Grown-in non-radiative defects in Si epilayers and SiGe/Si heterostructures, that had been prepared by molecular beam epitaxy, were studied by using the optically detected magnetic resonance technique. Several non-radiative defects were detected that were introduced by ion bombardment during growth or by a low surface adatom mobility during low-temperature growth. The introduction of these defects depended critically upon doping, growth temperature, and substrate bias. The mechanisms which were responsible for the formation of these non-radiative defects were explained in terms of bombardment with accelerated positive ions, and a low surface adatom mobility during low-temperature growth. It was shown that the predominant non-radiative defects, in undoped Si that had been prepared at temperatures below 500C, were probably related to vacancy complexes. These defects provided efficient channels for carrier recombination and largely controlled the carrier lifetime.

W.M.Chen, I.A.Buyanova, A.Henry, W.X.Ni, G.V.Hansson, B.Monemar: Applied Physics Letters, 1996, 68[9], 1256-8