Origin of improved luminescence efficiency after annealing of Ga(In)NAs materials grown by molecular beam epitaxy

Positron-annihilation measurements and nuclear reaction analysis (utilizing the 14 N(d, p) 15 N and 14 N(d, a) 12 C reactions) in conjunction with Rutherford backscattering spectrometry in the channeling geometry were used to study the defects in as-grown Ga(In)NAs materials grown by molecular beam epitaxy (MBE) using a radio-frequency (rf) plasma nitrogen source. Our data unambiguously show the existence of vacancy-type defects, which we attribute to Ga vacancies, and nitrogen interstitials in the as-grown Nitride-Arsenide epilayers. These point defects, we believe, are responsible for the low luminescence efficiency of as-grown Ga(In)NAs materials and the enhanced diffusion process during annealing.