Distribution Of Radiation Defects In Submicron Subsurface Crystal Layers

The degradation of the structure of a silicon surface irradiated with high-energy (6 MeV) electrons has been studied by x-ray asymptotic Bragg diffraction. The results of the investigation of the spatial distribution of radiation defects in subsurface layers with atomic scale resolution are presented. The thickness of the distorted layer on the Si-crystal surface is close to 6 nm. The interplanar distance in this layer was decreased, which means that the main radiation defects in the subsurface region are vacancylike. Previous oxidation of silicon has prevented the distortion on the real Si-surface. Interstitial atoms, which have been created under oxidation, have recombined with radiation defects. It has resulted in suppressing the subsurface distortions. The reasons for the observed effects are discussed.