A5078047991- Graphene research and applications
- Advanced Memory and Neural Computing
- Diamond and Carbon-based Materials Research
- Semiconductor materials and devices
- Carbon Nanotubes in Composites
- Graphene and Nanomaterials Applications
- Phase-change materials and chalcogenides
- Analytical Chemistry and Sensors
- Plasmonic and Surface Plasmon Research
- 2D Materials and Applications
- Metamaterials and Metasurfaces Applications
- Perovskite Materials and Applications
- Liquid Crystal Research Advancements
- Advanced Sensor and Energy Harvesting Materials
- Silicon Carbide Semiconductor Technologies
- Electronic and Structural Properties of Oxides
- Nanowire Synthesis and Applications
- Molecular Junctions and Nanostructures
- Semiconductor materials and interfaces
- Analog and Mixed-Signal Circuit Design
- Advanced Antenna and Metasurface Technologies
- Carbon and Quantum Dots Applications
- Ferroelectric and Negative Capacitance Devices
- Supercapacitor Materials and Fabrication
- Advancements in Battery Materials
University of Exeter
2016-2019
Google (United States)
2018
Newcastle University
2011-2013
University of Newcastle Australia
2011-2012
The transition metal dichalcogenide MoTe2 is fabricated into few-layer field-effect transistors that show hole conduction with a mobility of 2.04 V cm−2 s−1. Four-layer devices have high photoresponsivity 6 A W−1 and response time, at around 160 μs, over 100 times faster than previously reported, making them strong candidate for speed sensitivity photodetection. In the search optoelectronic materials suited to flexible1 transparent2 electronics photonics applications, (TMDC) are particularly...
Abstract Chalcogenide phase‐change materials, which exhibit a marked difference in their electrical and optical properties when amorphous crystalline phases can be switched between these quickly repeatedly, are traditionally exploited to deliver nonvolatile data storage the form of rewritable disks memories. However, exciting new potential applications now emerging areas such as integrated photonics, metamaterials/metasurfaces, optoelectronic displays. Here, ideas from last two fields fused...
Graphene oxide (GO) resistive memories offer the promise of low-cost environmentally sustainable fabrication, high mechanical flexibility and optical transparency, making them ideally suited to future flexible transparent electronics applications. However, dimensional temporal scalability GO memories, i.e., how small they can be made fast switched, is an area that has received scant attention. Moreover, a plethora switching characteristics mechanisms been reported in literature, sometimes...
Abstract Atomically thin materials such as graphene are uniquely responsive to charge transfer from adjacent materials, making them ideal charge‐transport layers in phototransistor devices. Effective implementation of organic semiconductors a photoactive layer would open up multitude applications biomimetic circuitry and ultra‐broadband imaging but polycrystalline amorphous films have shown inferior performance compared inorganic semiconductors. Here, the long‐range order rubrene single...
Electrical characteristics of Cr/Au and Ti/Au metal contacts on epitaxial graphene 4H-SiC showed significant variations in resistance parameters at 300 K. These decreased substantially as the temperature increased to 673 The work function, binding energy, diffusion energy deposited metals were used explain these observed variations. quantitative analysis our data demonstrates that non-reactive with higher functions result lower contact resistance, which can be further by 70% using...
Abstract A highly effective laser thinning method is demonstrated to accurately control the thickness of MoTe 2 layers. By utilizing humidity present in ambient atmosphere, multilayered films can be uniformly thinned all way down monolayer with layer‐by‐layer precision using an ultralow power density 0.2 mW µm −2 . Localized bandgap engineering also performed , by creating regions different bandgaps on same film, enabling formation lateral homojunctions sub‐200 nm spatial resolution....
We report a novel approach for the fabrication of micro-and nano-scale graphene devices via in-situ plasma functionalization and lithographic patterning large-area directly on CVD catalytic metal (Cu) substrates.This enables us to create graphene-based in their entirety prior any transfer processes, simplifying very significantly device process potentially opening up route use wider range target substrates.We demonstrate capabilities our technique flexible, transparent, graphene/graphene...
Tetrahedral amorphous (ta-C) carbon-based memory devices have recently gained traction due to their good scalability and promising properties like nanosecond switching speeds. However, cycling endurance is still a key challenge. In this paper, we present model that takes local fluctuations in sp <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$ </tex-math></inline-formula>...
