Free-Electron Laser Internal Photoemission Measurements of Heterojunction Band Discontinuities

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Disclosed is a diode device (1) including an insulator (7) extending between and in contact with two metal terminals (3, 5), wherein the insulator comprises at least one epsilon-near-zero (enz) material, or comprises at least one epsilon-negative (eng) material (7a) and a second insulator material (7b) forming a double insulator structure, and an electron source layer (9), particularly of graphene, between a metal terminal and the enz or eng material. the insulator provides a reduced effective capacitance w

We investigate the influence of AlN buffer thickness on the structural, electrical, and thermal properties of AlGaN/GaN high-electron mobility transistors (HEMTs) grown on semi-insulating SiC substrates by metal-organic chemical vapor deposition. X-ray diffraction and atomic force microscopy reveal that while thin AlN layers (120 nm) exhibit compressive strain and smooth step-flow surfaces, thicker single-layer buffers (550 nm) develop tensile strain and increased surface roughness. Multi-layer buffer struc

Zinc phosphide (Zn3P2) has been identified as a promising material for low-cost photovoltaics made of earth-abundant elements. In the 90's, the low performance of the devices based on Zn3P2 was attributed to the poor quality of the crystal. Recently, selective area epitaxy (SAE) has emerged as a method to obtain high quality materials on lattice mismatched substrates, thanks to efficient strain relaxation. Here, we study the relation between the SAE mask characteristics and the resulting optoelectronic prop

Incorporating atomically thin two-dimensional (2D) materials with optical fibers expands their potential for optoelectronic applications. Recent advancements in chemical vapor deposition have enabled the batch production of these hybrid fibers, paving the way for practical implementation. However, their functionality remains constrained by the integration of a single 2D material, restricting their versatile performance. Here, we introduce a boron nitride/graphene (BN/Gr) heterostructure in the antiresonant

Gyrokinetic simulations are extensively used as a tool to describe various phenomena in magnetically confined plasmas. Among others, turbulent transport induced by drift-wave type instabilities such as Ion Temperature Gradient (ITG), Trapped Electron Mode (TEM) and Electron Temperature Gradient (ETG) plays a central role in fusion research. While the ITG mode in first approximations can be modeled using a reduced adiabatic electron model, the TEM and ETG modes require a kinetic description. The global delta

This work demonstrates dielectric elastomer actuators controlled by the world's first thin-film transistors on flexible substrate operating at 1kV, thereby enabling locally switching high-voltages on DEAs using a low control voltage. The high voltages required to drive DEAs limit their integration in complex systems, such as high resolution haptic displays and multiple-degree-of-freedom robotics. We report here a top-gate, thin-film transistor (TFT) with coplanar electrodes specifically designed to drive DE

Ce document décrit l'ajustement d'un nouveau lot de capteurs CentoNewton-Bd' comportant plusieurs séries de substrats avec des forces nominales différentes. Des mesures complémentaires sont réalisées pour caractériser le comportement sous charge du capteur et sa sensibilité parasite aux forces exercées sur les plages de contact. // This document describes the trimming of a new lot of CentoNewton-Bd' sensors, encompassing several series of substrates with different nominal forces. Additional measurements are

Advantages and remaining issues of state-of-the-art m-plane freestanding GaN (FS-GaN) substrates grown by halide vapor phase epitaxy (HVPE) for m-plane InGaN epitaxial film growth by metalorganic vapor phase epitaxy are described. Because of the low threading dislocation and basal-plane stacking fault densities, improved quantum efficiency and short radiative lifetime are achieved for the near-band-edge emission of 200–250 nm thick m-plane pseudomorphic InGaN epilayers. As the surface flatness is greatly im

Fibers doped with bismuth show broad luminescence bands around 750, 1100, and 1400 nm with spectral bandwidths of 100 to 200 nm at room temperature. The luminescence bands can be observed by pumping broad absorption bands in the visible or near infrared spectrum (around 500, 700, 800, 1000, and 1360 nm). Bismuth fiber laser action has been demonstrated using FBG in standard germanosilicate fibers as intra-core laser mirrors. In this work we report about the investigation of refractive index and luminescence

The growth of GaAs nanowires by the gallium-assisted method with molecular beam epitaxy (MBE) is presented in this review article. The structure of the grown nanowires was investigated by means of scanning and transmission electron microscopy as well as Raman spectroscopy. Their optical properties were revealed by performing photoluminescence measurements at the single nanowire level. Furthermore, by tuning the MBE conditions to planar growth, quantum heterostructures on the side facets of the nanowires wer

We study the subpicosecond gain dynamics in a high-finesse semiconductor microcavity containing quantum wells by means of degenerate pump-probe spectroscopy. Tuning the optical excitation in resonance with both the exciton and the cavity modes, at high pump fields the probe pulses are strongly amplified near the energy of the empty-cavity mode. At zero probe delay, integration of the probe spectrum yields a net gain of several percents. The coherent nature of the gain is demonstrated by its oscillatory beha

