A5046936262- Quantum and electron transport phenomena
- Semiconductor Quantum Structures and Devices
- ZnO doping and properties
- Gas Sensing Nanomaterials and Sensors
- Molecular Junctions and Nanostructures
- Advancements in Semiconductor Devices and Circuit Design
- Physics of Superconductivity and Magnetism
- Surface and Thin Film Phenomena
- Microfluidic and Bio-sensing Technologies
- Topological Materials and Phenomena
- Acoustic Wave Resonator Technologies
- Quantum Information and Cryptography
- Electrowetting and Microfluidic Technologies
- Magnetic properties of thin films
- Nanowire Synthesis and Applications
- Copper-based nanomaterials and applications
- Ga2O3 and related materials
- Quantum Dots Synthesis And Properties
- Photorefractive and Nonlinear Optics
- Semiconductor materials and devices
- Cold Atom Physics and Bose-Einstein Condensates
- Electrochemical Analysis and Applications
- Optical and Acousto-Optic Technologies
- Phase-change materials and chalcogenides
- Electronic and Structural Properties of Oxides
University College London
2014-2025
University of Delhi
2003-2023
London Centre for Nanotechnology
2011-2021
University of Sheffield
2021
Lovely Professional University
2021
Government Medical College
2016
Dr. K.N.Modi University
2014
Inter-University Accelerator Centre
2012
Sungkyunkwan University
2007-2010
National Centre for Compositional Characterisation of Materials
2009
Abstract The conducting polymer composite material is desired to have a high dielectric constant and dissipation factor in low frequency ranges, so that it can be used charge storing devices, decoupling capacitors, electromagnetic interference (EMI) shielding applications. Currently, on‐going research trying enhance the of ceramic powder‐polymer, metal nanotube‐polymer composites region. In this article, we present properties polypropylene (PP)‐graphite (Gr) radio ranges. Furthermore, EMI...
Abstract We report the experimental observation of a spin-polarised conductance plateau at e 2 / h in clean one-dimensional (1D) quantum wire defined by back-gated, split gate devices on GaAs/AlGaAs heterostructure absence magnetic field. The 1D were fabricated using standard lithography techniques consisting gates, and custom-designed back allows for modulation carrier density within channel. differential shows regular quantised plateaus units as function voltage, including 0.7(2 ) anomaly....
The synthesis of ZnO nano-needles using unbalanced magnetron sputtering is reported. A multilayer structure comprised ZnO(50 nm)/Zn(20 nm)/ZnO(2 µm) was grown on a stainless steel substrate without heating. growth observed the surface after post-annealing treatment at 300–400 °C. were distributed randomly over entire and had an average diameter 20 nm; their length varied from 2 to 5 µm. ultra-thin Zn layer (20 nm) in attributed act as nucleating centre it activates coalescence process for...
We have investigated electron transport in a quasi-one dimensional (quasi-1D) gas as function of the confinement potential. At particular potential configuration, and concentration, ground state 1D quantum wire splits into two rows to form an incipient Wigner lattice. It was found that application transverse magnetic field can transform double-row configuration single-row due enhancement The movements energy levels been monitored under varying conditions in-plane field. is also shown when...
MgxZn1−xO (MZO) thin films prepared by an rf magnetron sputtering technique are reported. The were grown at room temperature and relatively low power of 50 W. MZO found to possess preferred c-axis orientation exhibited hexagonal wurtzite structure ZnO up a Mg concentration 42 mol%. A small variation in the lattice parameter around 0.3% was observed with increasing composition, showing complete solubility ZnO. band gap phase varied linearly maximum ∼4.19 eV achieved x = 0.42. refractive...
Since the discovery of fractional quantum Hall effect in 1982 there has been considerable theoretical discussion on possibility quantization conductance absence Landau levels formed by a quantizing magnetic field. Although various situations have theoretically envisaged, particularly lattice models which band flattening resembles levels, predicted fractions never observed. In this Letter, we show that odd and even denominator can be observed, manipulated, field, when low-density electron...
Gold nanoparticles (NPs) of different diameters i.e., 5, 10, and 20 nm, were assembled between nm gap electrodes using ac dielectrophoresis (DEP) process. DEP parameters, such as frequency, trapping time, voltage value 1 MHz, s, 2–3 V, respectively, led to the pearl-chain assembly corresponding each type NPs electrodes. Mutual could be attributed chaining in low field regions subsequently force directs these chains region. Such controlled individual may find application fabricating devices...
Ultraviolet photoconductivity in zinc oxide (ZnO) nanoneedles grown on the surface of a multilayer structure comprised ZnO film (50 nm)/Zn layer (20 nm)/ZnO (2 μm) fabricated stainless steel substrate using an unbalanced magnetron sputtering technique is reported. It was observed that multilayered with exhibited enhanced ultraviolet comparison to films were without nanoneedles. The enhancement attributed increase quantum yield photogenerated charge carriers due presence A successive slow...
