Recent advances in cadmium zinc telluride selenide gamma-ray detectors

CZT has proven to be instrumental for various applications to detect and image X- and gamma-rays at room temperature. The new quaternary compound cadmium zinc telluride selenide (CZTS) has emerged as a next-generation detector material and has been found to mitigate most of the long-standing material issues pertaining to defects in present-day CZT. However, the content of detrimental extrinsic impurities, such as Cr, Fe, Ni, and Cu remaining in the crystals, is very high as compared to commercial-grade, high quality CZT. Evidence suggests that these impurities are incorporated from the relatively impure, commercially available CdSe (5N) precursor. To address the issue, SRNL grew CZTS from higher purity CdSe (6N) source material. The material and detector quality were observed to be considerably improved for the higher purity CdSe source material. These recent advances on high-purity CZTS growth and detector response will be discussed. Surface passivation is another vital step for producing high-quality detectors. The effects of surface passivation of CZTS gamma-ray detectors will also be presented.