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

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.