The impact of complex defect pairs on SnO2 surface: Insight from first-principles calculations

SnO2 is a significant wide bandgap semiconductor, and the defect characteristics of its (110) surface substantially affect the performance of electronic devices. In this study, first-principles calculations were employed to analyze the impacts of six intrinsic point defects and 15 types of complex defect pairs on the material properties. The assessment was based on charged defect formation energy, transition energy levels, effective mass, and optical properties. The findings indicated that V-O, Sn-i, and Sn-O are deep-level donor defects, while V-Sn and O-i are deep-level acceptor defects. All complex defect pairs are also deep-level defects, and their formation is closely related to the growth conditions. Among the defect pairs, some are donor-like defects, some are acceptor-like defects, and some are amphoteric defects. The introduction of these defects leads to an increased effective mass on the SnO2 surface, restricting electron movement near local electronic states and subsequently affecting carrier transport efficiency. In addition, the increased energy loss resulted from defects is detrimental to the photoelectric conversion efficiency. This theoretical study provides foundation for deeper understanding of the nature of defective SnO2 (110) surface and material performance, aiding the optimization of material properties for practical applications.