ORCID Profile
0000-0003-1040-2794
Current Organisations
RMIT University
,
Deakin University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 12-2016
Publisher: Institution of Engineering and Technology (IET)
Date: 2003
Publisher: Elsevier BV
Date: 1989
Publisher: Wiley
Date: 15-05-2009
Publisher: Elsevier BV
Date: 08-1987
Publisher: Elsevier BV
Date: 11-2020
Publisher: AIP Publishing
Date: 04-2011
DOI: 10.1063/1.3562141
Abstract: Electron mobility in degenerate CdO thin films has been studied as a function of carrier concentration. The “optical” mobility has been determined from infrared reflectance measurements of the conduction band plasmon lifetime. The acquired values vary from ∼209 to ∼1116 cm2 V-1 s-1 for carrier concentrations between 2.5×1020 and 2.6×1019 cm-3. Ionized impurity scattering is shown to be the dominant effect reducing the intra-grain mobility of the electrons at room temperature. The transport mobilities from Hall effect measurements range between ̃20 and ̃124 cm2 V-1 s-1 which are much lower than the optical mobilities. Simulation of grain boundary scattering-limited mobility is commonly based on models that assume a depletion layer at the boundaries which causes an inter-grain potential barrier. These models are found not to be applicable to CdO as it has been previously shown to have surface electron accumulation. Therefore, simulation of the transport mobility has been performed using the Fuchs-Sondheimer and Mayadas-Shatzkes models to take into account the grain boundary and surface scattering mechanisms, in addition to intra-grain scattering. The results indicate that electron scattering at grain boundaries with ̃95 % reflection is the dominant mechanism in reducing the mobility across the layer. The effect of surface scattering plays only a minor role in electron transport.
Publisher: IOP Publishing
Date: 03-08-2011
DOI: 10.1088/0953-8984/23/33/334211
Abstract: Epitaxial films of In(2)O(3) have been grown on Y-stabilised ZrO(2)(111) substrates by molecular beam epitaxy over a range of thicknesses between 35 and 420 nm. The thinnest films are strained, but display a 'cross-hatch' morphology associated with a network of misfit dislocations which allow partial accommodation of the lattice mismatch. With increasing thickness a 'dewetting' process occurs and the films break up into micron sized mesas, which coalesce into continuous films at the highest coverages. The changes in morphology are accompanied by a progressive release of strain and an increase in carrier mobility to a maximum value of 73 cm(2) V(-1) s(-1). The optical band gap in strained ultrathin films is found to be smaller than for thicker films. Modelling of the system, using a combination of classical pair-wise potentials and ab initio density functional theory, provides a microscopic description of the elastic contributions to the strained epitaxial growth, as well as the electronic effects that give rise to the observed band gap changes. The band gap increase induced by the uniaxial compression is offset by the band gap reduction associated with the epitaxial tensile strain.
Publisher: American Physical Society (APS)
Date: 09-11-2010
Publisher: Elsevier BV
Date: 05-1993
Publisher: Elsevier BV
Date: 20-10-2003
Publisher: American Physical Society (APS)
Date: 30-09-2004
Publisher: IOP Publishing
Date: 16-05-2006
Publisher: American Physical Society (APS)
Date: 04-2004
Publisher: Wiley
Date: 11-04-2005
Publisher: AIP Publishing
Date: 02-1999
DOI: 10.1063/1.122983
Abstract: Medium-energy coaxial impact-collision ion scattering spectroscopy has been used to study the depth profile and lattice location of Sb atoms in Si/Sb(δ-doped)/Si(001) structures prepared by solid phase epitaxy. The Sb atoms are observed to diffuse into the Si capping layer at concentrations much higher than the solubility limit in a Si crystal. In addition, the concentration of diffused Sb atoms does not show a monotonic decrease with increasing distance from the δ-layer plane. The lattice locations of the diffused Sb atoms are found to be strongly dependent on the distance from the location of the original Sb δ layer.
Publisher: American Chemical Society (ACS)
Date: 18-08-2021
Publisher: American Physical Society (APS)
Date: 20-05-2004
Publisher: Elsevier BV
Date: 06-2007
Publisher: Elsevier BV
Date: 2004
Publisher: American Physical Society (APS)
Date: 05-03-2008
Publisher: Wiley
Date: 27-09-2020
Publisher: Springer Science and Business Media LLC
Date: 05-11-2021
Publisher: IOP Publishing
Date: 29-01-2009
DOI: 10.1088/0953-8984/21/7/075803
Abstract: The charge state of muonium has been investigated in p-type doped, nominally undoped (low n-type) and heavily n-type doped InAs. The donor Mu(+) state is shown to be the dominant defect in all cases. Consequently, muonium does not simply counteract the prevailing conductivity in this material. This is consistent with the charge neutrality level lying above the conduction band minimum in InAs.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TB01655A
Abstract: Broad-spectrum treatment of monoculture and mixed species biofilms using magnetically actuated, liquid metal particles.
Publisher: AIP Publishing
Date: 09-11-2009
DOI: 10.1063/1.3263725
Abstract: The effects of treatment with ammonium sulfide ((NH4)2Sx) solution on the electronic properties of InN surfaces have been investigated with high resolution x-ray photoemission spectroscopy. The valence band, In 3d, and N 1s x-ray photoemission spectra show that the surface Fermi level decreases by approximately 0.15 eV with (NH4)2Sx-treatment. This corresponds to a reduction of the downward band bending with the surface sheet charge density decreasing by 30%.
Publisher: Elsevier BV
Date: 02-1994
Publisher: Elsevier BV
Date: 03-2006
Publisher: Springer New York
Date: 11-08-2011
Publisher: AIP Publishing
Date: 11-09-2006
DOI: 10.1063/1.2349832
Abstract: Fourier transform infrared absorption measurements are presented from the dilute nitride semiconductor GaNSb with nitrogen incorporations between 0.2% and 1.0%. The ergence of transitions from the valence band to E− and E+ can be seen with increasing nitrogen incorporation, consistent with theoretical predictions. The GaNSb band structure has been modeled using a five-band k∙p Hamiltonian and a band anticrossing fitting has been obtained using a nitrogen level of 0.78eV above the valence band maximum and a coupling parameter of 2.6eV.
Publisher: Elsevier BV
Date: 02-1997
Publisher: American Chemical Society (ACS)
Date: 04-04-2022
DOI: 10.1021/ACS.LANGMUIR.1C03390
Abstract: Ionic liquids are versatile solvents that can be tailored through modification of the cation and anion species. Relatively little is known about the corrosive properties of protic ionic liquids. In this study, we have explored the corrosion of both zinc and copper within a series of protic ionic liquids consisting of alkylammonium or alkanolammonium cations paired with nitrate or carboxylate anions along with three aprotic imidazolium ionic liquids for comparison. Electrochemical studies revealed that the presence of either carboxylate anions or alkanolammonium cations tend to induce a cathodic shift in the corrosion potential. The effect in copper was similar in magnitude for both cations and anions, while the anion effect was slightly more pronounced than that of the cation in the case of zinc. For copper, the presence of carboxylate anions or alkanolammonium cations led to a notable decrease in corrosion current, whereas an increase was typically observed for zinc. The ionic liquid-metal surface interactions were further explored for select protic ionic liquids on copper using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to characterize the interface. From these studies, the oxide species formed on the surface were identified, and copper speciation at the surface linked to ionic liquid and potential dependent surface passivation. Density functional theory and ab initio molecular dynamics simulations revealed that the ethanolammonium cation was more strongly bound to the copper surface than the ethylammonium counterpart. In addition, the nitrate anion was more tightly bound than the formate anion. These likely lead to competing effects on the process of corrosion: the tightly bound cations act as a source of passivation, whereas the tightly bound anions facilitate the electrodissolution of the copper.