The assembly of ZnO nanoparticles into nanogap electrodes using ac dielectrophoresis (DEP) process is reported. DEP parameters such as frequency, voltage, and time were optimized to assemble minimum number electrodes. Frequency variation study revealed that positive active at frequencies less than 500 kHz; whereas negative starts dominating 1 MHz. fabricated device exhibited a nonlinear I-V characteristic under ultraviolet (UV) illumination remarkable change in conductivity one order...
The existence of Wigner crystallization, one the most significant hallmarks strong electron correlations, has to date only been definitively observed in two-dimensional systems. In one-dimensional (1D) quantum wires crystals correspond regularly spaced electrons; however, weakening confinement and allowing electrons relax a second dimension is predicted lead formation new ground state constituting zigzag chain with nontrivial spin phases properties. Here we report observation such by use...
Influence of wind speed, mass-flow rate water, irradiance, and ambient temperature on concentrated photovoltaic thermal module (PVT) equipped with linear Fresnel lens as primary optic element convex secondary have been investigated in this study. these parameters performance terms efficiency electrical are also examined during investigation. The without consideration was found to be 14.3% 51.2%, respectively. With mentioned four parameters, the results reveal that 17.2% 55.3% can achieved...
A surface acoustic wave (SAW) based ultraviolet (UV) light detector configured in the form of a SAW oscillator is investigated. The consists ZnO/LiNbO3 bilayer structure, where ZnO used as UV sensing material and LiNbO3 to excite waves. characterized for its functional performance at different Vcc, voltage circuit, under levels illumination. changes amplitude frequency shift output exhibit linear variation with intensity. shown be highly sensitive lower Vcc. low level intensity 450 nW cm−2...
This paper report on the disorder induced semiconductor to metal transition (SMT) and modifications of grain boundaries in nanocrystalline zinc oxide thin film. Disorder is using energetic ion irradiation. It eliminates possibility impurities transition. However, it revealed that some critical concentration defects needed for inducing such kind SMT at certain temperature. Above room temperature, current-voltage characteristics reverse bias attributes interesting phenomenon, as electric field...
We report the assembly of semiconducting ZnO nanoparticles into nanogap electrodes using ac dielectrophoresis (DEP) process. were grown sol-gel method. As (diameter approximately 4 nm) in a quasi-crystalline state and with increase annealing temperature (in air) upto 400 degrees C crystallinity was found to as revealed by X-ray diffraction transmission electron microscopy. Absorption spectroscopy that absorption edge annealed samples exhibited blue-shift could be attributed size...
We have investigated hole transport in quantum wires formed by electrostatic confinement strained germanium two-dimensional layers. The ballistic conductance characteristics show the regular staircase of levels with plateaux at n2e2/h, where n is an integer, e fundamental unit charge and h Planck's constant. However as carrier concentration reduced, quantised a behaviour that indicative formation zig-zag structure new appear low temperatures. In units 2e2/h correspond to values = 1/4...
This paper investigates how postgrowth annealing affects the structure and electro-optical properties of low-temperature grown GaAs (LT-GaAs). A systematic study as-grown annealed LT-GaAs revealed that carrier lifetime is directly related to density An duster distance between As clusters. The Ga/As compositional ratio crystal clusters were observed for first time. As/Ga higher than obtained from LT-GaAs. increases as temperature 400 (less 30 fs) 800 °C (824 fs). Under temperatures ranging...
The growth of multisegment nanorods comprising gold (Au) and sacrificial silver (Ag) segments (Au-Ag-Au or Au-Ag-Au-Ag-Au) using the electrochemical wet etching method is reported. were fabricated an alumina template thickness 100 microm pore size 200 nm. A variety from single to seven alternate Au Ag with better control rate. selectively etched by removing create gaps in nanorods. careful investigation led creation a wide nanogaps nanogap was controlled passage current through process,...
We present the results of transport measurements in a hybrid system consisting an arch-shaped quantum point contact (QPC) and reflector; together, they form electronic cavity between them. On tuning arch-QPC reflector, asymmetric resonance peak resistance is observed at one-dimension to two-dimension transition. Moreover, dip near pinch-off QPC found be strongly dependent on reflector voltage. These two structures fit very well with Fano line shape. The was get weakened applying transverse...
We present results on electron transport in quasi-one dimensional (1D) quantum wires GaAs/AlGaAs heterostructures obtained using an asymmetric confinement potential. The variation of the energy levels spatially quantized states is followed from strong through weak to onset two-dimensionality. An anticrossing initial ground and first excited found as asymmetry potential varied giving rise two events which occur either side symmetric confinement. analysing this behaviour showing how it can be...