It was pointed out that the vacancy-O complex was the predominant grown-in non-radiative center in undoped and B-doped layers which were grown by means of molecular beam epitaxy at low temperatures. Such defects were introduced due to low surface adatom mobility during low-temperature growth, and also by ion bombardment during potential-enhanced doping. When the deep-level defects were abundant, residual shallow P donors also took part in efficient non-radiative recombination.

W.M.Chen, I.A.Buyanova, W.X.Ni, G.V.Hansson, B.Monemar: Physical Review Letters, 1996, 77[20], 4214-7