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Journal of Synthetic Crystals ›› 2025, Vol. 54 ›› Issue (6): 960-969.DOI: 10.16553/j.cnki.issn1000-985x.2024.0321

• Research Articles • Previous Articles     Next Articles

Fine Modulation of Internal Point Defects in CZT Crystals Grown by the Traveling Heater Method

YU Chao1(), ZHANG Bo1, WANG Qiqi2, WANG Xi2, HU Yunan2, LIANG Xiaoyan1(), ZHANG Jijun1, MIN Jiahua1, WANG Linjun1   

  1. 1.School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China
    2.Beijing Hangxing Machinery Manufacturing Co.,Ltd.,China Aerospace Science and Industry Corporation,Beijing 100013,China
  • Received:2024-12-23 Online:2025-06-20 Published:2025-06-23

Abstract: There are a large number of intrinsic point defects and related composite defects in the growing CdZnTe (CZT) crystal. It is crucial to obtain information on these point defects and their effects. This article designs high-temperature Cd atmosphere annealing of CZT crystals, and controls the degree of atomic diffusion through annealing time to regulate the distribution of sample point defects. For Te-rich CZT crystals grown by the traveling heater method (THM), multiple advanced techniques, including photo-induced current transient spectroscopy (PICTS), low-temperature photoluminescence (PL), I-V tests and alpha-induced transient charge analysis, were utilized to investigate the relationship between the point defect distribution and various optoelectronic properties such as resistivity, carrier mobility and charge collection efficiency. The point defect measurement results indicate that TeCd defects dominate in the as-grown sample, with a concentration of 4.47×1013 cm-3 and a capture cross-section of 9.34×10-16 cm2. After 24 h of Cd annealing, the defect distribution changes, and Cdi defects gradually become dominant, reaching a concentration of 4.49×1013 cm-3 with a reduced capture cross-section of 5.82×10-19 cm2. The electrical performance test results indicate that the carrier mobility and charge collection efficiency are related to the total concentration of CZT point defects, the internal electric field is determined by the TeCd with the largest capture cross-section. Samples that were annealed under Cd vapor for 6 h are characterized by high charge collection efficiency, high mobility (697 cm2·V-1·s-1) and uniform internal electric field distribution, though the resistivity is relatively low. During the diffusion process, the positions of VCd and TeCd are preferentially occupied by Cd atoms, leading to an exponential decrease in the concentration of A-centers and TeCd, which is regarded as the main cause for the reduction in resistivity.

Key words: CdZnTe; point defect; ambient annealing; THM; photoelectric characteristic; resistivity

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