. TEM analyses reveal that amorphization occurs at extremely small scratching loads. Stacking faults and twins are nucleated at a smaller load than that for dislocation. Dislocations start to nucleate along Si {111} planes when the normal scratching load is greater than a threshold value and penetrate deeper into the Si subsurface with the increasing load. Both normal load and tip radius have significant influence on the deformation, which are somehow different from those associated with nanoindentation and nanogrinding.
Atomic Insights into Phase Evolution in Ternary Transition‐Metal Dichalcogenides Nanostructures
Publisher: Wiley
Date: 05-2018
Abstract: Phase engineering through chemical modification can significantly alter the properties of transition-metal dichalcogenides, and allow the design of many novel electronic, photonic, and optoelectronics devices. The atomic-scale mechanism underlying such phase engineering is still intensively investigated but elusive. Here, advanced electron microscopy, combined with density functional theory calculations, is used to understand the phase evolution (hexagonal 2H→monoclinic T'→orthorhombic T
Synthesis, growth mechanism and thermal stability of copper nanoparticles encapsulated by multi-layer graphene
Publisher: Elsevier BV
Date: 05-2012
Structural characteristics of GeMn diluted magnetic semiconductor nanostructures
Publisher: IEEE
Date: 12-2012
Understanding the Formation and Evolution of Oxide Inclusions in Si-Deoxidized Spring Steel
Publisher: Springer Science and Business Media LLC
Date: 03-06-2019
Wavelength shifting of adjacent quantum wells in V-groove quantum wire structure by selective implantation and annealing
Publisher: AIP Publishing
Date: 02-2000
DOI: 10.1063/1.372051
Abstract: Intermixing induced by selective implantation was used to modify the two-dimensional (2D) quantum wells in the V-grooved quantum wire structure. Photoluminescence measurement of the implanted s les shows the obvious blueshift of the interband transition energy while quantum wire is not influenced by implantation. So the selective implantation method has been demonstrated in this article as a useful technique to isolate the energy levels of quantum wire structure from its neighbor 2D structures, which is preferred for the optoelectronic device application of quantum wire.
Continuous flow fabrication of green graphene oxide in aqueous hydrogen peroxide
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NA00310D
Abstract: Herein, we have established a sequential two step continuous flow process for generating graphene oxide with properties comparable to the conventional Hummers' GO. The process is high yielding and with a dramatic reduction in the generation of waste.
Effects of Au catalyst on GaAs (111)<inf>B</inf> surface during annealing
Publisher: IEEE
Date: 12-2012
Synthesis of High-Curie-Temperature Fe0.02Ge0.98 Quantum Dots
Publisher: American Chemical Society (ACS)
Date: 30-07-2010
DOI: 10.1021/JA105036J
Abstract: Self-assembled Fe(0.02)Ge(0.98) dilute magnetic quantum dots show a high Curie temperature above 400 K. Such extraordinary magnetic properties can potentially resolve the critical problem of power dissipation in today's integrated circuits and lead to the realization of a new class of spintronics devices.
Thermal stability of Mg 2 Si epitaxial film formed on Si (111) substrate by solid phase reaction
Publisher: IOP Publishing
Date: 07-2009
Nature of heterointerfaces in GaAs/InAs and InAs/GaAs axial nanowire heterostructures
Publisher: AIP Publishing
Date: 08-09-2008
DOI: 10.1063/1.2978959
Abstract: The structural and compositional characteristics of heterointerfaces of Au-catalyzed GaAs/InAs and InAs/GaAs axial nanowire heterostructures were comprehensively investigated by transmission electron microscopy. It has been found that the GaAs/InAs interface is not sharp and contains an InGaAs transition segment, and in contrast, the InAs/GaAs interface is atomically sharp. This difference in the nature of heterointerfaces can be attributed to the difference in the affinity of the group III elements with the catalyst material.
Effect of V/III ratio on the structural quality of InAs nanowires
Publisher: IEEE
Date: 12-2014
Planar Vacancies in Sn1–xBixTe Nanoribbons
Publisher: American Chemical Society (ACS)
Date: 28-04-2016
Abstract: Vacancy engineering is a crucial approach to manipulate physical properties of semiconductors. Here, we demonstrate that planar vacancies are formed in Sn1-xBixTe nanoribbons by using Bi dopants via a facile chemical vapor deposition. Through combination of sub-angstrom-resolution imaging and density functional theory calculations, these planar vacancies are found to be associated with Bi segregations, which significantly lower their formation energies. The planar vacancies exhibit polymorphic structures with local variations in the lattice relaxation level, determined by their proximity to the nanoribbon surface. Such polymorphic planar vacancies, in conjunction with Bi dopants, trigger distinct localized electronic states, offering platforms for device applications of ternary chalcogenide materials.
Precursor flow rate manipulation for the controlled fabrication of twin-free GaAs nanowires on silicon substrates
Publisher: IOP Publishing
Date: 27-09-2012
DOI: 10.1088/0957-4484/23/41/415702
Abstract: Vertically oriented GaAs nanowires (NWs) are grown on Si(111) substrates using metal-organic chemical vapor deposition. Controlled epitaxial growth along the direction is demonstrated following the deposition of thin GaAs buffer layers and the elimination of structural defects, such as twin defects and stacking faults, is found for high growth rates. By systematically manipulating the AsH(3) (group-V) and TMGa (group-III) precursor flow rates, it is found that the TMGa flow rate has the most significant effect on the nanowire quality. After capping the minimal tapering and twin-free GaAs NWs with an AlGaAs shell, long exciton lifetimes (over 700 ps) are obtained for high TMGa flow rate s les. It is observed that the Ga adatom concentration significantly affects the growth of GaAs NWs, with a high concentration and rapid growth leading to desirable characteristics for optoelectronic nanowire device applications including improved morphology, crystal structure and optical performance.
Solving complex concentric circular mesostructures by using electron tomography
Publisher: Wiley
Date: 11-08-2008
Investigation of SiO<sub>2</sub>-SiC Interface by High-Resolution Transmission Electron Microscope
Publisher: Trans Tech Publications, Ltd.
Date: 10-2006
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.527-529.975
Abstract: High-resolution transmission electron microscopy (HR TEM) reveals an atomically flat SiC surface after oxidation in either NO or dry O2 ambients. This reopens the question of the origin of the electronically active defects at the SiO2–SiC interface, whose density remains orders of magnitude higher than in the SiO2–Si interface. Capacitance-transient measurements, analysed in this paper, demonstrate that the dominant electronically active defects are in the oxide at tunneling distances from the SiC surface (near-interface traps). The HR TEM results cannot rule out that these traps are related to carbon/oxygen bonds or even nanometer-sized carbon clusters, which resolves the apparent inconsistency with the earlier experimental evidence of carbon accumulation at (or near) the SiO2–SiC interface.
Effect of Sn Addition on Epitaxial GaAs Nanowire Grown at Different Temperatures in Metal–Organic Chemical Vapor Deposition
Publisher: American Chemical Society (ACS)
Date: 18-07-2019
T-Shaped Bi2Te3–Te Heteronanojunctions: Epitaxial Growth, Structural Modeling, and Thermoelectric Properties
Publisher: American Chemical Society (ACS)
Date: 07-06-2013
DOI: 10.1021/JP4041666
Achieving high Figure of Merit in p-type polycrystalline Sn0.98Se via self-doping and anisotropy-strengthening
Publisher: Elsevier BV
Date: 2018
Effects of growth rate on InP nanowires morphology and crystal structure
Publisher: Elsevier BV
Date: 11-2013
High strength and ductility of titanium matrix composites by nanoscale design in selective laser melting
Publisher: Elsevier BV
Date: 08-2022
Catalytic De/Hydrogenation in Mg by Co‐Doped Ni and VOx on Active Carbon: Extremely Fast Kinetics at Low Temperatures and High Hydrogen Capacity
Publisher: Wiley
Date: 11-03-2011
Evolution of Epitaxial InAs Nanowires on GaAs (111)B
Publisher: Wiley
Date: 06-02-2009
Thermoelectric GeTe with Diverse Degrees of Freedom Having Secured Superhigh Performance
Publisher: Wiley
Date: 13-02-2019
Abstract: Driven by the ability to harvest waste heat into reusable electricity and the exclusive role of serving as the power generator for deep spacecraft, intensive endeavors are dedicated to enhancing the thermoelectric performance of ecofriendly materials. Herein, the most recent progress in superhigh-performance GeTe-based thermoelectric materials is reviewed with a focus on the crystal structures, phase transitions, resonant bondings, multiple valance bands, and phonon dispersions. These features ersify the degrees of freedom to tune the transport properties of electrons and phonons for GeTe. On the basis of the optimized carrier concentration, strategies of alignment of multiple valence bands and density-of-state resonant distortion are employed to further enhance the thermoelectric performance of GeTe-based materials. To decrease the thermal conductivity, methods of strengthening intrinsic phonon-phonon interactions and introducing various lattice imperfections as scattering centers are highlighted. An overview of thermoelectric devices assembled from GeTe-based thermoelectric materials is then presented. In conclusion, possible future directions for developing GeTe in thermoelectric applications are proposed. The achieved high thermoelectric performance in GeTe-based thermoelectric materials with rationally established strategies can act as a reference for broader materials to tailor their thermoelectric performance.
Supra-Assembly of Siliceous Vesicles
Publisher: American Chemical Society (ACS)
Date: 21-11-2006
DOI: 10.1021/JA066707O
Abstract: We report a new approach to produce macroporous ( approximately 110 nm in diameter) ordered siliceous foams (MOSF) by using block copolymers as templates in the absence of any organic cosolvent. The fine three-dimensional honeycomb structure of MOSF was determined by electron tomography. A formation mechanism of MOSF that spans from the atomic to macroscopic scale is proposed, which involves the cooperative self-assembly of unilamellar vesicles followed by the supra-assembly of vesicles. The fusion of soft vesicles finally leads to MOSF with well-ordered and defined honeycomb structures.
Thermoelectric Coolers: Progress, Challenges, and Opportunities
Publisher: Wiley
Date: 05-01-2022
Abstract: Owing to the free of noise, mechanical component, working fluid, and chemical reaction, thermoelectric cooling is regarded as a suitable solution to address the greenhouse emission for the broad cooling scenarios. Here, the significant progress of state‐of‐the‐art thermoelectric coolers is comprehensively summarized and the related aspects of materials, fundamental design, heat sinks, and structures, are overviewed. Particularly, the usage of thermoelectric coolers in smart city, greenhouse, and personal and chip thermal management is highlighted. In the end, current challenges and future opportunities for further improvement of designs, performance, and applications of thermoelectric coolers are pointed out.
Depth profiling of GaN by cathodoluminescence microanalysis
Publisher: AIP Publishing
Date: 22-02-1999
DOI: 10.1063/1.123460
Abstract: We present the results of a depth-resolved cathodoluminescence (CL) and transmission electron microscopy study of autodoped GaN grown on sapphire. Depth-resolved CL analysis can be used for depth profiling of the yellow luminescence (YL) center concentration which was found to increase with depth. The results are consistent with the (ON–VGa)2− complex model of YL centers [J. Neugebauer and C. G. Van de Walle, Appl. Phys. Lett. 69, 503 (1996) and T. Mattila and R. M. Nieminen, Phys. Rev. B 55, 9571 (1996)]. Depth profiling of the near-edge emission in GaN layers thicker than ∼0.5 μm is not possible due to strong self-absorption.
Superior electrical properties of crystalline Er2O3 films epitaxially grown on Si substrates
Publisher: AIP Publishing
Date: 29-05-2006
DOI: 10.1063/1.2208958
Abstract: Crystalline Er2O3 thin films were epitaxially grown on Si (001) substrates. The dielectric constant of the film with an equivalent oxide thickness of 2.0nm is 14.4. The leakage current density as small as 1.6×10−4A∕cm2 at a reversed bias voltage of −1V has been measured. Atomically sharp Er2O3∕Si interface, superior electrical properties, and good time stability of the Er2O3 thin film indicate that crystalline Er2O3 thin film can be an ideal candidate of future electronic devices.
Eco-Friendly SnTe Thermoelectric Materials: Progress and Future Challenges
Publisher: Wiley
Date: 28-09-2017
A formation mechanism of oxygen vacancies in a MnO2 monolayer: A DFT + U study
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CP20634F
Abstract: Recently we reported the oxygen vacancy induced structural variations of the monolayer of manganese dioxide (MnO(2)) under the electronic irradiation. In this report, we further studied the formation mechanism of oxygen vacancies in a MnO(2) monolayer under the framework of density functional theory plus Hubbard model. The effect of injected electrons on the formation of oxygen vacancies has been investigated. It is believed that oxygen is most likely leaving in the form of neutral atoms or molecules. The origination of the role of negative charges has been particularly discussed.
Promising and Eco-Friendly Cu2X-Based Thermoelectric Materials: Progress and Applications
Publisher: Wiley
Date: 15-01-2020
Abstract: Due to the nature of their liquid-like behavior and high dimensionless figure of merit, Cu
Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn1-xSe via anisotropy and vacancy synergy
Publisher: Wiley
Date: 10-12-2020
DOI: 10.1002/INF2.12057
Realizing a 10 °C Cooling Effect in a Flexible Thermoelectric Cooler Using a Vortex Generator
Publisher: Wiley
Date: 04-09-2022
Abstract: In this study, flexible thermoelectric coolers (FTECs) are used to develop an alternative personalized cooling technology to achieve a large temperature drop of 10 °C and cooling capacity of 256 W m –2 . Such an excellent cooling performance is attributed to the innovative design of the quadra‐layered Ag 2 Se oly(3,4‐ethylenedioxythiophene) polystyrene sulfonate structure in FTECs and the induced air vortices by the vortex generator attached to the hot surface of the device. The applied pulse‐width modulation technique guarantees human body comfort at inconsistent ambient temperature by modulating the duty ratio of the power source, which also saves 35% of the power consumption. As a result, the as‐prepared FTECs only consume 68.5 W so as to maintain a comfortable skin temperature (32 ± 0.5 °C) when the ambient temperature is at 31 °C. This technology provides a reliable and adjustable solution for personalized cooling in environments where comfortable temperatures are exceeded.
Effect of Ag micro-alloying on the microstructure and properties of Cu–14Fe in situ composite
Publisher: Elsevier BV
Date: 07-2010
High quality InAs quantum dots grown on patterned Si with a GaAs buffer layer
Publisher: IOP Publishing
Date: 07-07-2009
DOI: 10.1088/0957-4484/20/30/305301
Abstract: Ordered and dense InAs quantum dots grown on patterned Si(100) with a thin GaAs buffer layer have been investigated by transmission electron microscopy and electron energy loss spectroscopy. {111} faceted InAs quantum dots with good crystallinity were observed on top of the underlying GaAs buffer layer. It was revealed that the GaAs buffer layer and the lateral expansion of InAs have played key roles in releasing the misfit strain between InAs and Si and suppressing the formation of lattice defects in InAs quantum dots. These results suggest a possible pathway for the strain relaxation in the formation of quantum dots.
Effects of annealing and substrate orientation on epitaxial growth of GaAs on Si
Publisher: AIP Publishing
Date: 15-10-2009
DOI: 10.1063/1.3248372
Abstract: GaAs thin films grown on Si (100) and (111) substrates by metal-organic chemical vapor deposition were investigated by electron microscopy. It was found that the growth rate of the GaAs epitaxial layers on Si (100) was faster than that on Si (111) due to a lower Si (111) surface energy. The morphologies and internal crystal structure quality of GaAs films grown on Si (111) were better than those grown on Si (100). It was also found that postannealing at high temperature can improve the morphology of the epitaxial layer surface and reduce lattice defects in the thin films.
Photoelectronic Properties of End-bonded InAsSb Nanowire Array Detector under Weak Light
Publisher: Springer Science and Business Media LLC
Date: 21-01-2021
DOI: 10.1186/S11671-021-03476-4
Abstract: A simple fabrication of end-bonded contacts InAsSb NW (nanowire) array detector to weak light is demonstrated in this study. The detector is fabricated using InAsSb NW array grown by molecular beam epitaxy on GaAs substrate. The metal-induced gap states are induced by the end-bonded contact which suppresses the dark current at various temperatures. The existence of the interface dipole due to the interfacial gap states enhances the light excitation around the local field and thus upgrades the photoresponsivity and photodetectivity to the weak light. The light intensity of the infrared light source in this report is 14 nW/cm 2 which is about 3 to 4 orders of magnitude less than the laser source. The responsivity of the detector has reached 28.57 A/W at room temperature with the light (945 nm) radiation, while the detectivity is 4.81 × 10 11 cm·Hz 1/2 W −1 . Anomalous temperature-dependent performance emerges at the variable temperature experiments, and we discussed the detailed mechanism behind the nonlinear relationship between the photoresponse of the device and temperatures. Besides, the optoelectronic characteristics of the detector clarified that the light-trapping effect and photogating effect of the NWs can enhance the photoresponse to the weak light across ultraviolet to near-infrared. These results highlight the feasibility of the InAsSb NW array detector to the infrared weak light without a cooling system.
Solvothermal Synthesis and Photoreactivity of Anatase TiO2 Nanosheets with Dominant {001} Facets
Publisher: American Chemical Society (ACS)
Date: 27-02-2009
DOI: 10.1021/JA808790P
Abstract: Owing to wide-ranging industrial applications and fundamental importance, tailored synthesis of well-faceted single crystals of anatase TiO(2) with high percentage of reactive facets has attracted much research interest. In this work, high-quality anatase TiO(2) single-crystal nanosheets mainly dominated by {001} facets have been prepared by using a water-2-propanol solvothermal synthetic route. The synergistic functions of 2-propanol and HF on the growth of anatase TiO(2) single-crystal nanosheets were studied by first-principle theoretical calculations, revealing that the addition of 2-propanol can strengthen the stabilization effect associated with fluorine adsorption over (001) surface and thus stimulate its preferred growth. By measuring the (*)OH species with terephthalic acid scavenger, the as-prepared anatase TiO(2) single-crystal nanosheets having 64% {001} facets show superior photoreactivity (more than 5 times), compared to P25 as a benchmarking material.
Field emitters: ultrathin BN nanosheets protruded from BN fibers
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0JM02955F
High Performance Thermoelectric Materials: Progress and Their Applications
Publisher: Wiley
Date: 07-11-2018
Photocatalytic water oxidation on F, N co-doped TiO2 with dominant exposed {001} facets under visible light
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC14453G
Abstract: Visible-light-responsive anatase TiO(2) platelets with dominant {001} facets were prepared via a facile nitridation reaction from a TiOF(2) precursor. The in situ co-doping of N and F in the anatase TiO(2) nanoparticles leads to drastically enhanced absorption and excellent water oxidation performance in the visible light region.
Mechanical properties of single crystal tungsten microwhiskers characterized by nanoindentation
Publisher: Elsevier BV
Date: 10-2009
Thermal stability and oxidation of layer-structured rhombohedral In3Se4 nanostructures
Publisher: AIP Publishing
Date: 23-12-2013
DOI: 10.1063/1.4857655
Abstract: The thermal stability and oxidation of layer-structured rhombohedral In3Se4 nanostructures have been investigated. In-situ synchrotron X-ray diffraction in a sealed system reveals that In3Se4 has good thermal stability up to 900 °C. In contrast, In3Se4 has lower thermal stability up to 550 or 200 °C when heated in an atmosphere flushed with Ar or in air, respectively. The degradation mechanism was determined to be the oxidation of In3Se4 by O2 in the heating environment. This research demonstrates how thermal processing conditions can influence the thermal stability of In3Se4, suggesting that appropriate heating environment for preserving its structural integrity is required.
