ORCID Profile
0000-0003-0160-1572
Current Organisation
Microsoft Corp
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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)
Photonics, Optoelectronics and Optical Communications | Quantum Information, Computation and Communication | Compound Semiconductors | Nanotechnology | Condensed Matter Physics | Electronic and Magnetic Properties of Condensed Matter; Superconductivity | Nanofabrication, Growth and Self Assembly
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in Technology | Integrated Circuits and Devices |
Related Links
Publications
Crystal Phase Engineering in Single InAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 13-08-2010
DOI: 10.1021/NL101632A
Abstract: Achieving phase purity and control in III-V nanowires is a necessity for future nanowire-based device applications. Many works have focused on cleaning specific crystal phases of defects such as twin planes and stacking faults, using parameters such as diameter, temperature, and impurity incorporation. Here we demonstrate an improved method for crystal phase control, where crystal structure variations in single InAs nanowires are designed with alternating wurtzite (WZ) and zinc blende (ZB) segments of precisely controlled length and perfect interfaces. We also demonstrate the inclusion of single twin planes and stacking faults with atomic precision in their placement, designed ZB quantum dots separated by thin segments of WZ, acting as tunnel barriers for electrons, and structural superlattices (polytypic and twin plane). Finally, we present electrical data to demonstrate the applicability of these designed structures to investigation of fundamental properties. From electrical measurements we observe clear signatures of controlled structural quantum dots in nanowires. This method will be directly applicable to a wide range of nanowire systems.
Dopant‐Free Twinning Superlattice Formation in InSb and InP Nanowires
Publisher: Wiley
Date: 05-10-2017
Simultaneous Selective-Area and Vapor-Liquid-Solid Growth of InP Nanowire Arrays
Publisher: American Chemical Society (ACS)
Date: 06-06-2016
DOI: 10.1021/ACS.NANOLETT.6B01461
Abstract: Selective-area epitaxy is highly successful in producing application-ready size-homogeneous arrays of III-V nanowires without the need to use metal catalysts. Previous works have demonstrated excellent control of nanowire properties but the growth mechanisms remain rather unclear. Herein, we report a detailed growth study revealing that fundamental growth mechanisms of pure wurtzite InP ⟨111⟩A nanowires can indeed differ significantly from the simple picture of a facet-limited selective-area growth process. A dual growth regime with and without metallic droplet is found to coexist under the same growth conditions for different diameter nanowires. Incubation times and highly nonmonotonous growth rate behaviors are revealed and explained within a dedicated kinetic model.
Erratum: In situ passivation of GaAsSb nanowires for enhanced infrared photoresponse (2020 Nanotechnology 31 244002)
Publisher: IOP Publishing
Date: 12-06-2020
Phonon Transport and Thermoelectricity in Defect-Engineered InAs Nanowires
Publisher: Springer Science and Business Media LLC
Date: 2012
DOI: 10.1557/OPL.2012.342
Abstract: There have been reports of improvements in the thermoelectric figure of merit through the use of nanostructured materials to suppress the lattice thermal conductivity. Here, we report on a fundamental study of the combined effects of defect planes and surface scattering on phonon transport and thermoelectric properties of defect-engineered InAs nanowires. A microfabricated device is employed to measure the thermal conductivity and thermopower of in idual suspended indium arsenide nanowires grown by metal organic vapor phase epitaxy. The four-probe measurement device consists of platinum resistance thermometers and electrodes patterned on two adjacent SiNx membranes. A nanowire was suspended between the two membranes, and electrical contact between the nanowire and the platinum electrodes was made with the evaporation of a Ni/Pd film through a shadow mask. The exposed back side of the device substrate allows for characterization of the crystal structure of the suspended nanowire with transmission electron microscopy (TEM) following measurement. The 100-200 nm diameter zincblende (ZB) InAs nanowire s les were grown with randomly spaced twin defects, stacking faults, or phases boundaries perpendicular to the nanowire growth direction, as revealed by transmission electron microscopy (TEM) analysis. Compared to single-crystal ZB InAs nanowires with a similar lateral dimension, the thermal conductivity of the defect-engineered nanowires is reduced by fifty percent at room temperature.
Innovative models of healthcare delivery: an umbrella review of reviews
Publisher: BMJ
Date: 02-2023
DOI: 10.1136/BMJOPEN-2022-066270
Abstract: To undertake a synthesis of evidence-based research for seven innovative models of care to inform the development of new hospitals. Umbrella review. Interventions delivered inside and outside of acute care settings. Children and adults with one or more identified acute or chronic health conditions. PsycINFO, Ovid MEDLINE and CINAHL. Clinical indicators and mortality, healthcare utilisation, quality of life, self-management and self-care and patient knowledge. A total of 66 reviews were included, synthesising evidence from 1272 primary studies across the 7 models of care. Virtual care was the most common model studied, addressed by 47 (73%) of the reviews. Common outcomes evaluated across reviews were clinical indicators and mortality, healthcare utilisation, self-care and self-management, patient knowledge, quality of life and cost-effectiveness. The findings indicate that the innovative models of healthcare we identified in this review may be effective in managing patients with a range of acute and chronic conditions. Most of the included reviews reported evidence of comparable or improved care. A consideration of local infrastructure and in idual patient characteristics, such as health literacy, may be critical in determining the suitability of models of care for patients and their implementation in local health systems. 10.17605/OSF.IO/PS6ZU.
Superconductor-nanowire devices from tunneling to the multichannel regime: Zero-bias oscillations and magnetoconductance crossover
Publisher: American Physical Society (APS)
Date: 06-06-2013
Carrier Relaxation Dynamics 1.55 μm InAs/InP Quantum Dots Under High Resonant Excitation
Publisher: AIP
Date: 2007
DOI: 10.1063/1.2730228
Temperature studies on a single InAs/InP QD layer laser emitting at 1.55 µm
Publisher: Wiley
Date: 21-02-2006
Critical thickness for InAs quantum dot formation on (311)B InP substrates
Publisher: Elsevier BV
Date: 04-2009
Innovative models of care for the health facility of the future
Publisher: BMJ
Date: 11-2022
DOI: 10.1136/BMJOPEN-2021-059330
Abstract: To address the challenges of rapidly changing healthcare, governments and health services are increasingly emphasising healthcare delivery models that are flexible, person centred, cost-effective and integrate hospital services more closely with primary healthcare and social services. In addition, such models increasingly embed consumer codesign, integration of services, and leverage digital technologies such as telehealth and sophisticated medical records systems. This paper provides a study protocol to describe a method to elicit consumer and healthcare provider needs and expectations for the development of innovative care models. A literature review identified six key models of care, supported by a common theme of consumer-focused care, along with the international evidence supporting the efficacy of these models. A mixed-methods study of the needs and expectations of consumer members and health providers who reside or work in the area of a new hospital catchment will be undertaken. They will complete a community-specific and provider-specific, short demographic questionnaire (delivered during the recruitment process) and be assigned to facilitator-coordinated online workshops comprising small focus groups. Follow-up interviews will be offered. Culturally and linguistically erse members and Aboriginal and Torres Strait Islander Elders and their communities will also be consulted. Data will be analysed thematically (qualitative) and statistically (quantitative), and findings synthesised using a triangulated approach. The results will be actively disseminated through peer-reviewed journals, conference presentations and in a report to stakeholders. This study was reviewed and approved by the relevant Ethics Committee in New South Wales, Australia.
Emission wavelength control of InAs quantum dots in a GaInAsP matrix grown on InP(311)B substrates
Publisher: Elsevier BV
Date: 2005
Atomic Scale Strain Relaxation in Axial Semiconductor III–V Nanowire Heterostructures
Publisher: American Chemical Society (ACS)
Date: 28-10-2014
DOI: 10.1021/NL503273J
Abstract: Combination of mismatched materials in semiconductor nanowire heterostructures offers a freedom of bandstructure engineering that is impossible in standard planar epitaxy. Nevertheless, the presence of strain and structural defects directly control the optoelectronic properties of these nanomaterials. Understanding with atomic accuracy how mismatched heterostructures release or accommodate strain, therefore, is highly desirable. By using atomic resolution high angle annular dark field scanning transmission electron microscopy combined with geometrical phase analyses and computer simulations, we are able to establish the relaxation mechanisms (including both elastic and plastic deformations) to release the mismatch strain in axial nanowire heterostructures. Formation of misfit dislocations, diffusion of atomic species, polarity transfer, and induced structural transformations are studied with atomic resolution at the intermediate ternary interfaces. Two nanowire heterostructure systems with promising applications (InAs/InSb and GaAs/GaSb) have been selected as key ex les.
High yield of self-catalyzed GaAs nanowire arrays grown on silicon via gallium droplet positioning
Publisher: IOP Publishing
Date: 20-05-2011
DOI: 10.1088/0957-4484/22/27/275602
Abstract: We report and detail a method to achieve growth of vertical self-catalyzed GaAs nanowires directly on Si(111) with a near-perfect vertical yield, using electron-beam-defined arrays of holes in a dielectric layer and molecular beam epitaxy. In our conditions, GaAs nanowires are grown along a vapor-liquid-solid mechanism, using in situ self-forming Ga droplets. The focus of this paper is to understand the role of the substrate preparation and of the pre-growth conditioning. Without changing temperature or the V/III ratio, the yield of vertical nanowires is increased incrementally up to 95%. The possibility to achieve very dense arrays, with center-to-center inter-wire distances less than 100 nm, is demonstrated.
Room Temperature GaAsSb Array Photodetectors
Publisher: IEEE
Date: 08-2018
Faceting, composition and crystal phase evolution in III–V antimonide nanowire heterostructures revealed by combining microscopy techniques
Publisher: IOP Publishing
Date: 10-02-2012
DOI: 10.1088/0957-4484/23/9/095702
Abstract: III-V antimonide nanowires are among the most interesting semiconductors for transport physics, nanoelectronics and long-wavelength optoelectronic devices due to their optimal material properties. In order to investigate their complex crystal structure evolution, faceting and composition, we report a combined scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning tunneling microscopy (STM) study of gold-nucleated ternary InAs/InAs(1-x)Sb(x) nanowire heterostructures grown by molecular beam epitaxy. SEM showed the general morphology and faceting, TEM revealed the internal crystal structure and ternary compositions, while STM was successfully applied to characterize the oxide-free nanowire sidewalls, in terms of nanofaceting morphology, atomic structure and surface composition. The complementary use of these techniques allows for correlation of the morphological and structural properties of the nanowires with the amount of Sb incorporated during growth. The addition of even a minute amount of Sb to InAs changes the crystal structure from perfect wurtzite to perfect zinc blende, via intermediate stacking fault and pseudo-periodic twinning regimes. Moreover, the addition of Sb during the axial growth of InAs/InAs(1-x)Sb(x) heterostructure nanowires causes a significant conformal lateral overgrowth on both segments, leading to the spontaneous formation of a core-shell structure, with an Sb-rich shell.
Giant, Level-Dependent g Factors in InSb Nanowire Quantum Dots
Publisher: American Chemical Society (ACS)
Date: 19-08-2009
DOI: 10.1021/NL901333A
Abstract: We report on magnetotransport measurements on InSb nanowire quantum dots. The measurements show that the quantum levels of the InSb quantum dots have giant g factors, with absolute values up to approximately 70, the largest value ever reported for semiconductor quantum dots. We also observe that the values of these g factors are quantum level dependent and can differ strongly between different quantum levels. The presence of giant g factors indicates that considerable contributions from the orbital motion of electrons are preserved in the measured InSb nanowire quantum dots, while the level-to-level fluctuations arise from spin-orbit interaction. We have deduced a value of Delta(SO) = 280 mueV for the strength of spin-orbit interaction from an avoided level crossing between the ground state and first excited state of an InSb nanowire quantum dot with a fixed number of electrons.
