A5031661764- GaN-based semiconductor devices and materials
- Advanced Semiconductor Detectors and Materials
- Advanced X-ray and CT Imaging
- Semiconductor Quantum Structures and Devices
- Radiation Detection and Scintillator Technologies
- Semiconductor materials and devices
- ZnO doping and properties
- Nuclear Physics and Applications
- Nanowire Synthesis and Applications
- Particle Detector Development and Performance
- Photonic and Optical Devices
- Diamond and Carbon-based Materials Research
- Magnetic confinement fusion research
- Fusion materials and technologies
- Ga2O3 and related materials
- Advanced MEMS and NEMS Technologies
- Metal and Thin Film Mechanics
- Magnesium Oxide Properties and Applications
- Concrete and Cement Materials Research
- Electron and X-Ray Spectroscopy Techniques
- CCD and CMOS Imaging Sensors
- Advanced Electron Microscopy Techniques and Applications
- Bone Tissue Engineering Materials
- Advanced X-ray Imaging Techniques
- Mechanical and Optical Resonators
Diamond Light Source
2011-2024
University of Surrey
2014
VTT Technical Research Centre of Finland
2014
Centre de Recerca Matemàtica
2014
University of Warwick
2014
Institut Català de Nanociència i Nanotecnologia
2014
Science and Technology Facilities Council
2014
Rutherford Appleton Laboratory
2014
National Research Tomsk State University
2014
University of Cambridge
2008
Epitaxial transparent oxide NixMg1-xO (0 ≤ x 1) thin films were grown on MgO(100) substrates by pulsed laser deposition. High-resolution synchrotron X-ray diffraction and high-resolution transmission electron microscopy analysis indicate that the are compositionally structurally homogeneous, forming a completely miscible solid solution. Nevertheless, composition dependence of optical band gap shows strong non-parabolic bowing with discontinuity at dilute NiO concentrations < 0.037. Density...
Magnetic semiconductors with coupled magnetic and electronic properties are of high technological fundamental importance. Rare-earth elements can be used to introduce moments associated the uncompensated spin 4f-electrons into semiconductor hosts. The luminescence produced by rare-earth doped also attracts considerable interest due possibility electrical excitation characteristic sharp emission lines from intra 4f-shell transitions. Recently, electroluminescence Eu-doped GaN in...
Abstract A robust disruption mitigation system (DMS) requires accurate characterization of key timescales, one the most notable being thermal quench (TQ). Recent modelling shattered pellet injection (SPI) into ITER plasmas, using JOREK and INDEX, suggests long TQ durations (6 – 10 ms) slow cold front propagation due to large plasma size. If validated, these predictions would have an impact on desired parameters strategies for DMS. To resolve questions, a database SPI experiments from several...
Semi-insulating wafers of GaAs material with a thickness 500μm have been compensated chromium by Tomsk State University. Initial measurements shown the to high resistivity (3 × 109Ωcm) and tests pixel detectors on 250 μm pitch produced uniform spectroscopic performance across an 80 array. At present, there is lack that are capable operating at X-ray fluxes (> 108 photons s-1 mm-2) in energy range 5–50 keV. Under these conditions, poor stopping power silicon, as well issues radiation...
A small pixel, spectroscopic, CdTe detector has been developed at the Rutherford Appleton Laboratory (RAL) for X-ray imaging applications. The consists of 80 × pixels on a 250 μm pitch with 50 inter-pixel spacing. Measurements an 241Am γ-source demonstrated that 96% all have FWHM better than 1 keV while majority remaining less 4 keV. Using Diamond Light Source synchrotron, 10 collimated beam monochromatic 20 X-rays used to map spatial variation in response and effects charge sharing...
Energy scalability of the excitation–emission spectra InGaN epilayers, quantum wells and light-emitting diodes provided indirect evidence for a fundamental common cause remarkable optical properties this commercially important semiconductor alloy. Phase segregation on nanoscale (accidental dot formation) has generally been accepted as mechanism spectral energy scaling (K.P. O'Donnell, R.W. Martin P.G. Middleton, Phys. Rev. Lett. 82 237 (1999)). Recently, however, downsizing InN bandgap, from...
Comparative Ga and In K-edge extended x-ray absorption fine structure studies provide the first direct evidence of an inequality mean In–Ga Ga–In next-nearest neighbor separations in InGaN alloys. The degree increases with decreasing InN fraction x range accessible to analysis alloys (0.9&lt;x&lt;0.1). Its concurrence increase luminescence efficiency this composition suggests that breakdown In∕Ga randomness is correlated efficient radiative recombination blue-green light emitting devices.
Segmentation of the anode-side a <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm M}\mathchar"702D \pi \mathchar"702D {\rm n}$</tex></formula> CdTe diode produces detectors with excellent spatial and energy resolution while maintaining an active area that extends to detector edge. The pixel reported have 250 ìm pitch, thicknesses 1 mm are bonded spectroscopic readout ASIC. results from edgeless...
Large area detectors capable of operating with high detection efficiency at energies above 30 keV are required in many contemporary X-ray imaging applications. The properties Z compound semiconductors, such as CdTe, make them ideally suitable to these STFC Rutherford Appleton Laboratory has developed a small pixel CdTe detector 80 × pixels on 250 μm pitch. Historically, have included 200 wide guard band around the pixelated anode reduce effect defects crystal edge. latest version ASIC is...
