Effect of Intrinsic Oxygen Vacancy on the Electronic Structure of γ-Bi 2 O 3 : 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 γ-Bi 2 O 3 has been studied. Results show that the vacancy is preferred to occupy the tetrahedral O3 (8c) site. It makes γ-Bi 2 O 3 lose I 23 symmetry and leads to flat band structure. The quadrivalence post-transition ions M 4+ (M = S, Se, or Te) doping can keep I 23 symmetry by forming MO 4 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.