Electronic properties of traps induced by gamma-irradiation in CdTe and CdZnTe detectors

The knowledge of a detector response to different types of radiation source s is becoming a key issue for its employment in many medical, space and sci entific applications. Nevertheless, a clear understanding of the effects of irradiation on the material properties is still a long way ahead and, ther efore, we have started a thorough investigation of room temperature CdTe an d CdZnTe detectors exposed to gamma-ray irradiation. As-grown detectors hav e been exposed to increasing gamma-ray doses, up to the virtual death of th e detector, which occurs at a dose of 30kGy. The modifications in the detec tor performance have been investigated by dark-current measurements and qua ntitative spectroscopic analyses at low and medium energies. The deep level s present in the material have been identified by means of Photo-induced Cu rrent Transient Spectroscopy (PICTS) analyses. The evolution of the trap pa rameters with increasing irradiation dose has been monitored and a comparis on of the results obtained from CdTe and CdZnTe detectors allows to achieve a better insight into the modifications of the material properties and per formances after gamma-ray exposure. (C) 2000 Elsevier Science B.V. All righ ts reserved.