Determination of Young's Modulus of Ultrathin Nanomaterials
Publisher: American Chemical Society (ACS)
Date: 22-07-2015
DOI: 10.1021/ACS.NANOLETT.5B01603
Abstract: Determination of the elastic modulus of nanostructures with sizes at several nm range is a challenge. In this study, we designed an experiment to measure the elastic modulus of amorphous Al2O3 films with thicknesses varying between 2 and 25 nm. The amorphous Al2O3 was in the form of a shell, wrapped around GaAs nanowires, thereby forming an effective core/shell structure. The GaAs core comprised a single crystal structure with a diameter of 100 nm. Combined in situ compression transmission electron microscopy and finite element analysis were used to evaluate the elastic modulus of the overall core/shell nanowires. A core/shell model was applied to deconvolute the elastic modulus of the Al2O3 shell from the core. The results indicate that the elastic modulus of amorphous Al2O3 increases significantly when the thickness of the layer is smaller than 5 nm. This novel nanoscale material can be attributed to the reconstruction of the bonding at the surface of the material, coupled with the increase of the surface-to-volume ratio with nanoscale dimensions. Moreover, the experimental technique and analysis methods presented in this study may be extended to measure the elastic modulus of other materials with dimensions of just several nanometers.
Epitaxially grown GaAsN random laser
Publisher: AIP Publishing
Date: 09-05-2003
DOI: 10.1063/1.1568533
Abstract: We have studied the photoluminescence properties of as-grown GaAs1−xNx epitaxial layers grown on GaAs containing 0.6%, 1.77%, and 2.8% nitrogen. We found laser emission from thick (d& nm) GaAs0.972N0.028 layers exhibiting the characteristic lasing properties of random lasers. This is unusual because random lasers have so far only been associated with highly disordered or random media. We believe that high gain in combination with structural inhomogeneities that are evident in these GaAs0.972N0.028 layers, can explain the random lasing in such epitaxial layers.
Enhancing Thermoelectric Properties of InTe Nanoprecipitate-Embedded Sn1–xInxTe Microcrystals through Anharmonicity and Strain Engineering
Publisher: American Chemical Society (ACS)
Date: 28-03-2019
Effect of directional solidification rate on the microstructure and properties of deformation-processed Cu–7Cr–0.1Ag in situ composites
Publisher: Elsevier BV
Date: 11-2014
Real-time observation of the thermally-induced phase transformation in GeTe and its thermal expansion properties
Publisher: Elsevier BV
Date: 02-2019
Rational structural design and manipulation advance SnSe thermoelectrics
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0MH00954G
Abstract: This review aims to comprehensively summarize the significant developments in nanostructural manipulations that benefit SnSe thermoelectrics.
Growth of defect-free InAs nanowires using Pd catalyst
Publisher: IEEE
Date: 12-2012
Atomic composition profile change of SiGe islands during Si capping
Publisher: AIP Publishing
Date: 04-09-2006
DOI: 10.1063/1.2345589
Abstract: The 6% Ge isocomposition profile change of in idual SiGe islands during Si capping at 640°C is investigated by atomic force microscopy combined with a selective etching procedure. The island shape transforms from a dome to a {103}-faceted pyramid at a Si capping thickness of 0.32nm, followed by the decreasing of pyramid facet inclination with increasing Si capping layer thickness. The 6% Ge isocomposition profiles show that the island with more highly Si enriched at its one base corner before Si capping becomes to be more highly Si intermixed along pyramid base diagonals during Si capping. This Si enrichment evolution inside an island during Si capping can be attributed to the exchange of capped Si atoms that aggregated to the island by surface diffusion with Ge atoms from inside the island by both atomic surface segregation and interdiffusion rather than to the atomic interdiffusion at the interface between the island and the Si substrate. In addition, the observed Si enrichment along the island base diagonals is attempted to be explained on the basis of the elastic constant anisotropy of the Si and Ge materials in (001) plane.
In situ TEM observation of the vapor–solid–solid growth of <001̄> InAs nanowires
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0NR02892D
Abstract: The VSS growth of InAs ̄ nanowires has been observed at the atomic level in the in situ TEM heating.
Taper-free and kinked germanium nanowires grown on silicon via purging and the two-temperature process
Publisher: IOP Publishing
Date: 28-02-2012
DOI: 10.1088/0957-4484/23/11/115603
Abstract: We investigate the growth procedures for achieving taper-free and kinked germanium nanowires epitaxially grown on silicon substrates by chemical vapor deposition. Singly and multiply kinked germanium nanowires consisting of segments were formed by employing a reactant gas purging process. Unlike non-epitaxial kinked nanowires, a two-temperature process is necessary to maintain the taper-free nature of segments in our kinked germanium nanowires on silicon. As an application, nanobridges formed between (111) side walls of V-grooved (100) silicon substrates have been demonstrated.
Mg-Based Nanocomposites with High Capacity and Fast Kinetics for Hydrogen Storage
Publisher: American Chemical Society (ACS)
Date: 26-05-2006
DOI: 10.1021/JP057526W
Abstract: Magnesium and its alloys have shown a great potential in effective hydrogen storage due to their advantages of high volumetric/gravimetric hydrogen storage capacity and low cost. However, the use of these materials in fuel cells for automotive applications at the present time is limited by high hydrogenation temperature and sluggish sorption kinetics. This paper presents the recent results of design and development of magnesium-based nanocomposites demonstrating the catalytic effects of carbon nanotubes and transition metals on hydrogen adsorption in these materials. The results are promising for the application of magnesium materials for hydrogen storage, with significantly reduced absorption temperatures and enhanced ab/desorption kinetics. High level Density Functional Theory calculations support the analysis of the hydrogenation mechanisms by revealing the detailed atomic and molecular interactions that underpin the catalytic roles of incorporated carbon and titanium, providing clear guidance for further design and development of such materials with better hydrogen storage properties.
Defect-Free GaAs/AlGaAs Core–Shell Nanowires on Si Substrates
Publisher: American Chemical Society (ACS)
Date: 27-05-2011
DOI: 10.1021/CG2003657
III-V compound semiconductor nanowires
Publisher: IEEE
Date: 06-2009
Achieving high thermoelectric performance of Ni/Cu modified Bi0.5Sb1.5Te3 composites by a facile electroless plating
Publisher: Elsevier BV
Date: 09-2018
Inclusion Characterization and Formation Mechanisms in Spring Steel Deoxidized by Silicon
Publisher: Springer Science and Business Media LLC
Date: 16-01-2019
A novel quaternary equiatomic Ti-Zr-Nb-Ta medium entropy alloy (MEA)
Publisher: Elsevier BV
Date: 10-2018
Computation-guided design of high-performance flexible thermoelectric modules for sunlight-to-electricity conversion
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0EE01895C
Abstract: A computation-guided design of a flexible thermoelectric module achieves a high output power density of 3 μW cm −2 by sunlight-to-electricity conversion.
Investigating the origin of Fermi level pinning in Ge Schottky junctions using epitaxially grown ultrathin MgO films
Publisher: AIP Publishing
Date: 08-03-2010
DOI: 10.1063/1.3357423
Abstract: Fermi level (FL) pinning at the Ge valence band results in a high Schottky barrier height for all metal/n-Ge contacts. The origin of this pinning effect has been ascribed to either metal induced gap states or surface states arise from the native defects at the Ge surface, such as dangling bonds. The discrepancy in the reported results/explanations is mainly due to the lack of an explicit characterization of a high quality metal/Ge or metal/ultrathin oxide/Ge junction, which should be ideally single crystalline, atomically smooth and free of process-induced defects or intermixing. We report the Schottky characteristics of high quality metal/MgO/n-Ge junctions with the ultrathin MgO epitaxially grown on Ge. We find the depinning effect displays a weak dependence on the MgO thickness, indicating the interface states due to the native defects on Ge surface are likely to play the dominant role in FL pinning.
Wafer-scale arrayed p-n junctions based on few-layer epitaxial GaTe
Publisher: Springer Science and Business Media LLC
Date: 27-08-2015
Achieving High-Performance Ge0.92Bi0.08Te Thermoelectrics via LaB6-Alloying-Induced Band Engineering and Multi-Scale Structure Manipulation
Publisher: Wiley
Date: 02-12-2021
Abstract: In this work, a LaB 6 ‐alloying strategy is reported to effectively boost the figure‐of‐merit (ZT) of Ge 0.92 Bi 0.08 Te‐based alloys up to ≈2.2 at 723 K, attributed to a synergy of La‐dopant induced band structuring and structural manipulation. Density‐function‐theory calculations reveal that La dopant enlarges the bandgap and converges the energy offset between the sub‐valence bands in cubic‐structured GeTe, leading to a significantly increased effective mass, which gives rise to a high Seebeck coefficient of ≈263 µV K −1 and in turn a superior power factor of ≈43 µW cm −1 K −2 at 723 K. Besides, comprehensive electron microscopy characterizations reveal that the multi‐scale phonon scattering centers, including a high density of planar defects, Boron nanoparticles in tandem with enhanced boundaries, dispersive Ge nanoprecipitates in the matrix, and massive point defects, contribute to a low lattice thermal conductivity of ≈0.67 W m −1 K −1 at 723 K. Furthermore, a high microhardness of ≈194 H v is witnessed in the as‐designed Ge 0.92 Bi 0.08 Te(LaB 6 ) 0.04 alloy, derived from the multi‐defect‐induced strengthening. This work provides a strategy for developing high‐performance and mechanical robust middle‐temperature thermoelectric materials for practical thermoelectric applications.
High-performance thermoelectric Cu2Se nanoplates through nanostructure engineering
Publisher: Elsevier BV
Date: 09-2015
Enhanced glass-forming ability of a Zr-based bulk metallic glass with yttrium doping
Publisher: Elsevier BV
Date: 08-2006
Evolution of Wurtzite Structured GaAs Shells Around InAs Nanowire Cores
Publisher: Springer Science and Business Media LLC
Date: 06-05-2009
DOI: 10.1007/S11671-009-9326-6
Abstract: GaAs was radially deposited on InAs nanowires by metal–organic chemical vapor deposition and resultant nanowire heterostructures were characterized by detailed electron microscopy investigations. The GaAs shells have been grown in wurtzite structure, epitaxially on the wurtzite structured InAs nanowire cores. The fundamental reason of structural evolution in terms of material nucleation and interfacial structure is given.
Structure and quality controlled growth of InAs nanowires through catalyst engineering
Publisher: Springer Science and Business Media LLC
Date: 23-08-2014
The effect of Sn addition on GaAs nanowire grown by vapor–liquid–solid growth mechanism
Publisher: IOP Publishing
Date: 19-09-2018
Abstract: Impurity addition is a crucial aspect for III-V nanowire growth. In this study, we demonstrated the effect of the Sn addition on GaAs nanowire growth by metal-organic chemical vapor deposition. With increasing the tetraethyltin flow rate, the nanowire axial growth was suppressed while the nanowire lateral growth was promoted, as well as planar defects were increased. Systematic electron microscopy characterizations suggested that the Sn addition tuned the catalyst composition, changed the vapor-solid-liquid surfaces energies and hindered the Ga atoms diffusion on nanowire sidewalls, which is responsible for the observed changes in morphology and structural quality of grown GaAs nanowires. This study contributes to understanding the role of impurity dopants on III-V nanowires growth, which will be of benefit for the design and fabrication of future nanowire-based devices.
Condensed point defects enhance thermoelectric performance of rare-earth Lu-doped GeTe
Publisher: Elsevier BV
Date: 07-2023
2D Porous TiO 2 Single‐Crystalline Nanostructure Demonstrating High Photo‐Electrochemical Water Splitting Performance
Publisher: Wiley
Date: 16-04-2018
Abstract: Porous single crystals are promising candidates for solar fuel production owing to their long range charge diffusion length, structural coherence, and sufficient reactive sites. Here, a simple template-free method of growing a selectively branched, 2D anatase TiO
Microworms self-assembled by boron nitride horns for optoelectronic applications
Publisher: Elsevier BV
Date: 12-2010
Super Deformability and Young's Modulus of GaAs Nanowires
Publisher: Wiley
Date: 15-02-2011
Superstructured Macroporous Carbon Rods Composed of Defective Graphitic Nanosheets for Efficient Oxygen Reduction Reaction
Publisher: Wiley
Date: 29-07-2021
Abstract: Rationally designed carbon materials with superstructures are promising candidates in applications such as electrocatalysis. However, the synthesis of highly porous carbon superstructures with macropores and carbon defects from a simple crystalline solid remains challenging. In this work, superstructured macroporous carbon rods composed of defective graphitic nanosheets are synthesized by direct carbonization of crystalline poly tannic acid (PTA) rods as precursors. During carbonization, PTA rods with a highly ordered lamellar structure induce a spatially confined two‐step localized contraction that takes place in different dimensions and directions in each step. The unexpected contraction behavior results in the sponge‐like macroporous carbon superstructure with large surface area, high porosity, and abundant defects, thus showing a superior electrocatalytic performance with high activity and selectivity for oxygen reduction reaction. The study provides new understandings in the design of functional carbon materials with distinctive structures and applications.
Composition and Strain Measurements of Ge(Si)/Si(001) Islands by HRTEM
Publisher: American Scientific Publishers
Date: 04-2009
DOI: 10.1166/JNN.2009.029
Abstract: The distributions of the composition and the strain in the Ge(Si)/Si(001) coherent islands grown by molecular-beam epitaxy are investigated by digital analysis of high resolution transmission electron microscopy (HRTEM) micrographs. Local composition and strain are obtained from the measurement of the lattice displacement based on the Poisson's formula and Vegard's law. The analysis suggests that the islands have high Ge content at the island's central region. The island is partially relaxed by the substrate deformation and strain concentrated around the edge of islands. The alloying of the islands was found due to the Si surface diffusion.
Phase Control and Formation Mechanism of New-Phase Layer-Structured Rhombohedral In3Se4 Hierarchical Nanostructures
Publisher: American Chemical Society (ACS)
Date: 22-10-2021
DOI: 10.1021/CG401269P
Carrier transfer between V-grooved quantum wire and vertical quantum well
Publisher: Elsevier BV
Date: 02-2001
Tadpole shaped Ge0.96Mn0.04 magnetic semiconductors grown on Si
Publisher: AIP Publishing
Date: 02-2010
DOI: 10.1063/1.3297880
Abstract: Magnetic and structural properties of a Ge0.96Mn0.04 thin film grown on Si has been investigated by transmission electron microscopy and superconducting quantum interference device. Tadpole shaped coherent GeMn clusters induced by spinodal decomposition were revealed in the film. Although these coherent clusters are dominant, Mn5Ge3 precipitates can be still detectable, contributing to a complex ferromagnetism. The Ge buffer layer, by relieving the misfit strain between Si and Ge, can significantly reduce the density of lattice defects in the subsequent GeMn layer. Our findings unveil a particular morphology of GeMn clusters, which would contribute to better understand the GeMn system.
Application of Selective Implantation in Al<SUB>0.5</SUB>Ga<SUB>0.5</SUB>As/In <SUB>0.25</SUB>Ga<SUB>0.75</SUB>As/GaAs Pseudomorphic Single Quantum Wire
Publisher: American Scientific Publishers
Date: 12-2001
DOI: 10.1166/JNN.2001.064
Abstract: A pseudomorphic Al0.5Ga0.5As/In0.25Ga0.75As/GaAs asymmetric quantum wire (QWR) structure was grown on GaAs V-grooved substrate by low pressure metal organic vapor phase epitaxy. The formation of crescent shaped QWRs at the bottom of the V-grooves was confirmed by both transmission electron microscopy and photoluminescence (PL) spectra. The temperature dependence of PL spectra demonstrated a fast decrease of the sidewall quantum well PL intensity with increasing temperature, which originates from relaxation of carriers from well to wire region. The self-aligned dual implantation technique was successfully used to selectively disable the adjacent quantum structures. Decrease of the PL intensity of QWR at 8 K was observed after selective implantation, which resulted from a decreased number of carriers relaxed from adjacent quantum structures.
Effect of over-doped yttrium on the microstructure, mechanical properties and thermal properties of a Zr-based metallic glass
Publisher: Elsevier BV
Date: 08-2006
Vortex fluidic mediated transformation of graphite into highly conducting graphene scrolls
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9NA00184K
Abstract: A facile one step process has been developed to fabricate high yield graphene scrolls directly from graphite flakes using a sustainable metrics, with the 3D nanomaterial having remarkable properties, unraveling into buckled graphene sheets °C and forming highly conducting electrical contacts.
Green Synthesis of Hexagonal-Shaped WO3 center dot 0.33H(2)O Nanodiscs Composed of Nanosheets
Publisher: American Chemical Society (ACS)
Date: 17-09-2008
DOI: 10.1021/CG800609N
High Purity GaAs Nanowires Free of Planar Defects: Growth and Characterization
Publisher: Wiley
Date: 08-12-2008
Glass-forming ability and thermal stability of a new bulk metallic glass in the quaternary Zr-Cu-Ni-Al system
Publisher: Elsevier BV
Date: 09-2005
Enhanced Thermoelectric Performance of Nanostructured Bi2Te3 through Significant Phonon Scattering
Publisher: American Chemical Society (ACS)
Date: 19-10-2015
Abstract: N-type Bi2Te3 nanostructures were synthesized using a solvothermal method and in turn sintered using sparking plasma sintering. The sintered n-type Bi2Te3 pellets reserved nanosized grains and showed an ultralow lattice thermal conductivity (∼0.2 W m(-1) K(-1)), which benefits from high-density small-angle grain boundaries accommodated by dislocations. Such a high phonon scattering leads an enhanced ZT of 0.88 at 400 K. This study provides an efficient method to enhance thermoelectric performance of thermoelectric nanomaterials through nanostructure engineering, making the as-prepared n-type nanostructured Bi2Te3 as a promising candidate for room-temperature thermoelectric power generation and Peltier cooling.
A focused review on nanoscratching-induced deformation of monocrystalline silicon
Publisher: Inderscience Publishers
Date: 2013
Synthesis and magnetic properties of Fe3C–C core–shell nanoparticles
Publisher: IOP Publishing
Date: 03-02-2015
DOI: 10.1088/0957-4484/26/8/085601
Abstract: Fe3C-C core-shell nanoparticles were fabricated on a large scale by metal-organic chemical vapor deposition at 700 °C with ferric acetylacetonate as the precursor. Analysis results of x-ray diffraction, transmission electron microscope and Raman spectroscope showed that the Fe3C cores with an average diameter of ∼35 nm were capsulated by the graphite-like C layers with the thickness of 2-5 nm. The comparative experiments revealed that considerable Fe3O4-Fe3C core-shell nanoparticles and C nanotubes were generated simultaneously at 600 and 800 °C, respectively. A formation mechanism was proposed for the as-synthesized core-shell nanostructures, based on the temperature-dependent catalytic activity of Fe3C nanoclusters and the coalescence process of Fe3C-C nanoclusters. The Fe3C-C core-shell nanoparticles exhibited a saturation magnetization of 23.6 emu g(-1) and a coercivity of 550 Oe at room temperature.
Confinement of Chemisorbed Phosphates in a Controlled Nanospace with Three-Dimensional Mesostructures
Publisher: Wiley
Date: 05-04-2013
Abstract: The confinement of phosphates inside adsorbents is important for not only entrophication control, but also the recovery of phosphorous, a depleting natural resource. However, the behaviour of chemisorbed phosphates inside nanoporous materials has not been systematically studied. Here, the confinement of chemisorbed phosphates in a three-dimensional cubic mesoporous material with adjustable structural parameters is systematically investigated. By taking advantage of advanced electron tomography techniques, the relationship between the growth of chemisorbed phosphates, the overall phosphate-adsorption performance and the mesostructural parameters is revealed. Cubic cage-type FDU-12 materials with tuneable entrance sizes were prepared and functionalised with different amounts of lanthanum oxide. When the entrance size is smaller than approximately 5 nm, phosphates are found only in isolated cages, thereby leading to low lanthanum (La) usage efficiency and phosphate removal capacity. When the entrance size is increased, chemisorption occurs in both cages and entrances, thus forming crystalline LaPO4 nanorods and increasing both the La usage efficiency and the phosphate removal capacity. In addition, the LaPO4 nanorods show a preferential orientation along the [110] direction. This study provides new insights in the rational design of phosphate adsorbents with controlled structures and high performance.