Publisher: Elsevier BV
Date: 09-1996
Publisher: American Chemical Society (ACS)
Date: 21-10-2014
DOI: 10.1021/AM5043388
Abstract: We investigate the effect of thermally induced phase transformations on a metastable oxide alloy film, a multiphase Be(x)Zn(1-x)O (BZO), grown on Al2O3(0001) substrate for annealing temperatures in the range of 600-950 °C. A pronounced structural transition is shown together with strain relaxation and atomic redistribution in the annealed films. Increasing annealing temperature initiates out-diffusion and segregation of Be and subsequent nucleation of nanoparticles at the surface, corresponding to a monotonic decrease in the lattice phonon energies and band gap energy of the films. Infrared reflectance simulations identify a highly conductive ZnO interface layer (thicknesses in the range of ≈ 10-29 nm for annealing temperatures ≥ 800 °C). The highly degenerate interface layers with temperature-independent carrier concentration and mobility significantly influence the electronic and optical properties of the BZO films. A parallel conduction model is employed to determine the carrier concentration and conductivity of the bulk and interface regions. The density-of-states-averaged effective mass of the conduction electrons for the interfaces is calculated to be in the range of 0.31 m0 and 0.67 m0. A conductivity as high as 1.4 × 10(3) S · cm(-1) is attained, corresponding to the carrier concentration n(Int) = 2.16 × 10(20) cm(-3) at the interface layers, and comparable to the highest conductivities achieved in highly doped ZnO. The origin of such a nanoscale degenerate interface layer is attributed to the counter-diffusion of Be and Zn, rendering a high accumulation of Zn interstitials and a giant reduction of charge-compensating defects. These observations provide a broad understanding of the thermodynamics and phase transformations in Be(x)Zn(1-x)O alloys for the application of highly conductive and transparent oxide-based devices and fabrication of their alloy nanostructures.
Publisher: Elsevier BV
Date: 04-1998
Publisher: Elsevier BV
Date: 08-2006
Publisher: Elsevier BV
Date: 2003
Publisher: Elsevier BV
Date: 05-1998
Publisher: Elsevier BV
Date: 07-1997
Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 10-1997
Publisher: AIP Publishing
Date: 13-09-2010
DOI: 10.1063/1.3488821
Abstract: The electronic properties of a-plane and m-plane InN have been investigated by x-ray photoemission spectroscopy, infrared reflectivity, and surface space-charge calculations. Electron accumulation has been observed at the surface of nonpolar InN and the surface Fermi level has been found to be lower than previously observed on InN s les. A high electron density in the InN close to the interface with GaN was found in each nonpolar InN s le.
Publisher: Elsevier BV
Date: 1993
Publisher: American Vacuum Society
Date: 07-06-2005
DOI: 10.1116/1.1927108
Abstract: Conventional methods of surface preparation for III–V semiconductors, such as thermal annealing and sputtering, are severely limited for InN, resulting in In-enrichment and the introduction of donorlike defects. This is explained in terms of the unusually low Γ-point conduction band minimum of InN with respect to its Fermi stabilization energy. Here, low energy atomic hydrogen irradiation is used to produce clean wurtzite InN surfaces without such detrimental effects. A combination of x-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy was used to confirm the removal of atmospheric contaminants. Low energy electron diffraction revealed a (1×1) surface reconstruction after cleaning. Finally, XPS revealed In∕N intensity ratios consistent with a predominantly In polarity InN film terminated by In-adlayers in analogy with c-plane GaN{0001}-(1×1) surfaces.
Publisher: American Vacuum Society
Date: 07-2002
DOI: 10.1116/1.1491987
Abstract: A method which allows the erosion rate to be established from the earliest stages of an ultralow energy secondary ion mass spectrometry (ule-SIMS) profile is described. Using the technique of medium energy ion scattering (MEIS), this method provides data which enables an accurate depth scale to be established from a depth of a few nanometers onwards. The method is applicable for a thin amorphous layer at the surface or a heavy element marker in the near-surface region, and enables the erosion rate as a function of SIMS ion dose to be established for particular bombardment conditions. The erosion rate obtained is used to calibrate the depth and intensity scales of implant profile measured using ule-SIMS and to interpret the near-surface distribution. In this article we demonstrate this methodology using a Ge preamorphized Si(001) surface with a 1 keV boron implant. The altered layer formed by the primary SIMS O2+ incorporation and the redistribution of Ge in the s les used, are also described. Based on the Ge redistribution results, the possibility of adapting this method for determining erosion rates in crystalline silicon and silicon surface recession measurements, is also discussed.
Publisher: AIP Publishing
Date: 26-03-2007
DOI: 10.1063/1.2716994
Abstract: The valence band offset of wurtzite-InN∕AlN (0001) heterojunctions is determined by x-ray photoelectron spectroscopy to be 1.52±0.17eV. Together with the resulting conduction band offset of 4.0±0.2eV, a type-I heterojunction forms between InN and AlN in the straddling arrangement.
Publisher: Elsevier BV
Date: 09-1987
Publisher: AIP Publishing
Date: 14-01-2013
DOI: 10.1063/1.4775691
Abstract: Temperature-dependent optical absorption, Hall effect, and infrared reflectance measurements have been performed on as-grown and post-growth annealed CdO films grown by metal organic vapor phase epitaxy on sapphire substrates. The evolution of the absorption edge and conduction electron plasmon energy with temperature has been modeled, including the effects arising from the Burstein-Moss shift and bandgap renormalization. The zero-temperature fundamental direct bandgap and band edge effective mass have been determined to be 2.31 ± 0.02 eV and 0.27±0.01m0, respectively. The associated Varshni parameters for the temperature dependence of the bandgap are found to be α=8×10−4 eV/K and β=260 K.
Publisher: IOP Publishing
Date: 05-07-1993
Publisher: Elsevier BV
Date: 12-1994
Publisher: AIP Publishing
Date: 27-08-2007
DOI: 10.1063/1.2775807
Abstract: Electron accumulation is found to occur at the surface of wurtzite (112¯0), (0001), and (0001¯) and zinc-blende (001) InN using x-ray photoemission spectroscopy. The accumulation is shown to be a universal feature of InN surfaces. This is due to the low Γ-point conduction band minimum lying significantly below the charge neutrality level.
Publisher: AIP Publishing
Date: 30-08-2004
DOI: 10.1063/1.1784886
Publisher: AIP Publishing
Date: 26-08-2003
DOI: 10.1063/1.1604463
Abstract: The electronic properties and nitrogen bonding configurations are investigated in dilute InNxSb1−x alloys grown by molecular beam epitaxy using a mixed nitrogen and hydrogen plasma. High-resolution electron-energy-loss spectroscopy is used to observe annealing-induced changes in the conduction band electron plasma frequency and plasmon lifetime. X-ray photoelectron spectroscopy of the N 1s core level indicates that a large proportion of the nitrogen in the InNxSb1−x alloy is contained within neutral N–H complexes. Annealing at 300 °C removes hydrogen from these complexes, increasing the concentration of isoelectronic nitrogen acceptors. This increases the ionized impurity scattering and reduces the background conduction electron density.
Publisher: IEEE
Date: 06-2012
Publisher: Wiley
Date: 21-09-2018
Publisher: American Chemical Society (ACS)
Date: 09-2009
DOI: 10.1021/CM901127R
Publisher: Elsevier BV
Date: 08-2006
Publisher: Elsevier BV
Date: 08-1999
Publisher: American Chemical Society (ACS)
Date: 04-04-2022
Abstract: Indium nitride (InN) has been of significant interest for creating and studying two-dimensional electron gases (2DEG). Herein we demonstrate the formation of 2DEGs in ultrathin doped and undoped 2D InN nanosheets featuring high carrier mobilities at room temperature. The synthesis is carried out via a two-step liquid metal-based printing method followed by a microwave plasma-enhanced nitridation reaction. Ultrathin InN nanosheets with a thickness of ∼2 ± 0.2 nm were isolated over large areas with lateral dimensions exceeding centimeter scale. Room temperature Hall effect measurements reveal carrier mobilities of ∼216 and ∼148 cm
Publisher: American Physical Society (APS)
Date: 15-01-2014
Publisher: Oxford University Press (OUP)
Date: 17-01-2020
Publisher: Springer Science and Business Media LLC
Date: 06-09-2018
DOI: 10.1038/S41467-018-06124-1
Abstract: Two-dimensional piezotronics will benefit from the emergence of new crystals featuring high piezoelectric coefficients. Gallium phosphate (GaPO 4 ) is an archetypal piezoelectric material, which does not naturally crystallise in a stratified structure and hence cannot be exfoliated using conventional methods. Here, we report a low-temperature liquid metal-based two-dimensional printing and synthesis strategy to achieve this goal. We exfoliate and surface print the interfacial oxide layer of liquid gallium, followed by a vapour phase reaction. The method offers access to large-area, wide bandgap two-dimensional (2D) GaPO 4 nanosheets of unit cell thickness, while featuring lateral dimensions reaching centimetres. The unit cell thick nanosheets present a large effective out-of-plane piezoelectric coefficient of 7.5 ± 0.8 pm V − 1 . The developed printing process is also suitable for the synthesis of free standing GaPO 4 nanosheets. The low temperature synthesis method is compatible with a variety of electronic device fabrication procedures, providing a route for the development of future 2D piezoelectric materials.