Shape Engineering of InP Nanostructures by Selective Area Epitaxy
Publisher: American Chemical Society (ACS)
Date: 10-06-2019
Abstract: Greater demand for III-V nanostructures with more sophisticated geometries other than nanowires is expected because of the recent intensive investigation of nanowire networks that show great potential in all-optical logic gates, nanoelectronics, and quantum computing. Here, we demonstrate highly uniform arrays of InP nanostructures with tunable shapes, such as membrane-, prism-, and ring-like shapes, which can be simultaneously grown by selective area epitaxy. Our in-depth investigation of shape evolution confirms that the shape is essentially determined by pattern confinement and the minimization of total surface energy. After growth optimization, all of the different InP nanostructures grown under the same growth conditions show perfect wurtzite structure regardless of the geometry and strong and homogeneous photon emission. This work expands the research field in terms of producing nanostructures with the desired shapes beyond the limits of nanowires to satisfy various requirements for nanoelectronics, optoelectronics, and quantum device applications.
Comparison of InAs quantum dot lasers emitting at 1.55 mu m under optical and electrical injection
Publisher: IOP Publishing
Date: 24-03-2005
Electrical characterization of semiconductor nanowires by scanning tunneling microscopy
Publisher: SPIE
Date: 19-02-2014
DOI: 10.1117/12.2042767
Engineering the Side Facets of Vertical [100] Oriented InP Nanowires for Novel Radial Heterostructures
Publisher: Springer Science and Business Media LLC
Date: 12-2019
Development of a Vertical Wrap-Gated InAs FET
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2008
Strong Hot Carrier Effects in Single Nanowire Heterostructures
Publisher: American Chemical Society (ACS)
Date: 26-06-2019
DOI: 10.1021/ACS.NANOLETT.9B01345
Abstract: We use transient Rayleigh scattering to study the thermalization of hot photoexcited carriers in single GaAs
Birang Daruganora: a protocol for a qualitative study to elicit Aboriginal and Torres Strait Islander community views about cultural needs and experiences for a new Australian health facility
Publisher: BMJ
Date: 04-2023
DOI: 10.1136/BMJOPEN-2022-069951
Abstract: To address challenges regarding the delivery of healthcare, governments and health services are focusing on the implementation of models that are flexible, person-centred, cost-effective and integrate hospital services more closely with primary healthcare and social services. Such models increasingly embed consumer codesign, multidisciplinary teams and leverage digital technologies, such as telehealth, attempting to deliver care more seamlessly and to continually improve services. This paper provides a study protocol to describe a method to explore Aboriginal and/or Torres Strait Islander consumer and healthcare provider needs and expectations for the design and development of a new healthcare facility in Australia. A qualitative study of consumer members’ and health providers’ needs and expectations. Data collection includes a short consumer-specific and provider-specific, demographic questionnaire and culturally appropriate facilitator-coordinated consultation workshops. Data will be analysed thematically (qualitatively). The results will be actively disseminated through peer-reviewed journals, conference presentations, reports to stakeholders and community meetings. This study was reviewed and approved by a health service-based Ethics Committee in New South Wales, Australia and the Aboriginal Health and Medical Research Committee.
Understanding the growth and composition evolution of gold-seeded ternary InGaAs nanowires
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5NR04129E
Abstract: A simple nanowire growth model is established to explain the observed growth trend of ternary InGaAs nanowires, in particular, their growth rate and composition.
Twinning Superlattice Formation in GaAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 05-09-2013
DOI: 10.1021/NN403390T
Abstract: Semiconductor nanowires have proven a versatile platform for the realization of novel structures unachievable by traditional planar epitaxy techniques. Among these, the periodic arrangement of twin planes to form twinning superlattice structures has generated particular interest. Here we demonstrate twinning superlattice formation in GaAs nanowires and investigate the diameter dependence of both morphology and twin plane spacing. An approximately linear relationship is found between plane spacing and nanowire diameter, which contrasts with previous results reported for both InP and GaP. Through modeling, we relate this to both the higher twin plane surface energy of GaAs coupled with the lower supersaturation relevant to Au seeded GaAs nanowire growth. Understanding and modeling the mechanism of twinning superlattice formation in III-V nanowires not only provides fundamental insight into the growth process, but also opens the door to the possibility of tailoring twin spacing for various electronic and mechanical applications.
Diameter Dependence of the Wurtzite−Zinc Blende Transition in InAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 12-02-2010
DOI: 10.1021/JP910821E
Electrical properties of InAs1−xSbx and InSb nanowires grown by molecular beam epitaxy
Publisher: AIP Publishing
Date: 04-06-2012
DOI: 10.1063/1.4726037
Abstract: Results of electrical characterization of Au nucleated InAs1−xSbx nanowires grown by molecular beam epitaxy are reported. An almost doubling of the extracted field effect mobility compared to reference InAs nanowires is observed for a Sb content of x = 0.13. Pure InSb nanowires on the other hand show considerably lower, and strongly diameter dependent, mobility values. Finally, InAs of wurtzite crystal phase overgrown with an InAs1−xSbx shell is found to have a substantial positive shift in threshold voltage compared to reference nanowires.
Solution‐Processed InAs Nanowire Transistors as Microwave Switches
Publisher: Wiley
Date: 23-10-2018
Supercurrent and Multiple Andreev Reflections in an InSb Nanowire Josephson Junction
Publisher: American Chemical Society (ACS)
Date: 13-12-2011
DOI: 10.1021/NL203380W
Abstract: Epitaxially grown, high quality semiconductor InSb nanowires are emerging material systems for the development of high performance nanoelectronics and quantum information processing and communication devices and for the studies of new physical phenomena in solid state systems. Here, we report on measurements of a superconductor-normal conductor-superconductor junction device fabricated from an InSb nanowire with aluminum-based superconducting contacts. The measurements show a proximity-induced supercurrent flowing through the InSb nanowire segment with a critical current tunable by a gate in the current bias configuration and multiple Andreev reflection characteristics in the voltage bias configuration. The temperature dependence and the magnetic field dependence of the critical current and the multiple Andreev reflection characteristics of the junction are also studied. Furthermore, we extract the excess current from the measurements and study its temperature and magnetic field dependences. The successful observation of the superconductivity in the InSb nanowire-based Josephson junction device indicates that InSb nanowires provide an excellent material system for creating and observing novel physical phenomena such as Majorana fermions in solid-state systems.
Correlation-Induced Conductance Suppression at Level Degeneracy in a Quantum Dot
Publisher: American Physical Society (APS)
Date: 04-05-2010
Is there an association between out-of-pocket hospital costs, quality and care outcomes?
Publisher: Springer Science and Business Media LLC
Date: 13-09-2023
Raman spectroscopy of self-catalyzed GaAs1−xSbxnanowires grown on silicon
Publisher: IOP Publishing
Date: 12-09-2013
DOI: 10.1088/0957-4484/24/40/405707
Abstract: Thanks to their wide band structure tunability, GaAs(1-x)Sb(x) nanowires provide exciting perspectives in optoelectronic and energy harvesting applications. The control of composition and strain of these ternary alloys is crucial in the determination of their optical and electronic properties. Raman scattering provides information on the vibrational properties of materials, which can be related to the composition and strain. We present a systematic study of the vibrational properties of GaAs(1-x)Sb(x) nanowires for Sb contents from 0 to 44%, as determined by energy-dispersive x-ray analyses. We find that optical phonons red-shift with increasing Sb content. We explain the shift by alloying effects, including mass disorder, dielectric changes and ionic plasmon coupling. The influence of Sb on the surface optical modes is addressed. Finally, we compare the luminescence yield between GaAs and GaAs(1-x)Sb(x), which can be related to a lower surface recombination rate. This work provides a reference for the study of ternary alloys in the form of nanowires, and demonstrates the tunability and high material quality of gold-free ternary antimonide nanowires directly grown on silicon.
Tunable Polarity in a III-V Nanowire by Droplet Wetting and Surface Energy Engineering
Publisher: Wiley
Date: 17-09-2015
Abstract: Controllable axial switching of polarity in GaAs nanowires with minimal tapering and perfect twin-free ZB structure based on the fundamental understanding of nanowire growth and kinking mechanism is presented. The polarity of the bottom segment is confirmed to be (111)A by atomically resolved scanning transmission electron microscopy.
Middle manager responses to hospital co-workers’ unprofessional behaviours within the context of a professional accountability culture change program
Publisher: Springer Science and Business Media LLC
Date: 20-09-2023
Controlling the morphology, composition and crystal structure in gold-seeded GaAs1-xSbx nanowires
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4NR06307D
Abstract: GaAs 1−x Sb x nanowires show zinc blende twin free structure at low TMSb flow while high TMSb flow results in inclined faults and nanowire kinking thanks to its surfactant role. Increase of wetting angle is observed, replying the change of surface energy.
Importance of point defect reactions for the atomic-scale roughness of III–V nanowire sidewalls
Publisher: IOP Publishing
Date: 13-05-2019
Abstract: The surface morphology of III-V semiconductor nanowires (NWs) protected by an arsenic cap and subsequently evaporated in ultrahigh vacuum is investigated with scanning tunneling microscopy and scanning transmission electron microscopy. We show that the changes of the surface morphology as a function of the NW composition and the nature of the seed particles are intimately related to the formation and reaction of surface point defects. Langmuir evaporation close to the congruent evaporation temperature causes the formation of vacancies which nucleate and form vacancy islands on {110} sidewalls of self-catalyzed InAs NWs. However, for annealing temperatures much smaller than the congruent temperature, a new phenomenon occurs: group III vacancies form and are filled by excess As atoms, leading to surface As
Metal-seeded growth of III-V semiconductor nanowires: towards gold-free synthesis
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3NR06692D
Abstract: The progress towards developing gold-free bottom-up synthesis techniques for III–V semiconductor nanowires is reviewed. Three main categories of nanowire synthesis are discussed: selective-area epitaxy, self-seeding and foreign metal seeding, with main focus on the metal-seeded techniques.
Guiding principles for effective collaborative implementation strategies for multisite hospital improvement initiatives
Publisher: BMJ
Date: 06-2023
DOI: 10.1136/BMJOPEN-2022-070799
Abstract: Large-scale, multisite hospital improvement initiatives can advance high-quality care for patients. Implementation support is key to adoption of change in this context. Strategies that foster collaboration within local teams, across sites and between initiative developers and users are important. However not all implementation strategies are successful in all settings, sometimes realising poor or unintended outcomes. Our objective here is to develop guiding principles for effective collaborative implementation strategies for multi-site hospital initiatives. Mixed-method realist evaluation. Realist studies aim to examine the underlying theories that explain differing outcomes, identifying mechanisms and contextual factors that may trigger them. We report on collaborative strategies used in four multi-site initiatives conducted in all public hospitals in New South Wales, Australia (n ). Using an iterative process, information was gathered on collaborative implementation strategies used, then initial programme theories hypothesised to underlie the strategies’ outcomes were surfaced using a realist dialogic approach. A realist interview schedule was developed to elicit evidence for the posited initial programme theories. Fourteen participants from 20 key informants invited participated. Interviews were conducted via Zoom, transcribed and analysed. From these data, guiding principles of fostering collaboration were developed. Six guiding principles were distilled: (1) structure opportunities for collaboration across sites (2) facilitate meetings to foster learning and problem-solving across sites (3) broker useful long-term relationships (4) enable support agencies to assist implementers by giving legitimacy to their efforts in the eyes of senior management (5) consider investment in collaboration as effective well beyond the current projects (6) promote a shared vision and build momentum for change by ensuring inclusive networks where everyone has a voice. Structuring and supporting collaboration in large-scale initiatives is a powerful implementation strategy if contexts described in the guiding principles are present.
