scholarly journals Degradation Under Influence of Radiation Defects of Detector Properties of CdTe and Cd0.9Zn0.1Te Irradiated by Neutrons

2020 ◽  
Keyword(s):  
Fermi Level ◽  
Neutron Irradiation ◽  
Radiation Resistance ◽  
Collection Efficiency ◽  
Energy Levels ◽  
Charge Carriers ◽  
Radiation Defects ◽  
Nonequilibrium Charge Carriers ◽  
Recombination Processes ◽  
Detector Material

This work is devoted to the study by computer simulation of the mechanisms of the influence of radiation defects, arising under the influence of neutron irradiation, on the changes in electrical properties: resistivity ρ, electron mobility μn, lifetime of nonequilibrium electrons τn and holes τp in Cd0.9Zn0.1Te and charge collection efficiency η of uncooled ionizing radiation detectors based on this material. Radiation defects, which are corresponded by deep energy levels in the band gap, act as trapping centers of nonequilibrium charge carriers, noticeably affect the degree of compensation by changing ρ of the detector material, the recombination processes, decreasing τn and τp, and also the scattering of conduction electrons, decreasing μn, that ultimately can cause degradation of the charges collection efficiency η. The specific reasons for the deterioration of the electrophysical and detector properties of this semiconductor under the influence of neutron irradiation were identified, and the main factors affecting the increase in the resistivity of Cd0.9Zn0.1Te during its bombardment by low-energy and high-energy neutrons, leading to complete degradation of the recording ability of detectors based on this materials, were found. The recombination of nonequilibrium charge carriers is noticeably stronger than the decrease in μn affects the degradation of detector properties, therefore, the effect of recombination processes at deep levels of radiation defects on the degradation of τn, τp, and η of detectors based on Cd0.9Zn0.1Te was studied. A comparative analysis of the properties of Cd0.9Zn0.1Te with the previously studied CdTe:Cl was made. An attempt was made to explain the higher radiation resistance of Cd0.9Zn0.1Te compared to CdTe:Cl under neutron irradiation by the influence of the radiation self-compensation mechanism with participation of deep donor energy levels: interstitial tellurium and tellurium at the site of cadmium. In addition, the rate of recombination at defect levels in Cd0.9Zn0.1Te is, ceteris paribus, lower than in CdTe:Cl due to the smaller difference between the Fermi level and the levels of radiation defects in cadmium telluride. The relationship between the band gaps of Cd0.9Zn0.1Te and CdTe:Cl, the concentration of radiation defects, the Fermi level drift during irradiation, and the radiation resistance of the detectors were also noted. The important role of purity and dopant shallow donor concentration in initial state of the detector material is indicated.

scholarly journals EFFECT OF DEFECTS ORIGINATING UNDER THE PROTON IRRADIATION ON THE ELECTROPHYSICAL AND DETECTOR PROPERTIES OF CdTe:Cl AND CdZnTe

2021 ◽  
pp. 43-50
Author(s):  
A.I. Kondrik
Keyword(s):  
Proton Irradiation ◽  
Collection Efficiency ◽  
Energy Levels ◽  
Radiation Detectors ◽  
High Energy ◽  
Charge Collection ◽  
Radiation Defects ◽  
Initial State ◽  
Charge Collection Efficiency ◽  
Factors Affecting

The work is dedicated to studying by computer modeling the mechanisms of the influence of radiation defects, originating under high energy proton irradiation, on the resistivity ρ, lifetime of nonequilibrium electrons n and holes p in CdTe:Cl and Cd0.9Zn0.1Te, and charge collection efficiency η of room temperature ionizing radiation detectors based on these materials. The effect of recombination at deep levels of radiation defects on the degradation of n, p, and  of detectors based on CdTe:Cl and Cd0.9Zn0.1Te was studied. Energy levels of radiation defects also substantially effect on compensation degree of semiconductor decreasing ρ. The main factors affecting the abrupt or gradual decrease in the resistivity and charge collection efficiency of these detectors during their bombardment by high-energy protons, leading to complete degradation of their recording ability, were found. The important role of purity and deep donor concentration in initial state of the detector material was indicated.

scholarly journals Influence of radiation defects on the electrophysical and detector properties of CdTe:Cl irradiated by neutrons

2020 ◽  
pp. 22-29 ◽  
Author(s):  
A. I. Kondrik ◽  
G. P. Kovtun
Keyword(s):  
Band Gap ◽  
Neutron Irradiation ◽  
Electron Mobility ◽  
Collection Efficiency ◽  
Radiation Detectors ◽  
High Energy ◽  
High Resistivity ◽  
Semiconductor Detectors ◽  
Radiation Defects ◽  
Charge Collection Efficiency