Publisher: Wiley
Date: 26-02-2202
Publisher: Elsevier BV
Date: 09-2010
Publisher: Springer Science and Business Media LLC
Date: 16-01-2015
DOI: 10.1038/SREP07719
Abstract: Bulk crystals and thin films of PbTi 1− x Fe x O 3−δ (PTFO) are multiferroic, exhibiting ferroelectricity and ferromagnetism at room temperature. Here we report that the Ruddlesden-Popper phase Pb n +1 (Ti 1− x Fe x ) n O 3 n +1−δ forms spontaneously during pulsed laser deposition of PTFO on LaAlO 3 substrates. High-resolution transmission electron microscopy, x-ray diffraction and x-ray photoemission spectroscopy were utilised to perform a structural and compositional analysis, demonstrating that "Equation missing" and "Equation missing" . The complex dielectric function of the films was determined from far-infrared to ultraviolet energies using a combination of terahertz time-domain spectroscopy, Fourier transform spectroscopy and spectroscopic ellipsometry. The simultaneous Raman and infrared activity of phonon modes and the observation of second harmonic generation establishes a non-centrosymmetric point group for Pb n +1 (Ti 0.5 Fe 0.5 ) n O 3 n +1−δ , a prerequisite for (but not proof of) ferroelectricity. No evidence of macroscopic ferromagnetism was found in SQUID magnetometry. The ultrafast optical response exhibited coherent magnon oscillations compatible with local magnetic order and additionally was used to study photocarrier cooling on picosecond timescales. An optical gap smaller than that of BiFeO 3 and long photocarrier lifetimes may make this system interesting as a ferroelectric photovoltaic.
Publisher: IOP Publishing
Date: 07-04-1997
Publisher: Royal Society of Chemistry (RSC)
Date: 1991
DOI: 10.1039/FT9918703259
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA01379K
Abstract: An electrocatalyst with trace vanadium alloyed with liquid metal reduces CO 2 directly into solid carbon.
Publisher: American Physical Society (APS)
Date: 03-04-2018
Publisher: American Chemical Society (ACS)
Date: 18-11-2019
Abstract: The resistance of pathogenic bacteria toward traditional biocidal treatment methods is a growing concern in various settings, including that of water treatment and in the medical industry. As such, advanced antibacterial technologies are needed to prevent infections, against which current antibiotics are failing. This study introduces copper oxide nanoparticles (CuONPs) doped in graphene oxide (GO) as a potential pathogenic bacterial treatment. The aim of the study was to evaluate the antibacterial properties of the GO-CuONP hybridized material against pathogenic
Publisher: AIP Publishing
Date: 08-02-2016
DOI: 10.1063/1.4941234
Abstract: Investigating nanometer and micron sized materials thought to exhibit topological surface properties that can present a challenge, as clean surfaces are a pre-requisite for band structure measurements when using nano-ARPES or laser-ARPES in ultra-high vacuum. This issue is exacerbated when dealing with nanometer or micron sized materials, which have been prepared ex-situ and so have been exposed to atmosphere. We present the findings of an XPS study where various cleaning methods have been employed to reduce the surface contamination and preserve the surface quality for surface sensitive measurements. Microcrystals of the topological crystalline insulator SnTe were grown ex-situ and transferred into ultra high vacuum (UHV) before being treated with either atomic hydrogen, argon sputtering, annealing, or a combination of treatments. The s les were also characterised using the scanning electron microscopy, both before and after treatment. It was found that atomic hydrogen cleaning with an anneal cycle (200 °C) gave the best clean surface results.
Publisher: IOP Publishing
Date: 12-1986
Publisher: AIP Publishing
Date: 10-03-2008
DOI: 10.1063/1.2896605
Publisher: Wiley
Date: 31-03-2011
Publisher: American Chemical Society (ACS)
Date: 19-12-2012
DOI: 10.1021/JP3075767
Publisher: American Vacuum Society
Date: 07-2004
DOI: 10.1116/1.1771672
Abstract: The electronic properties of clean InN(0001) surfaces have been investigated by high-resolution electron-energy-loss spectroscopy of the conduction band electron plasmon excitations and valence band x-ray photoemission spectroscopy. An intrinsic surface electron accumulation layer is found to exist, with the associated downward band bending occurring to neutralize charged donor-type surface states. Semiclassical dielectric theory simulations of the energy-loss spectra and charge profile calculations indicate a surface state density of 2.5(±0.2)×1013 cm−2 and a surface Fermi level of 1.64±0.10 eV above the valence band maximum and 0.89±0.10 eV above the conduction band minimum. This location of the surface Fermi level is in agreement with the valence band photoemission spectra. These observations are compared with recent evidence of electron accumulation at InN surfaces provided by capacitance–voltage profiling, Hall measurements, and synchrotron-radiation photoemission spectroscopy.
Publisher: AIP Publishing
Date: 07-2009
DOI: 10.1063/1.3153966
Abstract: The influence of Sn doping on the growth of In2O3 on Y-stabilized ZrO2(100) by oxygen plasma assisted molecular beam epitaxy has been investigated over a range of substrate temperatures between 650 and 900 °C. The extent of dopant incorporation under a constant Sn flux decreases monotonically with increasing substrate temperature, although the n-type carrier concentration in “overdoped” films grown at 650 °C is lower than in films with a lower Sn concentration grown at 750 °C. The small increase in lattice parameter associated with Sn doping leads to improved matching with the substrate and suppresses breakup of the films into square islands observed in high temperature growth of undoped In2O3 on Y-stabilized ZrO2(100). Plasmon energies derived from infrared reflection spectra of Sn-doped films are found to be close to satellite energies in core level photoemission spectroscopy, but for a nominally undoped reference s le there is evidence for carrier accumulation at the surface. This influences both the In 3d core line shape and the intensity of a peak close to the Fermi energy associated with photoemission from the conduction band.
Publisher: American Vacuum Society
Date: 07-2002
DOI: 10.1116/1.1491541
Abstract: High-resolution electron-energy-loss spectroscopy (HREELS) has been used as a noninvasive probe to investigate the plasmon excitations and accumulation layers and determine the nominal electron mobility in the near-surface region of undoped molecular beam epitaxial-grown InAs(100). HREEL spectra were recorded at 300 and 600 K, over a wide range of incident electron energies, to observe the effects of temperature on the electron mobility, carrier concentration, surface state density, accumulation layer profile, and plasmon d ing mechanisms. These data have been analyzed using semiclassical dielectric theory with a three-layer model, using a simple Drude dielectric function. A separate wave-vector-dependent Landau d ing term was included to allow momentum scattering to be described independently by the usual phenomenological d ing term. The probing electron energy and temperature dependence of this momentum d ing is used to gauge the relative contributions of surface scattering, ionized impurity scattering, and phonon scattering. By extracting the surface scattering component of the plasmon d ing, bulk mobility values have been estimated and are much higher than those determined from the high probing electron energy plasmon d ing parameters. The bulk electron mobilities and bulk carrier concentrations are 28 800 cm2 V−1 s−1 and 2×1016 cm−3 at 300 K, respectively, and 12 900 cm2 V−1 s−1 and 2×1017 cm−3 at 600 K.
Publisher: IOP Publishing
Date: 1993
Publisher: Elsevier BV
Date: 08-1990
Publisher: American Physical Society (APS)
Date: 23-05-2006
Publisher: Institution of Engineering and Technology (IET)
Date: 1989
DOI: 10.1049/EL:19890201
Publisher: AIP Publishing
Date: 28-10-2004
DOI: 10.1063/1.1792390
Abstract: The modification of the electronic properties of InSb by implantation of low-energy N2+ ions and annealing have been investigated. A non-uniform electron density depth profile is observed in the near-surface region. Detailed measurements of the conduction-band electron-plasma frequency as a function of temperature combined with carrier statistics reveal that the electron concentration profile in the near-surface region cannot be explained solely by donor-type defects induced by the nitrogen implantation. However, these experimental observations can readily be explained in terms of InNxSb1−x band structure, the different distributions of damage-induced donor defects, and the acceptor-type nitrogen.