Understanding the stepwise capacity increase of high energy low-Co Li-rich cathode materials for lithium ion batteries
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4TA03692A
Abstract: Li-rich layered materials as promising high-energy cathode candidates have attracted much attention in recent years for next generation lithium ion batteries.
Effect of a High Density of Stacking Faults on the Young's Modulus of GaAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 22-02-2016
DOI: 10.1021/ACS.NANOLETT.5B05095
Abstract: Stacking faults (SFs) are commonly observed crystalline defects in III-V semiconductor nanowires (NWs) that affect a variety of physical properties. Understanding the effect of SFs on NW mechanical properties is critical to NW applications in nanodevices. In this study, the Young's moduli of GaAs NWs with two distinct structures, defect-free single crystalline wurtzite (WZ) and highly defective wurtzite containing a high density of SFs (WZ-SF), are investigated using combined in situ compression transmission electron microscopy and finite element analysis. The Young's moduli of both WZ and WZ-SF GaAs NWs were found to increase with decreasing diameter due to the increasing volume fraction of the native oxide shell. The presence of a high density of SFs was further found to increase the Young's modulus by 13%. This stiffening effect of SFs is attributed to the change in the interatomic bonding configuration at the SFs.
High Thermoelectric Performance in p‐type Polycrystalline Cd‐doped SnSe Achieved by a Combination of Cation Vacancies and Localized Lattice Engineering
Publisher: Wiley
Date: 29-01-2019
Structural Evolution in a Hydrothermal Reaction between Nb2O5 and NaOH Solution: From Nb2O5 Grains to Microporous Na2Nb2O6
Publisher: American Chemical Society (ACS)
Date: 28-01-2006
DOI: 10.1021/JA056301W
Abstract: Niobium pentoxide reacts actively with concentrate NaOH solution under hydrothermal conditions at as low as 120 degrees C. The reaction ruptures the corner-sharing of NbO(7) decahedra and NbO(6) octahedra in the reactant Nb(2)O(5), yielding various niobates, and the structure and composition of the niobates depend on the reaction temperature and time. The morphological evolution of the solid products in the reaction at 180 degrees C is monitored via SEM: the fine Nb(2)O(5) powder aggregates first to irregular bars, and then niobate fibers with an aspect ratio of hundreds form. The fibers are microporous molecular sieve with a monoclinic lattice, Na(2)Nb(2)O(6).(2)/(3)H(2)O. The fibers are a metastable intermediate of this reaction, and they completely convert to the final product NaNbO(3) cubes in the prolonged reaction of 1 h. This study demonstrates that by carefully optimizing the reaction condition, we can selectively fabricate niobate structures of high purity, including the delicate microporous fibers, through a direct reaction between concentrated NaOH solution and Nb(2)O(5). This synthesis route is simple and suitable for the large-scale production of the fibers. The reaction first yields poorly crystallized niobates consisting of edge-sharing NbO(6) octahedra, and then the microporous fibers crystallize and grow by assembling NbO(6) octahedra or clusters of NbO(6) octahedra and NaO(6) units. Thus, the selection of the fibril or cubic product is achieved by control of reaction kinetics. Finally, niobates with different structures exhibit remarkable differences in light absorption and photoluminescence properties. Therefore, this study is of importance for developing new functional materials by the wet-chemistry process.
Morphology and Microstructure of InAs Nanowires on GaAs Substrates Grown by Molecular Beam Epitaxy
Publisher: IOP Publishing
Date: 09-2014
Anatase TiO2 single crystals with a large percentage of reactive facets
Publisher: Springer Science and Business Media LLC
Date: 05-2008
DOI: 10.1038/NATURE06964
Abstract: Owing to their scientific and technological importance, inorganic single crystals with highly reactive surfaces have long been studied. Unfortunately, surfaces with high reactivity usually diminish rapidly during the crystal growth process as a result of the minimization of surface energy. A typical ex le is titanium dioxide (TiO2), which has promising energy and environmental applications. Most available anatase TiO(2) crystals are dominated by the thermodynamically stable {101} facets (more than 94 per cent, according to the Wulff construction), rather than the much more reactive {001} facets. Here we demonstrate that for fluorine-terminated surfaces this relative stability is reversed: {001} is energetically preferable to {101}. We explored this effect systematically for a range of non-metallic adsorbate atoms by first-principle quantum chemical calculations. On the basis of theoretical predictions, we have synthesized uniform anatase TiO(2) single crystals with a high percentage (47 per cent) of {001} facets using hydrofluoric acid as a morphology controlling agent. Moreover, the fluorated surface of anatase single crystals can easily be cleaned using heat treatment to render a fluorine-free surface without altering the crystal structure and morphology.
Flower-like C@SnO X @C hollow nanostructures with enhanced electrochemical properties for lithium storage
Publisher: Springer Science and Business Media LLC
Date: 18-05-2017
Catalytically enhanced dehydrogenation of MgH2 by activated carbon supported Pd–VOx (x=2.38) nanocatalyst
Publisher: Elsevier BV
Date: 09-2012
Correction to Self-Assembly Growth of In-Rich InGaAs Core-Shell Structured Nanowires with Remarkable Near-Infrared Photoresponsivity.
Publisher: American Chemical Society (ACS)
Date: 27-02-2019
Indium Selenides: Structural Characteristics, Synthesis and Their Thermoelectric Performances
Publisher: Wiley
Date: 14-04-2014
Abstract: Indium selenides have attracted extensive attention in high-efficiency thermoelectrics for waste heat energy conversion due to their extraordinary and tunable electrical and thermal properties. This Review aims to provide a thorough summary of the structural characteristics (e.g. crystal structures, phase transformations, and structural vacancies) and synthetic methods (e.g. bulk materials, thin films, and nanostructures) of various indium selenides, and then summarize the recent progress on exploring indium selenides as high-efficiency thermoelectric materials. By highlighting challenges and opportunities in the end, this Review intends to shine some light on the possible approaches for thermoelectric performance enhancement of indium selenides, which should open up an opportunity for applying indium selenides in the next-generation thermoelectric devices.
Temperature-dependent chemical state of the nickel catalyst for the growth of carbon nanofibers
Publisher: Elsevier BV
Date: 2016
Nano-scale dislocations induced by self-vacancy engineering yielding extraordinary n-type thermoelectric Pb0.96-yInySe
Publisher: Elsevier BV
Date: 08-2018
Taper-Free and Vertically Oriented Ge Nanowires on Ge/Si Substrates Grown by a Two-Temperature Process
Publisher: American Chemical Society (ACS)
Date: 02-12-2011
DOI: 10.1021/CG2008914
Indentation-induced delamination of plasma-enhanced chemical vapor deposition silicon nitride film on gallium arsenide substrate
Publisher: Springer Science and Business Media LLC
Date: 27-03-2013
DOI: 10.1557/JMR.2013.31
Vertically oriented epitaxial germanium nanowires on silicon substrates using thin germanium buffer layers
Publisher: IOP Publishing
Date: 29-06-2010
DOI: 10.1088/0957-4484/21/29/295602
Abstract: We demonstrate a method to realize vertically oriented Ge nanowires on Si(111) substrates. Ge nanowires were grown by chemical vapor deposition using Au nanoparticles to seed nanowire growth via a vapor-liquid-solid growth mechanism. Rapid oxidation of Si during Au nanoparticle application inhibits the growth of vertically oriented Ge nanowires directly on Si. The present method employs thin Ge buffer layers grown at low temperature less than 600 degrees C to circumvent the oxidation problem. By using a thin Ge buffer layer with root-mean-square roughness of approximately 2 nm, the yield of vertically oriented Ge nanowires is as high as 96.3%. This yield is comparable to that of homoepitaxial Ge nanowires. Furthermore, branched Ge nanowires could be successfully grown on these vertically oriented Ge nanowires by a secondary seeding technique. Since the buffer layers are grown under moderate conditions without any high temperature processing steps, this method has a wide process window highly suitable for Si-based microelectronics.
Silicon-induced oriented ZnS nanobelts for hydrogen sensitivity
Publisher: IOP Publishing
Date: 14-01-2008
DOI: 10.1088/0957-4484/19/05/055710
Abstract: Oriented ZnS nanobelts were grown on an Si substrate using hydrogen-assisted thermal evaporation under moist gas conditions. It was found that these ZnS nanobelts had a single crystal hexagonal wurtzite structure growing along the [0001] direction. They had a rectangular cross section with lengths of up to tens of micrometres, a typical width of 50-150 nm, and a thickness of ∼40 nm. A silicon-induced vapour-liquid-solid process was proposed for the formation of the ZnS nanobelts and their assembly. These oriented nanobelts have much faster response time to hydrogen gas than that of pure ZnO and Pd-sensitized ZnO, showing excellent hydrogen sensing properties.
High-quality epitaxial wurtzite structured InAs nanosheets grown in MBE
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9NR08429K
Abstract: High-quality epitaxial wurtzite structured InAs nanosheets have been grown using Au catalysts in MBE.
Scalable Growth of High Mobility Dirac Semimetal Cd3As2 Microbelts
Publisher: American Chemical Society (ACS)
Date: 27-08-2015
DOI: 10.1021/ACS.NANOLETT.5B01885
Abstract: Three-dimensional (3D) Dirac semimetals are 3D analogues of graphene, which display Dirac points with linear dispersion in k-space, stabilized by crystal symmetry. Cd3As2 has been predicted to be 3D Dirac semimetals and was subsequently demonstrated by angle-resolved photoemission spectroscopy. As unveiled by transport measurements, several exotic phases, such as Weyl semimetals, topological insulators, and topological superconductors, can be deduced by breaking time reversal or inversion symmetry. Here, we reported a facile and scalable chemical vapor deposition method to fabricate high-quality Dirac semimetal Cd3As2 microbelts they have shown ultrahigh mobility up to 1.15 × 10(5) cm(2) V(-1) s(-1) and pronounced Shubnikov-de Haas oscillations. Such extraordinary features are attributed to the suppression of electron backscattering. This research opens a new avenue for the scalable fabrication of Cd3As2 materials toward exciting electronic applications of 3D Dirac semimetals.
Gate-Controlled Surface Conduction in Na-Doped Bi2Te3 Topological Insulator Nanoplates
Publisher: American Chemical Society (ACS)
Date: 09-02-2012
DOI: 10.1021/NL202920P
Abstract: Exploring exciting and exotic physics, scientists are pursuing practical device applications for topological insulators. The Dirac-like surface states in topological insulators are protected by the time-reversal symmetry, which naturally forbids backscattering events during the carrier transport process, and therefore offers promising applications in dissipationless spintronic devices. Although considerable efforts have been devoted to controlling their surface conduction, limited work has been focused on tuning surface states and bulk carriers in Bi(2)Te(3) nanostructures by external field. Here we report gate-tunable surface conduction in Na-doped Bi(2)Te(3) topological insulator nanoplates. Significantly, by applying external gate voltages, such topological insulators can be tuned from p-type to n-type. Our results render a promise in finding novel topological insulators with enhanced surface states.
High-Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges
Publisher: Wiley
Date: 13-02-2020
Growth of GaAs nanowires using different Au catalysts
Publisher: IEEE
Date: 12-2010
The stability of faceted SiGe quantum dots capped with a thin Si layer
Publisher: IOP Publishing
Date: 15-12-2007
Continuous flow synthesis of phosphate binding h-BN@magnetite hybrid material
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8RA08336C
Abstract: Vortex fluidic fabricated h-BN@magnetite under continuous flow in water exhibits recyclable high phosphate ion adsorption capacity.
Microstructural and chemical aspects of working-temperature aged Ca-doped CeO2
Publisher: Elsevier BV
Date: 09-2010
Twin-Free Uniform Epitaxial GaAs Nanowires Grown by a Two-Temperature Process
Publisher: American Chemical Society (ACS)
Date: 03-03-2007
DOI: 10.1021/NL062755V
Abstract: We demonstrate vertically aligned epitaxial GaAs nanowires of excellent crystallographic quality and optimal shape, grown by Au nanoparticle-catalyzed metalorganic chemical vapor deposition. This is achieved by a two-temperature growth procedure, consisting of a brief initial high-temperature growth step followed by prolonged growth at a lower temperature. The initial high-temperature step is essential for obtaining straight, vertically aligned epitaxial nanowires on the (111)B GaAs substrate. The lower temperature employed for subsequent growth imparts superior nanowire morphology and crystallographic quality by minimizing radial growth and eliminating twinning defects. Photoluminescence measurements confirm the excellent optical quality of these two-temperature grown nanowires. Two mechanisms are proposed to explain the success of this two-temperature growth process, one involving Au nanoparticle-GaAs interface conditions and the other involving melting-solidification temperature hysteresis of the Au-Ga nanoparticle alloy.
Dislocation-induced changes in quantum dots: Step alignment and radiative emission
Publisher: AIP Publishing
Date: 19-04-1999
DOI: 10.1063/1.123831
Abstract: A transition between two types of step alignment was observed in a multilayered InGaAs/GaAs quantum-dot (QD) structure. A change to larger QD sizes in smaller concentrations occurred after formation of a dislocation array. Cathodoluminescence (CL) spectra show a bimodal peak with lower energy peak enhancement when probing at lower e-beam energies. The two peaks separate as a result of QD interdiffusion. CL imaging and cross-sectional transmission electron microscopy showed contrast from a dislocation array formed at the interface between GaAs and the first InGaAs QD layer. Strong QD emission in the near infrared (800–1100 nm) was obtained despite the presence of dislocations.
Spontaneous formation of core-shell GaAsP nanowires and their enhanced electrical conductivity
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4TC02305F
Abstract: Spontaneous formation of core–shell GaAsP nanowires with P-enriched cores and As-enriched shells, demonstrating enhanced electrical conductivity.
Coherent magnetic semiconductor nanodot arrays
Publisher: Springer Science and Business Media LLC
Date: 11-02-2011
Abstract: In searching appropriate candidates of magnetic semiconductors compatible with mainstream Si technology for future spintronic devices, extensive attention has been focused on Mn-doped Ge magnetic semiconductors. Up to now, lack of reliable methods to obtain high-quality MnGe nanostructures with a desired shape and a good controllability has been a barrier to make these materials practically applicable for spintronic devices. Here, we report, for the first time, an innovative growth approach to produce self-assembled and coherent magnetic MnGe nanodot arrays with an excellent reproducibility. Magnetotransport experiments reveal that the nanodot arrays possess giant magneto-resistance associated with geometrical effects. The discovery of the MnGe nanodot arrays paves the way towards next-generation high-density magnetic memories and spintronic devices with low-power dissipation.
Carrier Lifetime and Mobility Enhancement in Nearly Defect-Free Core−Shell Nanowires Measured Using Time-Resolved Terahertz Spectroscopy
Publisher: American Chemical Society (ACS)
Date: 28-07-2009
DOI: 10.1021/NL9016336
Abstract: We have used transient terahertz photoconductivity measurements to assess the efficacy of two-temperature growth and core-shell encapsulation techniques on the electronic properties of GaAs nanowires. We demonstrate that two-temperature growth of the GaAs core leads to an almost doubling in charge-carrier mobility and a tripling of carrier lifetime. In addition, overcoating the GaAs core with a larger-bandgap material is shown to reduce the density of surface traps by 82%, thereby enhancing the charge conductivity.
Optimizing Electronic Quality Factor toward High-Performance Ge1-x-yTaxSbyTe Thermoelectrics: The Role of Transition Metal Doping
Publisher: Wiley
Date: 16-08-2021
Abstract: Owing to high intrinsic figure‐of‐merit implemented by multi‐band valleytronics, GeTe‐based thermoelectric materials are promising for medium‐temperature applications. Transition metals are widely used as dopants for developing high‐performance GeTe thermoelectric materials. Herein, relevant work is critically reviewed to establish a correlation among transition metal doping, electronic quality factor, and figure‐of‐merit of GeTe. From first‐principle calculations, it is found that Ta, as an undiscovered dopant in GeTe, can effectively converge energy offset between light and heavy conduction band extrema to enhance effective mass at high temperature. Such manipulation is verified by the increased Seebeck coefficient of synthesized Ge 1− x − y Ta x Sb y Te s les from 160 to 180 µV K −1 at 775 K upon doping Ta, then to 220 µV K −1 with further alloying Sb. Characterization using electron microscopy also reveals the unique herringbone structure associated with multi‐scale lattice defects induced by Ta doping, which greatly hinder phonon propagation to decrease thermal conductivity. As a result, a figure‐of‐merit of ≈2.0 is attained in the Ge 0.88 Ta 0.02 Sb 0.10 Te s le, reflecting a maximum heat‐to‐electricity efficiency up to 17.7% under a temperature gradient of 400 K. The rationalized beneficial effects stemming from Ta doping is an important observation that will stimulate new exploration toward high‐performance GeTe‐based thermoelectric materials.
Synthesis of silica vesicles with controlled entrance size for high loading, sustained release, and cellular delivery of therapeutical proteins
Publisher: Wiley
Date: 24-07-2014
Abstract: A rationally designed two-step synthesis of silica vesicles is developed with the formation of vesicular structure in the first step and fine control over the entrance size by tuning the temperature in the second step. The silica vesicles have a uniform size of ≈50 nm with excellent cellular uptake performance. When the entrance size is equal to the wall thickness, silica vesicles after hydrophobic modification show the highest loading amount (563 mg/g) towards Ribonuclease A with a sustained release behavior. Consequently, the silica vesicles are excellent nano-carriers for cellular delivery applications of therapeutical biomolecules.
Characteristics of silicon substrates fabricated using nanogrinding and chemo-mechanical-grinding
Publisher: Elsevier BV
Date: 04-2008
Cheap and scalable synthesis of alpha-Fe2O3 multi-shelled hollow spheres as high-performance anode materials for lithium ion batteries
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CC43867H
Abstract: Delicate α-Fe2O3 multi-shelled hollow spheres have been prepared by a simple and scalable spray drying method followed by annealing in air. The resulting material shows high specific capacity, good cycling stability, and excellent rate performance in lithium ion battery applications.
Nearly intrinsic exciton lifetimes in single twin-free GaAs∕AlGaAs core-shell nanowire heterostructures
Publisher: AIP Publishing
Date: 04-08-2008
DOI: 10.1063/1.2967877
Abstract: CW and time-resolved photoluminescence measurements are used to investigate exciton recombination dynamics in GaAs∕AlGaAs heterostructure nanowires grown with a recently developed technique which minimizes twinning. A thin capping layer is deposited to eliminate the possibility of oxidation of the AlGaAs shell as a source of oxygen defects in the GaAs core. We observe exciton lifetimes of ∼1ns, comparable to high quality two-dimensional double heterostructures. These GaAs nanowires allow one to observe state filling and many-body effects resulting from the increased carrier densities accessible with pulsed laser excitation.
Establishing the Golden Range of Seebeck Coefficient for Maximizing Thermoelectric Performance (vol 142, pg 2672, 2020)
Publisher: American Chemical Society (ACS)
Date: 02-06-2020
DOI: 10.1021/JACS.0C05548
Phase purification of GaAs nanowires by prolonging the growth duration in MBE
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6TC05209F
Abstract: Single-phase nanowire sections are observed by prolonging the growth duration of GaAs nanowires.