Thermal conductivity of indium arsenide nanowires with wurtzite and zinc blende phases
Publisher: American Physical Society (APS)
Date: 19-05-2011
Achievement of High Density InAs Quantum Dots on InP (311)B Substrate Emitting at 1.55 µm
Publisher: IOP Publishing
Date: 08-2005
Abstract: The As flux effect on InAs quantum dots formed by gas source molecular beam epitaxy on InP substrates, oriented following the (311)B crystallographic direction has been studied. Atomic force microscopy images show that the quantum dot (QD) density dramatically increases and quantum dot sizes decrease, when decreasing the As pressure. Moreover, the size dispersion is narrowed. Photoluminescence measurements on the high QD density s les is shifted to higher energy, toward the telecommunication important 1.55 µm emission.
Zn3As2 Nanowires and Nanoplatelets: Highly Efficient Infrared Emission and Photodetection by an Earth Abundant Material
Publisher: American Chemical Society (ACS)
Date: 03-12-2014
DOI: 10.1021/NL5036918
Abstract: The development of earth abundant materials for optoelectronics and photovoltaics promises improvements in sustainability and scalability. Recent studies have further demonstrated enhanced material efficiency through the superior light management of novel nanoscale geometries such as the nanowire. Here we show that an industry standard epitaxy technique can be used to fabricate high quality II-V nanowires (1D) and nanoplatelets (2D) of the earth abundant semiconductor Zn3As2. We go on to establish the optoelectronic potential of this material by demonstrating efficient photoemission and detection at 1.0 eV, an energy which is significant to the fields of both photovoltaics and optical telecommunications. Through dynamical spectroscopy this superior performance is found to arise from a low rate of surface recombination combined with a high rate of radiative recombination. These results introduce nanostructured Zn3As2 as a high quality optoelectronic material ready for device exploration.
Tunnel junctions in a III–V nanowire by surface engineering
Publisher: Springer Science and Business Media LLC
Date: 10-10-2014
Temperature dependent properties of InSb and InAs nanowire field-effect transistors
Publisher: AIP Publishing
Date: 12-04-2010
DOI: 10.1063/1.3402760
Abstract: We present temperature dependent electrical measurements on InSb and InAs nanowire field-effect transistors (FETs). The FETs are fabricated from InAs/InSb heterostructure nanowires, where one complete transistor is defined within each of the two segments. Both the InSb and the InAs FETs are n-type with good current saturation and low voltage operation. The off-current for the InSb FET shows a strong temperature dependence, which we attribute to a barrier lowering due to an increased band-to-band tunneling in the drain part of the channel.
Anomalous Zero-Bias Conductance Peak in a Nb–InSb Nanowire–Nb Hybrid Device
Publisher: American Chemical Society (ACS)
Date: 28-11-2012
DOI: 10.1021/NL303758W
Abstract: Semiconductor InSb nanowires are expected to provide an excellent material platform for the study of Majorana fermions in solid state systems. Here, we report on the realization of a Nb-InSb nanowire-Nb hybrid quantum device and the observation of a zero-bias conductance peak structure in the device. An InSb nanowire quantum dot is formed in the device between the two Nb contacts. Due to the proximity effect, the InSb nanowire segments covered by the superconductor Nb contacts turn to superconductors with a superconducting energy gap Δ(InSb) ∼ 0.25 meV. A tunable critical supercurrent is observed in the device in high back gate voltage regions in which the Fermi level in the InSb nanowire is located above the tunneling barriers of the quantum dot and the device is open to conduction. When a perpendicular magnetic field is applied to the devices, the critical supercurrent is seen to decrease as the magnetic field increases. However, at sufficiently low back gate voltages, the device shows the quasi-particle Coulomb blockade characteristics and the supercurrent is strongly suppressed even at zero magnetic field. This transport characteristic changes when a perpendicular magnetic field stronger than a critical value, at which the Zeeman energy in the InSb nanowire is E(z) ∼ Δ(InSb), is applied to the device. In this case, the transport measurements show a conductance peak at the zero bias voltage and the entire InSb nanowire in the device behaves as in a topological superconductor phase. We also show that this zero-bias conductance peak structure can persist over a large range of applied magnetic fields and could be interpreted as a transport signature of Majorana fermions in the InSb nanowire.
Implementation of consensus-based perioperative care pathways to reduce clinical variation for elective surgery in an Australian private hospital: a mixed-methods pre–post study protocol
Publisher: BMJ
Date: 07-2023
DOI: 10.1136/BMJOPEN-2023-075008
Abstract: Addressing clinical variation in elective surgery is challenging. A key issue is how to gain consensus between largely autonomous clinicians. Understanding how the consensus process works to develop and implement perioperative pathways and the impact of these pathways on reducing clinical variation can provide important insights into the effectiveness of the consensus process. The primary objective of this study is to understand the implementation of an organisationally supported, consensus approach to implement perioperative care pathways in a private healthcare facility and to determine its impact. A mixed-methods Effectiveness-Implementation Hybrid (type III) pre–post study will be conducted in one Australian private hospital. Five new consensus-based perioperative care pathways will be developed and implemented for specific patient cohorts: spinal surgery, radical prostatectomy, cardiac surgery, bariatric surgery and total hip and knee replacement. The in idual components of these pathways will be confirmed as part of a consensus-building approach and will follow a four-stage implementation process using the Exploration, Preparation, Implementation and Sustainment framework. The process of implementation, as well as barriers and facilitators, will be evaluated through semistructured interviews and focus groups with key clinical and non-clinical staff, and participant observation. We anticipate completing 30 interviews and 15–20 meeting observations. Administrative and clinical end-points for at least 152 participants will be analysed to assess the effectiveness of the pathways. This study received ethical approval from Macquarie University Human Research Ethics Medical Sciences Committee (Reference No: 520221219542374). The findings of this study will be disseminated through peer-reviewed publications, conference presentations and reports for key stakeholders.
High‐Quality InAs/InSb Nanowire Heterostructures Grown by Metal–Organic Vapor‐Phase Epitaxy
Publisher: Wiley
Date: 07-2008
Ballistic InSb Nanowires and Networks via Metal-Sown Selective Area Growth
Publisher: American Chemical Society (ACS)
Date: 15-11-2019
DOI: 10.1021/ACS.NANOLETT.9B04265
Abstract: Selective area growth is a promising technique to realize semiconductor-superconductor hybrid nanowire networks, potentially hosting topologically protected Majorana-based qubits. In some cases, however, such as the molecular beam epitaxy of InSb on InP or GaAs substrates, nucleation and selective growth conditions do not necessarily overlap. To overcome this challenge, we propose a metal-sown selective area growth (MS SAG) technique, which allows decoupling selective deposition and nucleation growth conditions by temporarily isolating these stages. It consists of three steps: (i) selective deposition of In droplets only inside the mask openings at relatively high temperatures favoring selectivity, (ii) nucleation of InSb under Sb flux from In droplets, which act as a reservoir of group III adatoms, done at relatively low temperatures, favoring nucleation of InSb, and (iii) homoepitaxy of InSb on top of the formed nucleation layer under a simultaneous supply of In and Sb fluxes at conditions favoring selectivity and high crystal quality. We demonstrate that complex InSb nanowire networks of high crystal and electrical quality can be achieved this way. We extract mobility values of 10 000-25 000 cm
Unit Cell Structure of Crystal Polytypes in InAs and InSb Nanowires
Publisher: American Chemical Society (ACS)
Date: 24-03-2011
DOI: 10.1021/NL1041512
Abstract: The atomic distances in hexagonal polytypes of III-V compound semiconductors differ from the values expected from simply a change of the stacking sequence of (111) lattice planes. While these changes were difficult to quantify so far, we accurately determine the lattice parameters of zinc blende, wurtzite, and 4H polytypes for InAs and InSb nanowires, using X-ray diffraction and transmission electron microscopy. The results are compared to density functional theory calculations. Experiment and theory show that the occurrence of hexagonal bilayers tends to stretch the distances of atomic layers parallel to the c axis and to reduce the in-plane distances compared to those in zinc blende. The change of the lattice parameters scales linearly with the hexagonality of the polytype, defined as the fraction of bilayers with hexagonal character within one unit cell.
What do consumer and providers view as important for integrated care?
Publisher: Springer Science and Business Media LLC
Date: 04-01-2023
DOI: 10.1186/S12913-022-08997-X
Abstract: Integrated care is a model recognised internationally, however, there is limited evidence about its usability in the community. This study aimed to elicit community and provider views about integrated care and how implementation could meet their healthcare needs in a new hospital. Using a qualitative approach, consumer and provider views on the strengths, barriers and enablers for integrated care were collected via a series of online workshops and supplementary interviews. A total of 22 consumers and 49 providers participated in 11 focus groups all perceived integrated care to be an accessible and efficient model that offers a high level of care which enhanced staff and patient well-being. Providers expressed concerns about longer waiting times and safety risks associated with communication gaps and insufficient staff. Enablers include supporting consumers in navigating the integrated care process, co-ordinating and integrating primary care into the model as well as centralising patient electronic medical records. Primary, tertiary and community linkages are key for integrated care. Successful interoperability of services and networks requires an investment in resources and infrastructure to build the capability for providers to seamlessly access information at all points along the patient pathway. Integrated care is perceived by consumers and providers to be a flexible and patient-focused model of healthcare that offers benefits for a hospital of the future.
InAs film grown on Si(111) by metal organic vapor phase epitaxy
Publisher: IOP Publishing
Date: 03-2008
Control of III–V nanowire crystal structure by growth parameter tuning
Publisher: IOP Publishing
Date: 22-01-2010
The appropriateness of and barriers to glaucoma care delivery by Australian optometrists
Publisher: Informa UK Limited
Date: 16-01-2022
DOI: 10.1080/08164622.2021.2004861
Abstract: Establishing the level of appropriateness and barriers to glaucoma care delivery by Australian optometrists are important first steps in developing tailored interventions aimed at improving glaucoma care delivery. To determine the appropriateness of and barriers to glaucoma care by optometrists. A mixed method study was conducted. Phase I was a retrospective cross-sectional medical record audit that assessed glaucoma care appropriateness against 37 clinical indicators from a nationally representative s le of 42 optometry practices. In Phase II, focus groups and interviews involving 31 optometrists explored audit findings to identify barriers to appropriate glaucoma care. Barriers were analysed by deductive and inductive qualitative analysis. Saliency analysis was used to identify key domains that influence glaucoma care. Appropriate glaucoma care was delivered for 63% (95% CI 61%, 64%) of the 420 patient encounters audited. Appropriate care was delivered above 80% for most (57%) indicators, while 14 (38%) indicators were delivered below 60% appropriateness. Good compliance to appropriate care was noted for key indicators of intraocular pressure measurement (90%, 95% CI 87%, 93%) and optic nerve head/retinal nerve fibre layer imaging (78%, 95% CI 74%, 82%). Important barriers identified were beliefs about expected outcomes, lack of perceived relevancy, time constraints, poor organisational culture, knowledge gaps, focusing on some aspects of glaucoma care to the detriment of others, the complexity of glaucoma care, information recall, and social norms. Glaucoma care was appropriate in most patient encounters, with opportunity to improve some aspects of history taking and physical examinations. Barriers to glaucoma care were erse, existing at both the practitioner and organisational levels. These findings provide direction for the development of a tailored improvement intervention.
Band offsets at zincblende-wurtzite GaAs nanowire sidewall surfaces
Publisher: AIP Publishing
Date: 16-09-2013
DOI: 10.1063/1.4821293
Abstract: The band structure and the Fermi level pinning at clean and well-ordered sidewall surfaces of zincblende (ZB)-wurtzite (WZ) GaAs nanowires are investigated by scanning tunneling spectroscopy and density functional theory calculations. The WZ-ZB phase transition in GaAs nanowires introduces p-i junctions at the sidewall surfaces. This is caused by the presence of numerous steps, which induce a Fermi level pinning at different energies on the non-polar WZ and ZB sidewall facets.
