The effect of low energy high-dose X-ray irradiation on the performance of CdZnTe detector

The paper investigated the irradiation damage of CZT detectors caused by high flux an X-ray from X-ray tube operated at a tube voltage of 140 kV and an accumulated dose of 130 kGy. Deep-level transient spectroscopy (i-DLTS) was employed to characterize the defects. Four types of irradiation-induced defects were identified, corresponding to the energy levels at Ec-0.1eV, Ev+0.17eV, Ev+0.27eV and Ec-0.55eV, which are associated with the point defects, In_Cd^+/0, V_Cd ^-/0, V_Cd ^2−/− and Te_Cd ^2+/+ respectively. After the irradiation, the concentration of V_Cd ^-/0 changed from 5.63 × 10¹² cm⁻³ to 3.30 × 10¹³ cm⁻³ and V_Cd ^2−/− increased from 1.13 × 10¹² cm⁻³ to 1.88 × 10¹³ cm⁻³. The resistivity of all samples showed an upward trend after the irradiation, with the most significant change observed in sample 1, where it doubled from 1.09 × 10¹¹ Ω cm to 1.94 × 10¹¹ Ω cm. However, the energy resolution for the spectrum peak of ²⁴¹Am (59.5 keV) decreased from 6.2% to 10.7% and the signal noise to ratio decreased from 42.24 to 27.33 when irradiated from anode. The counting performance of the photon counting module decreased by approximately 1.81% after irradiation on the cathode side.