A5047854321- GaN-based semiconductor devices and materials
- Ga2O3 and related materials
- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- ZnO doping and properties
- Semiconductor materials and devices
- Perovskite Materials and Applications
- Metal and Thin Film Mechanics
- Semiconductor materials and interfaces
- Semiconductor Quantum Structures and Devices
- Electron and X-Ray Spectroscopy Techniques
- Photocathodes and Microchannel Plates
- Silicon and Solar Cell Technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Acoustic Wave Resonator Technologies
- Organic Light-Emitting Diodes Research
- Crystallization and Solubility Studies
- Solid-state spectroscopy and crystallography
- X-ray Diffraction in Crystallography
- solar cell performance optimization
- Copper-based nanomaterials and applications
- Advanced Semiconductor Detectors and Materials
- Nanowire Synthesis and Applications
- Thin-Film Transistor Technologies
- Anodic Oxide Films and Nanostructures
University of Cambridge
2020-2025
University of Luxembourg
2023-2024
Durham University
2023
Luxembourg Institute of Science and Technology
2023
Northumbria University
2023
University of Strathclyde
2014-2022
Georgia Institute of Technology
2022
Cardiff University
2020-2021
University of Manchester
2020
Scottish Universities Physics Alliance
2020
Abstract Halide double perovskites have gained significant attention, owing to their composition of low‐toxicity elements, stability in air, and recent demonstrations long charge‐carrier lifetimes that can exceed 1 µs. In particular, Cs 2 AgBiBr 6 is the subject many investigations photovoltaic devices. However, efficiencies solar cells based on this perovskite are still far from theoretical efficiency limit material. Here, role grain size optoelectronic properties thin films investigated....
Perovskite light-emitting diodes have drawn great attention in the fields of displays and lighting, especially for applications requiring high efficiency brightness. While three-dimensional perovskite hold promise achieving higher brightness compared to low-dimensional counterparts, efficient blue remained a challenge due defect formation during disordered crystallization multiple A-cation perovskite. Here we demonstrate an all-site alloy method that enables sequential A-site doping growth...
Bright and efficient deep-red light-emitting diodes (LEDs) are important for applications in medical therapy biological imaging due to the high penetration of photons into human tissues. Metal-halide perovskites have potential achieve bright electroluminescence their favorable optoelectronic properties. However, perovskite-based LEDs not been achieved yet, either Auger recombination low-dimensional or trap-assisted nonradiative 3D perovskites. Here, a lateral Cs
Metal halide perovskite light-emitting diodes (LEDs) have achieved great progress in recent years. However, bright and spectrally stable blue LED remains a significant challenge. Three-dimensional mixed-halide perovskites potential to achieve high brightness electroluminescence, but their emission spectra are unstable as result of phase separation. Here, we reveal that there is already heterogeneous distribution halides the as-deposited films, which can trace back nonuniform mixture...
Three-dimensional core-shell nanostructures could resolve key problems existing in conventional planar deep UV light-emitting diode (LED) technology due to their high structural quality, high-quality nonpolar growth leading a reduced quantum-confined Stark effect and ability improve light extraction. Currently, major hurdle implementation LEDs is the difficulty of growing such from Al xGa1- xN materials with bottom-up approach. In this paper, we report successful fabrication an AlN/Al xN/AlN...
Abstract Cu(In, Ga)S 2 demonstrates potential as a top cell material for tandem solar cells. However, achieving high efficiencies has been impeded by open‐circuit voltage (V OC ) deficits arising from In‐rich and Ga‐rich composition segregation in the absorber layer. This study presents significant improvement optoelectronic quality of films through mitigation three‐stage co‐evaporated films. By elevating substrate temperature during first stage, intermixing In Ga is promoted, leading to...
Multi-microscopy offers significant benefits to the understanding of complex materials behaviour by providing complementary information from different properties. However, some characterisations may strongly influence other measurements in same workflow. To acquire reliable and valid datasets, optimising multi-microscopy procedure is necessary. In present work, we studied measurement order on quality datasets. incorporating tunnelling current AFM (TUNA), electron backscatter diffraction...
A CuPbSbS 3 thin film is mapped using several techniques, with variations in Raman and cathodoluminescence further explained through DFT STEM-EDX.
