A5080929272- Semiconductor Quantum Structures and Devices
- Photonic and Optical Devices
- GaN-based semiconductor devices and materials
- Semiconductor Lasers and Optical Devices
- Advanced Semiconductor Detectors and Materials
- Semiconductor materials and devices
- ZnO doping and properties
- Microwave Engineering and Waveguides
- Advancements in Semiconductor Devices and Circuit Design
- Ga2O3 and related materials
- Infrared Target Detection Methodologies
- Advanced Photonic Communication Systems
- Quantum and electron transport phenomena
- Silicon Nanostructures and Photoluminescence
- Electromagnetic Simulation and Numerical Methods
- Advanced Antenna and Metasurface Technologies
- Silicon Carbide Semiconductor Technologies
- Optical Network Technologies
- Microwave and Dielectric Measurement Techniques
- Photonic Crystals and Applications
- Thin-Film Transistor Technologies
- Advanced Optical Sensing Technologies
- Plasmonic and Surface Plasmon Research
- Metal and Thin Film Mechanics
- Molecular Junctions and Nanostructures
Polytechnic University of Turin
2016-2025
Institute of Electronics, Computer and Telecommunication Engineering
2016-2025
Institute of Informatics and Telematics
2014-2025
National Research Council
2017-2024
Vertically Integrated Systems (Germany)
2024
Cisco Systems (United States)
2023
AIM Infrarot-Module (Germany)
2020-2021
OSRAM (Germany)
2016
Anna University, Chennai
2016
University of Padua
2013-2016
We present a comprehensive study of the transport dynamics electrons in ternary compounds, Al/sub x/Ga/sub 1-x/N and In/sub 1-x/N. Calculations are made using nonparabolic effective mass energy band model. Monte Carlo simulation that includes all major scattering mechanisms. The parameters used extracted from optimized pseudopotential calculations to ensure excellent agreement with experimental information ab initio models. effects alloy on electron physics examined. steady state velocity...
Physical mechanisms causing the efficiency droop in InGaN/GaN blue light-emitting diodes and remedies proposed for mitigation are classified reviewed. Droop taken into consideration Auger recombination, reduced active volume effects, carrier delocalization, leakage. The latter can turn be promoted by polarization charges, inefficient hole injection, asymmetry between electron densities transport properties, lateral current crowding, quantum-well overfly ballistic electrons, defect-related...
In a combined experimental and numerical investigation, we present the effects of trap‐assisted tunneling on sub‐threshold forward bias characteristics blue InGaN/GaN single‐quantum‐well LED test structure grown SiC substrate. The different role donor‐ acceptor‐like traps has been studied, for information it can provide played by point defects. Using energy E t trap density N as only tunneling‐related fitting parameters, behavior measured I ( V ) curves is well reproduced our model over wide...
Direct interband and intraband Auger recombination due to electron-electron-hole hole-hole-electron transitions in bulk InGaN is investigated by first-order perturbation theory including Fermi statistics, realistic electronic structures obtained nonlocal empirical pseudopotential calculations, their corresponding wavevector-dependent dielectric functions. Our results confirm that the coefficient negligible alloy compositions relevant for solid-state lighting indicate resonant enhancement...
Indirect phonon-assisted Auger recombination mechanisms in bulk InGaN are investigated the framework of perturbation theory, using first-principles phonon spectral density functions and electronic structures obtained by nonlocal empirical pseudopotential calculations. Nonpolar carrier-phonon interactions treated within rigid pseudoion framework, thus avoiding introduction deformation potentials. The calculated indirect coefficients exhibit a weak temperature dependence dominate over direct...
This tutorial paper focuses on the physical origin of thermal droop, i.e., decrease in luminescence light-emitting diodes (LEDs) induced by increasing temperature. III-nitride-based LEDs are becoming a pervasive technology, covering several fields from lighting to displays, automotive portable electronics, and horticulture sensing. In all these environments, high efficiency is fundamental requirement, for reducing power consumption system cost. Over last decade, great deal effort has been...
