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Title: A Comparison of Point Defects in Cd 1-xZn xTe 1-ySe y Crystals Grown by Bridgman and Traveling Heater Methods

Abstract

In this study, the properties of point defects in Cd 1–xZn xTe 1–ySe y (CZTS) radiation detectors are characterized using deep-level transient spectroscopy and compared between materials grown using two different methods, the Bridgman method and the traveling heater method. The nature of the traps was analyzed in terms of their capture cross-sections and trap concentrations, as well as their effects on the measured charge-carrier trapping and de-trapping times, and then compared for the two growth techniques. The results revealed that Se addition to CdZnTe can reduce the V Cd concentration. In Travelling Heater Method (THM) and Bridgman Method (BM) grown CZTS detectors, besides a few similarities in the shallow and medium energy traps, there were major differences in the deep traps. It was observed that the excess-Te and lower growth-temperature conditions in THM-grown CZTS led to a complete compensation of V Cd and two additional traps (attributed to Te i and Te Cd ++ appearing at around E v + 0.26 eV and E c – 0.78 eV, respectively). The 1.1-eV deep trap related to large Te secondary phases was a dominant trap in the BM-grown CZTS crystals. In addition to i-DLTS data, the effects ofmore » point defects induced due to different processing techniques on the detector's resistivity, spectral response to gammas, and μτ product were determined.« less

Authors:
 [1];  [2];  [2];  [2];  [2];  [2];  [3];  [3];  [4]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States); Alabama A&M Univ., Normal, AL (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Brookhaven National Lab. (BNL), Upton, NY (United States); Savannah River National Lab., Aiken, SC (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1367976
Alternate Identifier(s):
OSTI ID: 1406493
Report Number(s):
LLNL-JRNL-718467; SRNL-STI-2017-00152
Journal ID: ISSN 0021-8979
Grant/Contract Number:
AC52-07NA27344; AC09-08SR22470
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 121; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CdZnTeSe; point defects; carrier trapping; iDLTS; deep levels; radiation detectors; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY

Citation Formats

Gul, R., Roy, U. N., Camarda, G. S., Hossain, A., Yang, G., Vanier, P., Varley, J., Lordi, V., and James, R. B. A Comparison of Point Defects in Cd1-xZnxTe1-ySey Crystals Grown by Bridgman and Traveling Heater Methods. United States: N. p., 2017. Web. doi:10.1063/1.4979012.
Gul, R., Roy, U. N., Camarda, G. S., Hossain, A., Yang, G., Vanier, P., Varley, J., Lordi, V., & James, R. B. A Comparison of Point Defects in Cd1-xZnxTe1-ySey Crystals Grown by Bridgman and Traveling Heater Methods. United States. doi:10.1063/1.4979012.
Gul, R., Roy, U. N., Camarda, G. S., Hossain, A., Yang, G., Vanier, P., Varley, J., Lordi, V., and James, R. B. Tue . "A Comparison of Point Defects in Cd1-xZnxTe1-ySey Crystals Grown by Bridgman and Traveling Heater Methods". United States. doi:10.1063/1.4979012. https://www.osti.gov/servlets/purl/1367976.
@article{osti_1367976,
title = {A Comparison of Point Defects in Cd1-xZnxTe1-ySey Crystals Grown by Bridgman and Traveling Heater Methods},
author = {Gul, R. and Roy, U. N. and Camarda, G. S. and Hossain, A. and Yang, G. and Vanier, P. and Varley, J. and Lordi, V. and James, R. B.},
abstractNote = {In this study, the properties of point defects in Cd1–xZnxTe1–ySey (CZTS) radiation detectors are characterized using deep-level transient spectroscopy and compared between materials grown using two different methods, the Bridgman method and the traveling heater method. The nature of the traps was analyzed in terms of their capture cross-sections and trap concentrations, as well as their effects on the measured charge-carrier trapping and de-trapping times, and then compared for the two growth techniques. The results revealed that Se addition to CdZnTe can reduce the VCd– concentration. In Travelling Heater Method (THM) and Bridgman Method (BM) grown CZTS detectors, besides a few similarities in the shallow and medium energy traps, there were major differences in the deep traps. It was observed that the excess-Te and lower growth-temperature conditions in THM-grown CZTS led to a complete compensation of VCd– and two additional traps (attributed to Tei– and TeCd++ appearing at around Ev + 0.26 eV and Ec – 0.78 eV, respectively). The 1.1-eV deep trap related to large Te secondary phases was a dominant trap in the BM-grown CZTS crystals. In addition to i-DLTS data, the effects of point defects induced due to different processing techniques on the detector's resistivity, spectral response to gammas, and μτ product were determined.},
doi = {10.1063/1.4979012},
journal = {Journal of Applied Physics},
number = ,
volume = 121,
place = {United States},
year = {Tue Mar 28 00:00:00 EDT 2017},
month = {Tue Mar 28 00:00:00 EDT 2017}
}