Controlled polytypic and twin-plane superlattices in iii–v nanowires
Publisher: Springer Science and Business Media LLC
Date: 30-11-2008
Abstract: Semiconductor nanowires show promise for use in nanoelectronics, fundamental electron transport studies, quantum optics and biological sensing. Such applications require a high degree of nanowire growth control, right down to the atomic level. However, many binary semiconductor nanowires exhibit a high density of randomly distributed twin defects and stacking faults, which results in an uncontrolled, or polytypic, crystal structure. Here, we demonstrate full control of the crystal structure of InAs nanowires by varying nanowire diameter and growth temperature. By selectively tuning the crystal structure, we fabricate highly reproducible polytypic and twin-plane superlattices within single nanowires. In addition to reducing defect densities, this level of control could lead to bandgap engineering and novel electronic behaviour.
Doping Incorporation in InAs nanowires characterized by capacitance measurements
Publisher: AIP Publishing
Date: 09-2010
DOI: 10.1063/1.3475356
Abstract: Sn and Se doped InAs nanowires are characterized using a capacitance-voltage technique where the threshold voltages of nanowire capacitors with different diameter are determined and analyzed using an improved radial metal-insulator-semiconductor field-effect transistor model. This allows for a separation of doping in the core of the nanowire from the surface charge at the side facets of the nanowire. The data show that the doping level in the InAs nanowire can be controlled on the level between 2×1018 to 1×1019 cm−3, while the surface charge density exceeds 5×1012 cm−2 and is shown to increase with higher dopant precursor molar fraction.
The diversity of providers’ and consumers’ views of virtual versus inpatient care provision
Publisher: Springer Science and Business Media LLC
Date: 04-07-2023
DOI: 10.1186/S12913-023-09715-X
Abstract: A broad-based international shift to virtual care models over recent years has accelerated following COVID-19. Although there are increasing numbers of studies and reviews, less is known about clinicians’ and consumers’ perspectives concerning virtual modes in contrast to inpatient modes of delivery. We conducted a mixed-methods study in late 2021 examining consumers’ and providers’ expectations of and perspectives on virtual care in the context of a new facility planned for the north-western suburbs of Sydney, Australia. Data were collected via a series of workshops, and a demographic survey. Recorded qualitative text data were analysed thematically, and surveys were analysed using SPSS v22. Across 12 workshops, 33 consumers and 49 providers from varied backgrounds, ethnicities, language groups, age ranges and professions participated. Four advantages, strengths or benefits of virtual care reported were: patient factors and wellbeing, accessibility, better care and health outcomes, and additional health system benefits, while four disadvantages, weaknesses or risks of virtual care were: patient factors and wellbeing, accessibility, resources and infrastructure , and quality and safety of care . Virtual care was widely supported but the model is not suitable for all patients. Health and digital literacy and appropriate patient selection were key success criteria, as was patient choice. Key concerns included technology failures or limitations and that virtual models may be no more efficient than inpatient care models. Considering consumer and provider views and expectations prior to introducing virtual models of care may facilitate greater acceptance and uptake.
Exploring the band structure of Wurtzite InAs nanowires using photocurrent spectroscopy
Publisher: Springer Science and Business Media LLC
Date: 14-04-2020
The electrical and structural properties of n-type InAs nanowires grown from metal–organic precursors
Publisher: IOP Publishing
Date: 23-04-2010
DOI: 10.1088/0957-4484/21/20/205703
Abstract: The electrical and structural properties of 111B-oriented InAs nanowires grown using metal-organic precursors have been studied. On the basis of electrical measurements it was found that the trends in carbon incorporation are similar to those observed in the layer growth, where an increased As/In precursor ratio and growth temperature result in a decrease in carbon-related impurities. Our results also show that the effect of non-intentional carbon doping is weaker in InAs nanowires compared to bulk, which may be explained by lower carbon incorporation in the nanowire core. We determine that differences in crystal quality, here quantified as the stacking fault density, are not the primary cause for variations in resistivity of the material studied. The effects of some n-dopant precursors (S, Se, Si, Sn) on InAs nanowire morphology, crystal structure and resistivity were also investigated. All precursors result in n-doped nanowires, but high precursor flows of Si and Sn also lead to enhanced radial overgrowth. Use of the Se precursor increases the stacking fault density in wurtzite nanowires, ultimately at high flows leading to a zinc blende crystal structure with strong overgrowth and very low resistivity.
Increase of charge-carrier redistribution efficiency in a laterally organized superlattice of coupled quantum dots
Publisher: American Physical Society (APS)
Date: 18-12-2006
Issues and complexities in safety culture assessment in healthcare
Publisher: Frontiers Media SA
Date: 15-06-2023
DOI: 10.3389/FPUBH.2023.1217542
Abstract: The concept of safety culture in healthcare—a culture that enables staff and patients to be free from harm—is characterized by complexity, multifacetedness, and indefinability. Over the years, disparate and unclear definitions have resulted in a proliferation of measurement tools, with lack of consensus on how safety culture can be best measured and improved. A growing challenge is also achieving sufficient response rates, due to “survey fatigue,” with the need for survey optimisation never being more acute. In this paper, we discuss key challenges and complexities in safety culture assessment relating to definition, tools, dimensionality and response rates. The aim is to prompt critical reflection on these issues and point to possible solutions and areas for future research.
GaAs/GaSb nanowire heterostructures grown by MOVPE
Publisher: Elsevier BV
Date: 08-2008
In situ passivation of GaAsSb nanowires for enhanced infrared photoresponse
Publisher: IOP Publishing
Date: 27-03-2020
Carrier Dynamics and Saturation Effect in (113)B InAs/InP Quantum Dot Lasers
Publisher: Springer Science and Business Media LLC
Date: 03-2006
Room temperature GaAsSb single nanowire infrared photodetectors
Publisher: IOP Publishing
Date: 09-10-2015
DOI: 10.1088/0957-4484/26/44/445202
Abstract: Antimonide-based ternary III-V nanowires (NWs) allow for a tunable bandgap over a wide range, which is highly interesting for optoelectronics applications, and in particular for infrared photodetection. Here we demonstrate room temperature operation of GaAs0.56Sb0.44 NW infrared photodetectors grown by metal organic vapor phase epitaxy. These GaAs0.56Sb0.44 NWs have uniform axial composition and show p-type conductivity with a peak field-effect mobility of ∼12 cm(2) V(-1) s(-1)). Under light illumination, single GaAs0.56Sb0.44 NW photodetectors exhibited typical photoconductor behavior with an increased photocurrent observed with the increase of temperature owing to thermal activation of carrier trap states. A broadband infrared photoresponse with a long wavelength cutoff at ∼1.66 μm was obtained at room temperature. At a low operating bias voltage of 0.15 V a responsivity of 2.37 (1.44) A/W with corresponding detectivity of 1.08 × 10(9) (6.55 × 10(8)) cm√Hz/W were achieved at the wavelength of 1.3 (1.55) μm, indicating that ternary GaAs0.56Sb0.44 NWs are promising photodetector candidates for small footprint integrated optical telecommunication systems.
InAs-Al hybrid devices passing the topological gap protocol
Publisher: American Physical Society (APS)
Date: 21-06-2023
Impact of invasive metal probes on Hall measurements in semiconductor nanostructures
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0NR04402D
Abstract: Experimental data and modelling show that invasive Hall probes lead to substantial misestimates of carrier concentration and mobility in 2D-nanostructure devices.
Self-Equilibration of the Diameter of Ga-Catalyzed GaAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 22-07-2015
DOI: 10.1021/ACS.NANOLETT.5B02226
Abstract: Designing strategies to reach monodispersity in fabrication of semiconductor nanowire ensembles is essential for numerous applications. When Ga-catalyzed GaAs nanowire arrays are grown by molecular beam epitaxy with help of droplet-engineering, we observe a significant narrowing of the diameter distribution of the final nanowire array with respect to the size distribution of the initial Ga droplets. Considering that the droplet serves as a nonequilibrium reservoir of a group III metal, we develop a model that demonstrates a self-equilibration effect on the droplet size in self-catalyzed III-V nanowires. This effect leads to arrays of nanowires with a high degree of uniformity regardless of the initial conditions, while the stationary diameter can be further finely tuned by varying the spacing of the array pitch on patterned Si substrates.
Gold-Free Ternary III–V Antimonide Nanowire Arrays on Silicon: Twin-Free down to the First Bilayer
Publisher: American Chemical Society (ACS)
Date: 18-12-2013
DOI: 10.1021/NL404085A
Antimony Induced {112}A Faceted Triangular GaAs1−xSbx/InP Core/Shell Nanowires and Their Enhanced Optical Quality
Publisher: Wiley
Date: 27-07-2015
Nanowires Grown on InP (100): Growth Directions, Facets, Crystal Structures, and Relative Yield Control
Publisher: American Chemical Society (ACS)
Date: 05-06-2014
DOI: 10.1021/NN5017428
Abstract: Growth of III-V nanowires on the [100]-oriented industry standard substrates is critical for future integrated nanowire device development. Here we present an in-depth analysis of the seemingly complex ensembles of epitaxial nanowires grown on InP (100) substrates. The nanowires are categorized into three types as vertical, nonvertical, and planar, and the growth directions, facets, and crystal structure of each type are investigated. The nonvertical growth directions are mathematically modeled using a three-dimensional multiple-order twinning concept. The nonvertical nanowires can be further classified into two different types, with one type growing in the ⟨111⟩ directions and the other in the ⟨100⟩ directions after initial multiple three-dimensional twinning. We find that 99% of the total nanowires are grown either along ⟨100⟩, ⟨111⟩, or ⟨110⟩ growth directions by {100} or {111} growth facets. We also demonstrate relative control of yield of these different types of nanowires, by tuning pregrowth annealing conditions and growth parameters. Together, the knowledge and controllability of the types of nanowires provide an ideal foundation to explore novel geometries that combine different crystal structures, with potential for both fundamental science research and device applications.
Growth of vertical InAs nanowires on heterostructured substrates
Publisher: IOP Publishing
Date: 23-06-2009
DOI: 10.1088/0957-4484/20/28/285303
Abstract: We investigate the Au-assisted growth of InAs nanowires on two different kinds of heterostructured substrates: GaAs/AlGaAs structures capped by a 50 nm thick InAs layer grown by molecular beam epitaxy and a 2 microm thick InAs buffer layer on Si(111) obtained by vapor phase epitaxy. Morphological and structural properties of substrates and nanowires are analyzed by atomic force and transmission electron microscopy. Our results indicate a promising direction for the integration of III-V nanostructures on Si-based electronics as well as for the development of novel micromechanical structures incorporating nanowires as their active elements.
Selective-Area Epitaxy of Pure Wurtzite InP Nanowires: High Quantum Efficiency and Room-Temperature Lasing
Publisher: American Chemical Society (ACS)
Date: 15-08-2014
DOI: 10.1021/NL5021409
Abstract: We report the growth of stacking-fault-free and taper-free wurtzite InP nanowires with diameters ranging from 80 to 600 nm using selective-area metal-organic vapor-phase epitaxy and experimentally determine a quantum efficiency of ∼50%, which is on par with InP epilayers. We also demonstrate room-temperature, photonic mode lasing from these nanowires. Their excellent structural and optical quality opens up new possibilities for both fundamental quantum optics and optoelectronic devices.
