A5100632186- Semiconductor Quantum Structures and Devices
- GaN-based semiconductor devices and materials
- Advanced Semiconductor Detectors and Materials
- Semiconductor materials and devices
- Ga2O3 and related materials
- Quantum Dots Synthesis And Properties
- ZnO doping and properties
- Semiconductor materials and interfaces
- Nanowire Synthesis and Applications
- Chalcogenide Semiconductor Thin Films
- Graphene research and applications
- Metal and Thin Film Mechanics
- Carbon Nanotubes in Composites
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor Lasers and Optical Devices
- Immune Cell Function and Interaction
- solar cell performance optimization
- Advanced Electron Microscopy Techniques and Applications
- Microstructure and mechanical properties
- Cytomegalovirus and herpesvirus research
- Acoustic Wave Resonator Technologies
- Diabetes and associated disorders
- Electronic and Structural Properties of Oxides
- Metal Forming Simulation Techniques
- Metallurgy and Material Forming
Universidad de Cádiz
2015-2024
University of Notre Dame
2021
Turing Institute
2021
University of Strathclyde
2021
University of California, Berkeley
2021
Stanford University
2021
Los Alamos National Laboratory
2020
Elecnor (Spain)
2020
University of Concepción
2017
Universidad Complutense de Madrid
2016-2017
The structure and composition of single GaAsBi/GaAs epilayers grown by molecular beam epitaxy were investigated optical transmission electron microscopy techniques. Firstly, the GaAsBi layers exhibit two distinct regions a varying Bi profile in growth direction. In lower (25 nm) region, content decays exponentially from an initial maximum value, while upper region comprises almost constant until end layer. Secondly, despite relatively low content, CuPtB-type ordering was observed both...
ZnO microrods were grown by laser assisted flow deposition technique in order to study their luminescence behaviour the near band edge spectral region. Transmission electron microscopy analysis put evidence high crystallinity degree and microrod's compositional homogeneity. Photoluminescence revealed a dominant 3.31 eV emission. The correlation between this emission presence of surface states was investigated performing plasma treatments with hydrogen nitrogen. significant modifications...
The influence of dislocations on electron transport properties undoped InN thin films grown by molecular-beam epitaxy AlN(0001) pseudosubstrates is reported. microstructure and the in InN(0001) varying thickness were analyzed transmission microscopy variable temperature Hall-effect measurements. It was found that crystal defects have strong effects concentration mobility carriers films. In particular, combined analysis Hall data showed a direct dependence between free carrier dislocation...
By using a marker technique based on nanowire (NW) heterostructure, we have identified the Ga-limited and N-limited GaN NW growth regimes, which are shifted in comparison to those two-dimensional layers. The results show that Ga atoms diffusing along sidewalls significant contribution vertical growth. reducing substrate temperature, Ga-rich conditions locally activate lateral In contrast atoms, of Al N adatom diffusion is negligible. Finally, control GaN/AlN heterostructures NWs demonstrated.
Graphite materials were prepared from two Spanish anthracites, AF and ATO, by heating at different temperatures within the range 2000−2800 °C. XRD Raman spectroscopy employed to characterize degrees of crystallinity crystal orientation materials. In addition studying evolution typical parameters such as interlayer spacing, d002, crystallite sizes, La Lc, with temperature, this work aimed evaluate influence elemental composition, texture (as measured optical microscopy), mineral matter raw...
The purpose of this research was to study the influence temperature, treatment time, and initial coal particle size on evolution structural order graphite materials that have been prepared from an anthracite at temperatures >2273 K. Crystalline parameters such as interlayer spacing crystallite sizes were calculated X-ray diffractometry measurements. analysis first- second-order Raman spectra allowed assessment degree orientation outermost layers these materials. graphitization happened in...
A new thermophoretic precipitator (TP) has been designed and used for the collection of nanosized aerosol particles. NaCl Fe particles, with mean diameters 55 nm 3.6 nm, respectively, were to determine deposition efficiency as well uniformity deposition. When average temperature gradients applied 2200 K/cm 2400 K/cm, a high efficiency, close 100%, was attained at flow rates below 15 sccm. gradual decay in observed rate increased. Theoretical calculations particle good agreement experimental...
