The redistribution of Be implants during post-implantation annealing was studied in order to evaluate the effect of implantation damage upon the diffusion process. The Be implants exhibited only uniform concentration-dependent diffusion, unlike the rapid up-hill diffusion which was observed in the peak of Mg implants. This difference was explained by invoking a substitutional-interstitial diffusion mechanism and by performing computer simulations of damage-generated point defects. In the up-hill diffusion region, the dopants diffused from areas of excess interstitial concentration towards areas of excess vacancy concentration. A critical point defect concentration was necessary in order to initiate up-hill diffusion. This behavior could be induced, in the case of Be implants, by co-implanting with a heavier element such as Ar.

H.G.Robinson, M.D.Deal, D.A.Stevenson: Applied Physics Letters, 1990, 56[6], 554-6