Search results for " semiconductor"
showing 10 items of 332 documents
Progress in the Development of CdTe and CdZnTe Semiconductor Radiation Detectors for Astrophysical and Medical Applications
2009
Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector…
Digital pulse processing techniques for X-ray and gamma ray semiconductor detectors
2012
Digital pulse processing (DPP) systems, based on direct digitizing and processing of detector signals, have recently been favoured over analog electronics, ensuring higher flexibility, stability and lower dead time. We present our research activities on the development of X-ray and gamma ray spectrometers based on semiconductor detectors and DPP systems. We developed off-line and real-time DPP systems able to perform precise height and shape analysis of detector pulses. X-ray and gamma ray spectra measurements with cadmium telluride (CdTe) and germanium (Ge) detectors highlight the excellent performance of the systems both at low and high rate environments (up to 800 kcps).
Deep traps in InGaN/GaN single quantum well structures grown with and without InGaN underlayers
2020
The electrical properties and deep trap spectra were compared for near-UV GaN/InGaN quantum well (QW) structures grown on free-standing GaN substrates. The structures differed by the presence or absence of a thin (110 nm) InGaN layer inserted between the high temperature GaN buffer and the QW region. Capacitance-voltage profiling with monochromatic illumination showed that in the InGaN underlayer (UL), the density of deep traps with optical threshold near 1.5 eV was much higher than in the QW and higher than for structures without InGaN. Irradiation with 5 MeV electrons strongly increased the concentration of these 1.5 eV traps in the QWs, with the increase more pronounced for samples witho…
Window-Based Energy Selecting X-ray Imaging and Charge Sharing in Cadmium Zinc Telluride Linear Array Detectors for Contaminant Detection
2023
The spectroscopic and imaging performance of energy-resolved photon counting detectors, based on new sub-millimetre boron oxide encapsulated vertical Bridgman cadmium zinc telluride linear arrays, are presented in this work. The activities are in the framework of the AVATAR X project, planning the development of X-ray scanners for contaminant detection in food industry. The detectors, characterized by high spatial (250 µm) and energy (<3 keV) resolution, allow spectral X-ray imaging with interesting image quality improvements. The effects of charge sharing and energy-resolved techniques on contrast-to-noise ratio (CNR) enhancements are investigated. The benefits of a new energy-resolved …
Influence of organic material and sample parameters on the surface potential in Kelvin probe measurements
2019
Financial support provided by ERDF 1.1.1.1 activity project Nr. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices” as well as Scientific Research Project for Students and Young Researchers Nr. SJZ2016/20 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged.
Use of electronic nose to determine defect percentage in oils. Comparison with sensory panel results
2010
Abstract An electronic nose based on an array of 6 metal oxide semiconductor sensors was used, jointly with linear discriminant analysis (LDA) and artificial neural network (ANN) method, to classify oils containing the five typical virgin olive oil (VOO) sensory defects (fusty, mouldy, muddy, rancid and winey). For this purpose, these defects, available as single standards of the International Olive Council, were added to refined sunflower oil. According to the LDA models and the ANN method, the defected samples were correctly classified. On the other hand, the electronic nose data was used to predict the defect percentage added to sunflower oil using multiple linear regression models. All …
Oxidation-Induced Changes in the ALD-Al2O3/InAs(100) Interface and Control of the Changes for Device Processing
2018
InAs crystals are emerging materials for various devices like radio frequency transistors and infrared sensors. Control of oxidation-induced changes is essential for decreasing amounts of the harmful InAs surface (or interface) defects because it is hard to avoid the energetically favored oxidation of InAs surface parts in device processing. We have characterized atomic-layer-deposition (ALD) grown Al2O3/InAs interfaces, preoxidized differently, with synchrotron hard X-ray photoelectron spectroscopy (HAXPES), low-energy electron diffraction, scanning tunneling microscopy, and time-of-flight elastic recoil detection analysis. The chemical environment and core-level shifts are clarified for w…
Alkylthio-tetrasubstituted μ-Nitrido Diiron Phthalocyanines: Spectroelectrochemistry, Electrical Properties, and Heterojunctions for Ammonia Sensing.
2020
Alkylthio-tetrasubstituted μ-nitrido diiron phthalocyanine complexes are synthesized with n-butyl, iso-butyl, tert-butyl, and n-hexadecyl alkyl moieties. For the first time, a spectroelectrochemical investigation of μ-nitrido diiron phthalocyanines is achieved at all the redox steps. The complexes are stable in all their redox states, unlike their unsubstituted analogues. The interest of the present complexes is to prepare sensing devices by a solution processing method. Films are characterized by electronic absorption and Raman spectroscopies. Electrical measurements on resistors show the highly resistive behavior of these complexes, whatever the chain length. However, when combined with t…
Surfactant-assisted synthesis of Cd1−xCoxS nanocluster alloys and their structural, optical and magnetic properties
2010
We report the synthesis of Co-doped CdS nanoclusters (Cd1−xCoxS) for different doping concentrations (x = 0.10, 0.20 and 0.30) and characterization of their structural, optical, and magnetic properties. The structural properties studied by X-ray diffraction revealed hexagonal-greenockite structure and a decrease of the lattice parameters (a and c) with doping, showing incorporation of Co in the lattice. The morphology of the nanoclusters was studied by scanning electron microscopy. The optical absorption studies, using diffused reflectance spectroscopy, revealed that Co doping modifies the absorption band edge. Ferromagnetic phase was observed in the magnetization measurements at room-tempe…
Molecular dynamics simulations of heavy ion induced defects in SiC Schottky diodes
2018
Heavy ion irradiation increases the leakage current in reverse-biased SiC Schottky diodes. This letter demonstrates, via molecular dynamics simulations, that a combination of bias and ion-deposited energy is required to produce the degradation. Peer reviewed