Strong Amplified Spontaneous Emission from High Quality GaAs1–xSbx Single Quantum Well Nanowires
Publisher: American Chemical Society (ACS)
Date: 05-04-2017
InSb heterostructure nanowires: MOVPE growth under extreme lattice mismatch
Publisher: IOP Publishing
Date: 11-11-2009
DOI: 10.1088/0957-4484/20/49/495606
Abstract: We demonstrate the growth of InSb-based nanowire heterostructures by metalorganic vapour phase epitaxy and use it to integrate InSb on extremely lattice-mismatched III-V nanowire templates made of InAs, InP, and GaAs. Influence of temperature, V/III ratio, and diameter are investigated in order to investigate the growth rate and morphology. The range of growth temperatures used for InSb nanowire growth is very similar to that used for planar growth due to the nature of the precursor decomposition. This makes optimization of growth parameters very important, and more difficult than for most other nanowire III-V materials. Analysis of the InSb nanowire epitaxial quality when grown on InAs, InP, and GaAs, along with InSb segment and particle compositions are reported. This successful direct integration of InSb nanowires, on nanowire templates with unprecedented strain levels show great promise for fabrication of vertical InSb devices.
Molecular beam epitaxy growth of quantum dot lasers emitting around 1.5μm on InP(311)B substrates
Publisher: Elsevier BV
Date: 05-2005
Characterization of GaSb nanowires grown by MOVPE
Publisher: Elsevier BV
Date: 11-2008
Impact of the capping layers on lateral confinement in InAs∕InP quantum dots for 1.55μm laser applications studied by magnetophotoluminescence
Publisher: AIP Publishing
Date: 30-11-2005
DOI: 10.1063/1.2132527
Abstract: We have used magnetophotoluminescence to study the impact of different capping layer material combinations (InP, GaInAsP quaternary alloy, or both InP and quaternary alloy) on lateral confinement in InAs∕InP quantum dots (QDs) grown on (311)B orientated substrates. Exciton effective masses, Bohr radii, and binding energies are measured for these s les. Conclusions regarding the strength of the lateral confinement in the different s les are supported by photoluminescence at high excitation power. Contrary to theoretical predictions, InAs QDs in quaternary alloy are found to have better confinement properties than InAs∕InP QDs. This is attributed to a lack of lateral intermixing with the quaternary alloy, which is present when InP is used to (partially) cap the dots. The implications of the results for reducing the temperature sensitivity of QD lasers are discussed.
Editorial—Focus on inorganic semiconductor nanowires for device applications
Publisher: IOP Publishing
Date: 15-12-2018
Persistent enhancement of the carrier density in electron irradiated InAs nanowires
Publisher: IOP Publishing
Date: 14-06-2013
DOI: 10.1088/0957-4484/24/27/275706
Abstract: We report a significant and persistent enhancement of the conductivity in free-standing non-intentionally doped InAs nanowires upon irradiation in ultra-high vacuum. Combining four-point probe transport measurements performed on nanowires with different surface chemistries, field effect based measurements and numerical simulations of the electron density, the change in the conductivity is found to be caused by an increase in the surface free carrier concentration. Although an electron beam of a few keV, typically used for the inspection and the processing of materials, propagates through the entire nanowire cross-section, we demonstrate that the electrical properties of the nanowire are predominantly affected by radiation-induced defects occurring at the nanowire surface and not in the bulk.
Consumer and provider perspectives on Hospital in the Home
Publisher: Hindawi Limited
Date: 26-10-2023
DOI: 10.1155/2023/7105751
Ballistic transport and quantum interference in InSb nanowire devices
Publisher: IOP Publishing
Date: 02-2017
Experience-based codesign approach to improve care in Australian emergency departments for complex consumer cohorts: the MyED project protocol, Stages 1.1–1.3
Publisher: BMJ
Date: 07-2023
DOI: 10.1136/BMJOPEN-2023-072908
Abstract: Emergency department (ED) care must adapt to meet current and future demands. In Australia, ED quality measures (eg, prolonged length of stay, re-presentations or patient experience) are worse for older adults with multiple comorbidities, people who have a disability, those who present with a mental health condition, Indigenous Australians, and those with a culturally and linguistically erse (CALD) background. Strengthened ED performance relies on understanding the social and systemic barriers and preferences for care of these different cohorts, and identifying viable solutions that may result in sustained improvement by service providers. A collaborative 5-year project (MyED) aims to codesign, with ED users and providers, new or adapted models of care that improve ED performance, improve patient outcomes and improve patient experience for these five cohorts. Experience-based codesign using mixed methods, set in three hospitals in one health district in Australia. This protocol introduces the staged and incremental approach to the whole project, and details the first research elements: ethnographic observations at the ED care interface, interviews with providers and interviews with two patient cohorts—older adults and adults with a CALD background. We aim to s le a erse range of participants, carefully tailoring recruitment and support. Ethics approval has been obtained from the Western Sydney Local Health District Human Research Ethics Committee (2022/PID02749-2022/ETH02447). Prior informed written consent will be obtained from all research participants. Findings from each stage of the project will be submitted for peer-reviewed publication. Project outputs will be disseminated for implementation more widely across New South Wales, Australia.
Characterization of InAs quantum wires on (001)InP: toward the realization of VCSEL structures with a stabilized polarization
Publisher: Wiley
Date: 06-2007
Rates of adherence to cancer treatment guidelines in Australia and the factors associated with adherence: A systematic review
Publisher: Wiley
Date: 07-03-2023
DOI: 10.1111/AJCO.13948
Abstract: Adherence to cancer treatment clinical practice guidelines (CPGs) varies enormously across Australia, despite being associated with improved patient outcomes. This systematic review aims to characterize adherence rates to active‐cancer treatment CPGs in Australia and related factors to inform future implementation strategies. Five databases were systematically searched, abstracts were screened for eligibility, a full‐text review and critical appraisal of eligible studies performed, and data extracted. A narrative synthesis of factors associated with adherence was conducted, and the median adherence rates within cancer streams calculated. A total of 21,031 abstracts were identified. After duplicates were removed, abstracts screened, and full texts reviewed, 20 studies focused on adherence to active‐cancer treatment CPGs were included. Overall adherence rates ranged from 29% to 100%. Receipt of guideline recommended treatments was higher for patients who were younger (diffuse large B‐cell lymphoma [DLBCL], colorectal, lung, and breast cancer) female (breast and lung cancer), and male (DLBCL and colorectal cancer) never smokers (DLBCL and lung cancer) non‐Indigenous Australians (cervical and lung cancer) with less advanced stage disease (colorectal, lung, and cervical cancer), without comorbidities (DLBCL, colorectal, and lung cancer) with good‐excellent Eastern Cooperative Oncology Group performance status (lung cancer) living in moderately accessible places (colon cancer) and treated in metropolitan facilities (DLBLC, breast and colon cancer). This review characterized active‐cancer treatment CPG adherence rates and associated factors in Australia. Future targeted CPG implementation strategies should account for these factors, to redress unwarranted variation particularly in vulnerable populations, and improve patient outcomes (Prospero number: CRD42020222962).
Magnetotransport Subband Spectroscopy in InAs Nanowires
Publisher: American Physical Society (APS)
Date: 20-02-2014
Morphology and composition controlled GaxIn1−xSb nanowires: understanding ternary antimonide growth
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3NR05079C
Abstract: Antimonide-based nanowires represent an important new class of material with great promise for both fundamental physics studies and various device applications. We report a comprehensive study on understanding the growth behaviour of GaxIn1-xSb nanowires on GaAs substrates using Au nanoparticles. First, the effect of growth parameters on the morphology and composition of GaxIn1-xSb nanowires is extensively studied over the entire compositional range (from 3 to ~100% of In). Second, the obtained compositional results are explained by a kinetic model, suggesting an Arrhenius-type behavior for the trimethylindium (TMIn) precursor. Third, the particle composition is fully investigated and the implications for growth are discussed with reference to our calculated Au-Ga-In phase diagram. Fourth, a mechanism is presented to explain the temperature-dependent morphology and radial growth of the GaxIn1-xSb nanowires. Finally, we demonstrate homogeneous compositions in both axial and radial directions and the nanowires remain entirely twin-free zinc blende. The understanding gained from this study together with the potential to precisely tailor the band gap, wavelength and carrier mobilities allows fabrication of various GaxIn1-xSb-based nanowire devices.
HIV-1–Specific CD8 T Cells Exhibit Limited Cross-Reactivity during Acute Infection
Publisher: The American Association of Immunologists
Date: 15-04-2016
Abstract: Prior work has demonstrated that HIV-1–specific CD8 T cells can cross-recognize variant epitopes. However, most of these studies were performed in the context of chronic infection, where the presence of viral quasispecies makes it difficult to ascertain the true nature of the original antigenic stimulus. To overcome this limitation, we evaluated the extent of CD8 T cell cross-reactivity in patients with acute HIV-1 clade B infection. In each case, we determined the transmitted founder virus sequence to identify the autologous epitopes restricted by in idual HLA class I molecules. Our data show that cross-reactive CD8 T cells are infrequent during the acute phase of HIV-1 infection. Moreover, in the uncommon instances where cross-reactive responses were detected, the variant epitopes were poorly recognized in cytotoxicity assays. Molecular analysis revealed that similar antigenic structures could be cross-recognized by identical CD8 T cell clonotypes mobilized in vivo, yet even subtle differences in a single TCR-accessible peptide residue were sufficient to disrupt variant-specific reactivity. These findings demonstrate that CD8 T cells are highly specific for autologous epitopes during acute HIV-1 infection. Polyvalent vaccines may therefore be required to provide optimal immune cover against this genetically labile pathogen.
Retrospective analysis of factors influencing the implementation of a program to address unprofessional behaviour and improve culture in Australian hospitals
Publisher: Springer Science and Business Media LLC
Date: 07-06-2023
DOI: 10.1186/S12913-023-09614-1
Abstract: Unprofessional behaviour among hospital staff is common. Such behaviour negatively impacts on staff wellbeing and patient outcomes. Professional accountability programs collect information about unprofessional staff behaviour from colleagues or patients, providing this as informal feedback to raise awareness, promote reflection, and change behaviour. Despite increased adoption, studies have not assessed the implementation of these programs utilising implementation theory. This study aims to (1) identify factors influencing the implementation of a whole-of-hospital professional accountability and culture change program, Ethos , implemented in eight hospitals within a large healthcare provider group, and (2) examine whether expert recommended implementation strategies were intuitively used during implementation, and the degree to which they were operationalised to address identified barriers. Data relating to implementation of Ethos from organisational documents, interviews with senior and middle management, and surveys of hospital staff and peer messengers were obtained and coded in NVivo using the Consolidated Framework for Implementation Research (CFIR). Implementation strategies to address identified barriers were generated using Expert Recommendations for Implementing Change (ERIC) strategies and used in a second round of targeted coding, then assessed for degree of alignment to contextual barriers. Four enablers, seven barriers, and three mixed factors were found, including perceived limitations in the confidential nature of the online messaging tool (‘Design quality and packaging’), which had downstream challenges for the capacity to provide feedback about utilisation of Ethos (‘Goals and Feedback’, ‘Access to Knowledge and Information’). Fourteen recommended implementation strategies were used, however, only four of these were operationalised to completely address contextual barriers. Aspects of the inner setting (e.g., ‘Leadership Engagement’, ‘Tension for Change’) had the greatest influence on implementation and should be considered prior to the implementation of future professional accountability programs. Theory can improve understanding of factors affecting implementation, and support strategies to address them.
