The electronic band structure of the β-phase, and the formation and properties of O vacancies, were analyzed on the basis of semi-empirical quantum-chemical calculations. The equilibrium geometries and formation energies of neutral and doubly-ionized vacancies were calculated. By using the calculated donor-level positions of the vacancies, the high-temperature n-type conductivity was explained. The vacancy concentration was obtained by fitting the experimentally determined resistivities and electron mobilities.

Role of Oxygen Vacancy Defect States in the n-Type Conduction of β-Ga2O3. Z.Hajnal, J.Miró, G.Kiss, F.Réti, P.Deák, R.C.Herndon, J.M.Kuperberg: Journal of Applied Physics, 1999, 86[7], 3792-6