Study on the effects of indentation-induced dislocations on the detector performance of CdZnTe crystals

The effects of indentation-induced dislocations on spectroscopic performances of CdZnTe detectors and on the deep-level defects of CdZnTe crystals are studied. The mobility-lifetime product (μτ) for electrons of the as-grown sample is determined to be 1.2 × 10^-3 cm²/V by the γ-ray energy spectral measurement. However, the value reduced to 4.5 × 10^-4 cm²/V after the dislocation is artificially increased by indentation. Meanwhile, the energy resolution is deteriorated from 7.45% to 28.15%. The ion beam induced charge (IBIC) measurements showed quite low carrier collection efficiency of electrons in the dislocation enriched areas. Moreover, the carrier recombination rate at dislocations was reduced with the increase in applied voltage. The thermally stimulated current measurements showed that the concentration of dislocation related defect levels observed at 0.107 eV and 0.159 eV increased almost twice after indentation. These defect levels could probably result in the carrier loss during the γ-ray energy spectrum and IBIC measurements.