Mono-energetic positron beams were used to study vacancies in ion-implanted and rare-earth-doped GaN. The defect species were identified and their concentrations were estimated from a comparison between the Doppler broadening spectra obtained through the experiments and those calculated using first-principles calculation (projector augmented-wave method). It was thus shown that positron annihilation was a useful tool for studying relationships between vacancy-type defects and the properties of group-III nitrides.

Point Defects in Group-III Nitride Semiconductors Studied by Positron Annihilation. A.Uedono, S.Ishibashi, T.Ohdaira, R.Suzuki: Journal of Crystal Growth, 2009, 311[10], 3075-9