Positron annihilation spectroscopy was used to study GaAsN/GaAs epilayers. The GaAsN layers were found to contain Ga vacancies in defect complexes. The density of the vacancy complexes increased rapidly, up to the order of 1018/cm3, with increasing N content and decreased after annealing at 700C. An anticorrelation of the vacancy concentration and the integrated photoluminescence intensity suggested that the Ga vacancy complexes acted as non-radiative recombination centers.
Observation of Defect Complexes Containing Ga Vacancies in GaAsN. J.Toivonen, T.Hakkarainen, M.Sopanen, H.Lipsanen, J.Oila, K.Saarinen: Applied Physics Letters, 2003, 82, 40-2