VARIATION OF END-OF-RANGE DENSITY WITH ION-BEAM ENERGY AND THE PREDICTIONS OF THE EXCESS INTERSTITIALS MODEL

The reduction of EOR (end-of-range) defect density seen after annealin g for thinner amorphous layers created by ion implantation can be hard ly explained by the motion of dislocation loops toward the surface. In fact, the thickness of the amorphous layer is the result of the reduc tion of the ion beam energy. The observed behaviour can be simply expl ained through collisional arguments, i.e., when the beam energy is low ered, the number of self-interstitials left beneath the c/a interface which survive total recombination with the vacancies and will cluster to form EOR decreases. There is a minimum threshold under which the su persaturation of interstitials is too low to promote clustering on (11 1) planes, i.e., formation of EOR defects.