Publisher: American Vacuum Society
Date: 07-1992
DOI: 10.1116/1.577996
Abstract: The adsorption site, and adsorbate-substrate bondlength, has been investigated for the adsorption system Al(111)/Rb, using normal incidence standing x-ray wavefield absorption (NISXW), over a range of coverages from 0.12 to 0.33 ML including the ordered (2×2) and (√3×√3)R30° phases. By measuring both (111) and (1̄11) Bragg reflections in NISXW we obtain Rb–Al layer spacings in two real space directions and can therefore fully determine the adsorption structure by triangulation. For all phases we find adsorption in the atop sites, with a coverage-independent bondlength corresponding to an effective radius for the adsorbed Rb of 1.70±0.10 Å, significantly closer to the ionic (1.48 Å) than the metallic (2.43 Å) value. The NISXW results also show that the adsorbed Rb atoms have large vibrational litudes parallel to the surface which may be associated with the atop site adsorption.
Publisher: Wiley
Date: 2006
Publisher: IOP Publishing
Date: 04-2009
DOI: 10.1088/0953-8984/21/17/174201
Abstract: A three-region model for the high n-type conductivity in InN, including contributions from the bulk, surface and buffer layer interface of the s le, is considered. In particular, a parallel conduction analysis is used to show that this model can account for the carrier concentration and mobility variation with film thickness that has previously been determined from single-field Hall effect measurements. Microscopic origins for the donors in each region are considered, and the overriding tendency towards n-type conductivity is discussed in terms of the bulk band structure of InN.
Publisher: IOP Publishing
Date: 10-1989
Publisher: Elsevier BV
Date: 2003
Publisher: Elsevier BV
Date: 12-2007
Publisher: AIP Publishing
Date: 29-08-1994
DOI: 10.1063/1.112115
Abstract: We report the observation of quantum confinement, using photoluminescence, in InSb-In1−xAlxSb (0.08≤x≤0.23) multiquantum well s les grown by molecular beam epitaxy. A series of s les were studied with different well widths and varying concentration of aluminum in the barriers. The upshifted luminescence energies behave qualitatively as expected due to changes in confinement, and are in good quantitative agreement with calculated upshifts taking into account strain in the barriers. These results demonstrate that good quality heterostructures can be obtained in this material system and show its potential for device applications.
Publisher: Wiley
Date: 20-05-2020
Publisher: IOP Publishing
Date: 1993
Publisher: Elsevier BV
Date: 09-2002
Publisher: Institution of Engineering and Technology (IET)
Date: 1988
DOI: 10.1049/EL:19880865
Publisher: Elsevier BV
Date: 05-1986
Publisher: SPIE
Date: 18-03-2013
DOI: 10.1117/12.2004359
Publisher: Elsevier BV
Date: 08-2006
Publisher: Elsevier BV
Date: 03-2002
Publisher: American Chemical Society (ACS)
Date: 10-03-2020
Publisher: American Chemical Society (ACS)
Date: 24-12-2018
Publisher: Elsevier BV
Date: 12-2011
Publisher: Elsevier BV
Date: 1990
Publisher: Wiley
Date: 05-08-2020
Publisher: AIP Publishing
Date: 17-11-2008
DOI: 10.1063/1.3032911
Abstract: The valence band offset of ZnO/AlN heterojunctions is determined by high resolution x-ray photoemission spectroscopy. The valence band of ZnO is found to be 0.43±0.17 eV below that of AlN. Together with the resulting conduction band offset of 3.29±0.20 eV, this indicates that a type-II (staggered) band line up exists at the ZnO/AlN heterojunction. Using the III-nitride band offsets and the transitivity rule, the valence band offsets for ZnO/GaN and ZnO/InN heterojunctions are derived as 1.37 and 1.95 eV, respectively, significantly higher than the previously determined values.
Publisher: American Physical Society (APS)
Date: 07-08-2001
Publisher: Elsevier BV
Date: 11-2199
Publisher: Elsevier BV
Date: 06-2005
Publisher: AIP Publishing
Date: 15-10-2008
DOI: 10.1063/1.3000567
Abstract: The electronic properties of clean and sulfur-terminated surfaces of InSb(001) and (111)B are investigated using x-ray photoemission spectroscopy and high-resolution electron energy loss spectroscopy. The clean surfaces exhibit upward band bending (electron depletion) consistent with the charge neutrality level in InSb lying at the valence band maximum. The surface Fermi level to valence band maximum separation is increased for the S terminated compared with the clean surface, leading to flat bands and downward band bending (electron accumulation) for the (001) and (111)B surfaces, respectively. This is discussed in terms of compensation of native acceptor surface states.
Publisher: No publisher found
Date: 1989
Publisher: American Chemical Society (ACS)
Date: 13-11-2018
Abstract: Nanostructured materials have potential as platforms for analytical assays and catalytic reactions. Herein, we report the synthesis of electrocatalytically active cobalt phosphate nanostructures (CPNs) using a simple, low-cost, and scalable preparation method. The electrocatalytic properties of CPNs toward the electrooxidation of glucose (Glu) were studied by cyclic voltammetry and chrono erometry in relevant biological electrolytes, such as phosphate-buffered saline (PBS), at physiological pH (7.4). Using CPNs, Glu detection could be achieved over a wide range of biologically relevant concentrations, from 1 to 30 mM Glu in PBS, with a sensitivity of 7.90 nA/mM cm
Publisher: Wiley
Date: 11-04-2005
Publisher: AIP Publishing
Date: 28-10-2005
DOI: 10.1063/1.2126117
Abstract: Photoluminescence (PL) has been observed from dilute InNxAs1−x epilayers grown by molecular-beam epitaxy. The PL spectra unambiguously show band gap reduction with increasing N content. The variation of the PL spectra with temperature is indicative of carrier detrapping from localized to extended states as the temperature is increased. The redshift of the free exciton PL peak with increasing N content and temperature is reproduced by the band anticrossing model, implemented via a (5×5)k∙p Hamiltonian.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9MH01365B
Abstract: The unique and long-range ordered-vacancy structure in wafer-scale grown single-unit-cell-thick In 2 S 3 facilitates excellent electronic performance.
Publisher: American Physical Society (APS)
Date: 06-04-1987
Publisher: Springer Science and Business Media LLC
Date: 24-01-2020
Publisher: American Physical Society (APS)
Date: 08-10-2014
Publisher: Elsevier BV
Date: 02-2008
Publisher: Elsevier BV
Date: 03-1984
Publisher: American Physical Society (APS)
Date: 14-12-2005
Publisher: Elsevier BV
Date: 04-1994
Publisher: Elsevier BV
Date: 06-1995
Publisher: AIP Publishing
Date: 10-09-2007
DOI: 10.1063/1.2783214
Abstract: The valence band offset of wurtzite InN(0001)/yttria stabilized cubic-zirconia (YSZ)(111) heterojunctions is determined by x-ray photoemission spectroscopy to be 1.19±0.17eV giving a conduction band offset of 3.06±0.20eV. Consequently, a type-I heterojunction forms between InN and YSZ in the straddling arrangement. The low lattice mismatch and high band offsets suggest potential for use of YSZ as a gate dielectric in high-frequency InN-based electronic devices.
Publisher: American Physical Society (APS)
Date: 29-10-2008
Publisher: Elsevier BV
Date: 09-1996
Publisher: Elsevier BV
Date: 10-1987
Publisher: American Chemical Society (ACS)
Date: 19-02-2016
Publisher: American Physical Society (APS)
Date: 22-01-2004
Publisher: Wiley
Date: 12-03-2007
Publisher: Elsevier BV
Date: 11-1997
Publisher: Elsevier BV
Date: 02-1995
Publisher: AIP Publishing
Date: 13-11-2006
DOI: 10.1063/1.2387976
Abstract: The composition dependence of the Fermi-level pinning at the oxidized (0001) surfaces of n-type InxGa1−xN films (0⩽x⩽1) is investigated using x-ray photoemission spectroscopy. The surface Fermi-level position varies from high above the conduction band minimum (CBM) at InN surfaces to significantly below the CBM at GaN surfaces, with the transition from electron accumulation to depletion occurring at approximately x=0.3. The results are consistent with the composition dependence of the band edges with respect to the charge neutrality level.