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  • In this paper, the properties of point defects in Cd1-xZnxTe1-ySey (CZTS) radiation detectors are characterized using deep-level transient spectroscopy and compared between materials grown using two different methods, the Bridgman method and the traveling heater method. The nature of the traps was analyzed in terms of their capture cross-sections and trap concentrations, as well as their effects on the measured charge-carrier trapping and de-trapping times, and then compared for the two growth techniques. The results revealed that Se addition to CdZnTe can reduce the VCd- concentration. In Travelling Heater Method (THM) and Bridgman Method (BM) grown CZTS detectors, besides amore » few similarities in the shallow and medium energy traps, there were major differences in the deep traps. It was observed that the excess-Te and lower growth-temperature conditions in THM-grown CZTS led to a complete compensation of VCd- and two additional traps (attributed to Tei- and TeCd++ appearing at around Ev + 0.26 eV and Ec - 0.78 eV, respectively). The 1.1-eV deep trap related to large Te secondary phases was a dominant trap in the BM-grown CZTS crystals. In addition to i-DLTS data, the effects of point defects induced due to different processing techniques on the detector's resistivity, spectral response to gammas, and μτ product were determined.« less
  • Narrow-gap semiconductors (Hg-,Cd-, and Pb-containing compounds and semimagnetic semiconductors among them) are now attracting investigators` attention. Their effectiveness in applications depends on crystal quality, which is determined by the ways of their production. accordingly, the study of the liquid-phase crystallization conditions is of great importance, as well as the study of features of the component distribution along the ingots, and on the effective coefficients of the component distribution during the crystal growth of the above materials. We grew single crystal of Cd{sub x}Hg{sub 1-x-y}Mn{sub y}Se(Te) solid solutions by the vertical Bridgman technique.
  • Single-crystal ingots of ZnSe/sub 1-x/Te/sub x/ (0< or =x< or =0.03), Zn/sub 1-x/ Cd/sub x/Se (0< or =x< or =0.15), and Zn/sub x/Cd/sub 1-x/S (0< or =x< or =0.35) with diameters up to 50 mm and height up to 20 mm were prepared from the vapor phase. Investigations were made of the cathodoluminescence emitted by these crystals and of the characteristics of the lasers made from them and subjected to longitudinal pumping with an electron beam. In contrast to the two other systems, single crystals of ZnSe/sub 1-x/ Te/sub x/ were unsuitable for semiconductor lasers emitting in the dark bluemore » range because deep levels appeared in the band gap at low Te concentrations.« less
  • We investigated cadmium telluride selenide (CdTeSe) crystals, newly grown by the Traveling Heater Method (THM), for the presence and abundance of point defects. Deep Level Transient spectroscopy (I-DLTS) was used to determine the energies of the traps, their capture cross sections, and densities. The bias across the detectors was varied from (1–30) V. Four types of point defects were identified, ranging from 10 meV to 0.35 eV. Two dominant traps at energies of 0.18 eV and 0.14 eV were studied in depth. Cd vacancies are found at lower concentrations than other point defects present in the material.