Graphene-based materials are being widely explored for a range of biomedical applications, from targeted drug delivery to biosensing, bioimaging and use antibacterial treatments, name but few. In many such it is not graphene itself that used as the active agent, one its chemically functionalized forms. The type chemical species functionalization will play key role in determining utility any graphene-based device particular application, because this determines large part physical, chemical,...
Carbon-based nonvolatile resistive memories are an emerging technology. Switching endurance remains a challenge in carbon based on tetrahedral amorphous (ta-C). One way to counter this is by oxygenation increase the repeatability of reversible switching. Here, we overview current status memories. We then present comparative study oxygen-free and oxygenated carbon-based memory devices, combining experiments molecular dynamics (MD) simulations.
Epitaxial graphene grown on SiC (0001) showed significant changes in electrical resistance upon exposure to polar protic and aprotic vapors the ambient atmosphere. The dipole moment of these chemicals was found have a strong impact magnitude sensor response, which increases with increasing moment. Using combination low-frequency noise Hall measurements, we demonstrate that chemical sensing mechanism epitaxial is based fluctuations charge carrier density induced by vapor molecules adsorbed...
All-dielectric metasurfaces consisting of arrays nanostructured high-refractive-index materials, typically Si, are re-writing what is achievable in terms the manipulation light. Such devices support very strong magnetic, as well electric, resonances, and free ohmic losses that severely limit performance their plasmonic counterparts. However, functionality dielectric-based fixed-by-design, i.e. optical response fixed by size, arrangement index nanoresonators. A far wider range applications...
We report the effect of nitrogen implantation on resistance switching tetrahedral amorphous carbon (ta-C) films. Both unimplanted and implanted films show resistive switching, with a characteristic threshold voltage required to switch from high-resistance low-resistance state. The voltages for are between 7 10 V ta-C thickness 15 40 nm. These significantly reduced upon by up 60% when using an dose ~3 × 1015 cm−2. attribute this increased sp2 bonding clustering in This demonstrates importance...
Oxygen functionalized epitaxial graphene (OFEG) sensors are demonstrated toward the sensing of polar chemical vapors at room temperature. The electrical characteristics sensor show an increase in resistance upon exposure to protic chemicals while decreased for aprotic average response and recovery times OFEG all analyte 10 100 s, respectively. In comparison, non-functionalized (NFEG) similar as OFEG, but with extremely long rates range ~1.5-2 hours. dipole moment is found have a strong...
Oxygen functionalised epitaxial graphene (OFEG) chemiresistor sensors were fabricated for sensing polar organic analyte vapours in the ambient atmosphere. The electrical characteristics of sensor showed an increase resistance to protic analytes, whilst decreased upon exposure aprotic vapours. OFEG a significant response time and order magnitude improvement recovery comparison non-functionalised (NFEG) sensors. A strong correlation between dipole moment was observed, where large linear small...
One of the emerging candidates to bridge gap between fast but volatile DRAM and non-volatile slow storage devices is tetrahedral amorphous carbon (ta-C) based memory [1]-[3]. This offers a very good scalability, data retention sub-5ns switching [2], [3]. Amorphous can be electrically optically switched from high resistance state (HRS) low (LRS) [4]. The electrical conduction in LRS thought through sp <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Epitaxial graphene produced from SiC substrates exhibits a carrier mobility re- duction thought to arise intercalated silicon. We present the results of density functional simulations and show that individual silicon atoms are highly mobile on between sheets, suggesting thermally stable structures involving Si impurities likely result interaction with defects in sheets.
We investigated the chemical sensing mechanism of epitaxial graphene grown on 6H-SiC (0001) to different polar solvents and their behavior at higher temperatures. show that 300 K sensitivity sensor increases exponentially with dipole moment a solvent decreases significantly as temperature increased 425 K. Using electrical measurements, we also can effectively discriminate between protic aprotic shift in device resistance
The combination of chalcogenide phase-change materials with optical metamaterial arrays is exploited to create new forms dynamic, tuneable and reconfigurable photonic devices including perfect absorbers, modulators, beam steerers filters.
The electrical characteristics of oxygen functionalized epitaxial graphene and Ti/Au metal contact interfaces were systematically investigated as a function temperature. As the temperature was increased from 300 K to 673 K, resistance sheet decreased by 75% 33%, respectively. vs exhibited Arrhenius type behavior with activation energy 38 meV. results showed no hysteresis effects in measurements over temperatures studied here, suggesting remain stable at high temperatures.