In Situ Study of Implantation-Induced Silican Amorphisation

The formation and evolution of radiation damage due to room temperature and 100K Bi ion implantation in Si at 50 keV and 200 keV was studied during implantation and annealing via in situ transmission electron microscopy (TEM) using the newly developed facility at Orsay. Individual cascades produce inhomogeneous visible tracks along the incident ion beam direction. Highly strained defect clusters are produced along these tracks, corresponding to regions in which the individual displacement cascade has deposited the highest energy densities However they cannot account alone for the formation of the amorphised Si layer observed at higher doses. The overall amorphisation is mainly due to the overlap of large, weakly contrasted zones which appear outside the cascade core. In contrast to previous work, we conclude that the amorphisation mechanism for heavy ion implantation in Si is basically similar to its counter part for lighter ions.