Publisher: AIP Publishing
Date: 28-10-1996
DOI: 10.1063/1.117681
Abstract: We show that the (001) surface of GaSb can be cleaned efficiently by exposure to atomic hydrogen at substrate temperatures in the range 400–470 °C. This treatment removes carbon and oxygen contamination, leaving a clean, ordered surface with a symmetric (1×3) reconstruction after a total H2 dose of approximately 150 kL. An ordered but partially oxidized surface is generated during cleaning, and the removal of this residual oxide is the most difficult part of the process. Auger electron spectroscopy and low energy electron diffraction were used to monitor the chemical cleanliness and the ordering of the surface during the cleaning process, whereas high resolution electron energy loss spectroscopy was used to probe the electronic structure in the near-surface region. The results obtained indicates that this cleaning procedure leaves no residual electronic damage in the near-surface region of the Te-doped (n∼5×1017 cm−3) s les of GaSb(001) studied.
Publisher: Elsevier BV
Date: 08-2005
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA00408B
Abstract: Gallium as a solvent liquid metal catalyst is used in an energy efficient, high yield and controlled reaction between lithium and CO 2 . A liquid metal electrode and the naturally formed surface products are used as a supercapacitor.
Publisher: Elsevier BV
Date: 1988
Publisher: IOP Publishing
Date: 05-10-1998
Publisher: Elsevier BV
Date: 08-2006
Publisher: American Physical Society (APS)
Date: 07-08-2014
Publisher: Elsevier BV
Date: 11-2012
Publisher: American Physical Society (APS)
Date: 11-09-2008
Publisher: Elsevier BV
Date: 04-2002
Publisher: Elsevier BV
Date: 04-1984
Publisher: AIP Publishing
Date: 07-03-2011
DOI: 10.1063/1.3562308
Abstract: Significant polarity-related effects were observed in the near-surface atomic composition and valence band electronic structure of ZnO single crystals, investigated by x-ray photoemission spectroscopy using both Al Kα (1486.6 eV) and synchrotron radiation (150 to 1486 eV). In particular, photoemission from the lowest binding energy valence band states was found to be significantly more intense on the Zn-polar face compared to the O-polar face. This is a consistent effect that can be used as a simple, nondestructive indicator of crystallographic polarity in ZnO and other wurtzite semiconductors.
Publisher: American Chemical Society (ACS)
Date: 12-08-2022
Publisher: American Physical Society (APS)
Date: 15-01-2009
Publisher: American Physical Society (APS)
Date: 15-06-1995
Publisher: Elsevier BV
Date: 1998
Publisher: American Physical Society (APS)
Date: 15-07-1986
Publisher: American Physical Society (APS)
Date: 15-11-1994
Publisher: American Physical Society (APS)
Date: 12-03-2007
Publisher: Wiley
Date: 07-12-2011
Abstract: The band bending, position of Fermi level at the cleaned surfaces and bulk Fermi level of In‐rich In x Ga 1– x N alloys grown by metal‐organic chemical vapor deposition with a composition of 0.20 ≤ x ≤ 1.00 have been investigated using X‐ray photoemission spectroscopy, infrared reflectivity and Hall effect measurements. Wet etching of In x Ga 1– x N alloys in HCl successfully reduced the native oxides at the surface, allowing these measurements to be performed more accurately. Electron accumulation layers, accompanied by downward band bending, are present at the surface, with a decrease to flatband conditions occurring at x ≈ 0.2 with increasing Ga fraction. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Publisher: Elsevier BV
Date: 2003
Publisher: Elsevier BV
Date: 03-2003
Publisher: Elsevier BV
Date: 08-2016
Publisher: Elsevier BV
Date: 1988
Publisher: AIP Publishing
Date: 07-04-2014
DOI: 10.1063/1.4870533
Abstract: The influence of growth temperature on the synthesis of BexZn1−xO alloy films, grown on highly-mismatched Al2O3(0001) substrates, was studied by synchrotron x-ray scattering, high-resolution transmission electron microscopy and photoluminescence measurements. A single-phase BexZn1−xO alloy with a Be concentration of x = 0.25, was obtained at the growth temperature, Tg = 400 °C, and verified by high-resolution transmission electron microscopy. It was found that high-temperature growth, Tg≥600 °C, caused phase separation, resulting in a random distribution of intermixed alloy phases. The inhomogeneity and structural fluctuations observed in the BexZn1−xO films grown at high temperatures are attributed to a variation in Be composition and mosaic distribution via atomic displacement and strain relaxation.
Publisher: AIP Publishing
Date: 09-09-2003
DOI: 10.1063/1.1611270
Abstract: Electron transport properties in InNxSb1−x are investigated for a range of alloy compositions. The band structure of InNxSb1−x is modeled using a modified k⋅p Hamiltonian. This enables the semiconductor statistics for a given x value to be calculated from the dispersion relation of the E− subband. These calculations reveal that for alloy compositions in the range 0.001⩽x⩽0.02 there is only a small variation of the carrier concentration at a given plasma frequency. A similar trend is observed for the effective mass at the Fermi level. Measurements of the plasma frequency and plasmon lifetime for InNxSb1−x alloys enable the carrier concentration and the effective mass at the Fermi level to be determined and a lower limit for the electron mobility to be estimated.
Publisher: Elsevier BV
Date: 1988
Publisher: American Chemical Society (ACS)
Date: 03-02-2016
Publisher: Elsevier BV
Date: 08-2000
Publisher: Elsevier BV
Date: 1997
Publisher: Elsevier BV
Date: 04-1989
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2020
Publisher: Elsevier BV
Date: 12-1996
Publisher: Wiley
Date: 28-04-2008
Publisher: Elsevier BV
Date: 05-1990
Publisher: Elsevier BV
Date: 1984
Publisher: Elsevier BV
Date: 03-1987
Publisher: Elsevier BV
Date: 04-1985
Publisher: American Chemical Society (ACS)
Date: 04-04-2020
Publisher: Elsevier BV
Date: 10-1994
Publisher: Wiley
Date: 16-06-2010
DOI: 10.1002/RCM.4623
Abstract: Ultra-low-energy secondary ion mass spectrometry has been used to undertake a structural analysis of GaN-In(x)Ga(1-x)N (x approximately 0.25) quantum wells used in optoelectronic devices. The high resistivity of intrinsic GaN-In(x)Ga(1-x)N restricts the necessary electrical path between the analyzed area and the instrument ground potential resulting in surface charge accumulation. Consequently, unstable and unrepresentative depth profiles tend to be produced. A technique known as optical conductivity enhancement (OCE) has been used during depth profiling to reduce the material resistivity. This creates an electrical path between the s le and holder, eliminating charge build up and resulting in accurate depth profiles.
Publisher: Elsevier BV
Date: 02-1986
Publisher: American Chemical Society (ACS)
Date: 20-12-2019
DOI: 10.1021/JACS.8B11483
Abstract: We report the synthesis of centimeter sized ultrathin GaN and InN. The synthesis relies on the ammonolysis of liquid metal derived two-dimensional (2D) oxide sheets that were squeeze-transferred onto desired substrates. Wurtzite GaN nanosheets featured typical thicknesses of 1.3 nm, an optical bandgap of 3.5 eV and a carrier mobility of 21.5 cm
Publisher: AIP Publishing
Date: 30-09-1991
DOI: 10.1063/1.106216
Abstract: InSb and related narrow-gap alloys have many potential applications in addition to the conventional one of infrared detection, provided that ambient temperature operation can be achieved. We report experimental results on multilayer InSb/In1−xAlxSb structures utilizing minority-carrier exclusion and extraction. At room temperature, diodes have R0A values several orders higher than homostructure InSb devices. Negative differential resistance associated with Auger suppression is observed under reverse bias. Enhancement-mode metal-insulator-semiconductor field-effect transistors have near classical output characteristics at 294 K, with a typical transconductance of 34 mS/mm and dynamic range of 23 dB.
