A5050765639- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Semiconductor Lasers and Optical Devices
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Semiconductor Detectors and Materials
- Semiconductor materials and interfaces
- Quantum Dots Synthesis And Properties
- Magnetic properties of thin films
- GaN-based semiconductor devices and materials
- Photonic and Optical Devices
- Surface and Thin Film Phenomena
- ZnO doping and properties
- Molecular Junctions and Nanostructures
- Electronic and Structural Properties of Oxides
- Terahertz technology and applications
- Chalcogenide Semiconductor Thin Films
- Nanowire Synthesis and Applications
- Advanced Chemical Physics Studies
- Spectroscopy and Laser Applications
- Quantum Information and Cryptography
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum optics and atomic interactions
- Acoustic Wave Resonator Technologies
University of Nottingham
2015-2024
National Research Foundation
2017-2023
University of South Africa
2016-2023
University of Johannesburg
2023
Jouf University
2021
Chalmers University of Technology
2014
Cairo University
2012-2014
Leibniz Institute for Crystal Growth
2014
Alimentation et Sciences Sociales
2011
University of Cambridge
2010
Abstract To photo-catalytically degrade RhB dye using solar irradiation, CeO 2 doped TiO nanocomposites were synthesized hydrothermally at 700 °C for 9 hrs. All emission spectra showed a prominent band centered 442 nm that was attributed to oxygen related defects in the -TiO nanocrystals. Two sharp absorption bands 1418 cm −1 and 3323 deformation stretching vibration, bending vibration of OH group water physisorbed , respectively. The photocatalytic activities Ce-TiO nanocrystals...
In the present work, we report effect and improvement of PVC polymer blend nanocomposites performance with addition lanthanum oxide (La2O3) nanofiller. The structural properties samples were studied using different characterization techniques such as XRD, FTIR, Ramman SEM. X-ray diffraction peaks La2O3 are agreement pure hexagonal phase. sample was found to have crystallites size an average about 15 nm. FTIR SEM analysis confirmed interaction PVC/La2O3 nanocomposites. obtained band gaps...
The effects of carrier thermal escape and retrapping on the temperature dependence photoluminescence InAs/GaAs self-assembled quantum dots are investigated. A systematic experimental study evolution spectra in two different sets samples is reported. behavior well reproduced terms a steady state model for dynamics which takes into account quantum-dot size distribution, random population effects, capture, relaxation, retrapping. relative contributions these processes to quenching discussed.
We report, for the first time, ballistic magnetoresistance effects in a two-dimensional electron gas (2DEG) subjected to spatially modulated periodic magnetic field. The field is formed by presence of superconducting stripes on surface heterostructure with 2DEG. observe oscillatory due commensurability effect between classical cyclotron diameter and period modulation. behavior agreement existing theory no adjustable parameters.
We describe a low-noise scanning Hall probe microscope having unprecedented magnetic field sensitivity (∼2.9×10−8 T/√Hz at 77 K), high spatial resolution, (∼0.85 μm), and operating in real-time (∼1 frame/s) for studying flux profiles surfaces. A submicron manufactured GaAs/AlGaAs two-dimensional electron gas (2DEG) is scanned over the sample to measure surface fields using conventional tunneling microscopy positioning techniques. Flux penetration into Tc YBa2Cu3O7−δ thin film has been...
We describe a novel magnetotunneling spectroscopy technique for probing the complicated dispersion curves of hole states in quantum well p-type double-barrier resonant-tunneling structures. Strong mixing between light- and heavy-hole is observed. Some clearly exhibit negative effective mass motion plane well.
We have observed a series of sharp peaks in the low-temperature I(V) characteristics gated 1 \ensuremath{\mu}m\ifmmode\times\else\texttimes\fi{}1 \ensuremath{\mu}m GaAs/(AlGa)As resonant tunneling diode, which gate is used to reduce effective cross-sectional area from 0.7 0.1 \ensuremath{\mu}${\mathrm{m}}^{2}$. These peaks, occur at voltages well below calculated threshold, show weak dependence on temperature, magnetic field, and area. argue that this subthreshold structure due an...
We report on the magnetoresistance of a two-dimensional electron gas subjected to an abrupt magnetic field gradient arising from ferromagnetic stripe fabricated at its surface. A sharp resistance resonance effect is observed B(p) due formation two types edge states that drift in opposite directions perpendicular for B<B(p) and B>B(p). semiclassical drift-diffusion model gives good description effects confinement both diagonal off-diagonal components resistivity tensor.
The photoluminescence properties of ${\mathrm{I}\mathrm{n}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{y}{\mathrm{Ga}}_{1\ensuremath{-}y}\mathrm{As}$ self-assembled quantum dots are studied as a function temperature from 10 to 290 K. By varying the Al content dot luminescence can be tuned over wavelength range 0.8 1.1 \ensuremath{\mu}m, and made thermally stable up room temperature. dependence carrier hopping between is discussed in terms depth confinement potential dispersion size composition.
Contents Preface v CHAPTER 1 MBE GROWTH AND CHARACTERIZATION OF LONG WAVELENGTH DILUTE NITRIDE IIIV ALLOYS 1.1. Introduction 1.2. Growth of Dilute Nitrides 1.3. Nitride Characterization 1.4. Energy Band and Carrier Transport Properties 1.5. Annealing NIn Nearest Neighbor Effects 1.6. Summary Acknowledgements References 2 EPITAXIAL NITRIDES BY METAL-ORGANIC VAPOUR PHASE EPITAXY 2.1. 2.2. Epitaxial GaInAsN-based Structures 2.3. Long Wavelength GaAs-based Laser Performances 2.4. Conclusion 3...
The current-voltage characteristics of a series double-barrier structures based on $n$-type GaAs/(Al,Ga)As are investigated in the presence quantizing magnetic-field perpendicular to barriers. Landau-level structure arising from elastic scattering and LO-phonon-assisted tunneling into quantum well is clearly resolved. For widths less than 6 nm, emission processes involving both AlAs- GaAs-like LO-phonon modes (Al,Ga)As barrier observed.
The bias voltage applied to a weakly coupled n-doped GaAs/AlAs superlattice increases the amplitude of coherent hypersound oscillations generated by femtosecond optical pulse. This bias-induced increase and experimentally observed spectral narrowing phonon mode with frequency 441 GHz provides evidence for amplification stimulated emission phonons in system where inversion electron populations phonon-assisted transitions exists.
A low energy bandgap between Ce3+ and Ce4+ states in cerium oxides, high oxygen mobility storage capacity are the properties that qualify them to be most widely used heterogeneous catalysts. This present work is an account of studies were carried out on synthesis catalytic pure CeO2, CeO2/La2O3 based binary metal oxide nanostructures prepared by hydrothermal method. Our results revealed temperature pressure during reactions played a critical role controlling shape, size, vacancy,...