Inhomogeneous Si-doping of gold-seeded InAs nanowires grown by molecular beam epitaxy
Publisher: AIP Publishing
Date: 03-06-2013
DOI: 10.1063/1.4809576
Abstract: We have investigated in situ Si doping of InAs nanowires grown by molecular beam epitaxy from gold seeds. The effectiveness of n-type doping is confirmed by electrical measurements showing an increase of the electron density with the Si flux. We also observe an increase of the electron density along the nanowires from the tip to the base, attributed to the dopant incorporation on the nanowire facets whereas no detectable incorporation occurs through the seed. Furthermore, the Si incorporation strongly influences the lateral growth of the nanowires without giving rise to significant tapering, revealing the complex interplay between axial and lateral growth.
Vertical “III–V” V-Shaped Nanomembranes Epitaxially Grown on a Patterned Si[001] Substrate and Their Enhanced Light Scattering
Publisher: American Chemical Society (ACS)
Date: 05-12-2012
DOI: 10.1021/NN304526K
Abstract: We report on a new form of III-V compound semiconductor nanostructures growing epitaxially as vertical V-shaped nanomembranes on Si(001) and study their light-scattering properties. Precise position control of the InAs nanostructures in regular arrays is demonstrated by bottom-up synthesis using molecular beam epitaxy in nanoscale apertures on a SiO(2) mask. The InAs V-shaped nanomembranes are found to originate from the two opposite facets of a rectangular pyramidal island nucleus and extend along two opposite B directions, forming flat {110} walls. Dark-field scattering experiments, in combination with light-scattering theory, show the presence of distinctive shape-dependent optical resonances significantly enhancing the local intensity of incident electromagnetic fields over tunable spectral regions. These new nanostructures could have interesting potential in nanosensors, infrared light emitters, and nonlinear optical elements.
Treating persistent pain after breast cancer: practice gaps and future directions
Publisher: Springer Science and Business Media LLC
Date: 11-03-2022
0 − π
Publisher: American Physical Society (APS)
Date: 20-01-2017
Formation of long single quantum dots in high quality InSb nanowires grown by molecular beam epitaxy
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5NR04273A
Abstract: Single electron transport is demonstrated in high-quality MBE-grown InSb nanowire single quantum dots with a dot length up to ∼700 nm.
Unipolar and bipolar operation of InAs/InSb nanowire heterostructure field-effect transistors
Publisher: AIP Publishing
Date: 15-09-2011
DOI: 10.1063/1.3633742
Abstract: We present temperature dependent electrical measurements on n-type InAs/InSb nanowire heterostructure field-effect transistors. The barrier height of the heterostructure junction is determined to be 220 meV, indicating a broken bandgap alignment. A clear asymmetry is observed when applying a bias to either the InAs or the InSb side of the junction. Impact ionization and band-to-band tunneling is more pronounced when the large voltage drop occurs in the narrow bandgap InSb segment. For small negative gate-voltages, the InSb segment can be tuned toward p-type conduction, which induces a strong band-to-band tunneling across the heterostructucture junction.
Scaling-up and future sustainability of a national reproductive genetic carrier screening program
Publisher: Springer Science and Business Media LLC
Date: 31-07-2023
DOI: 10.1038/S41525-023-00357-W
Abstract: An understanding of factors influencing implementation is essential to realise the benefits of population-based reproductive genetic carrier screening programs. The aim of this study was to synthesise data collected during the Australian Reproductive Genetic Carrier Screening Project (Mackenzie’s Mission) to track how priorities shifted over time and identify important factors during scaling-up and for sustainment. We used a multi-method qualitative approach to integrate longitudinal project data collected from 10 project committees with 16 semi-structured interviews conducted with study team members. Both datasets were analysed using the Consolidated Framework for Implementation Research (CFIR) to identify constructs of interest within early, mid-point, and future implementation phases. Several CFIR constructs were present across implementation. The complexity of implementation presented challenges that were overcome through a quality-designed and packaged product, formal and informal networks and communication, and access to knowledge and information. Addressing the erse consumer needs through resources and increasing community and non-genetic speciality engagement remained a priority throughout and for future sustainment. Going forward, further addressing program complexities and securing funding were emphasised. By applying an implementation framework, findings from this study may be useful for future effort towards building and/or sustaining reproductive genetic carrier screening programs.
Level of appropriate primary diabetic eyecare delivered and achievable in optometry practices in Australia
Publisher: Informa UK Limited
Date: 06-02-2023
DOI: 10.1080/08164622.2022.2033107
Abstract: Current levels of appropriateness for primary diabetic eyecare delivered by Australian optometrists are presented along with realistic targets (benchmarks) for quality improvement. The demonstrated methods can be used in practice evaluation and benchmarking of other clinical practice areas and settings. To examine the appropriateness of diabetic eye-care delivery and establish achievable benchmarks of care (ABCs) for optometry practices in Australia. In a retrospective audit, clinical records of patients with type-II diabetes obtained from a randomly selected nationally representative s le of optometry practices were assessed against evidence-based clinical indicators. Appropriate care is defined as care delivered in compliance with the indicators. The ABC for each indicator was calculated as the average performance for the top 10% of optometry practices after Bayesian adjustment to account for a low number of eligible records. The audit of 420 randomly selected patient records from 42 practices against 12 clinical indicators showed an overall appropriateness of 69% (95% confidence interval (CI) 66%, 73%) for overall diabetic eye care. While a high level of appropriateness was identified for recall period (93%, 95% CI 85%, 100%) and referral (100%, 95% CI 38%, 100%), larger gaps existed in history taking (46%, 95% CI 44%, 52%), dilated fundus examination (80%, 95% CI 76%, 84%) and iris examination (0%, 95% CI 0%, 56%). The ABCs for 8 of 12 indicators were 100%, and the remaining three indicators had ABCs above 80%. An ABC for the iris examination indicator could not be calculated owing to the low number of eligible patient record cards. This study demonstrated a systematic process of practice evaluation and benchmarking in optometry practices. The diabetic eye care delivered by Australian optometrists was largely appropriate however, improvement opportunities exist for history taking and physical examination. The ABCs demonstrate that excellence in primary diabetic eye care is attainable and will serve as an important tool in future initiatives to reduce the identified evidence-to-practice gaps.
Demonstration of Defect-Free and Composition Tunable GaxIn1–xSb Nanowires
Publisher: American Chemical Society (ACS)
Date: 30-08-2012
DOI: 10.1021/NL302497R
Abstract: The Ga(x)In(1-x)Sb ternary system has many interesting material properties, such as high carrier mobilities and a tunable range of bandgaps in the infrared. Here we present the first report on the growth and compositional control of Ga(x)In(1-x)Sb material grown in the form of nanowires from Au seeded nanoparticles by metalorganic vapor phase epitaxy. The composition of the grown Ga(x)In(1-x)Sb nanowires is precisely controlled by tuning the growth parameters where x varies from 1 to ∼0.3. Interestingly, the growth rate of the Ga(x)In(1-x)Sb nanowires increases with diameter, which we model based on the Gibbs-Thomson effect. Nanowire morphology can be tuned from high to very low aspect ratios, with perfect zinc blende crystal structure regardless of composition. Finally, electrical characterization on nanowire material with a composition of Ga(0.6)In(0.4)Sb showed clear p-type behavior.
Anisotropic transport properties of quasiballistic InAs nanowires under high magnetic field
Publisher: American Physical Society (APS)
Date: 27-03-2018
Wurtzite–zincblende superlattices in InAs nanowires using a supply interruption method
Publisher: IOP Publishing
Date: 17-05-2011
DOI: 10.1088/0957-4484/22/26/265606
Abstract: Crystal phase control in single III-V semiconductor nanowires has emerged recently as an important challenge and possible complement to conventional bandgap engineering in single material systems. Here we investigate a supply interruption method for precise crystal phase control in single nanowires. The nanowires are grown by metalorganic vapor phase epitaxy using gold particles as seeds and are analyzed by transmission electron microscopy. It is observed that wurtzite segments with controlled length and position can be inserted on demand into a pure InAs zincblende nanowire. The interface between wurtzite and zincblende segments can be made atomically sharp and the segments can be made only a few bilayers in thickness. The growth mechanisms, applicability and limitations of the technique are presented and discussed.
Crystal Phases in III--V Nanowires: From Random Toward Engineered Polytypism
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2011
Time-resolved pump probe of 1.55μm InAs∕InP quantum dots under high resonant excitation
Publisher: AIP Publishing
Date: 24-04-2006
DOI: 10.1063/1.2199454
Abstract: We have performed time-resolved resonant pump-probe experiment to study the dynamic response of InAs∕InP quantum dot transitions. A 72-stacked InAs∕InP quantum dot layer s le is grown on (311)B substrate. Photoluminescence at high excitation power reveals ground and excited transitions. Carrier radiative lifetimes and differential transmission are determined under strong excitation powers. The variation of measured carrier radiative lifetimes with increasing excitation powers is attributed to the exciton and biexciton lifetimes difference. The implications of such a difference on differential transmission are discussed, and finally exciton and biexciton lifetimes are measured to be about 1720 and 530ps, respectively.
Parameter space mapping of InAs nanowire crystal structure
Publisher: American Vacuum Society
Date: 03-06-2011
DOI: 10.1116/1.3593457
Abstract: Crystal structure and defects have been shown to have a strong impact on III-V nanowire properties. Recently, it was demonstrated that the issue of random stacking and polytypism in semiconductor nanowires can often be controlled using accessible growth parameters (such as temperature, diameter, and V/III ratio). In addition, it has been shown that crystal phase can be tuned selectively between cubic zinc blende and hexagonal wurtzite within in idual nanowires of III-V materials such as InAs. In order for such results to be generally applied to different growth setups, it is necessary to fully explore and understand the trends governing crystal phase dependencies on all accessible growth parameters, including how they relate to each other. In this study, the authors have systematically investigated the influence of temperature, diameter, V/III ratio, and total mass flow on the crystal structure of InAs nanowires grown by metal-organic vapor phase epitaxy over a broad parameter range. The authors observed that each of these accessible parameters can affect the resulting crystal structure, and that the trends for each parameter are affected by the magnitude of the others. The authors also noted that most of the parameter dependencies are nonlinear and, in fact, exhibit threshold values at which structure changes discontinuously. By optimizing each of the growth parameters, it is shown that pure ZB or pure WZ phase can be achieved for several different sets of growth conditions. The roles of nucleation kinetics, thermodynamics, and precursor chemistry are also discussed to compare the results to current nanowire growth models. The results in this work should facilitate comparison of data and transfer of knowledge between different growth systems and techniques, which, in turn, should lead to greater understanding of polytypism in nanowires and greater control and freedom in nanowire crystal phase engineering.
Comparing rates of adverse events detected in incident reporting and the Global Trigger Tool: a systematic review
Publisher: Oxford University Press (OUP)
Date: 07-2023
Abstract: Many hospitals continue to use incident reporting systems (IRSs) as their primary patient safety data source. The information IRSs collect on the frequency of harm to patients [adverse events (AEs)] is generally of poor quality, and some incident types (e.g. diagnostic errors) are under-reported. Other methods of collecting patient safety information using medical record review, such as the Global Trigger Tool (GTT), have been developed. The aim of this study was to undertake a systematic review to empirically quantify the gap between the percentage of AEs detected using the GTT to those that are also detected via IRSs. The review was conducted in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Studies published in English, which collected AE data using the GTT and IRSs, were included. In total, 14 studies met the inclusion criteria. All studies were undertaken in hospitals and were published between 2006 and 2022. The studies were conducted in six countries, mainly in the USA (nine studies). Studies reviewed 22 589 medical records using the GTT across 107 institutions finding 7166 AEs. The percentage of AEs detected using the GTT that were also detected in corresponding IRSs ranged from 0% to 37.4% with an average of 7.0% (SD 9.1 median 3.9 and IQR 5.2). Twelve of the fourteen studies found & % of the AEs detected using the GTT were also found in corresponding IRSs. The & -fold gap between the detection rates of the GTT and IRSs is strong evidence that the rate of AEs collected in IRSs in hospitals should not be used to measure or as a proxy for the level of safety of a hospital. IRSs should be recognized for their strengths which are to detect rare, serious, and new incident types and to enable analysis of contributing and contextual factors to develop preventive and corrective strategies. Health systems should use multiple patient safety data sources to prioritize interventions and promote a cycle of action and improvement based on data rather than merely just collecting and analysing information.