Ion damage buildup and amorphization processes in AlxGa1−xAs
Publisher: AIP Publishing
Date: 1995
DOI: 10.1063/1.359358
Abstract: The nature of keV ion damage buildup and amorphization in AlxGa1−xAs at liquid-nitrogen temperature is investigated for various Al compositions using Rutherford backscattering channeling, transmission electron microscopy, and in situ time-resolved-reflectivity techniques. Two distinct damage buildup processes are observed in AlxGa1−xAs depending on Al content. At low Al content, the behavior is similar to GaAs whereby collisional disorder is ‘‘frozen in’’ and amorphization proceeds with increasing dose via the overlap of damage cascades and small amorphous zones created by in idual ion tracks. However, some dynamic annealing occurs during implantation in AlGaAs and this effect is accentuated with increasing Al content. For high Al content, crystallinity is retained at moderate ion damage with disorder building up in the form of stacking faults, planar, and other extended defects. In the latter case, amorphization is nucleation limited and proceeds abruptly when the level of crystalline disorder exceeds a critical level. The amorphization threshold dose increases with increasing Al composition by over two orders of magnitude from GaAs to AlAs. Dynamic annealing and damage creation processes during implantation compete very strongly in AlxGa1−xAs even at liquid-nitrogen temperatures. This behavior is discussed in terms of both the availability of very fast mobile defects and bonding configurational changes related to the Al sublattice in AlxGa1−xAs of high Al content.
Electric-field-controlled ferromagnetism in high-Curie-temperature Mn0.05Ge0.95 quantum dots
Publisher: Springer Science and Business Media LLC
Date: 07-03-2010
DOI: 10.1038/NMAT2716
Abstract: Electric-field manipulation of ferromagnetism has the potential for developing a new generation of electric devices to resolve the power consumption and variability issues in today's microelectronics industry. Among various dilute magnetic semiconductors (DMSs), group IV elements such as Si and Ge are the ideal material candidates because of their excellent compatibility with the conventional complementary metal-oxide-semiconductor (MOS) technology. Here we report, for the first time, the successful synthesis of self-assembled dilute magnetic Mn(0.05)Ge(0.95) quantum dots with ferromagnetic order above room temperature, and the demonstration of electric-field control of ferromagnetism in MOS ferromagnetic capacitors up to 100 K. We found that by applying electric fields to a MOS gate structure, the ferromagnetism of the channel layer can be effectively modulated through the change of hole concentration inside the quantum dots. Our results are fundamentally important in the understanding and to the realization of high-efficiency Ge-based spin field-effect transistors.
Bismuth-induced phase control of GaAs nanowires grown by molecular beam epitaxy
Publisher: AIP Publishing
Date: 20-10-2014
DOI: 10.1063/1.4898702
Abstract: In this work, the crystal structure of GaAs nanowires grown by molecular beam epitaxy has been tailored only by bismuth without changing the growth temperature and V/III flux ratio. The introduction of bismuth can lead to the formation of zinc-blende GaAs nanowires, while the removal of bismuth changes the structure into a 4H polytypism before it turns back to the wurtzite phase eventually. The theoretical calculation shows that it is the steadiest for bismuth to adsorb on the GaAs(111)B surface compared to the liquid gold catalyst surface and the interface between the gold catalyst droplet and the nanowire, and these adsorbed bismuth could decrease the diffusion length of adsorbed Ga and hence the supersaturation of Ga in the gold catalyst droplet.
Role of implantation-induced defects on the response time of semiconductor saturable absorbers
Publisher: AIP Publishing
Date: 06-09-1999
DOI: 10.1063/1.124718
Abstract: Arsenic ion implantation with thermal annealing was used to shorten the response times of GaAs-based saturable absorber structures. Ultrafast absorption bleaching measurements indicated that the recovery time was decreased with increasing the implantation dose. However, above a certain dose the recovery time increased again. This behavior was correlated with the microstructure of the residual implantation defects.
Subsurface Structures of Monocrystalline Silicon Generated by Nanogrinding
Publisher: Trans Tech Publications, Ltd.
Date: 09-2008
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.389-390.465
Abstract: This paper reports the effect of nanogrinding conditions on the formation of subsurface structures of monocrystalline silicon (100) substrates. It was found that the amorphization and the transformation of high pressure phases were related to the grit depth of cut employed in nanogrinding. The formation mechanisms were found to be different from those previously reported from the nanoindentation studies.
Strain relaxation by alloying effects in ge islands grown on si(001)
Publisher: American Physical Society (APS)
Date: 15-12-1999
Paramagnetic Cu-doped Bi2Te3 nanoplates
Publisher: AIP Publishing
Date: 03-02-2014
DOI: 10.1063/1.4863966
Abstract: Uniform Cu-doped Bi2Te3 hexagonal nanoplates with widths of ∼200 nm and thicknesses of ∼20 nm were synthesized using a solvothermal method. According to the structural characterization and compositional analysis, the Cu2+ ions were found to substitute Bi3+ ions in the lattice. High-level Cu doping induces a lattice distortion and decreases the crystal lattice by 1.17% in the a axis and 2.38% in the c axis. A paramagnetic state is observed in these nanoplates from 2 to 295 K, which is a significant difference from their diamagnetic un-doped Bi2Te3.
Room-Temperature Electric-Field Controlled Ferromagnetism in Mn0.05Ge0.95 Quantum Dots
Publisher: American Chemical Society (ACS)
Date: 28-07-2010
DOI: 10.1021/NN101516T
Abstract: Room-temperature control of ferromagnetism by electric fields in magnetic semiconductors has been actively pursued as one of important approaches to realize practical spintronic and nonvolatile logic devices. While Mn-doped III-V semiconductors were considered as potential candidates for achieving this controllability, the search for an ideal material with high Curie temperature (T(c) > 300 K) and controllable ferromagnetism at room temperature has continued for nearly a decade. Recently, Mn(0.05)Ge(0.95) quantum dots (QDs) were demonstrated to have a T(c) above 300 K. However, the field control of ferromagnetism based on hole-mediated effect remained at low temperatures and thus prohibited spintronic devices operable at ambient environment. Here, we report a successful demonstration of electric-field control of ferromagnetism in the Mn(0.05)Ge(0.95) quantum dots up to 300 K. We show that, by using quantum structure, high-quality material can be obtained and effective hole mediation due to quantum confinement effect can be achieved. Upon the application of gate bias to a metal-oxide-semiconductor (MOS) capacitor, the ferromagnetism of the channel layer, that is, the Mn(0.05)Ge(0.95) quantum dots, was manipulated through the change of hole concentration. Our results are fundamentally and technologically important toward the realization of room-temperature spin field-effect transistors and nonvolatile spin logic devices.
Core-shell double phase crystal in an yttrium-containing Zr-based bulk metallic glass
Publisher: Elsevier BV
Date: 08-2008
Highly Thiolated Dendritic Mesoporous Silica Nanoparticles with High-Content Gold as Nanozymes: The Nano-Gold Size Matters
Publisher: American Chemical Society (ACS)
Date: 19-03-2019
Abstract: Thiolated dendritic mesoporous silica nanoparticles (T-DMSNs) with ultrahigh density of thiol groups (284.6 ± 9 μmol g
Enhanced Hydrogen Storage Kinetics and Stability by Synergistic Effects of in Situ Formed CeH2.73 and Ni in CeH2.73-MgH2-Ni Nanocomposites
Publisher: American Chemical Society (ACS)
Date: 08-04-2014
DOI: 10.1021/JP500439N
Synthesis of tungsten oxide tapered needles with nanotips
Publisher: Elsevier BV
Date: 05-2007
Boosting the thermoelectric performance of p-type heavily Cu-doped polycrystalline SnSe via inducing intensive crystal imperfections and defect phonon scattering
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8SC02397B
Abstract: In this study, we, for the first time, report a high Cu solubility of 11.8% in single crystal SnSe microbelts synthesized via a facile solvothermal route.
A thermodynamic structural model of graphene oxide
Publisher: AIP Publishing
Date: 09-10-2017
DOI: 10.1063/1.4991967
Abstract: Graphene oxide is an easy-to-make material that has a similar structure with graphene. However, the real structure of graphene oxide is still controversial, and an accurate structural model is crucial for understanding its various properties. In this study, by using molecular mechanics and density functional theory, we introduce a thermodynamically favorable structural model of graphene oxide with chemical composition variable from C1.5O to C2.5O. We also calculate their theoretical Raman spectra and electronic properties. It has been found that, in the proposed graphene oxide structure, the para-substituted epoxide groups stay in close proximity to the hydroxyl, but on the opposite sides of the carbon sheet. In addition, on the edge of graphene oxide sheet, the carboxyl prefers attachment in the armchair orientation, while the carbonyl prefers the zigzag orientation.
ZnS nanostructures for field emitters
Publisher: IEEE
Date: 02-2010
Structural characteristics of GaSb∕GaAs nanowire heterostructures grown by metal-organic chemical vapor deposition
Publisher: AIP Publishing
Date: 04-12-2006
DOI: 10.1063/1.2402234
Abstract: Highly lattice mismatched (7.8%) GaAs∕GaSb nanowire heterostructures were grown by metal-organic chemical vapor deposition and their detailed structural characteristics were determined by electron microscopy. The facts that (i) no defects have been found in GaSb and its interfaces with GaAs and (ii) the lattice mismatch between GaSb∕GaAs was fully relaxed suggest that the growth of GaSb nanowires is purely governed by the thermodynamics. The authors believe that the low growth rate of GaSb nanowires leads to the equilibrium growth.
Anatase TiO2 Crystal Facet Growth: Mechanistic Role of Hydrofluoric Acid and Photoelectrocatalytic Activity
Publisher: American Chemical Society (ACS)
Date: 07-06-2011
DOI: 10.1021/AM200363P
Abstract: This work reports a facile hydrothermal approach to directly grow anatase TiO(2) crystals with exposed {001} facets on titanium foil substrate by controlling pH of HF solution. The mechanistic role of HF for control growth of the crystal facet of anatase TiO(2) crystals has been investigated. The results demonstrate that controlling solution pH controls the extent of surface fluorination of anatase TiO(2), hence the size, shape, morphology, and {001} faceted surface area of TiO(2) crystals. The theoretical calculations reveal that {001} faceted surface fluorination of anatase TiO(2) can merely occur via dissociative adsorption of HF molecules under acidic conditions while the adsorption of Na(+)F(-) is thermodynamically prohibited. This confirms that the presence of molecular form of HF but not F(-) is essential for preservation of exposed {001} facets of anatase TiO(2). Anatase TiO(2) crystals with exposed {001} facets can be directly fabricated on titanium foil by controlling the solution pH ≤ 5.8. When pH is increased to near neutral and beyond (e.g., pH ≥ 6.6), the insufficient concentration of HF ([HF] ≤ 0.04%) dramatically reduces the extent of surface fluorination, leading to the formation of anatase TiO(2) crystals with {101} facets and titanate nanorods/nanosheets. The anatase TiO(2) nanocrystals with exposed {001} facets exhibits a superior photoelectrocatalytic activity toward water oxidation. The findings of this work clarify the mechanistic role of HF for controlling the crystal facet growth, providing a facile means for massive production of desired nanostructures with high reactive facets on solid substrates for other metal oxides.
Light-Induced Positive and Negative Photoconductances of InAs Nanowires toward Rewritable Nonvolatile Memory
Publisher: American Chemical Society (ACS)
Date: 13-08-2019
Growth temperature and V/III ratio effects on the morphology and crystal structure of InP nanowires
Publisher: IOP Publishing
Date: 15-10-2010
DOI: 10.1088/0022-3727/43/44/445402
Abstract: The effects of growth temperature and V/III ratio on the morphology and crystallographic phases of InP nanowires that are grown by metal organic chemical vapour deposition have been studied. We show that higher growth temperatures or higher V/III ratios promote the formation of wurtzite nanowires while zinc-blende nanowires are favourable at lower growth temperatures and lower V/III ratios. A schematic map of distribution of zinc-blende and wurtzite structures has been developed in the range of growth temperatures (400–510 °C) and V/III ratios (44 to 700) investigated in this study.
Compositional Varied Core–Shell InGaP Nanowires Grown by Metal–Organic Chemical Vapor Deposition
Publisher: American Chemical Society (ACS)
Date: 22-05-2019
DOI: 10.1021/ACS.NANOLETT.9B00915
Abstract: In this study, we report the growth of core-shell InGaP nanowires with compositional varied cores/shells using metal-organic chemical vapor deposition. These core-shell InGaP nanowires exhibit Ga-enriched cores attributed to the strong affinity between Au and In, and In-enriched shells due to In-rich vapor ambient. Detailed electron microscopy investigations indicate that the In and Ga concentrations in the nanowire cores and shells varied along the growth direction of InGaP nanowires. It is found that the strain relaxation through Ga diffusion outward and In diffusion inward leads to the decrease of compositional difference between the nanowire core and shell from top to bottom. This study offers a possibility to grow structural complex ternary nanowires that can be used for future applications.
Electrical and structural analysis of high-dose Si implantation in GaN
Publisher: AIP Publishing
Date: 19-05-1997
DOI: 10.1063/1.119254
Abstract: For the development of ion implantation processes for GaN to advanced devices, it is important to understand the dose dependence of impurity activation along with implantation-induced damage generation and removal. We find that Si implantation in GaN can achieve 50% activation at a dose of 1×1016 cm−2, despite significant residual damage after the 1100 °C activation anneal. The possibility that the generated free carriers are due to implantation damage alone and not Si-donor activation is ruled out by comparing the Si results to those for implantation of the neutral species Ar. Ion channeling and cross-sectional transmission electron microscopy are used to characterize the implantation-induced damage both as implanted and after a 1100 °C anneal. Both techniques confirm that significant damage remains after the anneal, which suggests that activation of implanted Si donors in GaN doses not require complete damage removal. However, an improved annealing process may be needed to further optimize the transport properties of implanted regions in GaN.
Multilayered carbon films for tribological applications
Publisher: Elsevier BV
Date: 02-2003
Fabrication and visible emission of single-crystal diameter-modulated gallium phosphide nanochains
Publisher: AIP Publishing
Date: 15-06-2010
DOI: 10.1063/1.3452378
Abstract: The diameter-modulated single crystalline gallium phosphide (GaP) nanochains were synthesized by a facile method within a confined reaction zone. By varying the Ga concentration in the reaction zone, the size of knots of GaP nanochains can be manipulated. These zinc-blende structured GaP nanochains with ⟨111⟩ axial directions possess strong visible emissions around 700 nm at room temperature, indicating their potential applications in light sources, laser or light emitting display devices.
Extracting composition and alloying information of coherent Ge(Si)/Si(001) islands from [001] on-zone bright-field diffraction contrast images
Publisher: AIP Publishing
Date: 15-09-2001
DOI: 10.1063/1.1394900
Abstract: Ge(Si)/Si(001) coherent islands grown at 700 °C by molecular beam epitaxy were investigated using transmission electron microscopy. [001] on-zone bright-field diffraction contrast imaging and image simulation techniques were used to investigate the structure of these coherent islands. Comparison of simulated and experimental images indicates nonuniform composition distribution within the coherent islands when the islands were grown at high temperatures (700 °C), but uniform composition for growth at lower temperatures (600 °C).
Novel growth and properties of GaAs nanowires on Si substrates
Publisher: IOP Publishing
Date: 07-12-2009
DOI: 10.1088/0957-4484/21/3/035604
Abstract: Straight, vertically aligned GaAs nanowires were grown on Si(111) substrates coated with thin GaAs buffer layers. We find that the V/III precursor ratio and growth temperature are crucial factors influencing the morphology and quality of buffer layers. A double layer structure, consisting of a thin initial layer grown at low V/III ratio and low temperature followed by a layer grown at high V/III ratio and high temperature, is crucial for achieving straight, vertically aligned GaAs nanowires on Si(111) substrates. An in situ annealing step at high temperature after buffer layer growth improves the surface and structural properties of the buffer layer, which further improves the morphology of the GaAs nanowire growth. Through such optimizations we show that vertically aligned GaAs nanowires can be fabricated on Si(111) substrates and achieve the same structural and optical properties as GaAs nanowires grown directly on GaAs(111)B substrates.
Revisiting the precipitation sequence in Al–Zn–Mg-based alloys by high-resolution transmission electron microscopy
Publisher: Elsevier BV
Date: 11-2010
Growth of Magnetic Yard‐Glass Shaped Boron Nitride Nanotubes with Periodic Iron Nanoparticles
Publisher: Wiley
Date: 04-10-2007
A TEM study on the crystallization behavior of an yttrium-doped Zr-based bulk metallic glass
Publisher: Elsevier BV
Date: 07-2007
Room-temperature chiral charge pumping in Dirac semimetals
Publisher: Springer Science and Business Media LLC
Date: 09-01-2017
DOI: 10.1038/NCOMMS13741
Abstract: Chiral anomaly, a non-conservation of chiral charge pumped by the topological nontrivial gauge fields, has been predicted to exist in Weyl semimetals. However, until now, the experimental signature of this effect exclusively relies on the observation of negative longitudinal magnetoresistance at low temperatures. Here, we report the field-modulated chiral charge pumping process and valley diffusion in Cd 3 As 2 . Apart from the conventional negative magnetoresistance, we observe an unusual nonlocal response with negative field dependence up to room temperature, originating from the diffusion of valley polarization. Furthermore, a large magneto-optic Kerr effect generated by parallel electric and magnetic fields is detected. These new experimental approaches provide a quantitative analysis of the chiral anomaly phenomenon which was inaccessible previously. The ability to manipulate the valley polarization in topological semimetal at room temperature opens up a route towards understanding its fundamental properties and utilizing the chiral fermions.
CdS/CdSe lateral heterostructure nanobelts by a two-step physical vapor transport method
Publisher: IOP Publishing
Date: 10-03-2010
DOI: 10.1088/0957-4484/21/14/145602
Abstract: The two-dimensional heterostructure nanobelts with a central CdSe region and lateral CdS structures are synthesized by a two-step physical vapor transport method. The large growth rate difference between lateral CdS structures on both +/- (0001) sides of the CdSe region is found. The growth anisotropy is discussed in terms of the polar nature of the side +/- (0001) surfaces of CdSe. High-resolution transmission electron microscopy reveals the CdSe central region covered with non-uniform CdS layer/islands. From micro-photoluminescence measurements, a systematic blueshift of emission energy from the central CdSe region in accordance with the increase of lateral CdS growth temperature is observed. This result indicates that the intermixing rate in the CdSe region with CdS increases with the increase of lateral CdS growth temperature. In conventional CdSSe ternary nanostructures, morphology and emission wavelength were correlated parameters. However, the morphology and emission wavelength are independently controllable in the CdS/CdSe lateral heterostructure nanobelts. This structure is attractive for applications in visible optoelectronic devices.
Crystal-phase control of GaAs–GaAsSb core–shell/axial nanowire heterostructures by a two-step growth method
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TC01529E
Abstract: This study provides a controllable approach to grow both wurtzite and zinc-blende III–Sb nanowire heterostructures.
Epitaxial orientation of Mg2Si(110) thin film on Si(111) substrate
Publisher: AIP Publishing
Date: 15-12-2007
DOI: 10.1063/1.2821916
Abstract: Epitaxial Mg2Si(110) thin film has been obtained on Si(111) substrate by thermally enhanced solid-phase reaction of epitaxial Mg film with underlying Si substrate. An epitaxial orientation relationship of Si(111)∥Mg2Si(110) and Si⟨11¯0⟩∥Mg2Si⟨11¯0⟩ has been revealed by transmission electron microscopy. The formation of the unusual epitaxial orientation relationship is attributed to the strain relaxation of Mg2Si film in a MgO∕Mg2Si∕Si double heterostructure.
