The migration of impurity atoms in solid-phase epitaxially grown layers was studied by means of back-scattering spectrometry. The samples were amorphized by As implantation into [100]- or [111]-oriented samples. The amorphized regions were then recrystallized by furnace annealing. Asymmetrically enhanced diffusion was observed in the case of [111]-type samples. A striking result was that, in the case of [111]-type samples, there was extensive smearing of the profiles while, in the case of [100]-type samples, this was hardly detectable. It was recalled that the re-growth features of [100]-type and [111]-type amorphized Si were different. In essential agreement with previous observations, it was found here (using cross-sectional electron microscopy) that the re-grown layer on [111]-type material was characterized by extensive multiple twinning. A 2-step annealing treatment usually led to a superior crystalline perfection, as confirmed by the cross-sectional transmission electron microscopy of samples which had first been annealed at 650C, and then at 1050C. Overall, the extent of diffusion was related to defects.

R.Turan, T.G.Finstad: Philosophical Magazine A, 1991, 63[3], 519-25