Post-growth thermal annealing study of CdZnTe for developing room-temperature X-ray and gamma-ray detectors

Post-growth annealing is a potentially promising method of improving the properties of CZT for fabricating room-temperature X-ray and gamma-ray detectors. In this paper, we summarize some of our recent research on annealing detector-grade CZT crystals. Our results show that annealing in a Cd vapor effectively removes Te inclusions from CZT. The migration of Te inclusions was also observed for annealing in a temperature-gradient field. We recorded a loss of resistivity of the detector-grade CZT after annealing in a Cd vapor. The underlying mechanism of this loss was discussed, and solutions including two-step annealing (Cd annealing followed by Te annealing) and one-step annealing with Cd and Zn pressure control were proposed to maintain high resistivity. ► Annealing in a Cd vapor effectively removes Te inclusions from CZT. ► Migration of Te inclusions was observed in the temperature-gradient annealing. ► We recorded a loss of resistivity of CZT after annealing in a Cd vapor. ► We discussed the underlying mechanism and the related solutions of this loss.