A5047327610- Semiconductor Quantum Structures and Devices
- Advanced Semiconductor Detectors and Materials
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- solar cell performance optimization
- Nanowire Synthesis and Applications
- GaN-based semiconductor devices and materials
- Semiconductor materials and interfaces
- Semiconductor materials and devices
- Advanced Electron Microscopy Techniques and Applications
- Ga2O3 and related materials
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced Sensor and Energy Harvesting Materials
- Electron and X-Ray Spectroscopy Techniques
- Silicon and Solar Cell Technologies
- Magnetic properties of thin films
- Chemical and Physical Properties of Materials
- Heusler alloys: electronic and magnetic properties
- Advanced X-ray Imaging Techniques
- Magnetic and transport properties of perovskites and related materials
- Image Processing Techniques and Applications
- Advanced Optical Sensing Technologies
- Aerogels and thermal insulation
- Surface Modification and Superhydrophobicity
- Photoacoustic and Ultrasonic Imaging
Universidad de Cádiz
2016-2024
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....
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...
A procedure to quantitatively analyse the relationship between wetting layer (WL) and quantum dots (QDs) as a whole in statistical way is proposed. As we will show manuscript, it allows determining, not only proportion of deposited InAs held WL, but also average In content inside QDs. First, amount measured for calibration three different WL structures without QDs by two methodologies: strain mappings high-resolution transmission electron microscopy images compositional with ChemiSTEM x-ray...
As promising candidates for solar cell and photodetection applications in the range 1.0–1.16 eV, growth of dilute nitride GaAsSbN alloys lattice matched to GaAs is studied. With this aim, we have taken advantage temperature gradient molecular beam epitaxy reactor analyse impact on incorporation Sb N species according wafer radial composition gradients. The results from combination X-ray diffraction (XRD) energy-dispersive spectroscopies (EDS) show an opposite rate between as move away centre...
Recently, thin AlAs capping layers (CLs) on InAs quantum dot solar cells (QDSCs) have been shown to yield better photovoltaic efficiency compared traditional QDSCs. Although it has proposed that this improvement is due the suppression of capture photogenerated carriers through wetting layer (WL) states by a de-wetting process, mechanisms operate during process are not clear. In work, structural analysis WL characteristics in AlAs/InAs QD system with different CL-thickness made scanning...
Recently, very thin AlAs capping layers (CLs) have been proposed as a useful tool to increase the performance of InAs/GaAs quantum dot (QDs) devices. However, structure QDs after deposition remains poorly understood and mechanisms explain it are often contradictory. In this work, structural compositional changes InAs using different CL thicknesses studied by state-of-the-art STEM-related techniques. First, heights contents progressively with thickness, demonstrating that produces strong...
For optoelectronic devices from the near to far infrared, advantages of using ultrathin III-Sb layers as quantum wells or in superlattices are well known. However, these alloys suffer severe surface segregation problems, so that actual profiles very different nominal ones. Here, by inserting AlAs markers within structure, state-of-the-art transmission electron microscopy techniques were used precisely monitor incorporation/segregation Sb GaAsSb films (from 1 20 monolayers (MLs)). Our...
Superlattice structures (SLs) with type-II (GaAsSb/GaAsN) and -I (GaAsSbN/GaAs) band alignments have received a great deal of attention for multijunction solar cell (MJSC) applications, as they present strongly intensified luminescence significant external quantum efficiency (EQE), respect to the GaAsSbN bulk layers. Despite difficulties in characterizing distribution N dilute III-V nitride alloys, this work we obtained N-compositional mappings before after rapid thermal annealing (RTA) both...
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