The effect of lattice defects, produced by Si ion implantation, upon dopant diffusivity was investigated after annealing specimens at temperatures of between 700 and 900C. The

nature and depth of residual implantation defects in undoped samples was determined by analysing the rocking curves which were obtained by using triple-crystal X-ray diffraction and transmission electron microscopy. As well as interstitial dislocation loops and clusters lying below the original amorphous/crystal interface, epitaxial re-growth of the amorphized Si left a vacancy-rich surface layer and a deeper region which was enriched in interstitials. These regions corresponded to those for which Monte Carlo simulations of defect production predicted an excess of point defects. According to whether the dopant was associated with vacancy or interstitial clusters, different anomalous diffusion behaviors were observed. In the deep region where an excess of interstitials was present, B underwent markedly enhanced diffusion. On the other hand, retarded diffusion of B was observed in the surface layer. This was consistent with the differing contributions which vacancies and interstitials made to the diffusion mechanisms of the dopants.

M.Servidori, R.Angelucci, F.Cembali, P.Negrini, S.Solmi, P.Zaumseil, U.Winter: Journal of Applied Physics, 1987, 61[5], 1834-40