Split and unrelaxed Ga vacancies in β-Ga₂O₃

So-called split Ga vacancies, where a next-nearest-neighbor Ga atom relaxes strongly creating a structure with two "half-Ga vacancies" are the main defect observed with positron annihilation in almost all as-grown β-Ga2O3, irrespective of doping or conduction type. Unrelaxed Ga vacancies are observed in some samples subjected to high-energy particle irradiation. It also appears to n-type doping with Si promotes the formation of unrelaxed Ga vacancies. In spite of the high concentrations of the Ga vacancy related defects in the as-grown materials, the electrical compensation appears not to be directly affected by the vacancies.