Neutron irradiation-induced defects in Cd0.9Zn0.1Te:In crystals

Bao, Lei; Zha, Gangqiang; Xu, Lingyan; Zhang, Binbin; Dong, Jiangpeng; Li, Yingrui; Wang, Jie

doi:10.1016/j.mssp.2019.05.002

Cited by 7 publications

(6 citation statements)

References 42 publications

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“…Besides, the complete degradation of the detector occurred already after an irradiation dose of 5•10 10 N/cm 2 , while in the experiment of paper [10], the detector degraded only after an irradiation dose of 10 13 N/cm 2 by fast neutrons. The position of the Fermi level in the band gap, measured in [18], relative to the bottom of the conduction band EC in the initial sample was equal to 0.707 eV, and in the sample irradiated with a dose of 5•10 10 N/cm 2 it became EC-0.513 eV with a decrease in resistivity from 3.49•10 9 to 6.12•10 8 Ohm•cm.…”

Section: Resultsmentioning

confidence: 93%

“…The results obtained in this and earlier studies can be compared with the data of [18], where, using the SRIM program, the Monte Carlo method was used to simulate the effect of neutron radiation with an energy of 1-2 MeV on the formation of radiation damage in Cd0.9Zn0,1Te crystals. The type and number of originating radiation defects was investigated.…”

Section: Resultsmentioning

confidence: 95%

“…The defect concentration was measured using thermally stimulated current spectroscopy (TSC), and the detector spectra were recorded for 241 Am gamma radiation source (59.5 keV). It was shown that the concentration of vacancies, anti-structural defects of cadmium substitution at the site of tellurium, interstitial atoms, and related defects increases during neutron irradiation, which, according to the authors of [18], caused a deterioration in the detector characteristics of Cd0.9Zn0.1Te. Besides, the complete degradation of the detector occurred already after an irradiation dose of 5•10 10 N/cm 2 , while in the experiment of paper [10], the detector degraded only after an irradiation dose of 10 13 N/cm 2 by fast neutrons.…”

Section: Resultsmentioning

confidence: 99%

“…We carried out a comparative analysis of the simulation results based on the experimental data of [10] with the experimental results of paper [18]. As a result, it was found that the very low radiation resistance of the detector in [18] can be explained by the fact that the as-grown Cd0.9Zn0.1Te crystal there turned out to be a material of lower detector quality. Namely, in the initial state, they produced a semiconductor with a high content of interstitial Cd ++ (CdI) and substitutional defect of cadmium in site of tellurium (Cd + Te), which are defects of the donor type.…”

Section: Resultsmentioning

confidence: 99%

“…Namely, in the initial state, they produced a semiconductor with a high content of interstitial Cd ++ (CdI) and substitutional defect of cadmium in site of tellurium (Cd + Te), which are defects of the donor type. Under the influence of these electrically active deep donors, the Fermi level already in the as-grown material was above the middle of the band gap, which determined the electronic conductivity registered in [18] using Hall measurements. The bombardment of such a material by fast neutrons led to a further increase in the concentration of CdI and CdTe defects with a shift of the Fermi level even closer to the conduction band and, as a result, a noticeable drop in resistivity, a sharp increase in the leakage current and complete detector degradation, which required a relatively small irradiation dose -5•10 10 N/cm 2 .…”

Section: Resultsmentioning

confidence: 99%

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

Kondrik

Kovtun

2020

EEJP

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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.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 95%