Publisher: Elsevier BV
Date: 05-1995
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 05-1987
Publisher: AIP Publishing
Date: 11-09-2000
DOI: 10.1063/1.1310211
Abstract: Controlled oxide removal from InAs(110) surfaces using atomic hydrogen (H*) has been achieved by monitoring the contaminant vibrational modes with high resolution electron energy loss spectroscopy (HREELS). The contributing oxide vibrational modes of the partially H* cleaned surface have been identified. Following hydrocarbon desorption during preliminary annealing at 360 °C, exposure to atomic hydrogen at 400 °C initially removes the arsenic oxides and indium suboxides complete indium oxide removal requires significantly higher hydrogen doses. After a total molecular hydrogen dose of 120 kL, a clean, ordered surface, exhibiting a sharp (1×1) pattern, was confirmed by low energy electron diffraction and x-ray photoelectron spectroscopy. Energy dependent HREELS studies of the near-surface electronic structure indicate that no residual electronic damage or dopant passivation results from the cleaning process.
Publisher: American Physical Society (APS)
Date: 25-02-2011
Publisher: AIP Publishing
Date: 19-06-2006
DOI: 10.1063/1.2214156
Abstract: As-grown InN is known to exhibit high unintentional n-type conductivity. Hall measurements from a range of high-quality single-crystalline epitaxially grown InN films reveal a dramatic reduction in the electron density (from low 1019 to low 1017cm−3) with increasing film thickness (from 50to12000nm). The combination of background donors from impurities and the extreme electron accumulation at InN surfaces is shown to be insufficient to reproduce the measured film thickness dependence of the free-electron density. When positively charged nitrogen vacancies (VN+) along dislocations are also included, agreement is obtained between the calculated and experimental thickness dependence of the free-electron concentration.
Publisher: Elsevier BV
Date: 07-2007
Publisher: American Physical Society (APS)
Date: 29-07-2008
Publisher: AIP Publishing
Date: 12-2008
DOI: 10.1063/1.3033373
Abstract: The band bending and carrier concentration profiles as a function of depth below the surface for oxidized InxGa1−xN alloys with a composition range of 0.39≤x≤1.00 are investigated using x-ray photoelectron, infrared reflection, and optical absorption spectroscopies, and solutions of Poisson’s equation within a modified Thomas–Fermi approximation. All of these InGaN s les exhibit downward band bending ranging from 0.19 to 0.66 eV and a high surface sheet charge density ranging from 5.0×1012 to 1.5×1013 cm−2. The downward band bending is more pronounced in the most In-rich InGaN s les, resulting in larger near-surface electron concentrations.
Publisher: AIP Publishing
Date: 04-06-2004
DOI: 10.1063/1.1737058
Abstract: The surface optical phonon spectra of GaNxAs1−x alloys have been measured using high-resolution electron-energy-loss spectroscopy. Multiple excitations of both GaAs-like and GaN-like Fuchs–Kliewer phonons were observed. Comparison is made with surface optical phonon spectra obtained from GaAs and GaN, semiclassical dielectric theory calculations and previous Raman scattering measurements of bulk phonon spectra of GaNxAs1−x alloys.
Publisher: American Chemical Society (ACS)
Date: 10-01-2020
Abstract: Antibiotic resistance has made the treatment of biofilm-related infections challenging. As such, the quest for next-generation antimicrobial technologies must focus on targeted therapies to which pathogenic bacteria cannot develop resistance. Stimuli-responsive therapies represent an alternative technological focus due to their capability of delivering targeted treatment. This study provides a proof-of-concept investigation into the use of magneto-responsive gallium-based liquid metal (LM) droplets as antibacterial materials, which can physically damage, disintegrate, and kill pathogens within a mature biofilm. Once exposed to a low-intensity rotating magnetic field, the LM droplets become physically actuated and transform their shape, developing sharp edges. When placed in contact with a bacterial biofilm, the movement of the particles resulting from the magnetic field, coupled with the presence of nanosharp edges, physically ruptures the bacterial cells and the dense biofilm matrix is broken down. The antibacterial efficacy of the magnetically activated LM particles was assessed against both Gram-positive and Gram-negative bacterial biofilms. After 90 min over 99% of both bacterial species became nonviable, and the destruction of the biofilms was observed. These results will impact the design of next-generation, LM-based biofilm treatments.
Publisher: American Physical Society (APS)
Date: 15-09-2000
Publisher: American Chemical Society (ACS)
Date: 19-09-2022
Abstract: Nanomaterials have the potential to transform biological and biomedical research, with applications ranging from drug delivery and diagnostics to targeted interference of specific biological processes. Most existing research is aimed at developing nanomaterials for specific tasks such as enhanced biocellular internalization. However, fundamental aspects of the interactions between nanomaterials and biological systems, in particular, membranes, remain poorly understood. In this study, we provide detailed insights into the molecular mechanisms governing the interaction and evolution of one of the most common synthetic nanomaterials in contact with model phospholipid membranes. Using a combination of atomic force microscopy (AFM) and molecular dynamics (MD) simulations, we elucidate the precise mechanisms by which citrate-capped 5 nm gold nanoparticles (AuNPs) interact with supported lipid bilayers (SLBs) of pure fluid (DOPC) and pure gel-phase (DPPC) phospholipids. On fluid-phase DOPC membranes, the AuNPs adsorb and are progressively internalized as the citrate capping of the NPs is displaced by the surrounding lipids. AuNPs also interact with gel-phase DPPC membranes where they partially embed into the outer leaflet, locally disturbing the lipid organization. In both systems, the AuNPs cause holistic perturbations throughout the bilayers. AFM shows that the lateral diffusion of the particles is several orders of magnitude smaller than that of the lipid molecules, which creates some temporary scarring of the membrane surface. Our results reveal how functionalized AuNPs interact with differing biological membranes with mechanisms that could also have implications for cooperative membrane effects with other molecules.
Publisher: American Physical Society (APS)
Date: 29-05-2009
Publisher: Elsevier BV
Date: 2011
Publisher: American Physical Society (APS)
Date: 21-02-2019
Publisher: AIP Publishing
Date: 26-09-1988
DOI: 10.1063/1.100405
Abstract: Molecular beam epitaxy has been used to grow thin (0.5 μm& t& μm) InSb epilayers on (100) GaAs substrates. Reflection high-energy electron diffraction studies indicate that the early stages of layer growth involve three-dimensional nucleation and the formation of a nonpseudomorphic structure. High-resolution electron microscopy studies of the interface are reported for the first time and directly confirm that the large lattice mismatch (14.6% at room temperature) is accommodated by the generation of misfit dislocations. Nevertheless, the structural quality of the InSb is observed to improve dramatically with increasing thickness. Detailed secondary-ion mass spectrometry measurements also demonstrate that there is no large-scale interdiffusion of constituent elements at the interface. Finally, electrical measurements show the InSb to be p type and comparable with homoepitaxial material.
Publisher: IOP Publishing
Date: 24-09-2009
Publisher: Elsevier BV
Date: 05-1983
Publisher: Springer Science and Business Media LLC
Date: 06-06-2022
DOI: 10.1038/S41557-022-00965-6
Abstract: Insights into metal-matrix interactions in atomically dispersed catalytic systems are necessary to exploit the true catalytic activity of isolated metal atoms. Distinct from catalytic atoms spatially separated but immobile in a solid matrix, here we demonstrate that a trace amount of platinum naturally dissolved in liquid gallium can drive a range of catalytic reactions with enhanced kinetics at low temperature (318 to 343 K). Molecular simulations provide evidence that the platinum atoms remain in a liquid state in the gallium matrix without atomic segregation and activate the surrounding gallium atoms for catalysis. When used for electrochemical methanol oxidation, the surface platinum atoms in the gallium-platinum system exhibit an activity of [Formula: see text] three orders of magnitude higher than existing solid platinum catalysts. Such a liquid catalyst system, with a dynamic interface, sets a foundation for future exploration of high-throughput catalysis.
Publisher: American Chemical Society (ACS)
Date: 25-02-2022
Abstract: The development of high-performing p-type transparent conducting oxides will enable immense progress in the fabrication of optoelectronic devices including invisible electronics and all-oxide power electronics. While n-type transparent electrodes have already reached widespread industrial production, the lack of p-type counterparts with comparable transparency and conductivity has created a bottleneck for the development of next-generation optoelectronic devices. In this work, we present the fabrication of delafossite copper chromium oxide p-type transparent electrodes with outstanding optical and electrical properties. These layers were deposited using ultrasonic spray pyrolysis, a wet chemical method that is fast, simple, and scalable. Through careful screening of the deposition conditions, highly crystalline, dense, and smooth CuCrO
Publisher: American Physical Society (APS)
Date: 15-10-1997
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1NR02529E
Abstract: Biosensors are essential components for effective healthcare management.