Preferential nucleation and growth of InAs/GaAs(0 0 1) quantum dots on defected sites by droplet epitaxy
Publisher: Elsevier BV
Date: 10-2013
Ion-beam-induced porosity of GaN
Publisher: AIP Publishing
Date: 04-09-2000
DOI: 10.1063/1.1290722
Abstract: Wurtzite GaN films bombarded with heavy ions (197Au+) show anomalous swelling of the implanted region with corresponding volume expansion up to ∼50%. Results show that this phenomenon is due to the formation of a porous layer of amorphous GaN. An important implication of this study for the fabrication of GaN-based devices is that amorphization of GaN should be avoided during ion implantation.
Effects of Initial Texture on Rolling Texture and Property of Electrodeposited Nickel Plate
Publisher: American Scientific Publishers
Date: 09-2015
Growth of ZnS heterostructures for optoelectronic applications
Publisher: IEEE
Date: 12-2010
Graphene Flash Memory
Publisher: American Chemical Society (ACS)
Date: 25-08-2011
DOI: 10.1021/NN201809K
Abstract: Graphene's single atomic layer of sp(2) carbon has recently garnered much attention for its potential use in electronic applications. Here, we report a memory application for graphene, which we call graphene flash memory (GFM). GFM has the potential to exceed the performance of current flash memory technology by utilizing the intrinsic properties of graphene, such as high density of states, high work function, and low dimensionality. To this end, we have grown large-area graphene sheets by chemical vapor deposition and integrated them into a floating gate structure. GFM displays a wide memory window of ∼6 V at significantly low program/erase voltages of ±7 V. GFM also shows a long retention time of more than 10 years at room temperature. Additionally, simulations suggest that GFM suffers very little from cell-to-cell interference, potentially enabling scaling down far beyond current state-of-the-art flash memory devices.
Preferred orientation in carbon films induced by energetic condensation
Publisher: Elsevier BV
Date: 12-1996
High-tensile-strength and ductile novel Ti-Fe-N-B alloys reinforced with TiB nanowires
Publisher: Elsevier BV
Date: 12-2017
Tunable Ambipolar Polarization-Sensitive Photodetectors Based on High-Anisotropy ReSe2 Nanosheets
Publisher: American Chemical Society (ACS)
Date: 03-08-2016
Abstract: Atomically thin 2D-layered transition-metal dichalcogenides have been studied extensively in recent years because of their intriguing physical properties and promising applications in nanoelectronic devices. Among them, ReSe2 is an emerging material that exhibits a stable distorted 1T phase and strong in-plane anisotropy due to its reduced crystal symmetry. Here, the anisotropic nature of ReSe2 is revealed by Raman spectroscopy under linearly polarized excitations in which different vibration modes exhibit pronounced periodic variations in intensity. Utilizing high-quality ReSe2 nanosheets, top-gate ReSe2 field-effect transistors were built that show an excellent on/off current ratio exceeding 10(7) and a well-developed current saturation in the current-voltage characteristics at room temperature. Importantly, the successful synthesis of ReSe2 directly onto hexagonal boron nitride substrates has effectively improved the electron motility over 500 times and the hole mobility over 100 times at low temperatures. Strikingly, corroborating with our density-functional calculations, the ReSe2-based photodetectors exhibit a polarization-sensitive photoresponsivity due to the intrinsic linear dichroism originated from high in-plane optical anisotropy. With a back-gate voltage, the linear dichroism photodetection can be unambiguously tuned both in the electron and hole regime. The appealing physical properties demonstrated in this study clearly identify ReSe2 as a highly anisotropic 2D material for exotic electronic and optoelectronic applications.
A systematic study of long-range ordered 3D-SBA-15 materials by electron tomography
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1NJ20146H
Vertically standing Ge nanowires on GaAs(110) substrates
Publisher: IOP Publishing
Date: 21-02-2008
DOI: 10.1088/0957-4484/19/12/125602
Abstract: The growth of epitaxial Ge nanowires is investigated on (100), (111) B and (110) GaAs substrates in the growth temperature range from 300 to 380 °C. Unlike epitaxial Ge nanowires on Ge or Si substrates, Ge nanowires on GaAs substrates grow predominantly along the [Formula: see text] direction. Using this unique property, vertical [Formula: see text] Ge nanowires epitaxially grown on GaAs(110) surface are realized. In addition, these Ge nanowires exhibit minimal tapering and uniform diameters, regardless of growth temperatures, which is an advantageous property for device applications. Ge nanowires growing along the [Formula: see text] directions are particularly attractive candidates for forming nanobridge devices on conventional (100) surfaces.
Anomalous Photoelectrical Properties through Strain Engineering Based on a Single Bent InAsSb Nanowire
Publisher: American Chemical Society (ACS)
Date: 20-01-2021
Nanowires for optoelectronic device applications
Publisher: Wiley
Date: 12-2009
Metallic and Ionic Fe Induced Growth of Si−SiOx Core−Shell Nanowires
Publisher: American Chemical Society (ACS)
Date: 19-08-2010
DOI: 10.1021/JP105952M
Polarity driven simultaneous growth of free-standing and lateral GaAsP epitaxial nanowires on GaAs (001) substrate
Publisher: AIP Publishing
Date: 25-11-2013
DOI: 10.1063/1.4834377
Abstract: Simultaneous growth of ⟨111⟩B free-standing and ±[110] lateral GaAsP epitaxial nanowires on GaAs (001) substrates were observed and investigated by electron microscopy and crystallographic analysis. It was found that the growth of both free-standing and lateral ternary nanowires via Au catalysts was driven by the fact that Au catalysts prefer to maintain low-energy {111}B interfaces with surrounding GaAs(P) materials: in the case of free-standing nanowires, Au catalysts maintain {111}B interfaces with their underlying GaAsP nanowires while in the case of lateral nanowires, each Au catalyst remain their side {111}B interfaces with the surrounding GaAs(P) material during the lateral nanowire growth.
High activity electrocatalysts from metal–organic framework-carbon nanotube templates for the oxygen reduction reaction
Publisher: Elsevier BV
Date: 02-2015
Sulfur-doped gallium phosphide nanowires and their optoelectronic properties
Publisher: IOP Publishing
Date: 17-08-2010
DOI: 10.1088/0957-4484/21/37/375701
Abstract: Sulfur-doped gallium phosphide nanowires were synthesized in a high yield by a facile sublimation of ball-milled mixture powders in a confined reaction zone. The nanowires have diameters in the range of 50-200 nm and lengths up to tens of micrometers. They consist of single-crystalline zinc blende structure crystals with a (111) growth direction. Electron energy-loss spectroscopy reveals that the sulfur doping occurs in the uniform forms of the body. Amorphous Ga-O containing a self-catalyst growth mechanism is proposed based on the detailed characterizations. Photoluminescence shows strong visible emissions at room temperature, indicating their potential applications in light sources, laser or light emitting display devices.
Dynamics of Strongly Degenerate Electron−Hole Plasmas and Excitons in Single InP Nanowires
Publisher: American Chemical Society (ACS)
Date: 29-09-2007
DOI: 10.1021/NL071733L
Abstract: Low-temperature time-resolved photoluminescence spectroscopy is used to probe the dynamics of photoexcited carriers in single InP nanowires. At early times after pulsed excitation, the photoluminescence line shape displays a characteristic broadening, consistent with emission from a degenerate, high-density electron-hole plasma. As the electron-hole plasma cools and the carrier density decreases, the emission rapidly converges toward a relatively narrow band consistent with free exciton emission from the InP nanowire. The free excitons in these single InP nanowires exhibit recombination lifetimes closely approaching that measured in a high-quality epilayer, suggesting that in these InP nanowires, electrons and holes are relatively insensitive to surface states. This results in higher quantum efficiencies than other single-nanowire systems as well as significant state-filling and band gap renormalization, which is observed at high electron-hole carrier densities.
Science in brief: Highlights from the applied physiology, muscle and genetics abstracts at the International Conference on Equine Exercise Physiology.
Publisher: Wiley
Date: 10-12-2016
DOI: 10.1111/EVJ.12484
Quality Control of GaAs Nanowire Structures by Limiting As Flux in Molecular Beam Epitaxy
Publisher: American Chemical Society (ACS)
Date: 24-08-2015
Mn behavior in Ge0.96Mn0.04 magnetic thin films grown on Si
Publisher: AIP Publishing
Date: 15-03-2008
DOI: 10.1063/1.2875110
Abstract: Mn behaviors in the Ge0.96Mn0.04 thin films grown on Si (001) substrates by molecular beam epitaxy were investigated by high resolution transmission electron microscopy, electron energy loss spectroscopy, and energy dispersive spectroscopy. Unlike the previously reported case of GeMn thin films grown on Ge, Mn has been found to be diffused toward to the surface during the thin film growth. When the Mn concentration is sufficiently high, Mn5Ge3 clusters may be formed. Further annealing of the high Mn concentrated thin film promotes the formation of α-Mn metallic clusters. We believe that all these extraordinary phenomena are attributed to Si as the substrate.
Growth of single-crystal W whiskers during humid H2/N2 reduction of Ni, Fe–Ni, and Co–Ni doped tungsten oxide
Publisher: Elsevier BV
Date: 08-2009
High tensile-strength and ductile titanium matrix composites strengthened by TiB nanowires
Publisher: Elsevier BV
Date: 12-2017
Anodic-oxide-induced interdiffusion in GaAs/AlGaAs quantum wells
Publisher: AIP Publishing
Date: 02-1998
DOI: 10.1063/1.366830
Abstract: Enhancement of interdiffusion in GaAs/AlGaAs quantum wells due to anodic oxides was studied. Photoluminescence, transmission electron microscopy, and quantum well modeling were used to understand the effects of intermixing on the quantum well shape. Residual water in the oxide was found to increase the intermixing, though it was not the prime cause for intermixing. Injection of defects such as group III vacancies or interstitials was considered to be a driving force for the intermixing. Different current densities used in the experimental range to create anodic oxides had little effect on the intermixing.
Facile Synthesis and Characterization of Potassium-Doped MnO2 Nanowires
Publisher: American Scientific Publishers
Date: 04-2008
DOI: 10.1166/JNN.2008.046
Abstract: A new type of potassium doped manganese oxide nanowires were synthesized using a simple hydrothermal route. The reduction of MnO – 4 in the presence of acetate species led to the formation of the Multi-filamentous nanowire structure. Detailed TEM and chemical characterizations indicated that potassium ions were homogeneously distributed in the nanowires. XPS results show a clear binding energy shift (1 eV) for K 2p peak in nanowires compared with its starting material of KMnO 4 . Detailed synthetic condition investigation indicated that the presence of acetate ions played an important role in the formation of such a type of nanowires other than layered structures.
Adherent carbon film deposition by cathodic arc with implantation
Publisher: American Vacuum Society
Date: 03-1995
DOI: 10.1116/1.579372
Abstract: A method of improving the adhesion of carbon thin films deposited using a cathodic vacuum arc by the use of implantation at energies up to 20 keV is described. A detailed analysis of carbon films deposited onto silicon in this way is carried out using complementary techniques of transmission electron microscopy and x-ray photoelectron spectroscopy (XPS) is presented. This analysis shows that an amorphous mixing layer consisting of carbon and silicon is formed between the grown pure carbon film and the crystalline silicon substrate. In the mixing layer, it is shown that some chemical bonding occurs between carbon and silicon. Damage to the underlying crystalline silicon substrate is observed and believed to be caused by interstitial implanted carbon atoms which XPS shows are not bonded to the silicon. The effectiveness of this technique is confirmed by scratch testing and by analysis with scanning electron microscopy which shows failure of the silicon substrate occurs before delamination of the carbon film.
Carrier capture and relaxation in Stranski-KrastanowIn
Publisher:
American Physical Society (APS)
Date:
15-07-2000
Publisher: American Physical Society (APS)
Date: 15-07-2000
Correction to “Strong Phonon–Phonon Interactions Securing Extraordinary Thermoelectric Ge1–xSbxTe with Zn-Alloying-Induced Band Alignment”
Publisher: American Chemical Society (ACS)
Date: 03-10-2019
DOI: 10.1021/JACS.9B10240
Crowding-out effect strategy using AgCl for realizing a super low lattice thermal conductivity of SnTe
Publisher: Elsevier BV
Date: 09-2020
Arrayed Van Der Waals Broadband Detectors for Dual‐Band Detection
Publisher: Wiley
Date: 16-02-2017
Abstract: An advanced visible/infrared dual-band photodetector with high-resolution imaging at room temperature is proposed and demonstrated for intelligent identification based on the 2D GaSe/GaSb vertical heterostructure. It resolves the challenges of producing large-scale 2D growth, achieving fast response speed, outstanding detectivity, and lower manufacture cost, which are the main obstacles for industrialization of 2D-materials-based photodetection.
Defect-Free <110> Zinc-Blende Structured InAs Nanowires Catalyzed by Palladium
Publisher: American Chemical Society (ACS)
Date: 05-10-2012
DOI: 10.1021/NL303028U
Abstract: We report the epitaxial growth of defect-free zinc-blende structured InAs nanowires on GaAs{111}(B) substrates using palladium catalysts in a metal-organic chemical vapor deposition reactor. Through detailed morphological, structural, and chemical characterizations using electron microscopy, it is found that these defect-free InAs nanowires grew along the directions with four low-energy {111} faceted side walls and {1[combining overline]1[combining overline]3[combining overline]} nanowire/catalyst interfaces. It is anticipated that these defect-free nanowires benefit from the fact that the nanowire/catalyst interfaces does not contain the {111} planes, and the nanowire growth direction is not along the directions. This study provides an effective approach to control the crystal structure and quality of epitaxial III-V nanowires.
Catalytic growth of metallic tungsten whiskers based on the vapor–solid–solid mechanism
Publisher: IOP Publishing
Date: 16-07-2008
DOI: 10.1088/0957-4484/19/34/345604
Abstract: Metallic W whiskers with tip diameters of 50-250 nm and lengths of 2-4 µm have been successfully synthesized in large quantities using Co-Ni alloyed catalysts. The relatively low growth temperature of 850 °C and the large catalyst size (over 100 nm) suggest that the growth of the W whiskers must be governed by the vapor-solid-solid mechanism. Our results show that the vapor-solid-solid model is suitable not only for the growth of nano-scaled whiskers with diameters below 100 nm, but also for submicro-scaled whiskers with diameters well above 100 nm. This technique has great potential to synthesize well controlled metallic whiskers.
III-V nanowires for optoelectronics
Publisher: SPIE
Date: 22-09-2006
DOI: 10.1117/12.692715
Polarity driven formation of InAs/GaAs hierarchical nanowire heterostructures
Publisher: AIP Publishing
Date: 17-11-2008
DOI: 10.1063/1.3033551
Abstract: The structural and morphological characteristics of InAs/GaAs radial nanowire heterostructures were investigated using transmission electron microscopy. It has been found that the radial growth of InAs was preferentially initiated on the {112}A sidewalls of GaAs nanowires. This preferential deposition leads to extraordinarily asymmetric InAs/GaAs radial nanowire heterostructures. Such formation of radial nanowire heterostructures provides an opportunity to engineer hierarchical nanostructures, which further widens the potential applications of semiconductor nanostructures.
Structural and optical characterization of vertical GaAs/GaP core-shell nanowires grown on Si substrates
Publisher: IEEE
Date: 12-2010
Advanced Thermoelectric Design: From Materials and Structures to Devices
Publisher: American Chemical Society (ACS)
Date: 02-07-2020
Strengthening brittle semiconductor nanowires through stacking faults: Insights from in situ mechanical testing
Publisher: American Chemical Society (ACS)
Date: 03-09-2013
DOI: 10.1021/NL402180K
Abstract: Quantitative mechanical testing of single-crystal GaAs nanowires was conducted using in situ deformation transmission electron microscopy. Both zinc-blende and wurtzite structured GaAs nanowires showed essentially elastic deformation until bending failure associated with buckling occurred. These nanowires fail at compressive stresses of ~5.4 GPa and 6.2 GPa, respectively, which are close to those values calculated by molecular dynamics simulations. Interestingly, wurtzite nanowires with a high density of stacking faults fail at a very high compressive stress of ~9.0 GPa, demonstrating that the nanowires can be strengthened through defect engineering. The reasons for the observed phenomenon are discussed.
Effect of cooling rate on microstructure and deformation behavior of Ti-based metallic glassy/crystalline powders
Publisher: Elsevier BV
Date: 08-2010
Thermoelectrics for medical applications: Progress, challenges, and perspectives
Publisher: Elsevier BV
Date: 06-2022
Rational Design of Bi2Te3 Polycrystalline Whiskers for Thermoelectric Applications
Publisher: American Chemical Society (ACS)
Date: 24-12-2014
DOI: 10.1021/AM5078528
Abstract: Bi2Te3 polycrystalline whiskers consisting of interconnected nanoplates have been synthesized through chemical transformation from In2Te3 polycrystalline whisker templates assembled by nanoparticles. The synthesized Bi2Te3 whiskers preserve the original one-dimensional morphology of the In2Te3, while the In2Te3 nanoparticles can be transformed into the Bi2Te3 thin nanoplates, accompanied by the formation of high-density interfaces between nanoplates. The hot-pressed nanostructures consolidated from Bi2Te3 polycrystalline whiskers at 400 °C demonstrate a promising figure of merit (ZT) of 0.71 at 400 K, which can be attributed to their low thermal conductivity and relatively high electrical conductivity. The small nanoparticles inherited from the polycrystalline whiskers and high-density nanoparticle interfaces in the hot-pressed nanostructures contribute to the significant reduction of thermal conductivity. This study provides a rational chemical transformation approach to design and synthesize polycrystalline microstructures for enhanced thermoelectric performances.
Thickness-Controlled Three-Dimensional Dirac Semimetal for Scalable High-Performance Terahertz Optoelectronics
Publisher: American Chemical Society (ACS)
Date: 07-06-2021
Distinct Photocurrent Response of Individual GaAs Nanowires Induced by n-Type Doping
Publisher: American Chemical Society (ACS)
Date: 29-06-2012
DOI: 10.1021/NN300962Z
Abstract: The doping-dependent photoconductive properties of in idual GaAs nanowires have been studied by conductive atomic force microscopy. Linear responsivity against the bias voltage is observed for moderate n-doped GaAs wires with a Schottky contact under illumination, while that of the undoped ones exhibits a saturated response. The carrier lifetime of a single nanowire can be obtained by simulating the characteristic photoelectric behavior. Consistent with the photoluminescence results, the significant drop of minority hole lifetime, from several hundred to subpicoseconds induced by n-type doping, leads to the distinct photoconductive features. Moreover, by comparing with the photoelectric behavior of AlGaAs shelled nanowires, the equivalent recombination rate of carriers at the surface is assessed to be >1 × 10(12) s(-1) for 2 × 10(17)cm(-3) n-doped bare nanowires, nearly 30 times higher than that of the doping-related bulk effects. This work suggests that intentional doping in nanowires could change the charge status of the surface states and impose significant impact on the electrical and photoelectrical performances of semiconductor nanostructures.
Surface-States-Modulated High-Performance InAs Nanowire Phototransistor
Publisher: American Chemical Society (ACS)
Date: 16-07-2020
Superconductivity and magnetotransport of single-crystalline NbSe2nanoplates grown by chemical vapour deposition
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7NR06617A
Abstract: High-quality NbSe 2 nanoplates can be grown by a facile chemical vapour deposition method, exhibiting a two-dimensional characteristic in their superconductivities.
Crystallographically oriented Zn nanocrystals formed in ZnO by Mn+-implantation
Publisher: AIP Publishing
Date: 29-09-2008
DOI: 10.1063/1.2996028
Abstract: The nanostructural characteristics of ZnO implanted with Mn+ to doses ranging from 1×1015to1×1017cm−2 are systematically studied for both as-implanted and postannealed cases. The detailed structural characterizations confirmed that the Mn+ implantation and postannealing result in (1) the formation of crystallographically orientated Zn nanocrystals in the ZnO matrix and (2) Mn atoms occupy the Zn sites in ZnO.
