An analysis of point defects in ZnTe using density functional theory calculations

Abstract

Zinc Telluride, a wide bandgap semiconductor, is a promising candidate material for a number of optoelectronic applications. It is important to accurately characterize the effects of point defects on this material and how they may impact its performance. In this work, GGA + U density functional theory calculations were employed to study point defects in ZnTe. Vacancies, interstitials, and anti-site defects were all considered and Jahn-Teller distortions were reported. For each point defect five charge states were considered ranging from + 2 to − 2. It was found that VZn−2, Zni2+ and TeZn2+ were the most stable defects. The zinc vacancy acted as a double acceptor introducing shallow acceptor levels 0.05 eV away from the valence band maximum mediating p-type conduction. The equilibrium concentration of holes was found to be about four orders of magnitude bigger than the free electron concentration under Te-rich conditions. An analysis of the kinetics of the stable defects showed that VZn0 was the fastest diffusing defect with a migration energy of 0.97 eV. This study suggests that zinc vacancies and interstitials are the most relevant defects to account for in radiation damage studies on ZnTe and that devising strategies to limit the formation of such defects may be useful for extending the operational lifetime of the semiconductor device. This work also provides useful input parameters for higher scale defect evolution models to enable improved prediction of radiation damage which may ultimately inform the design for appropriate extenuation measures.