Plasma-induced defects in n-type material were studied by using a mono-energetic positron beam. The depth distribution of the point defects was deduced from Doppler broadening profiles of the annihilation radiation as a function of the incident positron energy. From these measurements, it was found that the damaged layer that was produced by Ar plasma irradiation extended far beyond the stopping range of Ar ions. The dominant defects were of interstitial type, as deduced from the S-parameter. The results were in good agreement with those which were obtained by means of photo-reflectance spectroscopy. It was concluded that positrons provided a sensitive non-destructive probe for point defects that were introduced by dry etching.

A.Uedono, L.Wei, T.Kawano, S.Tanigawa, K.Wada, H.Nakanishi: Journal de Physique IV, 1995, 5[C1], 87-90