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 N-14(d,p)N-15 and N-14(d,He)C-12 reactions] in conjunction with Ruther ford backscattering spectrometry in the channeling geometry were used to st udy the defects in as-grown Ga(In)NAs materials grown by molecular beam epi taxy using a radio-frequency plasma nitrogen source. Our data unambiguously show the existence of vacancy-type defects, which we attribute to Ga vacan cies, 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 proc ess during annealing. (C) 2001 American Institute of Physics.