The amorphization of Si(001) by 3 to 5keV Ar+-ion bombardment was investigated by using high-resolution Rutherford back-scattering spectroscopy/channelling with a depth resolution of about 0.6nm. Particular attention was paid to the effect of O atoms which were knocked-in from a native oxide layer at the surface. No essential difference was observed, in amorphization, between (001) wafers with and without a native oxide layer. This showed that no important role in the amorphization process was played by knocked-in O atoms. Amorphization was found to proceed from the surface, instead of from the projected range of implanted ions or the peak depth of ion-induced defects. The results were explained in terms of preferential defect clustering at surfaces.

Anomalous Surface Amorphization of Si(001) Induced by 3-5keV Ar+ Ion Bombardment. K.Nakajima, H.Toyofuku, K.Kimura: Japanese Journal of Applied Physics - 1, 2001, 40[4A], 2119-22