Near-thermal limit gating in heavily-doped III-V semiconductor nanowires using polymer electrolytes

Doping is a common route to reducing nanowire transistor on-resistance but has limits. High doping level gives significant loss in gate performance and ultimately complete gate failure. We show that electrolyte gating remains effective even when the Be doping in our GaAs nanowires is so high that traditional metal-oxide gates fail. In this regime we obtain a combination of sub-threshold swing and contact resistance that surpasses the best existing p-type nanowire MOSFETs. Our sub-threshold swing of 75 mV/dec is within 25% of the room-temperature thermal limit and comparable with n-InP and n-GaAs nanowire MOSFETs. Our results open a new path to extending the performance and application of nanowire transistors, and motivate further work on improved solid electrolytes for nanoscale device applications.Comment: 6 pages, 2 figures, supplementary available at journa

InAs nanowire transistors with multiple, independent wrap-gate segments

We report a method for making horizontal wrap-gate nanowire transistors with up to four independently controllable wrap-gated segments. While the step up to two independent wrap-gates requires a major change in fabrication methodology, a key advantage to this new approach, and the horizontal orientation more generally, is that achieving more than two wrap-gate segments then requires no extra fabrication steps. This is in contrast to the vertical orientation, where a significant subset of the fabrication steps needs to be repeated for each additional gate. We show that cross-talk between adjacent wrap-gate segments is negligible despite separations less than 200 nm. We also demonstrate the ability to make multiple wrap-gate transistors on a single nanowire using the exact same process. The excellent scalability potential of horizontal wrap-gate nanowire transistors makes them highly favourable for the development of advanced nanowire devices and possible integration with vertical wrap-gate nanowire transistors in 3D nanowire network architectures.Comment: 18 pages, 5 figures, In press for Nano Letters (DOI below

Using ultra-thin parylene films as an organic gate insulator in nanowire field-effect transistors

We report the development of nanowire field-effect transistors featuring an ultra-thin parylene film as a polymer gate insulator. The room temperature, gas-phase deposition of parylene is an attractive alternative to oxide insulators prepared at high temperatures using atomic layer deposition. We discuss our custom-built parylene deposition system, which is designed for reliable and controlled deposition of <100 nm thick parylene films on III-V nanowires standing vertically on a growth substrate or horizontally on a device substrate. The former case gives conformally-coated nanowires, which we used to produce functional $\Omega$-gate and gate-all-around structures. These give sub-threshold swings as low as 140 mV/dec and on/off ratios exceeding $10^3$ at room temperature. For the gate-all-around structure, we developed a novel fabrication strategy that overcomes some of the limitations with previous lateral wrap-gate nanowire transistors. Finally, we show that parylene can be deposited over chemically-treated nanowire surfaces; a feature generally not possible with oxides produced by atomic layer deposition due to the surface `self-cleaning' effect. Our results highlight the potential for parylene as an alternative ultra-thin insulator in nanoscale electronic devices more broadly, with potential applications extending into nanobioelectronics due to parylene's well-established biocompatible properties

Food system innovation and policy at the local level: A report on six local governments in New South Wales and Victoria

Transformative change is required from ‘paddock to fork’ to ensure access to healthy food for all, within finite planetary boundaries. Collaboration and coordination between diverse stakeholders is necessary to achieve this transformation, including all levels of government. However, while state and national governments’ influence over food systems has been the focus of much research and reporting, less is known about the role of Australian local governments (LGs) in addressing these health, sustainability, and equity challenges. This report provides a summary of six case studies of Australian LGs conducted by researchers from the University of Sydney, University of Wollongong, and William Angliss Institute of TAFE (Melbourne). The researchers interviewed staff members from six LGs (3 from NSW, 3 from Victoria) to gather information on these LGs’ food system policies and initiatives, as well as their perceptions of the barriers to and enablers of this work

The role of Australian local governments in creating a healthy, sustainable and equitable food system: Results of a policy mapping study in New South Wales and Victoria

Transformation of the food system is required to ensure food security for an increasing global population within finite planetary and climate boundaries. While much attention has been paid to how state and national governments can influence food systems, less is known about the role of Australian local governments in addressing these health, sustainability, and equity challenges. This report provides a summary of a policy mapping study conducted by researchers from the University of Sydney, University of Wollongong, and William Angliss Institute of TAFE (Melbourne)

Epitaxially Driven Phase Selectivity of Sn in Hybrid Quantum Nanowires

Hybrid semiconductor-superconductor nanowires constitute a pervasive platform for studying gate-tunable superconductivity and the emergence of topological behavior. Their low dimensionality and crystal structure flexibility facilitate unique heterostructure growth and efficient material optimization, crucial prerequisites for accurately constructing complex multicomponent quantum materials. Here, we present an extensive study of Sn growth on InSb, InAsSb, and InAs nanowires and demonstrate how the crystal structure of the nanowires drives the formation of either semimetallic α-Sn or superconducting β-Sn. For InAs nanowires, we observe phase-pure superconducting β-Sn shells. However, for InSb and InAsSb nanowires, an initial epitaxial α-Sn phase evolves into a polycrystalline shell of coexisting α and β phases, where the β/α volume ratio increases with Sn shell thickness. Whether these nanowires exhibit superconductivity or not critically relies on the β-Sn content. Therefore, this work provides key insights into Sn phases on a variety of semiconductors with consequences for the yield of superconducting hybrids suitable for generating topological systems

An audit of vending machines in public places in regional NSW, Australia

Abstract of paper that presented at 20th International Congress of Nutrition, Granada, September 2013

Results from a policy mapping study: Local government action on creating a healthy, sustainable, and equitable food system

This study was the first to systematically map local government (LG) action on creating a healthy, sustainable, and equitable food system in Australia, focusing on NSW and Victoria. We searched the websites of all LGs in NSW and Victoria for policy documents with actions related to a healthy, sustainable, and equitable food system. We then analysed these documents against a framework of recommendations for LG action on addressing food system challenges. This infographic provides a visual representation of the study's findings

The role of Australian local governments in creating a healthy, sustainable, and equitable food system: Discussion themes from the workshop 'Healthy, sustainable, and equitable food systems: The role of local government'

On Friday 19 November 2021, our project team hosted a workshop, ‘Healthy, sustainable, equitable food systems: The role of local government.’ During the event, the team members presented a project overview, and the findings of two of the four project phases: a policy mapping study of all local governments in New South Wales (NSW) and Victoria; and case studies with six local governments that explored the process of developing and implementing a food system policy, and the barriers to and enablers of these processes. We also launched a report that details the findings of the policy mapping study, and our Australian Local Food System Policy Database. Following the presentations, attendees were placed into small groups and asked to discuss a set of questions. This report provides a summary of the key themes that arose from the discussions