In YBa2Cu3O6+x the tetragonal to orthorhombic transition occurs around x equals 0.3, followed by a continuum variation of lattice parameters. Hence both, the structural and superconducting properties, depend upon the oxygen content in CuO chains. Conversely, the epitaxial stress, exerted by the substrate on YBCO films, modified the lattice parameters, influencing the oxygen stability in the chains. The understanding of this mechanism is essential when growing epitaxial films for in-situ photoemission studie

Electrode stability, interdiffusion, phase purity and deviation from stoichiometry at the PZT-electrode interface are key issues in PZT thin film integration. This article highlights the use of transmission electron imaging combined with energy dispersive spectroscopy (EDS) for the investigation of these phenomena. The accuracy of the EDS analysis is discussed. It will be shown that using a standard PZT sample and controlled conditions, reliable analysis can be performed. Diffusion mechanisms have been stud

We report a modification by thin silicon nitride intralayers of the Au/n-GaAs)(100) Schottky barrier height. Thin intralayers were obtained by nitridation of evaporated Si films on decapped GaAs substrates in an argon-nitrogen mixture plasma. The nitridation was performed at a beam energy

Platinum silicide films are widely used in silicon devices for ohmic and Schottky contacts. It has been demonstrated in the recent years that Schottky barriers employing ultra-thin platinum silicide films (thickness < 10 nm) are useful for photodetection in the near infrared. We have studied the formation of thin platinum silicide films and their electrical properties as a function of the annealing temperature in presence of an interfacial native silicon oxide layer and with plasma etching damage on the Si

Low-frequency noise measurements have been performed in the linear range of the I-V characteristics of pseudomorphic Al0.3Ga0.7As/In0.25Ga0.75As/GaAs high electron mobility transistors (HEMTs) grown by molecular beam epitaxy with different channel thicknesses. The results obtained show that the 1/f noise in such devices depends greatly on channel thickness. It is controlled by the penetration of the electron wavefunction into the barrier as well as by Coulombic effects for thin channels and by the increase

The purpose of this work is to predict the behaviour of electric devices using superconducting tapes, including the transition of those tapes to the normal state, which implies a typical non linear behaviour. The frequency domain studied is as wide as possible, from dc to the highest frequency measurable involving current intensities up to 100 A. The measurements are made on silver sheathed Bi(2223) tapes produced at the University of Geneva.

Contact potential difference (CPD) measurements using a Kelvin probe coupled with synchrotron radiation are used to investigate the surface photovoltage (SPV) induced by synchrotron radiation at GaAs surfaces. A large and quasi-permanent SPV is found at surfaces of low-doped and low-temperature samples. SPV discharge mechanisms are investigated. The CPD technique is used to define conditions under which SPV is negligible, leading to reliable measurements of band bending at low temperature. Band bending meas

The measurement of the tokamak plasma ion temperature can be obtained by collective Thomson scattering. This method requires a far infrared laser to achieve useful spatial resolution for typical tokamak plasma parameters. The very low Thomson scattering cross section (10-28 m2) implies the use of a pulsed far infrared laser with 1 MW power and 1 µs pulse duration. With the best technology of far infrared heterodyne receivers available today, with a noise equivalent power (NEP) below 10-18 W/Hz, it should be

Free-Electron Laser Internal Photoemission Measurements of Heterojunction Band Discontinuities

Chat with Graph Search

Metal-insulator-metal tunnelling diode for operation in the visible or infrared spectrum

Impact of AlN buffer thickness on electrical and thermal characteristics of AlGaN/GaN/AlN HEMTs

Nanopatterning optimization of zinc phosphide: hole mobility up to 560 cm2/V s with selective area epitaxy

Vertically Stacked Boron Nitride/Graphene Heterostructure for Tunable Antiresonant Hollow-Core Fiber

An improved hybrid electron model for global gyrokinetic simulations using the ORB5 PIC code

Flexible 1kV thin-film transistor driving out-of-plane dielectric elastomer actuator

CentoNewton : types 10A, 20B, 40A, 40B & 100A

Advantages and remaining issues of state-of-the-art m-plane freestanding GaN substrates grown by halide vapor phase epitaxy for m-plane InGaN epitaxial growth

ArF laser induced refractive index and luminescence changes in Bi-doped aluminosilicate fibers - INVITED

GaAs nanowires and related prismatic heterostructures

Net coherent optical gain in strongly pumped semiconductor microcavities

Structural properties of strained YBa2Cu3O6+x superconducting films grown by pulsed laser deposition

Stoichiometry and interdiffusion in PZT thin films studied by transmission electron microscopy

Au/GaAs(100) interface Schottky barrier modification by a silicon nitride intralayer

Formation and properties of nanometer-thick platinum silicide layers

Low-Frequency Noise Measurements of Alxga1-Xas/Inyga1-Y as/Gaas High-Electron-Mobility Transistors

Measurement and Modeling of the Dynamic Behavior of Ag sheathed Bi(2223) Superconducting Tapes

Kelvin Probe and Synchrotron Radiation Study of Surface Photovoltage and Band Bending at Metal GaAs (100) Interfaces

Developement and use of far infrared lasers in studies of collective electron density fluctuations in a tokamak plasma by Thomson scattering