Elucidating the role of Zn doping in the defect properties and electronic structure of CdZnTe via first-principles calculation

High-resistivity CdZnTe (CZT) is an important material for room-temperature radiation detectors. In this study, we systematically investigate the defect thermodynamics and electronic structures, and charge-transfer behavior of intrinsic and Zn-doped CdTe using first-principles calculations. The results demonstrate that in intrinsic CdTe, the cadmium vacancy (V Cd ) serves as a dominant acceptor, resulting in p-type conductivity. Zn exhibits a strong preference for occupying the Cd sublattice (Zn Cd ), and can be stably incorporated into the CdTe lattice at concentrations as high as 10 21 cm -3 . The interstitial Zn (Zn i ) acts as a donor, with a transition level located 0.13 eV below the conduction band minimum (CBM), thereby compensating the V Cd acceptor. The projected density of states (PDOS) shows that the defect state of Zn i near the CBM is predominantly derived from Zn 4s states. Differential charge density and Bader charge analyses further reveal that ZnCd induces only weak and nearly uniform local charge redistribution, whereas other intrinsic and Zn-related defects produce much stronger local perturbations. This work provides a quantitative atomistic understanding of the semi-insulating mechanism in CZT and offers theoretical insights for optimizing the growth of high-performance detector crystals.