Oxygen vacancies in α-(Al x Ga1−x )2O3 alloys: a first-principles study

Abstract α -(Al x Ga 1− x ) 2 O 3 alloys have attracted increasing interest as semiconductors with tunable wide band gaps. We report a systematic analysis of O vacancies in α -Al 2 O 3 , α -Ga 2 O 3 , and α -(Al x Ga 1− x ) 2 O 3 alloys using first-principles calculations. The formation energies and electronic levels of the O vacancies are sensitive to not only the nearest-neighbor Al/Ga ratio but also the atomic relaxation around the vacancies. Consequently, the vacancy formation energies vary by up to ∼2 eV, reflecting diverse local atomic environments in the alloys. These results provide insight into further understanding and controlling the properties of α -(Al x Ga 1− x ) 2 O 3 alloys.