Using hybrid functional, an investigation was made of the role played by oxygen vacancies and various impurities in the electrical and optical properties of the transparent conducting oxide β-Ga2O3. It was found that oxygen vacancies were deep donors, and thus could not explain unintentional n-type conductivity. Instead, the conductivity was attributed to common background impurities such as silicon and hydrogen. Monatomic hydrogen had a low formation energy and acted as a shallow donor in both interstitial and substitutional configurations. Other dopants, where substitutional forms of Si, Ge, Sn, F and Cl were shown to behave as shallow donors, were also explored.

Oxygen Vacancies and Donor Impurities in β-Ga2O3. J.B.Varley, J.R.Weber, A.Janotti, C.G.Van de Walle: Applied Physics Letters, 2010, 97[14], 142106