Positron annihilation spectroscopy, supported by ab initio theory, was used to verify the decoration of Ga vacancies in GaN by O and H. The results indicated that the Doppler broadening measurement of electron momentum distribution was sensitive enough to distinguish even between N and O atoms neighboring the Ga vacancy. Isolated VGa in electron-irradiated GaN and VGa-ON complexes in highly O-doped high-purity GaN were identified. Evidence of H decoration of Ga vacancies was obtained in epitaxial GaN grown by metalorganic chemical-vapor deposition.

Direct Evidence of Impurity Decoration of Ga Vacancies in GaN from Positron Annihilation Spectroscopy. S.Hautakangas, I.Makkonen, V.Ranki, M.J.Puska, K.Saarinen, X.Xu, D.C.Look: Physical Review B, 2006, 73[19], 193301 (4pp)