Gold-free GaAs/GaAsSb heterostructure nanowires grown on silicon
Publisher: AIP Publishing
Date: 22-03-2010
DOI: 10.1063/1.3367746
Abstract: Growth of GaAs/GaAsSb heterostructure nanowires on silicon without the need for gold seed particles is presented. A high vertical yield of GaAs nanowires is first obtained, and then GaAsxSb1-x segments are successfully grown axially in these nanowires. GaAsSb can also be integrated as a shell around the GaAs core. Finally, two GaAsSb segments are grown inside a GaAs nanowire and passivated using an AlxGa1-xAs shell. It is found that no stacking faults or twin planes occur in the GaAsSb segments.
Clinical indicators for diabetic eyecare delivered by optometrists in Australia: a Delphi study
Publisher: Informa UK Limited
Date: 17-10-2023
Postgrowth Shaping and Transport Anisotropy in Two-Dimensional InAs Nanofins
Publisher: American Chemical Society (ACS)
Date: 07-04-2021
Regaining a Spatial Dimension: Mechanically Transferrable Two-Dimensional InAs Nanofins Grown by Selective Area Epitaxy.
Publisher: American Chemical Society (ACS)
Date: 20-06-2019
DOI: 10.1021/ACS.NANOLETT.9B01703
Abstract: We report a method for growing rectangular InAs nanofins with deterministic length, width, and height by dielectric-templated selective-area epitaxy. These freestanding nanofins can be transferred to lay flat on a separate substrate for device fabrication. A key goal was to regain a spatial dimension for device design compared to nanowires, while retaining the benefits of bottom-up epitaxial growth. The transferred nanofins were made into devices featuring multiple contacts for Hall effect and four-terminal resistance studies, as well as a global back-gate and nanoscale local top-gates for density control. Hall studies give a 3D electron density 2.5-5 × 10
Nanosails Showcasing Zn 3 As 2 as an Optoelectronic‐Grade Earth Abundant Semiconductor
Publisher: Wiley
Date: 26-03-2019
The Role of Polarity in Nonplanar Semiconductor Nanostructures
Publisher: American Chemical Society (ACS)
Date: 30-04-2019
DOI: 10.1021/ACS.NANOLETT.9B00459
Abstract: The lack of mirror symmetry in binary semiconductor compounds turns them into polar materials, where two opposite orientations of the same crystallographic direction are possible. Interestingly, their physical properties (e.g., electronic or photonic) and morphological features (e.g., shape, growth direction, and so forth) also strongly depend on the polarity. It has been observed that nanoscale materials tend to grow with a specific polarity, which can eventually be reversed for very specific growth conditions. In addition, polar-directed growth affects the defect density and topology and might induce eventually the formation of undesirable polarity inversion domains in the nanostructure, which in turn will affect the photonic and electronic final device performance. Here, we present a review on the polarity-driven growth mechanism at the nanoscale, combining our latest investigation with an overview of the available literature highlighting suitable future possibilities of polarity engineering of semiconductor nanostructures. The present study has been extended over a wide range of semiconductor compounds, covering the most commonly synthesized III-V (GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb) and II-VI (ZnO, ZnTe, CdS, CdSe, CdTe) nanowires and other free-standing nanostructures (tripods, tetrapods, belts, and membranes). This systematic study allowed us to explore the parameters that may induce polarity-dependent and polarity-driven growth mechanisms, as well as the polarity-related consequences on the physical properties of the nanostructures.
Selectivity Map for Molecular Beam Epitaxy of Advanced III–V Quantum Nanowire Networks
Publisher: American Chemical Society (ACS)
Date: 06-12-2018
p-GaAs Nanowire Metal–Semiconductor Field-Effect Transistors with Near-Thermal Limit Gating
Publisher: American Chemical Society (ACS)
Date: 22-08-2018
DOI: 10.1021/ACS.NANOLETT.8B02249
Abstract: Difficulties in obtaining high-performance p-type transistors and gate insulator charge-trapping effects present two major challenges for III-V complementary metal-oxide semiconductor (CMOS) electronics. We report a p-GaAs nanowire metal-semiconductor field-effect transistor (MESFET) that eliminates the need for a gate insulator by exploiting the Schottky barrier at the metal-GaAs interface. Our device beats the best-performing p-GaSb nanowire metal-oxide-semiconductor field effect transistor (MOSFET), giving a typical subthreshold swing of 62 mV/dec, within 4% of the thermal limit, on-off ratio ∼10
Combinatorial Approaches to Understanding Polytypism in III–V Nanowires
Publisher: American Chemical Society (ACS)
Date: 20-06-2012
DOI: 10.1021/NN301477X
Abstract: Polytypism in III-V semiconductor nanowires is a topic that has received considerable attention in recent years. Achieving a pure nanowire crystal phase requires well-controlled and advanced parameter tuning for most III-V materials. Additionally, the new and unusual phases sometimes observed may present unique material properties if they can be controllably fabricated. With the prospect of using nanowires in applications within several different fields (including electronics, photonics, and life science), theoretical models are necessary to explain experimental trends and to attain a high level of crystal phase control. At present, there is no theoretical model (or combination of models) that fully explains how and why nanowire crystal structures commonly include several different polytypes. Here we use combinatorics and interlayer interactions to include higher order polytypes (4H and 6H) with the aim to explain nanowire crystal structure beyond the well-investigated zinc blende-wurtzite polytypism. Predictions from our theoretical models compare well with experimental results.
Self-assembled InAs quantum dots grown on InP (3 1 1)B substrates: Role of buffer layer and amount of InAs deposited
Publisher: Elsevier BV
Date: 08-2006
Type I band alignment in GaAs81Sb19/GaAs core-shell nanowires
Publisher: AIP Publishing
Date: 14-09-2015
DOI: 10.1063/1.4930991
Abstract: The composition and band gap of the shell that formed during the growth of axial GaAs/GaAs81Sb19/ GaAs heterostructure nanowires have been investigated by transmission electron microscopy combined with energy dispersion spectroscopy, scanning tunneling spectroscopy, and density functional theory calculations. On the GaAs81Sb19 intermediate segment, the shell is found to be free of Sb (pure GaAs shell) and transparent to the tunneling electrons, despite the (110) biaxial strain that affects its band gap. As a result, a direct measurement of the core band gap allows the quantitative determination of the band offset between the GaAs81Sb19 core and the GaAs shell and identifies it as a type I band alignment.
Vapor Phase Growth of Semiconductor Nanowires: Key Developments and Open Questions
Publisher: American Chemical Society (ACS)
Date: 18-04-2019
DOI: 10.1021/ACS.CHEMREV.8B00649
Abstract: Nanowires are filamentary crystals with a tailored diameter that can be obtained using a plethora of different synthesis techniques. In this review, we focus on the vapor phase, highlighting the most influential achievements along with a historical perspective. Starting with the discovery of VLS, we feature the variety of structures and materials that can be synthesized in the nanowire form. We then move on to establish distinct features such as the three-dimensional heterostructure/doping design and polytypism. We summarize the status quo of the growth mechanisms, recently confirmed by in situ electron microscopy experiments and defining common ground between the different synthesis techniques. We then propose a selection of remaining defects, starting from what we know and going toward what is still to be learned. We believe this review will serve as a reference for neophytes but also as an insight for experts in an effort to bring open questions under a new light.
Highly regular rosette-shaped cathodoluminescence in GaN self-assembled nanodisks and nanorods
Publisher: Springer Science and Business Media LLC
Date: 22-06-2020
Doping-enhanced radiative efficiency enables lasing in unpassivated GaAs nanowires
Publisher: Springer Science and Business Media LLC
Date: 17-06-2016
DOI: 10.1038/NCOMMS11927
Abstract: Nanolasers hold promise for applications including integrated photonics, on-chip optical interconnects and optical sensing. Key to the realization of current cavity designs is the use of nanomaterials combining high gain with high radiative efficiency. Until now, efforts to enhance the performance of semiconductor nanomaterials have focused on reducing the rate of non-radiative recombination through improvements to material quality and complex passivation schemes. Here we employ controlled impurity doping to increase the rate of radiative recombination. This unique approach enables us to improve the radiative efficiency of unpassivated GaAs nanowires by a factor of several hundred times while also increasing differential gain and reducing the transparency carrier density. In this way, we demonstrate lasing from a nanomaterial that combines high radiative efficiency with a picosecond carrier lifetime ready for high speed applications.
Effects of Crystal Phase Mixing on the Electrical Properties of InAs Nanowires
Publisher: American Chemical Society (ACS)
Date: 29-04-2011
DOI: 10.1021/NL2008339
Abstract: We report a systematic study of the relationship between crystal quality and electrical properties of InAs nanowires grown by MOVPE and MBE, with crystal structure varying from wurtzite to zinc blende. We find that mixtures of these phases can exhibit up to 2 orders of magnitude higher resistivity than single-phase nanowires, with a temperature-activated transport mechanism. However, it is also found that defects in the form of stacking faults and twin planes do not significantly affect the resistivity. These findings are important for nanowire-based devices, where uncontrolled formation of particular polytype mixtures may lead to unacceptable device variability.
Nanowire Biocompatibility in the Brain - Looking for a Needle in a 3D Stack
Publisher: American Chemical Society (ACS)
Date: 21-10-2009
DOI: 10.1021/NL902413X
Abstract: We investigated the brain-tissue response to nanowire implantations in the rat striatum after 1, 6, and 12 weeks using immunohistochemistry. The nanowires could be visualized in the scar by confocal microscopy (through the scattered laser light). For the nanowire-implanted animals, there is a significant astrocyte response at week 1 compared to controls. The nanowires are phagocytized by ED1 positive microglia, and some of them are degraded and/or transported away from the brain.
Approach to wetting-layer-assisted lateral coupling ofIn As ∕
Publisher:
American Physical Society (APS)
Date:
20-07-2005
Publisher: American Physical Society (APS)
Date: 20-07-2005
Unsafe care in residential settings for older adults
Publisher: Oxford University Press (OUP)
Date: 05-10-2023
Protocol for the implementation evaluation of an integrated paediatric and primary care model: Strengthening Care for Children (SC4C)
Publisher: BMJ
Date: 09-2022
DOI: 10.1136/BMJOPEN-2022-063450
Abstract: Implementation evaluations provide insight into how interventions are delivered across varying contexts and why interventions work in some contexts and not in others. This manuscript outlines a detailed protocol of an implementation evaluation embedded in a stepped-wedge cluster randomised controlled trial of a model of care, Strengthening Care for Children (SC4C), that integrates paediatric care in general practice. The purpose of this manuscript is to describe the pragmatic methods that will be used to capture implementation evaluation process and outcome data within this trial. Our implementation evaluation will use a mixed methods design, with data collected in the intervention arm of the SC4C trial guided by a logic model developed using the Consolidated Framework for Implementation Research (CFIR) and Proctor and colleague’s taxonomy of implementation outcomes. Data collection will be via questionnaires and semistructured interviews with general practitioners, paediatricians, general practice administrative staff and children and families. Each of the 21 general practices recruited into the study will be described in terms of staffing, patient throughput and location, in addition to the nuanced inner and outer contexts, use of the intervention and its acceptability. We will quantify implementation effectiveness in each general practice clinic using the CFIR validated scoring system. Importantly, we have embedded data collection post intervention to enable assessment of the sustainable adoption of the intervention. An inductive approach to the analysis of qualitative data will identify additional emerging themes that may not be covered by the formal frameworks underpinning our analysis. Ethical approval was granted by the Royal Children’s Hospital Ethics Committee in August 2020 (HREC: 65955). Results will be submitted for publication in peer-reviewed journals and presented at relevant conferences. Australia New Zealand Clinical Trials Registry 12620001299998 on 1 December 2020.