New crystalline phases formed in a slowly-cooled Zr-based metallic glass
Publisher: Elsevier BV
Date: 05-2007
Effectively restricting MnSi precipitates for simultaneously enhancing the Seebeck coefficient and electrical conductivity in higher manganese silicide
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TC01937E
Abstract: Introducing Mg 2 Si into higher manganese silicide synthesis successfully suspended the precipitation of MnSi, leading to reduced effective mass, reduced optimized carrier concentration, and enhanced figure of merit, zT .
Growth of single-crystalline, atomically smooth MgO films on Ge(001) by molecular beam epitaxy
Publisher: Elsevier BV
Date: 12-2009
Observations of a Metal-Insulator Transition and Strong Surface States in Bi2-xSbxSe3 Thin Films
Publisher: Wiley
Date: 10-09-2014
Abstract: High-quality thin films of the topological insulator Bi2-xSbxSe3 are grown by molecular beam epitaxy. A metal-insulator transition along with strong surface states - revealed by Shubnikov-de Haas oscillations - is observed as the Sb concentration is increased. This system represents a widely tunable platform for achieving high surface conduction, suppressing the bulk influence, and manipulating the band structure of topological insulators.
Hot-Filament-Assisted Growth of Straight SiOx Nanowires for Optoelectronic Application
Publisher: American Chemical Society (ACS)
Date: 27-06-2013
DOI: 10.1021/JP403588P
In situ preparation of TiB nanowires for high-performance Ti metal matrix nanocomposites
Publisher: Elsevier BV
Date: 02-2018
Synthesis of thermoelectric materials
Publisher: Elsevier
Date: 2021
Unequal P distribution in nanowires and the layer during the growth of GaAsP nanowires on GaAs
Publisher: IEEE
Date: 12-2012
Effects of anodic oxide induced intermixing on the structural and optical properties of quantum wire structure grown on nonplanar GaAs substrate
Publisher: AIP Publishing
Date: 11-1996
DOI: 10.1063/1.363546
Abstract: Effects of anodic oxide induced intermixing on the structural and optical properties of stacked GaAs quantum wire (QWR) structures grown on a sawtooth-type nonplanar GaAs substrate are investigated. Cross-sectional transmission electron microscope (XTEM) observation, temperature dependent photoluminescence (PL) and cathodoluminescence (CL) imaging were used. Intermixing was achieved by pulsed anodic oxidation of the GaAs cap layer and subsequent rapid thermal annealing, was verified by XTEM analysis. A significant enhancement of QWR PL is observed accompanied by a notable blueshift of the sidewall quantum well (SQWL) PL due to the intermixing. Furthermore, an extended necking region is observed after the intermixing by spatially resolved CL. The temperature dependence of the PL intensities of both SQWL and QWR show maxima at approximately T∼110 K indicating the role of the extended necking region in feeding carriers to SQWL and QWR.
Structure Transition from Hexagonal Mesostructured Rodlike Silica to Multilamellar Vesicles
Publisher: American Chemical Society (ACS)
Date: 19-03-2008
DOI: 10.1021/LA8000569
Abstract: We studied the synthesis of siliceous structures by using a nonionic block copolymer (Pluronic P123) and perfluorooctanoic acid (PFOA) as cotemplates in an acid-catalyzed sol-gel process. Different siliceous structures were obtained through systematically varying the molar ratio (R) of PFOA/P123, and the resultant materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen sorption analysis, and Fourier-transform infrared spectroscopy. The results are consistent and reveal a structure transition from a highly ordered 2D hexagonal (HEX) mesostructure with a rodlike morphology to multilamellar vesicles (MLVs) with sharp edges when R is increased. The fact that the MLVs are initiated from the end of hexagonally mesostructured rods provides key evidence in such a novel structure transition. Our finding indicates that, at least in our observations, the MLVs are developed gradually from HEX structures, rather than by a direct cooperative self-assembly mechanism. It is suggested that PFOA molecules with rigid fluorocarbon chains closely interact with PEO. This interaction model may well explain (1) the "wall-thicken" effect in HEX mesostructures by enlarging the hydrophilic PEO moiety (R = 0-1.4), (2) the subsequent HEX to multilamellar structure transition by modifying the hydrophilic/hydrophobic volume ratio (R = 1.4-2.8), and (3) the formation of MLVs with sharp edges by increasing the bending energy. This model provides insight into the fabrication of novel porous materials by the use of block copolymers and fluorinated surfactant mixed templates.
Thermoelectric coolers for on-chip thermal management: Materials, design, and optimization
Publisher: Elsevier BV
Date: 10-2022
An A‐Site‐Deficient Perovskite offers High Activity and Stability for Low‐Temperature Solid‐Oxide Fuel Cells
Publisher: Wiley
Date: 23-10-2013
Abstract: Solid oxide fuel cells (SOFCs) directly convert fossil and/or renewable fuels into electricity and/or high-quality heat in an environmentally friendly way. However, high operating temperatures result in high cost and material issues, which have limited the commercialization of SOFCs. To lower their operating temperatures, highly active and stable cathodes are required to maintain a reasonable power output. Here, we report a layer-structured A-site deficient perovskite Sr0.95 Nb0.1 Co0.9 O3-δ (SNC0.95) prepared by solid-state reactions that shows not only high activity towards the oxygen reduction reaction (ORR) at operating temperatures below 600 °C, but also offers excellent structural stability and compatibility, and improved CO2 resistivity. An anode-supported fuel cell with SNC0.95 cathode delivers a peak power density as high as 1016 mW cm(-2) with an electrode-area-specific resistance of 0.052 Ω cm(2) at 500 °C.
Siliceous Nanopods from a Compromised Dual‐Templating Approach
Publisher: Wiley
Date: 08-11-2007
Achieving zT > 2 in p-Type AgSbTe2-xSex Alloys via Exploring the Extra Light Valence Band and Introducing Dense Stacking Faults
Publisher: Wiley
Date: 18-12-2018
Abstract: Through simultaneously enhancing the power factor by engineering the extra light band and enhancing phonon scatterings by introducing a high density of stacking faults, a record figure‐of‐merit over 2.0 is achieved in p‐type AgSbTe 2− x Se x alloys. Density functional theory calculations confirm the presence of the light valence band with large degeneracy in AgSbTe 2 , and that alloying with Se decreases the energy offset between the light valence band and the valence band maximum. Therefore, a significantly enhanced power factor is realized in p‐type AgSbTe 2− x Se x alloys. In addition, transmission electron microscopy studies indicate the appearance of stacking faults and grain boundaries, which together with grain boundaries and point defects significantly strengthen phonon scatterings, leading to an ultralow thermal conductivity. The synergetic strategy of simultaneously enhancing power factor and strengthening phonon scattering developed in this study opens up a robust pathway to tailor thermoelectric performance.
Impacts of Cu deficiency on the thermoelectric properties of Cu2−XSe nanoplates
Publisher: Elsevier BV
Date: 07-2016
Controllable Growth of Vertical Heterostructure GaTexSe1–x/Si by Molecular Beam Epitaxy
Publisher: American Chemical Society (ACS)
Date: 04-08-2015
Abstract: Two dimensional (2D) alloys, especially transition metal dichalcogenides, have attracted intense attention owing to their band-gap tunability and potential optoelectrical applications. Here, we report the controllable synthesis of wafer-scale, few-layer GaTexSe1-x alloys (0 ≤ x ≤ 1) by molecular beam epitaxy (MBE). We achieve a layer-by-layer growth mode with uniform distribution of Ga, Te, and Se elements across 2 in. wafers. Raman spectroscopy was carried out to explore the composition-dependent vibration frequency of phonons, which matches well with the modified random-element-isodisplacement model. Highly efficient photodiode arrays were also built by depositing few-layer GaTe0.64Se0.36 on n-type Si substrates. These p-n junctions have steady rectification characteristics with a rectifying ratio exceeding 300 and a high external quantum efficiency around 50%. We further measured more devices on MBE-grown GaTexSe1-x/Si heterostructures across the full range to explore the composition-dependent external quantum efficiency. Our study opens a new avenue for the controllable growth of 2D alloys with wafer-scale homogeneity, which is a prominent challenge in 2D material research.
Compositional design and microstructure analysis of Zr-based bulk metallic glasses
Publisher: Elsevier BV
Date: 12-2007
Cooling rate dependent as-cast microstructure and mechanical properties of Zr-based metallic glasses
Publisher: Springer Science and Business Media LLC
Date: 03-03-2007
High Thermoelectric Performance in Sintered Octahedron-Shaped Sn(CdIn)xTe1+2x Microcrystals
Publisher: American Chemical Society (ACS)
Date: 18-10-2018
Abstract: In this study, we fabricate In/Cd codoped octahedron-shape Sn(CdIn)
High-efficiency thermocells driven by thermo-electrochemical processes
Publisher: Elsevier BV
Date: 07-2021
Chemoselective and Continuous Flow Hydrogenations in Thin Films Using a Palladium Nanoparticle Catalyst Embedded in Cellulose Paper
Publisher: American Chemical Society (ACS)
Date: 20-12-2018
Structure and Field‐Emission Properties of Sub‐Micrometer‐Sized Tungsten‐Whisker Arrays Fabricated by Vapor Deposition
Publisher: Wiley
Date: 10-06-2009
An improved loop test for experimentally approaching the intrinsic strength of alumina nanoscale whiskers
Publisher: IOP Publishing
Date: 20-06-2013
DOI: 10.1088/0957-4484/24/28/285703
Abstract: An improved loop test, which consists of twisting a loop in a nanoscale whisker adhered to a transmission electron microscopy (TEM) grid or other flat substrate and pulling the ends until the loop breaks, was developed for experimentally approaching the intrinsic strength of the whisker material. Alumina whiskers with diameters in the 82-320 nm range, as test targets, exhibited an average fracture strength of 39.1 GPa with a maximum of 48.8 ± 1.8 GPa, which is close to the theoretical prediction of ∼46 GPa. In situ TEM fracture analysis demonstrated the brittle fracture of alumina whiskers with thicknesses down to 82 nm. Conventional SEM/TEM imaging induced fracture of the whisker loops that had experienced high strain and a possible mechanism were discussed.
Rationally designed functional macroporous materials as new adsorbents for efficient phosphorus removal
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM16681J
Destabilization of Mg-H bonding through nano-interfacial confinement by unsaturated carbon for hydrogen desorption from MgH2
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CP50515D
Abstract: We propose a new mechanism for destabilizing Mg-H bonding by means of a combination of the size effect and MgH2-carbon scaffold interfacial bonding, and experimentally realize low temperature hydrogen release starting from 50 °C using an MgH2@CMK-3 nanoconfinement system (37.5 wt% MgH2 loading amount). Based on computational calculations, it is found that the charge transfer from MgH2 to the carbon scaffold plays a critical role in the significant reduction of thermodynamics of MgH2 dehydrogenation. Our results suggest how to explore an alternative route for the enhancement of nano-interfacial confinement to destabilize the Mg-H hydrogen storage system.
A novel bottom-up solvothermal synthesis of carbon nanosheets
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TA13593D
Self-assembly and cathodoluminescence of microbelts from Cu-doped boron nitride nanotubes
Publisher: American Chemical Society (ACS)
Date: 29-07-2008
DOI: 10.1021/NN800211Z
Oxygen vacancy induced structural variations of exfoliated monolayer MnO2 sheets
Publisher: American Physical Society (APS)
Date: 03-02-2010
Transmission electron microscopy investigation of semiconductor quantum dots
Publisher: IEEE
Date: 2000
Outstanding thermoelectric properties of solvothermal-synthesized Sn1−3xInxAg2xTe micro-crystals through defect engineering and band tuning
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9TA11614A
Abstract: In eco-friendly SnTe thermoelectrics, In and Ag co-doping induces the synergistic effect of resonance energy levels and valence band convergence to enhance its electrical transport properties, while defects ameliorates its thermal transport.
Transmission electron microscopy investigation of substitution reactions from carbon nanotube template to silicon carbide nanowires
Publisher: IOP Publishing
Date: 18-05-2007
Alternative mechanism for misfit dislocation generation during high-temperature Ge(Si)/Si(001) island growth
Publisher: AIP Publishing
Date: 05-09-2002
DOI: 10.1063/1.1506414
Abstract: The misfit dislocations in [001] Ge(Si)/Si islands grown at 700 °C were investigated using transmission electron microscopy. 30° partial misfit dislocations are found both in the island/substrate interface and near the island surface. Since the 30° partial leads the movement of the 60° dissociated misfit dislocation in a (001) compressively strained system such as (001) GeSi/Si, a generation mechanism of misfit dislocations through partial misfit dislocations half loops is proposed.
Epitaxial growth of metal-organic framework nanosheets into single-crystalline orthogonal arrays
Publisher: Springer Science and Business Media LLC
Date: 18-09-2023
Thin boron nitride nanotubes with exceptionally high strength and toughness
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3NR00651D
Abstract: Bending manipulation and direct force measurements of ultrathin boron nitride nanotubes (BNNTs) were performed inside a transmission electron microscope. Our results demonstrate an obvious transition in mechanics of BNNTs when the external diameters of nanotubes are in the range of 10 nm or less. During in situ transmission electron microscopy bending tests, characteristic "hollow" ripple-like structures formed in the bent ultrathin BNNTs with diameters of sub-10 nm. This peculiar buckling/bending mode makes the ultrathin BNNTs hold very high post-buckling loads which significantly exceed their initial buckling forces. Exceptional compressive/bending strength as high as ∼1210 MPa was observed. Moreover, the analysis of reversible bending force curves of such ultrathin nanotubes indicates that they may store/adsorb strain energy at a density of ~400 × 10(6) J m(-3). Such nanotubes are thus very promising for strengthening and toughening of structural ceramics and may find potential applications as effective energy-absorbing materials like armor.
Express penetration of hydrogen on Mg(10͞13) along the close-packed-planes
Publisher: Springer Science and Business Media LLC
Date: 06-2015
DOI: 10.1038/SREP10776
Abstract: Metal atoms often locate in energetically favorite close-packed planes, leading to a relatively high penetration barrier for other atoms. Naturally, the penetration would be much easier through non-close-packed planes, i.e. high-index planes. Hydrogen penetration from surface to the bulk (or reversely) across the packed planes is the key step for hydrogen diffusion, thus influences significantly hydrogen sorption behaviors. In this paper, we report a successful synthesis of Mg films in preferential orientations with both close- and non-close-packed planes, i.e. (0001) and a mix of (0001) and (10"Equation missing" 3), by controlling the magnetron sputtering conditions. Experimental investigations confirmed a remarkable decrease in the hydrogen absorption temperature in the Mg (10"Equation missing" 3), down to 392 K from 592 K of the Mg film (0001), determined by the pressure-composition-isothermal (PCI) measurement. The ab initio calculations reveal that non-close-packed Mg(10"Equation missing" 3) slab is advantageous for hydrogen sorption, attributing to the tilted close-packed-planes in the Mg(10"Equation missing" 3) slab.
Transmission electron microscopy characterization of the deformation of CdZnTe single crystals induced by nanoscratching
Publisher: Elsevier BV
Date: 09-2011
Ultrahigh conductivity in Weyl semimetal NbAs nanobelts
Publisher: Springer Science and Business Media LLC
Date: 18-03-2019
DOI: 10.1038/S41563-019-0320-9
Abstract: In two-dimensional (2D) systems, high mobility is typically achieved in low-carrier-density semiconductors and semimetals. Here, we discover that the nanobelts of Weyl semimetal NbAs maintain a high mobility even in the presence of a high sheet carrier density. We develop a growth scheme to synthesize single crystalline NbAs nanobelts with tunable Fermi levels. Owing to a large surface-to-bulk ratio, we argue that a 2D surface state gives rise to the high sheet carrier density, even though the bulk Fermi level is located near the Weyl nodes. A surface sheet conductance up to 5-100 S per □ is realized, exceeding that of conventional 2D electron gases, quasi-2D metal films, and topological insulator surface states. Corroborated by theory, we attribute the origin of the ultrahigh conductance to the disorder-tolerant Fermi arcs. The evidenced low-dissipation property of Fermi arcs has implications for both fundamental study and potential electronic applications.
Selectively grown GaAs nanodisks on Si(100) by molecular beam epitaxy
Publisher: American Vacuum Society
Date: 18-02-2014
DOI: 10.1116/1.4865477
Abstract: The authors report the molecular beam epitaxial growth and the structural and optical characterizations of self-assembled/catalyst-free GaAs nanodisks on SiO2 masked Si(100) patterned substrates. Pure zincblende GaAs nanodisks with precise positioning and low defect density are demonstrated by selective area epitaxy. The influence of the growth temperature and deposition duration is investigated. Excellent morphological and structural properties are characterized by scanning electron microscopy and cross-sectional transmission electron microscopy. Defects in the epilayers are reduced by strain relaxation through facets formation and by a lateral overgrowth scheme atop the SiO2 mask which is corroborated by microRaman spectroscopy. In particular, the authors show how the material quality contributes to excellent optical properties observed by microphotoluminescence spectroscopy from 77 K to room temperature.
Structural Evolution of High-Performance Mn-Alloyed Thermoelectric Materials: A Case Study of SnTe
Publisher: Wiley
Date: 25-05-2021
Abstract: Mn alloying in thermoelectrics is a long‐standing strategy for enhancing their figure‐of‐merit through optimizing electronic transport properties by band convergence, valley perturbation, or spin‐orbital coupling. By contrast, mechanisms by which Mn contributes to suppressing thermal transports, namely thermal conductivity, is still ambiguous. A few precedent studies indicate that Mn introduces a series of hierarchical defects from the nano‐ to meso‐scale, leading to effective phonon scattering scoping a wide frequency spectrum. Due to insufficient insights at the atomic level, the theory remains as phenomenological and cannot be used to quantitatively predict the thermal conductivity of Mn‐alloyed thermoelectrics. Herein, by choosing the SnTe as a case study, aberration‐corrected transmission electron microscopy (TEM)/scanning transmission electron microscopy (STEM) to characterize the lattice complexity of Sn 1.02− x Mn x Te is employed. Mn as a “dynamic” dopant that plays an important role in SnTe with respect to different alloying levels or post treatments is revealed. The results indicate that Mn precipitates at x = 0.08 prior to reaching solubility (≈10 mol%), and then splits into Mn Sn substitution and γ‐MnTe hetero‐phases via mechanical alloying. Understanding such unique crystallography evolution, combined with a modified Debye‐Callaway model, is critical in explaining the decreased thermal conductivity of Sn 1.02− x Mn x Te with rational phonon scattering pathways, which should be applicable for other thermoelectric systems.
Determination of Al compositional profiles across AlAs/GaAs heterostructural interface at sub-nanometer spatial resolution by thickness fringe imaging
Publisher: Elsevier BV
Date: 08-2002
Microstructures and mechanical properties of Ce1-x Cax O2-y (x = 0.05, 0.1, 0.2) with different sintering temperatures
Publisher: Elsevier BV
Date: 02-2010
Large-scale synthesis of tungsten single-crystal microtubes via vapor-deposition process
Publisher: Elsevier BV
Date: 02-2011
Nitrogen doping in ion-exchangeable layered tantalate towards visible-light induced water oxidation
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0CC05440B
The effect of V/III ratio and catalyst particle size on the crystal structure and optical properties of InP nanowires
Publisher: IOP Publishing
Date: 13-05-2009
DOI: 10.1088/0957-4484/20/22/225606
Abstract: InP nanowires were grown on 111B InP substrates by metal-organic chemical vapour deposition in the presence of colloidal gold particles as catalysts. Transmission electron microscopy and photoluminescence measurements were carried out to investigate the effects of V/III ratio and nanowire diameter on structural and optical properties. Results show that InP nanowires grow preferably in the wurtzite crystal structure than the zinc blende crystal structure with increasing V/III ratio or decreasing diameter. Additionally, time-resolved photoluminescence (TRPL) studies have revealed that wurtzite nanowires show longer recombination lifetimes of approximately 2500 ps with notably higher quantum efficiencies.
