The migration of B in ion-implanted and annealed monocrystalline or amorphous material was compared in order to determine the effect of amorphization upon the initial transient B motion in single crystals. The B was implanted at 20keV to doses of 1015 or 3 x 1015/cm2. The material was either pre-amorphized or post-amorphized, to a depth of 320nm, by implanting Si ions at 3 different energies. The B profile always lay within the amorphized depth. The samples were furnace-annealed or rapidly thermally annealed at 900 to 1100C, and were sometimes pre-annealed at 600C. An initial rapid diffusion transient in the tail region of the B profile was observed in crystalline samples but was absent from amorphous samples. When significant motion occurred, the profiles of the amorphized samples could be fitted by a model which did not take account of transient effects. It was suggested that excess interstitials caused transient diffusion in crystalline samples. The source of the interstitials was attributed to the thermal dissolution of small clusters which were formed by the implantation process. Since there was no enhanced diffusion in the amorphous regions, it was proposed that either interstitial clusters were not produced or that they did not survive the re-growth process in that region. It was further concluded that interstitials which were generated by damage beyond the amorphous/crystalline boundary were prevented from entering the re-grown region by dislocation loops which formed at the boundary. These acted as sinks which intercepted interstitials that were diffusing towards the surface.

T.O.Sedgwick, A.E.Michel, V.R.Deline, S.A.Cohen, J.B.Lasky: Journal of Applied Physics, 1988, 63[5], 1452-63