It was noted that the preparation of shallow dopant distributions, via solid-phase epitaxial growth following amorphization by low-energy self-ion implantation, introduced defects that could lead to unwanted dopant impurity diffusion. The use of a double implantation method, which involved both low- and high-energy self-ion implantation, removed most of the interstitials. Nevertheless, crystalline imperfections remained following annealing. Measurements of the defect profiles, using variable-energy positron spectroscopy, showed that there were divacancy-impurity complexes in the treated layer, and V6 or larger vacancy clusters near to the re-grown/crystalline interface.

Vacancy defects in solid-phase epitaxially grown layers of self-implanted Si J.Xu, E.G.Roth, O.W.Holland, A.P.Mills, R.Suzuki: Applied Physics Letters, 1999, 74[7], 997-9