2H-Benzotriazol-2-ylethylammonium bromide and iodide its difluorinated derivatives are synthesized employed as interlayers for passivation of formamidinium lead triiodide (FAPbI3) solar cells. In combination with PbI2 PbBr2, these benzotriazole form two-dimensional (2D) Ruddlesden-Popper perovskites (RPPs) evidenced by their crystal structures thin film characteristics. When used to passivate n-i-p FAPbI3 cells, the power conversion efficiency improves from 20% close 22% enhancing...
The influence of substrate miscut on Al0.5Ga0.5 N layers was investigated using cathodoluminescence (CL) hyperspectral imaging and secondary electron in an environmental scanning microscope. samples were also characterized atomic force microscopy high resolution X-ray diffraction. It found that small changes have a strong the morphology luminescence properties AlGaN layers. Two different types are resolved. For low angle, crack-free consisting randomly sized domains is observed, between...
A series of Si-doped AlN-rich AlGaN layers with low resistivities was characterized by a combination nanoscale imaging techniques. Utilizing the capability scanning electron microscopy to reliably investigate same sample area different techniques, it possible determine effect doping concentration, defect distribution, and morphology on luminescence properties these layers. Cathodoluminescence shows that dominant depends Si-doping concentration. For lower doped samples, most intense peak...
During the epitaxy of AlGaN on sapphire for deep UV emitters, significant lattice mismatch leads to highly strained heterojunctions and formation threading dislocations. Combining cathodoluminescence, electron beam induced current x-ray microanalysis reveal that dislocations with a screw component permeate through state-of-the-art UVC LED heterostructure into active region perturb their local environment in each layer as growth progresses. In addition acting non-radiative recombination...
Existing barriers to efficient deep ultraviolet (UV) light-emitting diodes (LEDs) may be reduced or overcome by moving away from conventional planar growth and toward three-dimensional nanostructuring. Nanorods have the potential for enhanced doping, dislocation densities, improved light extraction efficiency, quantum wells free quantum-confined Stark effect. Here, we demonstrate a hybrid top-down/bottom-up approach creating highly uniform AlGaN core-shell nanorods on sapphire repeatable...
Abstract In this article, porous GaN distributed Bragg reflectors (DBRs) were fabricated by epitaxy of undoped/doped multilayers followed electrochemical etching. We present backscattered electron scanning microscopy (BSE-SEM) for sub-surface plan-view imaging, enabling efficient, non-destructive pore morphology characterization. mesoporous DBRs, BSE-SEM images the same branching pores and Voronoi-like domains as transmission microscopy. microporous micrographs dominated first layer features...
Abstract Cathodoluminescence and electron backscatter diffraction have been applied to exactly the same grain boundaries (GBs) in a Cu(In,Ga)S 2 solar absorber order investigate influence of microstructure on radiative recombination behaviour at GBs. Two different types GB with were analysed detail: random high angle (RHAGBs) Σ3 We found that all RHAGBs was inhibited some extent, whereas GBs three observations made: unchanged, hindered, or promoted recombination. These distinct behaviours...
Microcavities based on group-III nitride material offer a notable platform for the investigation of light-matter interactions as well development devices such high efficiency light emitting diodes (LEDs) and low-threshold nanolasers.Disk or tube geometries in particular are attractive lasing applications due to their ability support finesse whispering gallery modes (WGMs) small modal volumes.In this article we present fabrication homogenous dense arrays axial InGaN/GaN nanotubes via...
Core–shell nanostructures are predicted to highly improve the efficiency of deep‐UV light emitting diodes (LEDs), owing their low defect density, reduced quantum‐confined Stark effect, high‐quality non‐polar growth and improved extraction efficiency. In this paper, we report on nanofabrication AlN nanorod arrays using a hybrid top‐down/bottom‐up approach for use as scaffold UV LED structures. We describe Displacement Talbot Lithography fabricate metallic hard etch mask allow be dry etched...
Time-resolved cathodoluminescence is an emerging tool to investigate carrier recombination mechanisms at defects in semiconductors – here applied trench InGaN quantum wells.
Detailed knowledge of the dopant concentration and composition wide band gap AlxGa layers is crucial importance for fabrication ultra violet light emitting diodes. This paper demonstrates capabilities wavelength dispersive x-ray (WDX) spectroscopy in accurately determining these parameters compares results with those from high resolution diffraction (HR-XRD) secondary ion mass spectrometry (SIMS). WDX has been carried out on different silicon-doped bandgap samples (x between 0.80 1). study...