Hybrid density functional studies of cadmium vacancy in CdTe

The intrinsic defect of cadmium vacancy (V Cd ) in cadmium telluride (CdTe) has been studied by first-principles calculations using potentials with both the screened hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE) approximation and the generalized gradient approximation of the Perdew—Burke—Ernzerhof form (PBE-GGA). Both results show that the T d structure of the V Cd defect for different charges is the most stable structure as compared with the distorted C 3 v structure with one hole localized at one of the four nearest Te atoms. This indicates that the John—Teller distortion ( C 3 v ) structure may be unstable in bulk CdTe crystal. The reason likely lies in the delocalized resonance nature of the t 2 state of the V Cd defect. Moreover, the formation energy obtained by the HSE method is about 0.6–0.8 eV larger than that obtained by the PBE method. The transition levels calculated by the PBE method and the HSE method are similar and well consistent with the experimental results.