Two-step annealing to remove te secondary-phase defects in CdZnTe while preserving the high electrical resistivity

Kihyun Kim, Seokjin Hwang, Hwangseung Yu, Yoonseok Choi, Yongsu Yoon, Aleksey E. Bolotnikov, Ralph B. James

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The presence of Te secondary-phase defects (i.e., Te inclusions and Te precipitates) is a major factor limiting the performance of CdZnTe (CZT) X-ray and gamma-ray radiation detectors. We find that Te secondary-phase defects in CZT crystals can be removed through postgrowth two-step annealing without creating new trapping centers (i.e., prismatic punching defects). Two-step annealing (with the first under a Cd pressure and the second one under a Te pressure) was demonstrated to be effective in removing the Te secondary-phase defects, while preserving the electrical resistivity of the CZT detector. The first step involves annealing of semi-insulating CZT under a Cd overpressure at 700 °C/600 °C (CZT/Cd) for 24 h, which completely eliminated the Te-rich secondary-phase defects (Te inclusions). However, it resulted in a lower resistivity of the samples (down to 2 × 104-6},Ω · cm ). A subsequent annealing step involves processing CZT under a Te ambient condition at 540 °C/380 °C (CZT/Te) for 120 h, which restored the crystal's resistivity to 6.4 × 1010, Ω · cm without creating new Te secondary-phase defects. However, Te inclusions reappeared in the case of unnecessarily long Te ambient annealing. Pulse-height spectra taken with the two-step annealed CZT detectors showed an improved detector performance due to a reduced concentration and the size of Te secondary-phase defects.

Original languageEnglish
Article number8412222
Pages (from-to)2333-2337
Number of pages5
JournalIEEE Transactions on Nuclear Science
Volume65
Issue number8
DOIs
Publication statusPublished - Aug 2018

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preserving
Annealing
Defects
electrical resistivity
annealing
defects
inclusions
Detectors
detectors
Radiation detectors
Crystals
Punching
overpressure
radiation detectors
pulse amplitude
Gamma rays
crystals
Precipitates
precipitates
trapping

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Electrical and Electronic Engineering

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Two-step annealing to remove te secondary-phase defects in CdZnTe while preserving the high electrical resistivity. / Kim, Kihyun; Hwang, Seokjin; Yu, Hwangseung; Choi, Yoonseok; Yoon, Yongsu; Bolotnikov, Aleksey E.; James, Ralph B.

In: IEEE Transactions on Nuclear Science, Vol. 65, No. 8, 8412222, 08.2018, p. 2333-2337.

Research output: Contribution to journalArticle

Kim, Kihyun ; Hwang, Seokjin ; Yu, Hwangseung ; Choi, Yoonseok ; Yoon, Yongsu ; Bolotnikov, Aleksey E. ; James, Ralph B. / Two-step annealing to remove te secondary-phase defects in CdZnTe while preserving the high electrical resistivity. In: IEEE Transactions on Nuclear Science. 2018 ; Vol. 65, No. 8. pp. 2333-2337.
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