Reduced edge or ``edgeless'' detector design offers seamless tileability of sensors for a wide range applications from particle physics to synchrotron and free election laser (FEL) facilities medical imaging. Combined with through-silicon-via (TSV) technology, this would allow reduced material trackers an increase in the active area FEL pixel systems. In order quantify performance different edgeless fabrication methods, 2 detectors were characterized at Diamond Light Source using 11 μm FWHM...
Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality thin suspended germanium (Ge) membrane. A series reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on strain distribution, thickness, and tilt membrane was obtained. We are able to detect systematic variation across membranes, but show that this is negligible in context using membranes platforms for further growth. In addition, we...
A novel beam position monitor, operated at zero bias voltage, based on high-quality chemical-vapor-deposition single-crystal Schottky diamond for use under intense synchrotron X-ray beams was fabricated and tested. The total thickness of the thin-film monitor is about 60 µm. inserted in B16 beamline Diamond Light Source Harwell (UK). device characterized monochromatic high-flux from 6 to 20 keV a micro-focused 10 with spot size approximately 2 µm × 3 square. Time response, linearity...
Abstract A method to grow high quality, single crystalline semiconductor material irrespective of the substrate would allow a cost-effective improvement functionality and performance optoelectronic devices. Recently, novel type substrate-insensitive growth process called Evolutionary Selection Selective Area Growth (ES-SAG) has been proposed. Here we report use X-ray microdiffraction study structural properties GaN microcrystals grown by ES-SAG. Utilizing resolution in both direct reciprocal...
A thin, flat, and single crystal germanium membrane would be an ideal platform on which to mount sensors or integrate photonic electronic devices, using standard silicon processing technology. We present a fabrication technique compatible with integrated-circuit wafer scale produce membranes of thickness between 60 nm 800 nm, large areas up 3.5 mm2. show how the optical properties change thickness, including appearance Fabry-Pérot type interference in thin membranes. The have low Q-factors,...
Certain cases are studied in which quantum dots (QDs) show no collective properties. It is demonstrated that physically isolated QDs (IQDs) typical of the single-layer metastable QD arrays grown by submonolayer migration enhanced epitaxy on vicinal substrates. Their formation attributed to isolation separate InAs clusters terraces due wetting layer ruptures edges bunched multiatomic steps. The carrier exchange between such not observed. Coalesced formed upper layers multi-layer arrays....
We report the use of microfocused three-dimensional x-ray reciprocal space mapping to study InGaN epilayers with average InN content ∼20%-22%. Analysis full volume space, while probing samples on microscale a focused beam, allowed us gain valuable information about nanostructure InN-rich epilayers. It is found that “seed” mosaic nanocrystallites are twisted respect ensemble and strain-free. The initial stages InGaN-on-GaN epitaxial growth, therefore, conform Volmer-Weber growth mechanism...
CdTe and CdZnTe material is an excellent candidate for the fabrication of high energy X-ray spectroscopic detectors due to their good quantum efficiency room temperature operation. The main limitation associated with poor charge transport properties holes. motivation this work investigate performance characteristics a detector fabricated drift ring geometry that insensitive prototype Ohmic by Acrorad 3 rings reported; measurements include current voltage (IV) performance. data shows...
Abstract X‐ray Reciprocal Space Mapping (RSM) is a powerful tool to explore the structure of semiconductor materials. However, conventional lab‐based RSMs are usually measured in two dimensions (2D) ignoring third dimension diffraction‐space volume. We report use combination microfocusing and state‐of‐the‐art 2D area detectors study full volume diffraction–space while probing III‐nitride materials on microscale. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charge transport in one- and two-dimensional GaAs-based electronic systems by surface acoustic waves (SAWs) is expected to find application quantum information processing metrology. In the charge a SAW (referred as (ACT)), electrons are transported packets residing potential minima along channels formed GaAs well or heterojunction, which play role similar that of wires standard circuits. The ACT circuits for stems from their ability precisely control position spin single electrons. Traps...
CdTe and CZT detectors are considered better choices for high energy γ X-ray spectroscopy in comparison to Si HPGe due their good quantum efficiency room temperature operation. The performance limitations mainly associated with poor hole transport trapping phenomena. Among many techniques that can be used eliminate the effect of charge properties holes material, drift ring technique shows promising results. In this work, a 2.3 mm thick detector is investigated. Spatially resolved...
The structural properties of Er-doped AlNO epilayers grown by radio frequency magnetron sputtering were studied Extended X-ray Absorption Fine Structure spectra recorded at the Er L3 edge. analysis revealed that substitutes for Al in all samples, and increase concentration from 0.5 to 3.6 at. % is not accompanied formation ErN, Er2O3, or clusters. Simultaneously Near Edge verify bonding configuration similar samples. Er-N distance constant 2.18–2.19 Å, i.e., approximately 15% larger than...
Magnesium hydroxide (Mg(OH)2) suspensions are encountered in the nuclear industry as legacy waste that is to be packaged for long-term storage. It desirable increase solids content of minimize total volume, yet this would produce high yield stress fluids difficult process. However, low strength desired. Blending nano-silica (nano-SiO2) into a suspension 27 vol% Mg(OH)2, was reduced from 86 Pa 47 Pa. X-ray CT imaging revealed approximately two-thirds 3 nano-SiO2 added Mg(OH)2 well-dispersed,...