Vacancy defects in Ga2O3: First-principles calculations of electronic structure

First-principles density functional theory (DFT) is employed to study the electronic structure of oxygen and gallium vacancies in monoclinic bulk β-Ga₂ O₃ crystals. Hybrid exchange– correlation functional B3LYP within the density functional theory and supercell approach were successfully used to simulate isolated point defects in β-Ga₂ O₃. Based on the results of our calcu-lations, we predict that an oxygen vacancy in β-Ga₂ O₃ is a deep donor defect which cannot be an effective source of electrons and, thus, is not responsible for n-type conductivity in β-Ga₂ O₃. On the other hand, all types of charge states of gallium vacancies are sufficiently deep acceptors with transition levels more than 1.5 eV above the valence band of the crystal. Due to high formation energy of above 10 eV, they cannot be considered as a source of p-type conductivity in β-Ga₂ O₃.