Publisher: Springer Science and Business Media LLC
Date: 03-02-2022
Publisher: AIP Publishing
Date: 14-01-2008
DOI: 10.1063/1.2833269
Abstract: The bandgap and band-edge effective mass of single crystal cadmium oxide, epitaxially grown by metal-organic vapor-phase epitaxy, are determined from infrared reflectivity, ultraviolet/visible absorption, and Hall effect measurements. Analysis and simulation of the optical data, including effects of band nonparabolicity, Moss-Burstein band filling and bandgap renormalization, reveal room temperature bandgap and band-edge effective mass values of 2.16±0.02eV and 0.21±0.01m0 respectively.
Publisher: IOP Publishing
Date: 11-1991
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.BIOS.2021.113814
Abstract: The detection of cancer cells at the single-cell level enables many novel functionalities such as next-generation cancer prognosis and accurate cellular analysis. While surface-enhanced Raman spectroscopy (SERS) has been widely considered as an effective tool in a low-cost and label-free manner, however, it is challenging to discriminate single cancer cells with an accuracy above 90% mainly due to the poor biocompatibility of the noble-metal-based SERS agents. Here, we report a dual-functional nanoprobe based on dopant-driven plasmonic oxides, demonstrating a maximum accuracy above 90% in distinguishing single THP-1 cell from peripheral blood mononuclear cell (PBMC) and human embryonic kidney (HEK) 293 from human macrophage cell line U937 based on their SERS patterns. Furthermore, this nanoprobe can be triggered by the bio-redox response from in idual cells towards stimuli, empowering another complementary colorimetric cell detection, approximately achieving the unity discrimination accuracy at a single-cell level. Our strategy could potentially enable the future accurate and low-cost detection of cancer cells from mixed cell s les.
Publisher: American Physical Society (APS)
Date: 19-02-2010
Publisher: SAGE Publications
Date: 14-10-2013
Abstract: We carried out experiments in cats to determine the thalamo-cortical projection sites of trigeminovascular sensory neurons. 1) We stimulated the middle meningeal artery (MMA) with C-fibre intensity electrical shocks and made field potential recordings over the somatosensory cortical surface. 2) We then recorded neurons in the ventroposteromedial (VPM) nucleus of the thalamus in search of neurons which could be activated from the skin, MMA and superior sagittal sinus. 3) Finally, we attempted to antidromically activate the neurons found in stage 2 by stimulating the responsive cortical areas revealed in stage 1. VPM neurons received trigeminovascular input, input from the V1 facial skin and could also be activated by electrical stimulation of the somatosensory cortex. VPM neurons activated from the cortex responded with short and invariant latencies (6.7 ± 7.7 msec mean and SD). They could follow high rates of stimulation and sometimes showed collision with orthodromic action potentials. We conclude that somatosensory (SI) cortical stimulation excites trigeminovascular VPM neurons antidromically. In consequence, these VPM neurons project to the somatosensory cortex. These findings may help to explain the ability of migraineurs with headache in the trigeminal distribution to localise their pain to a particular region in this distribution.
Publisher: Springer Science and Business Media LLC
Date: 13-01-2016
DOI: 10.1038/SREP18449
Abstract: Physiochemical interactions which occur at the surfaces of oxide materials can significantly impair their performance in many device applications. As a result, surface passivation of oxide materials has been attempted via several deposition methods and with a number of different inert materials. Here, we demonstrate a novel approach to passivate the surface of a versatile semiconducting oxide, zinc oxide (ZnO), evoking a self-assembly methodology. This is achieved via thermodynamic phase transformation, to passivate the surface of ZnO thin films with BeO nanoparticles. Our unique approach involves the use of Be x Zn 1- x O (BZO) alloy as a starting material that ultimately yields the required coverage of secondary phase BeO nanoparticles and prevents thermally-induced lattice dissociation and defect-mediated chemisorption, which are undesirable features observed at the surface of undoped ZnO. This approach to surface passivation will allow the use of semiconducting oxides in a variety of different electronic applications, while maintaining the inherent properties of the materials.
Publisher: AIP Publishing
Date: 22-12-1997
DOI: 10.1063/1.120482
Abstract: High resolution electron energy loss spectroscopy, dielectric theory simulations, and charge profile calculations have been used to study the accumulation layer and surface plasmon excitations at the In-terminated (001)-(4×1) and (111)A-(2×2) surfaces of InAs. For the (001) surface, the surface state density is 4.0±2.0×1011 cm−2, while for the (111)A surface it is 7.5±2.0×1011 cm−2, these values being independent of the surface preparation procedure, bulk doping level, and substrate temperature. Changes of the bulk Fermi level with temperature and bulk doping level do, however, alter the position of the surface Fermi level. Ion bombardment and annealing of the surface affect the accumulation layer only through changes in the effective bulk doping level and the bulk momentum scattering rate, with no discernible changes in the surface charge density.
Publisher: American Physical Society (APS)
Date: 12-05-2009
Publisher: American Physical Society (APS)
Date: 15-08-1986
Publisher: Elsevier BV
Date: 10-1996
Publisher: Wiley
Date: 12-09-2021
Abstract: The introduction of trace impurities within the doping processes of semiconductors is still a technological challenge for the electronics industries. By taking advantage of the selective enrichment of liquid metal interfaces, and harvesting the doped metal oxide semiconductor layers, the complexity of the process can be mitigated and a high degree of control over the outcomes can be achieved. Here, a mechanism of natural filtering for the preparation of doped 2D semiconducting sheets based on the different migration tendencies of metallic elements in the bulk competing for enriching the interfaces is proposed. As a model, liquid metal alloys with different weight ratios of Sn and Bi in the bulk are employed for harvesting Bi 2 O 3 ‐doped SnO nanosheets. In this model, Sn shows a much stronger tendency than Bi to occupy surface sites of the Bi–Sn alloys, even at the very high concentrations of Bi in the bulk. This provides the opportunity for creating SnO 2D sheets with tightly controlled Bi 2 O 3 dopants. By way of ex le, it is demonstrated how such nanosheets could be made selective to both reducing and oxidizing environmental gases. The process demonstrated here offers significant opportunities for future synthesis and fabrication processes in the electronics industries.
Publisher: American Physical Society (APS)
Date: 27-07-2006
Publisher: IOP Publishing
Date: 24-07-2004
Publisher: American Physical Society (APS)
Date: 04-12-2006
Publisher: American Physical Society (APS)
Date: 15-12-1998
Publisher: American Physical Society (APS)
Date: 11-04-2014
Publisher: AIP Publishing
Date: 15-11-2008
DOI: 10.1063/1.3020528
Abstract: Electron accumulation at the oxidized surface of In- and N-polarity indium nitride is shown to exhibit no dependence on the growth conditions (varied from In- to N-rich), revealing the surface Fermi level to be pinned 1.4±0.1 eV above the valence band maximum for all cases. This is in contrast to the interpretation of recent multiple-field Hall effect measurements, which suggested almost an order of magnitude increase in the sheet density of the accumulation layer upon moving from In-rich to N-rich growth conditions, and s le thickness dependent single-field Hall effect measurements which suggested different surface sheet densities for In- and N-polarity s les. However, an increase in the electron density approaching the InN/GaN (buffer layer) interface was not considered in the analysis of these Hall effect measurements, and this is invoked here to reconcile the constant surface Fermi level with the variations in “excess” sheet density observed in the previous Hall effect studies.
Publisher: American Physical Society (APS)
Date: 15-07-1996
Publisher: American Physical Society (APS)
Date: 29-08-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3CE42011F
Abstract: Pinning effect on crystalline Be x Zn 1−x O alloy films on Al 2 O 3 (0001).
