Significant Carrier Extraction Enhancement at the Interface of an InN/p-GaN Heterojunction under Reverse Bias Voltage

In this paper, a superior-quality InN/p-GaN interface grown using pulsed metalorganic vapor-phase epitaxy (MOVPE) is demonstrated. The InN/p-GaN heterojunction interface based on high-quality InN (electron concentration 5.19 × 1018 cm−3 and mobility 980 cm2/(V s)) showed good rectifying behavior. The heterojunction depletion region width was estimated to be 22.8 nm and showed the ability for charge carrier extraction without external electrical field (unbiased). Under reverse bias, the external quantum efficiency (EQE) in the blue spectral region (300⁻550 nm) can be enhanced significantly and exceeds unity. Avalanche and carrier multiplication phenomena were used to interpret the exclusive photoelectric features of the InN/p-GaN heterojunction behavior

<title>Evaluation of deep trap compensation ratio and recombination parameters by transient grating techniques</title>

International audienc

Photoelectric properties of highly excited ZnTe:V(Al, Sc) bulk crystals

Degenerate four-wave mixing experiments with 25-ps pulses at a wavelength of 1.06 µm have been performed in ZnTe crystals doped with deep vanadium impurity and codoped by aluminum or scandium. Complex analysis of the time resolved measurements together with exposure characteristics at various delay times of the probe beam revealed effective carrier generation from defect complexes and their subsequent recombination to Zn-vacancies in Al codoped samples. On the other hand, significantly faster carrier diffusion in Sc codoped crystal disclosed the build-up of a space charge field in deep traps through its feedback to carrier transport

Investigation of photoelectric properties of ZnSe:Cr and ZnTe:V:Al by picosecond four-wave mixing technique

Role of deep impurity levels in carrier generation, transport, and recombination were investigated in bulk ZnSe:Cr and ZnTe:V:Al crystals by four-wave mixing technique..

Investigation of photoelectric properties of ZnSe:Cr and ZnTe:V:Al by picosecond four-wave mixing technique

Role of deep impurity levels in carrier generation, transport, and recombination were investigated in bulk ZnSe:Cr and ZnTe:V:Al crystals by four-wave mixing technique..

Evaluation of photoelectrical properties of Bi doped CdTe crystals

Nonequilibrium carrier generation, transport, and recombination features have been investigated in Bi-doped and Yb-codoped bulk CdTe crystals, using time-resolved picosecond free-carrier and photorefractive grating techniques. Peculiarities of deep-impurity dependent carrier generation were studied at below band-gap photoexcitation using 1064 nm wavelength. Carrier transport in light created space charge field provided the instantaneous diffusion coefficient values, dependent on excitation energy, and revealed a sign of the dominant photoexcited carriers in the crystals. The studies provided also a deeper insight into an initial occupation of deep impurity levels, which was found strongly dependent on doping and co-doping. At low Bi density (∼2 × 1017 cm−3), the hole generation was dominant, while at higher doping (8 × 1017 cm−3) the bipolar plasma generation prevailed. Codoping by Yb (∼5 × 1017 cm−3) revealed deep donor features of deep defects and formation of a strong space charge field. Carrier dynamics in the given crystals was compared with CdTe:V ones, where vanadium is known to form the mid-gap donor levels

Black silicon: substrate for laser 3D micro/nano-polymerization

We demonstrate that black silicon (b-Si) made by dry plasma etching is a promising substrate for laser three-dimensional (3D) micro/nano-polymerization. High aspect ratio Si-needles, working as sacrificial support structures, have flexibility required to relax interface stresses between substrate and the polymerized micro-/nano- objects. Surface of b-Si can be made electrically conductive by metal deposition and, at the same time, can preserve low optical reflectivity beneficial for polymerization by direct laser writing. 3D laser polymerization usually performed at the irradiation conditions close to the dielectric breakdown is possible on non-reflective and not metallic surfaces. Here we show that low reflectivity and high metallic conductivity are not counter- exclusive properties for laser polymerization. Electrical conductivity of substrate and its permeability in liquids are promising for bio- and electroplating applications

RD50 Status Report 2008 - Radiation hard semiconductor devices for very high luminosity colliders

The objective of the CERN RD50 Collaboration is the development of radiation hard semiconductor detectors for very high luminosity colliders, particularly to face the requirements of a possible upgrade scenario of the LHC.This document reports the status of research and main results obtained after the sixth year of activity of the collaboration