Innovative approaches to analysing aged care falls incident data: international classification for patient safety and correspondence analysis
Publisher: Oxford University Press (OUP)
Date: 27-09-2023
Growth and optical properties of In x Ga1−x P nanowires synthesized by selective-area epitaxy
Publisher: Springer Science and Business Media LLC
Date: 12-2016
Growth mechanisms and process window for InAs V-shaped nanoscale membranes on Si[001]
Publisher: IOP Publishing
Date: 09-10-2013
DOI: 10.1088/0957-4484/24/43/435603
Abstract: Organized growth of high aspect-ratio nanostructures such as membranes is interesting for opto-electronic and energy harvesting applications. Recently, we reported a new form of InAs nano-membranes grown on Si substrates with enhanced light scattering properties. In this paper we study how to tune the morphology of the membranes by changing the growth conditions. We examine the role of the V/III ratio, substrate temperature, mask opening size and inter-hole distances in determining the size and shape of the structures. Our results show that the nano-membranes form by a combination of the growth mechanisms of nanowires and the Stranski-Krastanov type of quantum dots: in analogy with nanowires, the length of the membranes strongly depends on the growth temperature and the V/III ratio the inter-hole distance of the s le determines two different growth regimes: competitive growth for small distances and an independent regime for larger distances. Conversely, and similarly to quantum dots, the width of the nano-membranes increases with the growth temperature and does not exhibit dependence on the V/III ratio. These results constitute an important step towards achieving rational design of high aspect-ratio nanostructures.
Formation of InAs islands on InP(311)B surface by molecular beam epitaxy
Publisher: Elsevier BV
Date: 09-2003
InP–InxGa1−xAs core-multi-shell nanowire quantum wells with tunable emission in the 1.3–1.55 μm wavelength range
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7NR04598K
Abstract: Wurtzite phase InP–In x Ga 1−x As nanowire radial quantum wells were grown for the first time, with tunable emission in the 1.3–1.55 μm optical communication wavelength range.
InSb Nanowire Field-Effect Transistors and Quantum-Dot Devices
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2011
InP-based radial heterostructures grown on [100] nanowires
Publisher: IEEE
Date: 12-2014
Optical properties and morphology of InAs∕InP (113)B surface quantum dots
Publisher: AIP Publishing
Date: 09-06-2008
DOI: 10.1063/1.2943651
Abstract: We report on long-wavelength photoluminescence (PL) emission at room temperature from self-organized InAs surface quantum dots grown by gas-source molecular beam epitaxy on a GaInAsP∕InP (113)B substrate. The influence of arsenic pressure conditions during growth on the PL emission of surface quantum dots is detailed as well as oxide/contamination layer formation after growth. Experimental results are in good agreement with six-band k⋅p theory in the envelope function approximation.
Gold-free growth of GaAs nanowires on silicon: arrays and polytypism
Publisher: IOP Publishing
Date: 27-08-2010
DOI: 10.1088/0957-4484/21/38/385602
Abstract: We report growth by molecular beam epitaxy and structural characterization of gallium-nucleated GaAs nanowires on silicon. The influences of growth temperature and V/III ratio are investigated and compared in the case of oxide-covered and oxide-free substrates. We demonstrate a precise positioning process for Ga-nucleated GaAs nanowires using a hole array in a dielectric layer thermally grown on silicon. Crystal quality is analyzed by high resolution transmission electron microscopy. Crystal structure evolves from pure zinc blende to pure wurtzite along a single nanowire, with a transition region.
Exciton and biexciton lifetimes in InAs/InP quantum dots emitting at 1.55 µm wavelength under resonant excitation
Publisher: Wiley
Date: 02-2007
Coherent Charge Transport in Ballistic InSb Nanowire Josephson Junctions
Publisher: Springer Science and Business Media LLC
Date: 22-04-2016
DOI: 10.1038/SREP24822
Abstract: Hybrid InSb nanowire-superconductor devices are promising for investigating Majorana modes and topological quantum computation in solid-state devices. An experimental realisation of ballistic, phase-coherent superconductor-nanowire hybrid devices is a necessary step towards engineering topological superconducting electronics. Here, we report on a low-temperature transport study of Josephson junction devices fabricated from InSb nanowires grown by molecular-beam epitaxy and provide a clear evidence for phase-coherent, ballistic charge transport through the nanowires in the junctions. We demonstrate that our devices show gate-tunable proximity-induced supercurrent and clear signatures of multiple Andreev reflections in the differential conductance, indicating phase-coherent transport within the junctions. We also observe periodic modulations of the critical current that can be associated with the Fabry-Pérot interference in the nanowires in the ballistic transport regime. Our work shows that the InSb nanowires grown by molecular-beam epitaxy are of excellent material quality and hybrid superconducting devices made from these nanowires are highly desirable for investigation of the novel physics in topological states of matter and for applications in topological quantum electronics.
Twin-Induced InSb Nanosails: A Convenient High Mobility Quantum System
Publisher: American Chemical Society (ACS)
Date: 11-01-2016
DOI: 10.1021/ACS.NANOLETT.5B05125
Abstract: Ultra narrow bandgap III-V semiconductor nanomaterials provide a unique platform for realizing advanced nanoelectronics, thermoelectrics, infrared photodetection, and quantum transport physics. In this work we employ molecular beam epitaxy to synthesize novel nanosheet-like InSb nanostructures exhibiting superior electronic performance. Through careful morphological and crystallographic characterization we show how this unique geometry is the result of a single twinning event in an otherwise pure zinc blende structure. Four-terminal electrical measurements performed in both the Hall and van der Pauw configurations reveal a room temperature electron mobility greater than 12,000 cm(2)·V(-1)·s(-1). Quantized conductance in a quantum point contact processed with a split-gate configuration is also demonstrated. We thus introduce InSb "nanosails" as a versatile and convenient platform for realizing new device and physics experiments with a strong interplay between electronic and spin degrees of freedom.
High-gain and low-threshold InAs quantum-dot lasers on InP
Publisher: AIP Publishing
Date: 06-12-2005
DOI: 10.1063/1.2146063
Abstract: InAs quantum-dot (QD) laser structures are grown on (113)B-oriented InP substrate by gas-source molecular-beam epitaxy. Following an optimized growth procedure, a high density of 1.1×1011cm−2 of uniformly sized QDs is achieved. Broad-area lasers containing three stacked QD layers have been realized and tested. Laser emission on the ground-state transition (λ=1.59μm) is obtained at room temperature (RT), at a threshold current density as low as 190A∕cm2. Ground-state modal gain and transparency current density is measured to be 7cm−1 and 23A∕cm2 per dot layer. Ground-state laser emission is also demonstrated from low temperature (100 K, Jth=33A∕cm2) to high temperature (350 K), exhibiting an insensitive threshold in the [100, 170] K range, and a 55 K characteristic temperature at RT.
InxGa1−xAs nanowires with uniform composition, pure wurtzite crystal phase and taper-free morphology
Publisher: IOP Publishing
Date: 30-04-2015
DOI: 10.1088/0957-4484/26/20/205604
Abstract: Obtaining compositional homogeneity without compromising morphological or structural quality is one of the biggest challenges in growing ternary alloy compound semiconductor nanowires. Here we report growth of Au-seeded InxGa1-xAs nanowires via metal-organic vapour phase epitaxy with uniform composition, morphology and pure wurtzite (WZ) crystal phase by carefully optimizing growth temperature and V/III ratio. We find that high growth temperatures allow the InxGa1-xAs composition to be more uniform by suppressing the formation of typically observed spontaneous In-rich shells. A low V/III ratio results in the growth of pure WZ phase InxGa1-xAs nanowires with uniform composition and morphology while a high V/III ratio allows pure zinc-blende (ZB) phase to form. Ga incorporation is found to be dependent on the crystal phase favouring higher Ga concentration in ZB phase compared to the WZ phase. Tapering is also found to be more prominent in defective nanowires hence it is critical to maintain the highest crystal structure purity in order to minimize tapering and inhomogeneity. The InP capped pure WZ In0.65Ga0.35As core-shell nanowire heterostructures show 1.54 μm photoluminescence, close to the technologically important optical fibre telecommunication wavelength, which is promising for application in photodetectors and nanoscale lasers.
Temperature and frequency characterization of InAs nanowire and HfO2 interface using capacitance–voltage method
Publisher: Elsevier BV
Date: 04-2011
MOVPE growth and structural charactrization of extremely lattice-mismatched InP-InSb nanowire heterostructures
Publisher: IEEE
Date: 05-2009
The effect of nitridation on the polarity and optical properties of GaN self-assembled nanorods
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8NR00737C
Abstract: After nitridation, nanorods show better optical properties, while their polarity changes from mixed-to N-polarity.
Parity independence of the zero-bias conductance peak in a nanowire based topological superconductor-quantum dot hybrid device
Publisher: Springer Science and Business Media LLC
Date: 12-2014
DOI: 10.1038/SREP07261
Temperature dependence of GaSb overgrowth of tungsten on GaSb (001) substrates using movpe
Publisher: IEEE
Date: 05-2008
Radial Growth Evolution of InGaAs/InP Multi-Quantum-Well Nanowires Grown by Selective-Area Metal Organic Vapor-Phase Epitaxy
Publisher: American Chemical Society (ACS)
Date: 03-10-2018
Abstract: III-V semiconductor multi-quantum-well nanowires (MQW NWs) via selective-area epitaxy (SAE) is of great importance for the development of nanoscale light-emitting devices for applications such as optical communication, silicon photonics, and quantum computing. To achieve highly efficient light-emitting devices, not only the high-quality materials but also a deep understanding of their growth mechanisms and material properties (structural, optical, and electrical) are extremely critical. In particular, the three-dimensional growth mechanism of MQWs embedded in a NW structure by SAE is expected to be different from that of those grown in a planar structure or with a catalyst and has not yet been thoroughly investigated. In this work, we reveal a distinctive radial growth evolution of InGaAs/InP MQW NWs grown by the SAE metal organic vapor-phase epitaxy (MOVPE) technique. We observe the formation of zinc blende (ZB) QW discs induced by the axial InGaAs QW growth on the wurtzite (WZ) base-InP NW and propose it as the key factor driving the overall structure of radial growth. The role of the ZB-to-WZ change in the driving of the overall growth evolution is supported by a growth formalism, taking into account the formation-energy difference between different facets. Despite a polytypic crystal structure with mixed ZB and WZ phases across the MQW region, the NWs exhibit high uniformity and desirable QW spatial layout with bright room-temperature photoluminescence at an optical communication wavelength of ∼1.3 μm, which is promising for the future development of high-efficiency light-emitting devices.
Comparing InSb, InAs, and InSb/InAs nanowire MOSFETs
Publisher: IEEE
Date: 06-2009
Related Organisations
Cardiff University
Location: United Kingdom of Great Britain and Northern Ireland
Institut D'Électronique De Microélectronique Et De Nanotechnologie - CNRS UMR 8520
Location: France
Related Funding Activities
Future Fellowship
Start Date: 2013
End Date: 2016
Funder: Australian Research Council
View Funded ActivityARC Future Fellowships - Grant ID: FT120100498
Start Date: 02-2013
End Date: 11-2016
Amount: $714,528.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP170102552
Start Date: 06-2017
End Date: 12-2020
Amount: $300,000.00
Funder: Australian Research Council
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