Electrical Compensation And Cation Vacancies In Al Rich Si-Doped Algan

We report positron annihilation results on vacancy defects in Si-doped Al0.90Ga0.10N alloys grown by metalorganic vapor phase epitaxy. By combining room temperature and temperature-dependent Doppler broadening measurements, we identify negatively charged in-grown cation vacancies in the concentration range from below1 x1016 cm(-3) to2 x1018 cm(-3) in samples with a high C content, strongly correlated with the Si doping level in the samples ranging from1 x1017 cm(-3) to7 x1018 cm(-3). On the other hand, we find predominantly neutral cation vacancies with concentrations above5 x1018 cm(-3) in samples with a low C content. The cation vacancies are important as compensating centers only in material with a high C content at high Si doping levels.