Radiation damage on CdZnTe:In crystals under high dose 60Co γ-rays

Abstract

A radiation damage mechanism of CdZnTe:In crystals under 60Co γ-rays with a cumulated radiation dose of ~2.4 kGy was proposed and discussed. Thermally stimulated current (TSC) measurements were carried out to characterize the γ-ray induced radiation damage. Four main trap levels (T1–T4) originating at four main microscopic defective states were identified. We attributed traps T1 and T2 to shallow donor impurities and shallow acceptor A-centers, respectively. Trap T3 was ascribed to dislocations and a great increase in defect concentration occurred after radiation. Trap T4 originated at deep acceptor Cd vacancies and vacancy related defect complexes and a considerable increase in the trap density, after radiation, lead to the conversion of conduction type from n to p in the Hall measurements and a Fermi level shift in the temperature-dependent resistivity analyses. Radiation induced electrically active defects contributed to the variation of the electrical compensation conditions and the worsening of the charge transport properties, which were consequently reflected by a significant deterioration in CZT detector performance.