Effect of Intrinsic Oxygen Vacancy on the Electronic Structure of γ-Bi2O3: First-Principles Calculations

Oxygen vacancy is an intrinsic defect in metal oxides, which has a great effect on the electronic structures and physical properties. The influence of the intrinsic oxygen vacancy on the crystal and electronic structures of y-Bi2O3 has been studied. Results show that the vacancy is preferred to occupy the tetrahedral O3 (8c) site. It makes gamma-Bi2O3 lose I23 symmetry and leads to flat band structure. The quadrivalence post-transition ions M4+ (M = S, Se, or Te) doping can keep I23 symmetry by forming MO4 units, and can result in dispersive valence bands and energy levels in the band gaps. These characters are beneficial for the mobility of the photogenerated carriers.