A promising material for semiconductor detectors of ionizing radiation is CdTe:Cl which allows obtaining detectors with high resistivity ρ and electron mobility μn. During operation, the detector materials may be exposed to neutron irradiation, which causes radiation defects to form in crystal lattice and deep levels to appear in the band gap, acting as centers of capture and recombination of nonequilibrium charge carriers, thus reducing the detection capability. The aim of this study was to use computer simulation to investigate the mechanisms of the influence of such radiation defects on the electrophysical properties (ρ, μn) of CdTe:Cl and the charge collection efficiency η of radiation detectors based on this material. The simulations were based on the models tested for reliability. It was found that the increase of the CdTe:Cl resistivity ρ during low-energy neutrons bombardment and at the initial stages of high-energy neutrons bombardment is caused by an increase in the concentration of radiation donor defect Z (with an energy level EC – 0.47 eV), presumably interstitial tellurium, which shifts the Fermi level into the middle of the band gap. The sharp rise of ρ observed at high-energy neutron bombardment is probably caused by the restructuring of the crystalline structure of the detector material with a change in the lattice constant and with an increase of the band gap, accompanied by a change in the conductivity properties. The degradation of the detector properties of CdTe:Cl during neutron irradiation is due to the capture and recombination of nonequilibrium electrons at radiation defects: Te interstitial, Te substitutional at the cadmium site, on tellurium vacancies and cadmium vacancies. The degradation of electron mobility μn can be caused by the scattering of electrons at microscopic areas of radiation defect clusters. The increase in concentration of the defects over the volume of the crystal at their uniform distribution of up to 1016 cm–3 does not significantly affect the electron mobility at room temperature.

Improvement of Radiation Resistance of Multijunction GaInP/Ga(In)As/Ge Solar Cells with Application of Bragg Reflectors

2010 ◽  
Vol 74 ◽  
pp. 225-230 ◽  
Author(s):  
Vladimir M. Lantratov ◽  
Viktor M. Emelyanov ◽  
Nikolay A. Kalyuzhnyy ◽  
Sergey A. Mintairov ◽  
Maxim Z. Shvarts
Keyword(s):  
Solar Cells ◽  
Radiation Resistance ◽  
Radiation Treatment ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Charge Carriers ◽  
Bragg Reflectors ◽  
Multijunction Solar Cells ◽  
Operation Period ◽  
Long Operation

Feasibility to increase the radiation resistance of multijunction solar cells in using Bragg reflectors has been shown. Two designs of Bragg reflectors for multijunction solar cells, which allow ensuring in the Ga(In)As subcell base an effective collection of minority charge carriers at the decrease of their diffusion length caused by radiation treatment, have been investigated. Influence of subcells’ thicknesses of n-p GaInP/Ga(In)As/Ge solar cell under 1 MeV electron irradiation with fluences up to 3•1015 cm–2 on short circuit current was considered. Optimal thicknesses of GaInP and GaInAs subcells with Bragg reflectors, depending on the rated operation period on the geostationary orbit, were estimated. It has been shown that such an optimization allows to achieve efficiency at long operation of solar cells on the orbit noticeably higher than that of non-optimized cells.

scholarly journals Progress on the Synthesis and Application of CuSCN Inorganic Hole Transport Material in Perovskite Solar Cells

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2592 ◽  
Author(s):  
Funeka Matebese ◽  
Raymond Taziwa ◽  
Dorcas Mutukwa
Keyword(s):  
Solar Cells ◽  
Energy Levels ◽  
Perovskite Solar Cells ◽  
Hole Mobility ◽  
Cost Effective ◽  
Vital Role ◽  
Hole Transport ◽  
Recombination Processes ◽  
Short Synthesis ◽  
P Type

P-type wide bandgap semiconductor materials such as CuI, NiO, Cu2O and CuSCN are currently undergoing intense research as viable alternative hole transport materials (HTMs) to the spiro-OMeTAD in perovskite solar cells (PSCs). Despite 23.3% efficiency of PSCs, there are still a number of issues in addition to the toxicology of Pb such as instability and high-cost of the current HTM that needs to be urgently addressed. To that end, copper thiocyanate (CuSCN) HTMs in addition to robustness have high stability, high hole mobility, and suitable energy levels as compared to spiro-OMeTAD HTM. CuSCN HTM layer use affordable materials, require short synthesis routes, require simple synthetic techniques such as spin-coating and doctor-blading, thus offer a viable way of developing cost-effective PSCs. HTMs play a vital role in PSCs as they can enhance the performance of a device by reducing charge recombination processes. In this review paper, we report on the current progress of CuSCN HTMs that have been reported to date in PSCs. CuSCN HTMs have shown enhanced stability when exposed to weather elements as the solar devices retained their initial efficiency by a greater percentage. The efficiency reported to date is greater than 20% and has a potential of increasing, as well as maintaining thermal stability.

The neutron irradiation effects on the temperature dependencies of the electrical conductivity of nanosilicon particles

2017 ◽  
Vol 31 (28) ◽  
pp. 1750257 ◽  
Author(s):  
Elchin Huseynov ◽  
Aydan Garibli
Keyword(s):  
Electrical Conductivity ◽  
Neutron Flux ◽  
Neutron Irradiation ◽  
Silicon Nanoparticles ◽  
Activation Energies ◽  
Radiation Defects ◽  
Irradiation Effects ◽  
Active Radiation ◽  
Before And After ◽  
Effects Of Temperature

The effects of temperature and neutron irradiation on the silicon nanoparticles have been studied at different frequencies. It has been defined that additional electro-active radiation defects occur in the silicon nanomaterial after neutron irradiation. Therefore, the change of neutron flux at the interval of [Formula: see text]–[Formula: see text] increases the conductivity of nanosilicon. Activation energies of the silicon nanoparticles were calculated for 10 different constant frequencies according to Arrhenius approach before and after neutron irradiation. The mechanism of electrical conductivity which explains results has been established.

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