This work presents nonlocal pseudopotential calculations based on realistic, effective atomic potentials of the wurtzite phase GaN, InN, and AlN. A formulation for model has been introduced. For each constitutive atoms in these materials, form is optimized through an iterative scheme which band structures are recursively calculated selected features compared to experimental and/or ab initio results. The forms used calculate binary compounds, excellent overall agreement with experimental/ab...
A nonlocal semiempirical pseudopotential calculation of the electronic structure wurtzite ZnO is proposed. The local and components atomic effective potentials have been sequentially optimized an excellent quantitative agreement has achieved with a wide range band features (energy gaps at high symmetry points, valence ordering, in-plane perpendicular masses for electrons holes Γ), selected not only from available experimental ab initio results, but also new calculations performed code...
This paper reports an investigation of the physical origin thermal droop (the drop optical power at high temperatures) in InGaN-based light-emitting diodes. We critically investigate role various mechanisms including Shockley-Read-Hall recombination, thermionic escape from quantum well, phonon-assisted tunneling, and trap-assisted tunneling; addition, to explain droop, we propose a closed-form model which is able accurately fit experimental data by using values extracted measurements...
A microscopic model, based on a full-Brillouin-zone description of the electronic structure, is used to investigate Auger transitions in InGaN/GaN quantum wells. The lack momentum conservation along confining direction enhances direct (i.e., phononless) transitions, leading coefficients range those predicted for phonon-dressed processes bulk InGaN. dependence temperature and well thickness analyzed. limitations conventional multiband models, zone-center approximations band are discussed.
This work presents detailed information on the band structures of III-nitride wurtzite ternary alloys, computed through virtual crystal approximation approach. The key ingredient this study is set realistic atomic effective potentials described in Part I present work, dedicated to constituent binary compounds. model relies linear interpolation structural parameters and local nonlocal potentials: no further empirical corrections are included. dependence mole fraction for energy gaps at all...
Wave-vector-dependent rates of disorder-induced alloy scattering have been computed for wurtzite AlGaN and InGaN to determine the transport properties III-nitride alloys through full band Monte Carlo simulation. Contrary previous studies, empirical selection a constant potential has replaced by more fundamental approach based on detailed information about electronic structure corresponding screened atomic potentials. Band structures potentials determined in framework nonlocal pseudopotential...
Portable Fortran subroutines computing the Fermi-Dirac integral F j (x) and incomplete (x,b) are presented. For first time a set of series expansions is implemented allowing these special functions to be evaluated efficiently within prescribed accuracy for real x .
The properties of vertical-cavity surface-emitting lasers (VCSELs) are investigated by means a multiphysical Vcsel Electro-opto-thermal NUmerical Simulator (VENUS). VENUS includes three-dimensional vectorial electromagnetic code, description the quantum well optical response, heat equation solver, and quantum-corrected drift-diffusion simulator. proposed suite coupling mechanisms often overlooked in VCSEL simulation allows to reassess impact parameters, which can be critically dependent on...
Defects can significantly modify the electro-optical characteristics of InGaN light-emitting diodes (LEDs); however, modeling impact defects on electrical LEDs is not straightforward. In this paper, we present an extensive investigation and InGaN-based LEDs, as a function thickness quantum well (QW). First, demonstrate that density in active region III-N scales with increasing QW. Since device layers high indium content tend to incorporate more defects, ascribed experimental evidence...
In this work we investigate the ultrabroadband dynamics of transverse coupled cavity VCSELs.This study is based on a multimode rate equation model, whose parameters are directly provided by full-wave vectorial electromagnetic solver.This approach sets step towards comprehensive physicsbased modeling transverse-coupled VCSELs, providing relation between features optical supermodes and enhancements intensity modulation response.The emphasizes how bandwidth enhancement, ascribable to...