Efficient production of ZnO nanowires by a ball milling and annealing method
Publisher: IOP Publishing
Date: 02-04-2007
The creep behaviour of poly(vinylidene fluoride)/“bud-branched” nanotubes nanocomposites
Publisher: Elsevier BV
Date: 09-2012
A Heterostructure Coupling of Exfoliated Ni–Fe Hydroxide Nanosheet and Defective Graphene as a Bifunctional Electrocatalyst for Overall Water Splitting
Publisher: Wiley
Date: 03-03-2017
Abstract: Herein, the authors demonstrate a heterostructured NiFe LDH-NS@DG10 hybrid catalyst by coupling of exfoliated Ni-Fe layered double hydroxide (LDH) nanosheet (NS) and defective graphene (DG). The catalyst has exhibited extremely high electrocatalytic activity for oxygen evolution reaction (OER) in an alkaline solution with an overpotential of 0.21 V at a current density of 10 mA cm
Computer-aided design of high-efficiency GeTe-based thermoelectric devices
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0EE01004A
Abstract: Enhanced thermoelectric performance by band convergence and superlattice precipitates combined with geometry optimization by computer-aided design produced a segmented thermoelectric device with a record-high conversion efficiency.
Growth and optical properties of stacked-pyramid zinc sulfide architectures
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CE05212H
Transmission electron microscopy study of (formula presented) quantum dots on a gaas(001) substrate
Publisher: American Physical Society (APS)
Date: 15-05-1999
Field Emission and Cathodoluminescence of ZnS Hexagonal Pyramids of Zinc Blende Structured Single Crystals
Publisher: Wiley
Date: 02-02-2009
Inhibited carrier transfer in ensembles of isolated quantum dots
Publisher: American Physical Society (APS)
Date: 15-12-1999
Hierarchical structures of single-crystalline anatase TiO2 nanosheets dominated by {001} facets
Publisher: Wiley
Date: 12-01-2011
Space-charge trap mediated conductance blockade in tunnel junctions with half-metallic electrodes
Publisher: AIP Publishing
Date: 10-11-2008
DOI: 10.1063/1.3025851
Abstract: A conductance blockade effect has been observed in the magnetic tunnel junction consisting of La0.7Sr0.3MnO3 electrodes and a SrTiO3 barrier. The blockade effect is correlated with the space-charge trap states in the barrier. The blockade threshold eVB=128meV is significantly greater than Coulomb charging energy EC=11meV. The blockade can be lifted with a magnetic field, accompanied by a very large magnetoresistance up to 10 000%. The intriging blockade behavior is distinctly different from the conventional Coulomb blockade effect, showing a unique spin-dependent tunneling process mediated by the localized charge trap states.
Ag doping induced abnormal lattice thermal conductivity in Cu2Se
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TC04129F
Abstract: Schematic diagram of Cu + /Ag + diffusion in the Se sublattice of Cu 2 Se, in which blocked diffusion of Ag + may subsequently block the diffusion of other Cu + and weaken the scattering of phonons.
Temperature and Bias-Assisted Transport Properties of LSMO/AlO/CoFeB Magnetic Tunnel Junction
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2010
Cuboid-like nanostructure strengthened equiatomic Ti–Zr–Nb–Ta medium entropy alloy
Publisher: Elsevier BV
Date: 11-2020
Evolution of InAs branches in InAs∕GaAs nanowire heterostructures
Publisher: AIP Publishing
Date: 24-09-2007
DOI: 10.1063/1.2790486
Abstract: Branched nanowire heterostructures of InAs∕GaAs were observed during Au-assisted growth of InAs on GaAs nanowires. The evolution of these branches has been determined through detailed electron microscopy characterization with the following sequence: (1) in the initial stage of InAs growth, the Au droplet is observed to slide down the side of the GaAs nanowire, (2) the downward movement of Au nanoparticle later terminates when the nanoparticle encounters InAs growing radially on the GaAs nanowire sidewalls, and (3) with further supply of In and As vapor reactants, the Au nanoparticles assist the formation of InAs branches with a well-defined orientation relationship with GaAs∕InAs core/shell stems. We anticipate that these observations advance the understanding of the kink formation in axial nanowire heterostructures.
Magnetotransport Properties of Cd3As2 Nanostructures
Publisher: American Chemical Society (ACS)
Date: 27-08-2015
Abstract: Three-dimensional (3D) topological Dirac semimetal has a linear energy dispersion in 3D momentum space, and it can be viewed as an analogue of graphene. Extensive efforts have been devoted to the understanding of bulk materials, but yet it remains a challenge to explore the intriguing physics in low-dimensional Dirac semimetals. Here, we report on the synthesis of Cd3As2 nanowires and nanobelts and a systematic investigation of their magnetotransport properties. Temperature-dependent ambipolar behavior is evidently demonstrated, suggesting the presence of finite-size of bandgap in nanowires. Cd3As2 nanobelts, however, exhibit metallic characteristics with a high carrier mobility exceeding 32,000 cm(2) V(-1) s(-1) and pronounced anomalous double-period Shubnikov-de Haas (SdH) oscillations. Unlike the bulk counterpart, the Cd3As2 nanobelts reveal the possibility of unusual change of the Fermi sphere owing to the suppression of the dimensionality. More importantly, their SdH oscillations can be effectively tuned by the gate voltage. The successful synthesis of Cd3As2 nanostructures and their rich physics open up exciting nanoelectronic applications of 3D Dirac semimetals.
Twin structures, transformation and symmetry of superconducting Y1Ba2Cu3O7–x, observed by transmission electron microscopy
Publisher: Informa UK Limited
Date: 03-1988
Hierarchical Structuring to Break the Amorphous Limit of Lattice Thermal Conductivity in High-Performance SnTe-Based Thermoelectrics
Publisher: American Chemical Society (ACS)
Date: 15-07-2020
High-Performance PEDOT:PSS Flexible Thermoelectric Materials and Their Devices by Triple Post-Treatments
Publisher: American Chemical Society (ACS)
Date: 28-06-2019
Carrier Dynamics and Quantum Confinement in type II ZB-WZ InP Nanowire Homostructures
Publisher: American Chemical Society (ACS)
Date: 26-01-2009
DOI: 10.1021/NL802997P
Abstract: We use time-resolved photoluminescence from single InP nanowires containing both wurtzite (WZ) and zincblende (ZB) crystalline phases to measure the carrier dynamics of quantum confined excitons in a type-II homostructure. The observed recombination lifetime increases by nearly 2 orders of magnitude from 170 ps for excitons above the conduction and valence band barriers to more than 8400 ps for electrons and holes that are strongly confined in quantum wells defined by monolayer-scale ZB sections in a predominantly WZ nanowire. A simple computational model, guided by detailed high-resolution transmission electron microscopy measurements from a single nanowire, demonstrates that the dynamics are consistent with the calculated distribution of confined states for the electrons and holes.
Mn-rich clusters in GeMn magnetic semiconductors: Structural evolution and magnetic property
Publisher: Elsevier BV
Date: 10-2010
n-Type Bi2Te3-xSex Nanoplates with Enhanced Thermoelectric Efficiency Driven by Wide-Frequency Phonon Scatterings and Synergistic Carrier Scatterings
Publisher: American Chemical Society (ACS)
Date: 11-04-2016
Abstract: Driven by the prospective applications of thermoelectric materials, massive efforts have been dedicated to enhancing the conversion efficiency. The latter is governed by the figure of merit (ZT), which is proportional to the power factor (S(2)σ) and inversely proportional to the thermal conductivity (κ). Here, we demonstrate the synthesis of high-quality ternary Bi2Te3-xSex nanoplates using a microwave-assisted surfactant-free solvothermal method. The obtained n-type Bi2Te2.7Se0.3 nanostructures exhibit a high ZT of 1.23 at 480 K measured from the corresponding sintered pellets, in which a remarkably low κ and a shift of peak S(2)σ to high temperature are observed. By detailed electron microscopy investigations, coupled with theoretical analysis on phonon transports, we propose that the achieved κ reduction is attributed to the strong wide-frequency phonon scatterings. The shifting of peak S(2)σ to high temperature is due to the weakened temperature dependent transport properties governed by the synergistic carrier scatterings and the suppressed bipolar effects by enlarging the band gap.
Ni-induced stepwise capacity increase in Ni-poor Li-rich cathode materials for high performance lithium ion batteries
Publisher: Springer Science and Business Media LLC
Date: 20-09-2015
Unexpected Benefits of Rapid Growth Rate for III−V Nanowires
Publisher: American Chemical Society (ACS)
Date: 30-12-2008
DOI: 10.1021/NL803182C
Abstract: In conventional planar growth of bulk III-V materials, a slow growth rate favors high crystallographic quality, optical quality, and purity of the resulting material. Surprisingly, we observe exactly the opposite effect for Au-assisted GaAs nanowire growth. By employing a rapid growth rate, the resulting nanowires are markedly less tapered, are free of planar crystallographic defects, and have very high purity with minimal intrinsic dopant incorporation. Importantly, carrier lifetimes are not adversely affected. These results reveal intriguing behavior in the growth of nanoscale materials, and represent a significant advance toward the rational growth of nanowires for device applications.
Phase Separation Induced by Au Catalysts in Ternary InGaAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 18-01-2013
DOI: 10.1021/NL304237B
Abstract: We report a novel phase separation phenomenon observed in the growth of ternary In(x)Ga(1-x)As nanowires by metalorganic chemical vapor deposition. A spontaneous formation of core-shell nanowires is investigated by cross-sectional transmission electron microscopy, revealing the compositional complexity within the ternary nanowires. It has been found that for In(x)Ga(1-x)As nanowires high precursor flow rates generate ternary In(x)Ga(1-x)As cores with In-rich shells, while low precursor flow rates produce binary GaAs cores with ternary In(x)Ga(1-x)As shells. First-principle calculations combined with thermodynamic considerations suggest that this phenomenon is due to competitive alloying of different group-III elements with Au catalysts, and variations in elemental concentrations of group-III materials in the catalyst under different precursor flow rates. This study shows that precursor flow rates are critical factors for manipulating Au catalysts to produce nanowires of desired composition.
A scalable colloidal approach to prepare hematite films for efficient solar water splitting
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CP52153B
Abstract: The development of technologically and economically viable strategies for large-scale fabrication of photoelectrodes is crucial for solar H2 production from photoelectrochemical water splitting. Herein, a low-cost and facile colloidal electrophoretic deposition approach was developed for scalable fabrication of hematite (α-Fe2O3) films. Large-sized uniform films (e.g. 80 mm × 70 mm) with tailored thickness and nanostructures can be easily prepared on conductive substrates within 2 minutes. The resultant films showed a high photocurrent of ∼1.1 mA cm(-2) at 1.23 V(RHE) under standard AM 1.5G illumination, which is among the highest reported values achieved on hematite films prepared using other complex colloidal approaches. The present work will pave a new avenue for fabrication of efficient photoelectrodes toward practically viable solar H2 production.
Kinetic condition driven phase and vacancy enhancing thermoelectric performance of low-cost and eco-friendly Cu2−xS
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TC00819E
Abstract: Cu 2−x S pellets sintered from powders synthesized with different NaOH amounts have different phase compositions and average Cu vacancy levels. This has subsequently led to enhanced thermoelectric performance due to both enhanced hole concentration and reduced phase transition temperature.
Synthesis of Silicon Carbide Nanowires on Carbon Nanotube Template
Publisher: IEEE
Date: 2006
High Curie Temperature Bi1.85Mn0.15Te3 Nanoplates
Publisher: American Chemical Society (ACS)
Date: 07-11-2012
DOI: 10.1021/JA308933K
Abstract: Bi(1.85)Mn(0.15)Te(3) hexagonal nanoplates with a width of ~200 nm and a thickness of ~20 nm were synthesized using a solvothermal method. According to the structural characterization and compositional analysis, the Mn(2+) and Mn(3+) ions were found to substitute Bi(3+) ions in the lattice. High-level Mn doping induces significant lattice distortion and decreases the crystal lattice by 1.07% in the a axis and 3.18% in the c axis. A high ferromagnetic state with a Curie temperature of ~45 K is observed in these nanoplates due to Mn(2+) and Mn(3+) ion doping, which is a significant progress in the field of electronics and spintronics.
Evolution of Helical Mesostructures
Publisher: Wiley
Date: 26-01-2010
Abstract: An intriguing evolution from a simple internal helix to a hierarchical helical (HH) mesostructure with both internal and external helices or a complicated screwlike and concentric circular (CC) mesostructure is successfully observed. The complicated helical structures are determined by TEM studies and 3D electron tomography. We demonstrate a topological helix-coil transition between the internal and external helices to reveal the origin of the HH mesostructure and the relationship between the straight helical and HH rods. Moreover, the boundary condition of the helix-coil transition is clarified to explain in detail the formation of complex helical structures, such as the screwlike mesostructure. It is proposed that the final structural characteristics are determined exactly by the balance between the decrease in the surface free energy and the maintenance of the hexagonal packing in one in idual rod, which explains the formation of unusual CC, HH, and screwlike morphologies in one pot. Our success has opened new opportunities in the characterization of complex porous architectures, thus paving a way to remarkable advances in the fields of synthesis, understanding, and application of novel porous materials.
Investigation of AlGaAs/GaAs V-grooved Quantum Wire Infrared Photodetector Structures
Publisher: IOP Publishing
Date: 09-2000
DOI: 10.1143/JJAP.39.5124
Abstract: An Al 0.5 Ga 0.5 As/GaAs quantum wires infrared photo-detectors (QWRIP) based on V-grooved substrate is fabricated. The inter-band transition in the quantum wires is characterized by spatially resolved micro-photoluminescence (micro-PL) measurement. The theoretical calculation of electronic structures is accomplished based on the Green function. The inter-subband transition is measured by photocurrent at 80 K, and the origin of the infrared response at 9 µm is from the inter-subband transition in quantum wire region, which is confirmed by the theoretical calculation results.
Advances in conducting polymer-based thermoelectric materials and devices
Publisher: OAE Publishing Inc.
Date: 2021
Quality of epitaxial InAs nanowires controlled by catalyst size in molecular beam epitaxy
Publisher: AIP Publishing
Date: 12-08-2013
DOI: 10.1063/1.4818682
Abstract: In this study, the structural quality of Au-catalyzed InAs nanowires grown by molecular beam epitaxy is investigated. Through detailed electron microscopy characterizations and analysis of binary Au-In phase diagram, it is found that defect-free InAs nanowires can be induced by smaller catalysts with a high In concentration, while comparatively larger catalysts containing less In induce defected InAs nanowires. This study indicates that the structural quality of InAs nanowires can be controlled by the size of Au catalysts when other growth conditions remain as constants.
Structural evolution of GeMn/Ge superlattices grown by molecular beam epitaxy under different growth conditions
Publisher: Springer Science and Business Media LLC
Date: 12-12-2011
Abstract: GeMn/Ge epitaxial 'superlattices' grown by molecular beam epitaxy with different growth conditions have been systematically investigated by transmission electron microscopy. It is revealed that periodic arrays of GeMn nanodots can be formed on Ge and GaAs substrates at low temperature (approximately 70°C) due to the matched lattice constants of Ge (5.656 Å) and GaAs (5.653 Å), while a periodic Ge/GeMn superlattice grown on Si showed disordered GeMn nanodots with a large amount of stacking faults, which can be explained by the fact that Ge and Si have a large lattice mismatch. Moreover, by varying growth conditions, the GeMn/Ge superlattices can be manipulated from having disordered GeMn nanodots to ordered coherent nanodots and then to ordered nanocolumns. PACS : 75.50.Pp 61.72.-y 66.30.Pa 68.37.L.
Attraction of semiconductor nanowires: An in situ observation
Publisher: Elsevier BV
Date: 11-2013
Intercalation-Induced Disintegrated Layer-By-Layer Growth of Ultrathin Ternary Mo(Te1–xSx)2 Plates
Publisher: American Chemical Society (ACS)
Date: 27-12-0001
Ternary MOF-on-MOF heterostructures with controllable architectural and compositional complexity via multiple selective assembly
Publisher: Springer Science and Business Media LLC
Date: 02-10-2020
DOI: 10.1038/S41467-020-18776-Z
Abstract: Assembly of different metal-organic framework (MOF) building blocks into hybrid MOF-on-MOF heterostructures is promising in chemistry and materials science, however the development of ternary MOF-on-MOF heterostructures with controllable architectural and compositional complexity is challenging. Here we report the synthesis of three types of ternary MOF-on-MOF heterostructures via a multiple selective assembly strategy. This strategy relies on the choice of one host MOF with more than one facet that can arrange the growth of a guest MOF, where the arrangement is site-selective without homogenous growth of guest MOF or homogenous coating of guest on host MOF. The growth of guest MOF on a selected site of host MOF in each step provides the opportunity to further vary the combinations of arrangements in multiple steps, leading to ternary MOF-on-MOF heterostructures with tunable complexity. The developed strategy paves the way towards the rational design of intricate and unprecedented MOF-based superstructures for various applications.
Indium segregation and enrichment in coherent InxGa1-x As/GaAs quantum dots
Publisher: American Physical Society (APS)
Date: 21-06-1999
Fundamental and progress of Bi2Te3-based thermoelectric materials
Publisher: IOP Publishing
Date: 04-2018
Limit ofz T
Publisher: American Physical Society (APS)
Date: 14-10-2016
Achieving enhanced thermoelectric performance of Ca1-x-yLaxSryMnO3 via synergistic carrier concentration optimization and chemical bond engineering
Publisher: Elsevier BV
Date: 03-2021
Annealing effects on the microstructure of Ge/Si(001) quantum dots
Publisher: AIP Publishing
Date: 27-08-2001
DOI: 10.1063/1.1398615
Abstract: Ge/Si(001) multilayer islands produced by gas-source molecular-beam epitaxy at 575 °C were investigated using energy-filtering transmission electron microscopy. Results show, for as-grown s les, not only a continuous enlargement of island size in upper layers but also a continuous increase of Ge concentration within islands in upper layers. As a result of the increasing island size and Ge concentration within the islands, the island density in upper layers decreases. For s les annealed at 900 °C for 5 min, the aspect ratio of buried islands increases significantly, and the average Ge concentration within islands of different layers becomes uniform.
Novel B-site ordered double perovskite Ba2Bi0.1Sc0.2Co1.7O6−xfor highly efficient oxygen reduction reaction
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0EE00451K
TiB Nanowhisker Reinforced Titanium Matrix Composite with Improved Hardness for Biomedical Applications
Publisher: MDPI AG
Date: 10-12-2020
DOI: 10.3390/NANO10122480
Abstract: Titanium and its alloys have been employed in the biomedical industry as implants and show promise for more broad applications because of their excellent mechanical properties and low density. However, high cost, poor wear properties, low hardness and associated side effects caused by leaching of alloy elements in some titanium alloys has been the bottleneck to their wide application. TiB reinforcement has shown promise as both a surface coating for Ti implants and also as a composite reinforcement phase. In this study, a low-cost TiB-reinforced alpha titanium matrix composite (TMC) is developed. The composite microstructure includes ultrahigh aspect ratio TiB nanowhiskers with a length up to 23 μm and aspect ratio of 400 and a low average Ti grain size. TiB nanowhiskers are formed in situ by the reaction between Ti and BN nanopowder. The TMC exhibited hardness of above 10.4 GPa, elastic modulus above 165 GPa and hardness to Young’s modulus ratio of 0.062 representing 304%, 170% and 180% increases in hardness, modulus and hardness to modulus ratio, respectively, when compared to commercially pure titanium. The TiB nanowhisker-reinforced TMC has good biocompatibility and shows excellent mechanical properties for biomedical implant applications.
