Samples were implanted with 5MeV ions at room temperature, and the microstructures were investigated by means of cross-sectional transmission electron microscopy. Buried amorphous layers were found in specimens which had been obtained by using ion doses of 1017 or 2 x 1017/cm2; with abrupt amorphous/crystalline interfaces. The damaged layers which were adjacent to the amorphous layers contained many dislocation loops, and the concentration increased in going towards the amorphous region. Micro-diffraction patterns and high-resolution images showed that this damaged region was defective crystalline material; thus suggesting that homogeneous amorphization occurred due to the accumulation of defects. The structures of the damaged regions were analyzed by comparing high-resolution electron microscopic images with those calculated on the basis of a previously proposed model for amorphization.

M.Ishimaru, S.Harada, T.Motooka: Journal of Applied Physics, 1997, 81[3], 1126-30