Abstract 2D semiconductors (2SEM) can transform many sectors, from information and communication technology to healthcare. To date, top‐down approaches their fabrication, such as exfoliation of bulk crystals by “scotch‐tape,” are widely used, but have limited prospects for precise engineering functionalities scalability. Here, a bottom‐up technique based on epitaxy is used demonstrate high‐quality, wafer‐scale 2SEM the wide band gap gallium selenide (GaSe) compound. GaSe layers well‐defined...
Schwannoma (neurilemmoma) is a rare benign tumor that originates from Schwann cells of peripheral nerves, accounting for approximately 0.1 to 0.7% eyelid tumors. The occurrence schwannoma in the extremely rare, with very few cases reported literature date. These tumors are typically solitary, asymptomatic, and slow-growing, which can make early diagnosis challenging. Clinically, they present as solid masses without skin involvement be mistaken other conditions such inclusion cysts, recurrent...
The strain-relaxation phenomena and the formation of a dislocation network in 2H-InN epilayers during molecular beam epitaxy are reported. Plastic elastic strain relaxations were studied by reflection high-energy electron diffraction, transmission microscopy, high resolution x-ray diffraction. Characterization surface properties has been performed using atomic force microscopy photoelectron spectroscopy. In framework growth model following stages relief have proposed: plastic relaxation...
This paper investigates the effect of GaAsBi strain reduction layers (SRLs) on InAs QDs with different Bi fluxes to achieve nanostructures improved temperature stability. The SRLs are grown at a lower (370 °C) than usual capping for (510 °C). study finds that GaAs low temperatures reduces QD decomposition and leads larger pyramidal dots but also increases threading dislocation (TD) density. When adding layer, significant in TD density is observed, unexpected structural changes occur....
Cubic InN layers were grown by molecular beam epitaxy on buffer of indium oxide prepared onto sapphire (0001) substrates. The structure was analyzed means electron diffraction and transmission microscopy. intermediate layer presents a body centered cubic (bcc) structure, with bcc-In2O3(001)‖Al2O3(0001) plane relationship. Thereupon, zinc-blende phase (001) reticular misfit 1.6% significant reduction mismatch-related defects. This good coherence offers promising expectation to obtain high...
The photoluminescence efficiency of GaAsSb-capped InAs/GaAs type II quantum dots (QDs) can be greatly enhanced by rapid thermal annealing while preserving long radiative lifetimes which are ∼20 times larger than in standard GaAs-capped QDs. Despite the reduced electron-hole wavefunction overlap, type-II samples more efficient type-I counterparts terms luminescence, showing a great potential for device applications. Strain-driven In-Ga intermixing during is found to modify QD shape and...
This work analyses the Bi incorporation in InAs1-xBix/InAs(100) epilayers grown by MBE through advanced transmission electron microscopy techniques. Samples from 350–400 °C resulted contents <3.3% exhibiting compositional variation growth direction. In contrast, roughly spherical clusters appeared sample at lower temperatures. The are made up of binary InBi with a tetragonal PbO phase surrounded matrix InAs0.95Bi0.05 indicating solubility limit InAs. These crystals underwent cubic distortion...
The effect of the capping process on morphology InAs/GaAs quantum dots (QDs) by using different GaAs-based layers (CLs), ranging from strain reduction to compensating layers, has been studied transmission microscopic techniques. For this, we have measured simultaneously height and diameter in buried uncapped QDs covering populations hundreds that are statistically reliable. First, QD population evolves all cases a pyramidal shape into more homogenous distribution with spherical-dome shape,...
Multi-junction solar cells made by assembling semiconductor materials with different bandgap energies have hold the record conversion efficiencies for many years and are currently approaching 50%. Theoretical efficiency limits make use of optimum designs right lattice constant-bandgap energy combination, which requires a 1.0-1.15 eV material lattice-matched to GaAs/Ge. Nevertheless, lack suitable is hindering achievement predicted efficiencies, since only candidates were up now complex...
The strain state on InN quantum dots (QDs) over GaN/sapphire substrates was analyzed by transmission electron microscopy. Changes in the in-plane lattice parameter of uncapped and capped QD heterostructures have been measured using moiré fringe analysis. QDs are almost completely relaxed, due to a misfit dislocation network present at InN∕GaN interface without generating any threading dislocations inside QDs. In addition, low-temperature-GaN capping process evaluated. Although this...