The action of Ar plasma-induced defects in deactivating Si donors was studied. Photo-reflectance spectroscopy, combined with step-wise wet etching, was used to depth-profile defects and to determine the concentrations and profiles of defects in the sub-surface layer. It was found that the point defects which were responsible for deactivation underwent electronically enhanced diffusion in the presence of photo-excited carriers. This demonstrated that ultra-violet light from the plasma helped to cause the deep penetration of defects to far beyond the stopping range of ions. It was also found that the generation of these point defects was enhanced by photo-excited carriers, and that diffusing point defects were trapped, by the background defects or impurities, to form immobile complexes. A model was proposed in which self-interstitials were the defects which were most probably responsible for deactivation.

H.Nakanishi, K.Wada, W.Walukiewicz: Journal of Applied Physics, 1995, 78[8], 5103-8