Defect formation on (100) planes, due to 60keV Sn+ ion-implantation at 150 to 153K, was investigated by using cross-sectional transmission electron microscopy, scanning electron microscopy and EDX. An anomalous structure which consisted of many cells, and which resembled a honeycomb, was formed at surfaces which were implanted to 8 x 1018/m2. The diameters and depths of the cells were about 50nm and 220 to 350nm, respectively. The thickness of the walls which separated the cells was about 10nm. The upper part of the partitioning wall was amorphous and Ga-rich, while the lower part had a crystalline structure. A heavily-strained region, 50nm in thickness, which corresponded to the maximum depth of projected Sn ions was observed under the cells. This structure was explained in terms of the movement of implantation-induced point defects. It was assumed that hills and hollows were formed in the early stages of implantation. Point defects which were created on the hills did not contribute to the development of the defect structure because they were annihilated almost completely by the recombination of vacancies and interstitials, and by movement to the near-surface sink. In the hollows, on the other hand, vacancies remained which had escaped recombination and interstitial atoms (which were highly mobile at low temperatures) migrated far and aggregated under the hills. The hollows became deeper due to the movement of the remaining vacancies to the surface, and the hills developed into walls via the migration of interstitial atoms from the surrounding hollows.

Anomalous Defect Structure Formed on GaSb Surface by Low-Temperature Sn Ion-Implantation and its Formation Mechanism. N.Nitta, M.Taniwaki, T.Suzuki, Y.Hayashi, Y.Satoh, T.Yoshiie: Journal of the Japan Institute of Metals, 2000, 64[12], 1141-7