Publisher: Elsevier BV
Date: 09-1996
Publisher: American Physical Society (APS)
Date: 15-09-1996
Publisher: Public Library of Science (PLoS)
Date: 23-06-2016
Publisher: SAGE Publications
Date: 22-09-2011
Abstract: Aim: To use an animal model to test whether migraine pain arises peripherally or centrally. Methods: We monitored the spontaneous and evoked activity of second-order trigeminovascular neurons in rats to test whether traffic increased following a potential migraine trigger (cortical spreading depression, CSD) and by what mechanism any such change was mediated. Results: Neurons ( n = 33) responded to stimulation of the dura mater and facial skin with A-δ latencies. They were spontaneously active with a discharge rate of 6.1 ± 6.4 discharges s −1 . Injection of 10 µg lignocaine into the trigeminal ganglion produced a fully reversible reduction of the spontaneous discharge rate of neurons. Neuronal discharge rate returned to normal by 90 min. Lignocaine reduced the evoked responses of neurons to dural stimulation to 37% and to facial skin stimulation to 53% of control. Induction of CSD by cortical injection of KCl increased the spontaneous discharge rate of neurons from 2.9 to 16.3 discharges s −1 at 20 min post CSD. Injection of 10 µg lignocaine into the trigeminal ganglion at this time failed to arrest or reverse this increase. Injection of lignocaine prior to the initiation of CSD failed to prevent the subsequent development of CSD-induced increases in discharge rates. Conclusions: These results suggest that there is a continuous baseline traffic in primary trigeminovascular fibres and that CSD does not act to increase this traffic by a peripheral action alone − rather, it must produce some of its effect by a mechanism intrinsic to the central nervous system. Thus the pain of migraine may not always be the result of peripheral sensory stimulation, but may also arise by a central mechanism.
Publisher: Elsevier BV
Date: 05-2005
Publisher: AIP Publishing
Date: 28-04-2008
DOI: 10.1063/1.2913765
Abstract: The variation in surface electronic properties of undoped c-plane InxAl1−xN alloys has been investigated across the composition range using a combination of high-resolution x-ray photoemission spectroscopy and single-field Hall effect measurements. For the In-rich alloys, electron accumulation layers, accompanied by a downward band bending, are present at the surface, with a decrease to approximately flatband conditions with increasing Al composition. However, for the Al-rich alloys, the undoped s les were found to be insulating with approximate midgap pinning of the surface Fermi level observed.
Publisher: Wiley
Date: 02-2007
Publisher: American Physical Society (APS)
Date: 16-01-2008
Publisher: American Vacuum Society
Date: 05-1997
DOI: 10.1116/1.580732
Abstract: Strain relaxation during the growth of InAs thin films on GaAs substrates by molecular beam epitaxy has been studied by scanning tunneling microscopy (STM). A two-dimensional growth mode operates for InAs layers grown on both GaAs(110) and GaAs(111)A. Detailed STM profiles of the InAs surfaces reveal small relaxation phenomena that are related to the presence of misfit dislocations at the buried heterointerface. The origin of these surface features is discussed, and their utility in studying the relaxation of strained semiconductor thin films is demonstrated.
Publisher: Elsevier BV
Date: 09-1987
Publisher: American Chemical Society (ACS)
Date: 29-10-2013
DOI: 10.1021/CG4011136
Publisher: American Physical Society (APS)
Date: 07-04-2006
Publisher: AIP Publishing
Date: 27-09-1999
DOI: 10.1063/1.124877
Abstract: In this letter we present evidence from scanning tunneling microscopy studies in support of a recently proposed structural model for the indium-terminated c(8×2) surface of InSb(001). This structural model, by Norris and co-workers, is based on a surface x-ray diffraction study [Surf. Sci. 409, 27 (1998)], and represents a significant departure from previously suggested models for the c(8×2) reconstruction on any (001) surface of the common III–V semiconductor materials. Although filled state images of the InSb(001)-c(8×2) surface have previously been published, empty states image of sufficient quality to extract any meaningful information have not previously been reported. The observations are in excellent agreement with the recently proposed model for this surface reconstruction.
Publisher: Elsevier BV
Date: 05-1998
Publisher: AIP Publishing
Date: 14-11-2017
DOI: 10.1063/1.4986967
Abstract: NixCd1-xO has a ∼3 eV band edge offset and bandgap varying from 2.2 to 3.6 eV, which is potentially important for transparent electronic and photovoltaic applications. We present a systematic study of the electronic band structure of NixCd1-xO alloys across the composition range. Ion irradiation of alloy s les leads to a saturation of the electron concentration associated with pinning of the Fermi level (EF) at the Fermi stabilization energy, the common energy reference located at 4.9 eV below the vacuum level. The composition dependence of the pinned EF allows determination of the conduction band minimum (CBM) energy relative to the vacuum level. The unusually strong deviation of the CBM energy observed from the virtual crystal approximation is explained by a band anticrossing interaction between localized 3d states of Ni and the extended states of the NixCd1-xO alloy host. The resulting band structure explains the dependence between the composition and the electrical and optical properties of the alloys—the rapid reduction of the electron mobility as well as previously observed positive band gap bowing parameter. X-ray photoelectron spectroscopy studies confirm that the L-point valence band maximum in the Cd-rich alloys are unaffected by the interaction with Ni d-states.
Publisher: Wiley
Date: 06-2006
Publisher: American Physical Society (APS)
Date: 15-05-1998
Publisher: SPIE
Date: 05-05-2006
DOI: 10.1117/12.667232
Publisher: American Physical Society (APS)
Date: 15-12-1997
Publisher: Elsevier BV
Date: 05-1991
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1CS01166A
Abstract: The surfaces of liquid metals can serve as a platform to synthesise two-dimensional materials. By exploiting the self-limiting Cabrera-Mott oxidation reaction that takes place at the surface of liquid metals exposed to ambient air, an ultrathin oxide layer can be synthesised and isolated. Several synthesis approaches based on this phenomenon have been developed in recent years, resulting in a erse family of functional 2D materials that covers a significant fraction of the periodic table. These straightforward and inherently scalable techniques may enable the fabrication of novel devices and thus harbour significant application potential. This review provides a brief introduction to liquid metals and their alloys, followed by detailed guidance on each developed synthesis technique, post-growth processing methods, integration processes, as well as potential applications of the developed materials.
Publisher: Wiley
Date: 21-08-2018
Abstract: A surge in interest of oxide-based materials is testimony for their potential utility in a wide array of device applications and offers a fascinating landscape for tuning the functional properties through a variety of physical and chemical parameters. In particular, selective electronic/defect doping has been demonstrated to be vital in tailoring novel functionalities, not existing in the bulk host oxides. Here, an extraordinary interstitial doping effect is demonstrated centered around a light element, boron (B). The host matrix is a novel composite system, made from discrete bulk LaAlO
Publisher: American Physical Society (APS)
Date: 24-06-2010
Publisher: American Physical Society (APS)
Date: 25-01-2012
Publisher: American Physical Society (APS)
Date: 07-03-2002
Publisher: Wiley
Date: 22-09-2020
Publisher: American Physical Society (APS)
Date: 09-08-2007
Publisher: American Physical Society (APS)
Date: 26-03-2008
Publisher: AIP Publishing
Date: 19-09-2005
DOI: 10.1063/1.2058224
Abstract: The structural and optoelectronic properties in GaNxSb1−x alloys (0⩽x& .02) grown by molecular-beam epitaxy on both GaSb substrates and AlSb buffer layers on GaAs substrates are investigated. High-resolution x-ray diffraction (XRD) and reciprocal space mapping indicate that the GaNxSb1−x epilayers are of high crystalline quality and the alloy composition is found to be independent of substrate, for identical growth conditions. The band gap of the GaNSb alloys is found to decrease with increasing nitrogen content from absorption spectroscopy. Strain-induced band-gap shifts, Moss-Burstein effects, and band renormalization were ruled out by XRD and Hall measurements. The band-gap reduction is solely due to the substitution of dilute amounts of highly electronegative nitrogen for antimony, and is greater than observed in GaNAs with the same N content.
Publisher: AIP Publishing
Date: 06-10-2005
DOI: 10.1063/1.2099533
Abstract: The composition profile along the [001] growth direction of low-growth-rate InAs–GaAs quantum dots (QDs) has been determined using medium-energy ion scattering (MEIS). A linear profile of In concentration from 100% In at the top of the QDs to 20% at their base provides the best fit to MEIS energy spectra.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TA07710D
Abstract: Bismuth vanadate coatings are fabricated via a sequential solution-based method and used as photoanodes for water oxidation achieving exceptional performances.
Publisher: American Chemical Society (ACS)
Date: 03-2022
Publisher: Elsevier BV
Date: 07-1998
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Chris McConville.