Crystalline structures and misfit strain inside Er silicide nanocrystals self-assembled on Si(001) substrates
Publisher: IOP Publishing
Date: 04-05-2011
DOI: 10.1088/0957-4484/22/24/245707
Abstract: The morphology and crystalline structure of Er silicide nanocrystals self-assembled on the Si(001) substrate were investigated using scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). It was found that the nanowires and nanorods formed at 630 °C has dominant hexagonal AlB(2)-type structure, while inside the nanoislands self-organized at 800 °C the tetragonal ThSi(2)-type structure is prevalent. The lattice analysis via cross-sectional high-resolution TEM demonstrated that internal misfit strain plays an important role in controlling the growth of nanocrystals. With the relaxation of strain, the nanoislands could evolve from a pyramid-like shape into a truncated-hut-like shape.
Growth Mechanism of Truncated Triangular III–V Nanowires
Publisher: Wiley
Date: 05-03-2007
Zeeman splitting and dynamical mass generation in Dirac semimetal ZrTe5
Publisher: Springer Science and Business Media LLC
Date: 12-08-2016
DOI: 10.1038/NCOMMS12516
Abstract: Dirac semimetals have attracted extensive attentions in recent years. It has been theoretically suggested that many-body interactions may drive exotic phase transitions, spontaneously generating a Dirac mass for the nominally massless Dirac electrons. So far, signature of interaction-driven transition has been lacking. In this work, we report high-magnetic-field transport measurements of the Dirac semimetal candidate ZrTe 5 . Owing to the large g factor in ZrTe 5 , the Zeeman splitting can be observed at magnetic field as low as 3 T. Most prominently, high pulsed magnetic field up to 60 T drives the system into the ultra-quantum limit, where we observe abrupt changes in the magnetoresistance, indicating field-induced phase transitions. This is interpreted as an interaction-induced spontaneous mass generation of the Dirac fermions, which bears resemblance to the dynamical mass generation of nucleons in high-energy physics. Our work establishes Dirac semimetals as ideal platforms for investigating emerging correlation effects in topological matters.
Towards p-type doping of ZnO by ion implantation
Publisher: IEEE
Date: 2005
In3Se4 and S-doped In3Se4 nano/micro-structures as new anode materials for Li-ion batteries
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TA00688K
Abstract: In 3 Se 4 and S-doped In 3 Se 4 nano/micro-structures consisting of thin nanosheets have been explored as new anode materials for Li-ion batteries.
Synthesis and characterization of TiO2-incorporated silica foams
Publisher: Springer Science and Business Media LLC
Date: 12-2009
Corrigendum to ‘‘Mn behaviors in Mn-implanted ZnO” [Acta Mater 57 (2009) 2291–2299]
Publisher: Elsevier BV
Date: 06-2009
Effect of Mn concentration and growth temperature on nanostructures and magnetic properties of Ge1−xMnx grown on Si
Publisher: Elsevier BV
Date: 10-2010
Roles of Anion Sites in High-performance GeTe Thermoelectrics
Publisher: Research Square Platform LLC
Date: 21-01-2022
DOI: 10.21203/RS.3.RS-1237133/V1
Abstract: Cation doping has been mainly used to enhance the performance of rocksalt GeTe thermoelectric materials. However, its counterpart, anion doping, is still in infancy. Here, we provide a theoretical insight into modifying the anion sites of GeTe for obtaining a better thermoelectric performance, envisaging its coordinate-based bonding mechanisms accounting for carrier and phonon transport characteristics. To support our point, we experimentally synthesized anion I doped GeTe s les, which show comparably optimized electrical and thermal properties compared to Sb or Bi doped GeTe s les. The (Bi, I) co-doped GeTe s les further obtain an enhanced figure-of-merit from 0.8 to 2.5 at 675 K, which can be assembled as an 8-couple thermoelectric generator to yield a conversion efficiency of ~11.6% under a temperature difference of 500 K. This work rationalizes the potential of anion doping for high-performance GeTe thermoelectrics.
Formation of GaAs/GaSb Core-Shell Heterostructured Nanowires Grown by Molecular-Beam Epitaxy
Publisher: MDPI AG
Date: 24-03-2017
DOI: 10.3390/CRYST7040094
Optimal array alignment to deliver high performance in flexible conducting polymer-based thermoelectric devices
Publisher: Elsevier BV
Date: 10-2022
Morphology and Texture Engineering Enhancing Thermoelectric Performance of Solvothermal Synthesized Ultralarge SnS Microcrystal
Publisher: American Chemical Society (ACS)
Date: 13-02-2020
MBE Growth and Characterization of Strained HgTe (111) Films on CdTe/GaAs*
Publisher: IOP Publishing
Date: 03-2020
DOI: 10.1088/0256-307X/37/3/038101
Abstract: Strained HgTe thin films are typical three-dimensional topological insulator materials. Most works have focused on HgTe (100) films due to the topological properties resulting from uniaxial strain. In this study, strained HgTe (111) thin films are grown on GaAs (100) substrates with CdTe (111) buffer layers using molecular beam epitaxy (MBE). The optimal growth conditions for HgTe films are determined to be a growth temperature of 160°C and an Hg/Te flux ratio of 200. The strains of HgTe films with different thicknesses are investigated by high-resolution x-ray diffraction, including reciprocal space mapping measurements. The critical thickness of HgTe (111) film on CdTe/GaAs is estimated to be approximately 284 nm by Matthews’ equations, consistent with the experimental results. Reflection high-energy electron diffraction and high-resolution transmission electron microscopy investigations indicate that high-quality HgTe films are obtained. This exploration of the MBE growth of HgTe (111) films provides valuable information for further studies of HgTe-based topological insulators.
Stable and Metastable InGaAs/GaAs Island Shapes and Surfactantlike Suppression of the Wetting Transformation
Publisher: American Physical Society (APS)
Date: 21-09-1998
Island shape instabilities and surfactant-like effects in the growth of InGaAs/GaAs quantum dots
Publisher: Elsevier BV
Date: 12-1999
Nanostructured thermoelectric materials: Current research and future challenge
Publisher: Elsevier BV
Date: 12-2012
Arrays of Planar Vacancies in Superior Thermoelectric Ge 1− x − y Cd x Bi y Te with Band Convergence
Publisher: Wiley
Date: 19-09-2018
Crystal symmetry induced structure and bonding manipulation boosting thermoelectric performance of GeTe
Publisher: Elsevier BV
Date: 07-2020
Unusual corrugated nanowires of zinc oxide
Publisher: Elsevier BV
Date: 06-2008
Formation of Hierarchical InAs Nanoring / GaAs Nanowire Heterostructures
Publisher: Wiley
Date: 12-01-2009
Unexpected formation of a hierarchical structure in ternary InGaAs nanowires via “one-pot” growth
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7NR04606E
Abstract: A hierarchical nanowire structure was spontaneously formed: the respective core, core–shell and core–multishell structure in the nanowire tip, middle and bottom regions.
Damage to epitaxial GaN layers by silicon implantation
Publisher: AIP Publishing
Date: 14-10-1996
DOI: 10.1063/1.117526
Abstract: Ion channeling and cross-sectional transmission electron microscopy were used to study the extent and nature of Si ion implantation damage in epitaxial GaN layers at liquid nitrogen temperature. Results indicate that displacement damage produced by the implantation undergoes substantial dynamic annealing during implantation. As a result, at moderate implantation doses residual implantation damage consists of a dense network of secondary defects, such as clusters and loops, which are a consequence of incomplete annihilation of implantation-produced defects. Amorphous layers can be produced, but the doses required are extremely high (≳1016 cm−2) and amorphization appears to ‘‘nucleate’’ at the surface.
Bi0.5Sb1.5Te3/PEDOT:PSS-based flexible thermoelectric film and device
Publisher: Elsevier BV
Date: 10-2020
Signature of quantum Griffiths singularity state in a layered quasi-one-dimensional superconductor
Publisher: Springer Science and Business Media LLC
Date: 07-11-2018
DOI: 10.1038/S41467-018-07123-Y
Abstract: Quantum Griffiths singularity was theoretically proposed to interpret the phenomenon of ergent dynamical exponent in quantum phase transitions. It has been discovered experimentally in three-dimensional (3D) magnetic metal systems and two-dimensional (2D) superconductors. But, whether this state exists in lower dimensional systems remains elusive. Here, we report the signature of quantum Griffiths singularity state in quasi-one-dimensional (1D) Ta 2 PdS 5 nanowires. The superconducting critical field shows a strong anisotropic behavior and a violation of the Pauli limit in a parallel magnetic field configuration. Current-voltage measurements exhibit hysteresis loops and a series of multiple voltage steps in transition to the normal state, indicating a quasi-1D nature of the superconductivity. Surprisingly, the nanowire undergoes a superconductor-metal transition when the magnetic field increases. Upon approaching the zero-temperature quantum critical point, the system uncovers the signature of the quantum Griffiths singularity state arising from enhanced quenched disorders, where the dynamical critical exponent becomes erging rather than being constant.
Realizing High Thermoelectric Performance in n-Type Highly Distorted Sb-Doped SnSe Microplates via Tuning High Electron Concentration and Inducing Intensive Crystal Defects
Publisher: Wiley
Date: 04-05-2021
Thermal Reductive Perforation of Graphene Cathode for High‐Performance Aluminum‐Ion Batteries
Publisher: Wiley
Date: 19-02-2021
Metalorganic chemical vapor deposition of GaAsN epilayers: microstructures and optical properties
Publisher: Elsevier BV
Date: 03-2004
A new crystal: layer-structured rhombohedral In3Se4
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3CE41815D
In situ liquid cell transmission electron microscopy guiding the design of large-sized cocatalysts coupled with ultra-small photocatalysts for highly efficient energy harvesting
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TA02975D
Abstract: In situ liquid cell transition electron microscopy guides the precise design of large-sized cocatalysts for highly efficient photocatalytic hydrogen evolution.
Can misfit dislocations be located above the interface of InAs/GaAs (001) epitaxial quantum dots?
Publisher: Springer Science and Business Media LLC
Date: 31-08-2012
Abstract: InAs/GaAs(001) quantum dots grown by droplet epitaxy were investigated using electron microscopy. Misfit dislocations in relaxed InAs/GaAs(001) islands were found to be located approximately 2 nm above the crystalline s le surface, which provides an impression that the misfit dislocations did not form at the island/substrate interface. However, detailed microscopy data analysis indicates that the observation is in fact an artefact caused by the surface oxidation of the material that resulted in substrate surface moving down about 2 nm. As such, caution is needed in explaining the observed interfacial structure.
Compositional design of strong and ductile (tensile) Ti-Zr-Nb-Ta medium entropy alloys (MEAs) using the atomic mismatch approach
Publisher: Elsevier BV
Date: 2019
Roles of Anion Sites in High‐Performance GeTe Thermoelectrics
Publisher: Wiley
Date: 22-09-2022
Abstract: Cationic doping is mainly used to improve the performance of rocksalt‐structured GeTe thermoelectric materials. However, its counterpart anionic doping is scarcely facilitated. Here, a comprehensive discussion is provided on doping at the anion site of rocksalt‐structured thermoelectric materials, surrounding its influence on bonding mechanisms, carrier and phonon transport characteristics, and thermoelectric figure‐of‐merit. To verify the viewpoint, a modified flux‐assist method is adopted to synthesize anionic Iodine (I) doped GeTe s les, which show comparably optimized electrical and thermal properties with that of cationic Antimony (Sb) or Bismuth (Bi) doped GeTe s les. Further combining cationic Bi and anionic I co‐doping, an enhanced figure‐of‐merit from 0.8 in pristine GeTe to 2.5 at 675 K can be realized in 8% (Bi and I) co‐doped GeTe, which corresponds to a maximum heat‐to‐electricity conversion efficiency of 14.6% under a temperature difference of 430 K. This study rationalizes the influence of anionic doping on the electrical and thermal properties of the rocksalt‐structured materials, which serves as an effective yet previously neglected strategy toward high‐performance GeTe thermoelectrics.
ZnS nanowires and their coaxial lateral nanowire heterostructures with BN
Publisher: AIP Publishing
Date: 05-03-2007
DOI: 10.1063/1.2711288
Abstract: ZnS nanowires and their coaxial lateral BN nanowire heterostructures with a length of hundreds of micrometers and an average diameter of ∼300nm were fabricated via one-step chemical vapor deposition method. Wurtzite ZnS nanowires were coated by a shell of fluffylike hexagonal BN sheets distributed randomly. Thermogravimetric analysis indicates that the heterostructures have a much better oxidation resistance compared with ZnS nanowires. Their similar optical property suggests that the ZnS∕BN heterostructures would have potential applications in thermally and chemically rigorous environments.
V-grooved GaAs/AlGaAs quantum wires with side wall quantum wells intermixed by pulsed anodization and rapid thermal annealing
Publisher: IEEE
Date: 1996
High-density, defect-free, and taper-restrained epitaxial GaAs nanowires induced from annealed Au thin films
Publisher: American Chemical Society (ACS)
Date: 08-03-2012
DOI: 10.1021/CG201725G
Formation mechanisms of inclusions in spring steels
Publisher: Springer International Publishing
Date: 2017
A new indium selenide phase: controllable synthesis, phase transformation and photoluminescence properties
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TC04635F
Abstract: A new rhombohedral In 2.45 Se 4 phase has been controllably synthesized via a chemical solution method and reveals near-infrared photoluminescence emissions.
High‐Content, Well‐Dispersed γ‐Fe2O3 Nanoparticles Encapsulated in Macroporous Silica with Superior Arsenic Removal Performance
Publisher: Wiley
Date: 10-2013
n-type Bi-doped PbTe Nanocubes with Enhanced Thermoelectric Performance
Publisher: Elsevier BV
Date: 2017
Effect of MgO in ZnO films grown on nitrided sapphires
Publisher: Elsevier BV
Date: 07-2007
Laser-Ablated Vortex Fluidic-Mediated Synthesis of Superparamagnetic Magnetite Nanoparticles in Water Under Flow
Publisher: American Chemical Society (ACS)
Date: 14-09-2018
Epitaxial GaAs/AlGaAs core–multishell nanowires with enhanced photoluminescence lifetime
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9NR01715A
Abstract: The complex GaAs/AlGaAs core–multishell nanowire heterostructure was epitaxially grown, which has a long photoluminescence lifetime.
High-Performance Thermoelectric Materials for Solar Energy Application
Publisher: Elsevier
Date: 2018
Surface-energy engineered Bi-doped SnTe nanoribbons with weak antilocalization effect and linear magnetoresistance
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6NR07140F
Abstract: The rational design of semiconductor nanocrystals with well-defined surfaces is a crucial step towards the realization of next-generation photodetectors, and thermoelectric and spintronic devices. SnTe nanocrystals, as an ex le, are particularly attractive as a type of topological crystalline insulator, where surface facets determine their surface states. However, most of the available SnTe nanocrystals are dominated by thermodynamically stable {100} facets, and it is challenging to grow uniform nanocrystals with {111} facets. In this study, guided by surface-energy calculations, we employ a chemical vapour deposition approach to fabricate Bi doped SnTe nanostructures, in which their surface facets are tuned by Bi doping. The obtained Bi doped SnTe nanoribbons with distinct {111} surfaces show a weak antilocalization effect and linear magnetoresistance under high magnetic fields, which demonstrate their great potential for future spintronic applications.
Microstructure and Properties of a Deformation-Processed Cu-Cr-Ag In Situ Composite by Directional Solidification
Publisher: Springer Science and Business Media LLC
Date: 11-09-2013
Morphological control of SnTe nanostructures by tuning catalyst composition
Publisher: Springer Science and Business Media LLC
Date: 06-08-2015
Reducing electric current and energy consumption of spark plasma sintering via punch configuration design
Publisher: Elsevier BV
Date: 12-2017
Quantitative study of GaAs nanowires catalyzed by Au film of different thicknesses
Publisher: Springer Science and Business Media LLC
Date: 24-10-2012
Abstract: In this letter, we quantitatively investigated epitaxial GaAs nanowires catalyzed by thin Au films of different thicknesses on GaAs (111) B substrates in a metal-organic chemical vapor deposition reactor. Prior to nanowire growth, the de-wetting of Au thin films to form Au nanoparticles on GaAs (111) B in AsH 3 ambient at different temperatures is investigated. It is found that with increasing film thickness, the size of the Au nanoparticles increases while the density of the nanoparticles reduces. Furthermore, higher annealing temperature produces larger Au nanoparticles for a fixed film thickness. As expected, the diameters and densities of the as-grown GaAs nanowires catalyzed by these thin Au films reflect these trends.
Enhanced Thermoelectric Performance of Ultrathin Bi2Se3 Nanosheets through Thickness Control
Publisher: Wiley
Date: 20-04-2015
Thermo-Responsive Nanomaterials for Thermoelectric Generation
Publisher: Springer International Publishing
Date: 2020
Versatile Vanadium Doping Induces High Thermoelectric Performance in GeTe via Band Alignment and Structural Modulation
Publisher: Wiley
Date: 20-04-2021
Thermal stability of ion-implanted ZnO
Publisher: AIP Publishing
Date: 12-2005
DOI: 10.1063/1.2140481
Abstract: Zinc oxide single crystals implanted at room temperature with high-dose (1.4×1017cm−2) 300 keV As+ ions are annealed at 1000–1200 °C. Damage recovery is studied by a combination of Rutherford backscattering/channeling spectrometry (RBS/C), cross-sectional transmission electron microscopy (XTEM), and atomic force microscopy. Results show that such a thermal treatment leads to the decomposition and evaporation of the heavily damaged layer instead of apparent defect recovery and recrystallization that could be inferred from RBS/C and XTEM data alone. This study shows that heavily damaged ZnO has relatively poor thermal stability compared to as-grown ZnO which is a significant result and has implications for understanding results on thermal annealing of ion-implanted ZnO.
Arrayed van der Waals Vertical Heterostructures Based on 2D GaSe Grown by Molecular Beam Epitaxy
Publisher: American Chemical Society (ACS)
Date: 05-2015
DOI: 10.1021/ACS.NANOLETT.5B01058
Abstract: Vertically stacking two-dimensional (2D) materials can enable the design of novel electronic and optoelectronic devices and realize complex functionality. However, the fabrication of such artificial heterostructures on a wafer scale with an atomically sharp interface poses an unprecedented challenge. Here, we demonstrate a convenient and controllable approach for the production of wafer-scale 2D GaSe thin films by molecular beam epitaxy. In situ reflection high-energy electron diffraction oscillations and Raman spectroscopy reveal a layer-by-layer van der Waals epitaxial growth mode. Highly efficient photodetector arrays were fabricated, based on few-layer GaSe on Si. These photodiodes show steady rectifying characteristics and a high external quantum efficiency of 23.6%. The resultant photoresponse is super-fast and robust, with a response time of 60 μs. Importantly, the device shows no sign of degradation after 1 million cycles of operation. We also carried out numerical simulations to understand the underlying device working principles. Our study establishes a new approach to produce controllable, robust, and large-area 2D heterostructures and presents a crucial step for further practical applications.
Unequal P Distribution in Nanowires and the Planar Layer during GaAsP Growth on GaAs {111}B by Metal–Organic Chemical Vapor Deposition
Publisher: American Chemical Society (ACS)
Date: 04-09-2013
DOI: 10.1021/JP406294T
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