Positron annihilation spectroscopy was used to study defects created during ion implantation and annealing of Ge. Here, Ge and Si ions with energies of 600keV to 2MeV were implanted to fluences of 1012/cm2 to 4 x 1014/cm2. Ion channelling measurements of as-implanted samples revealed considerable lattice damage at a fluence of 1013/cm2, and a fluence of 1014/cm2 was enough to amorphize the samples. Positron experiments revealed that the average free volume in as-irradiated samples was of divacancy size. Larger vacancy clusters were formedduring re-growth of the damaged layers when the samples were annealed at 200 to 400C. Evolution of the vacancy-related defects upon annealing depended noticeably upon the fluence of ion implantation and, for the highest fluencies, also upon the ion species.

Evolution of Vacancy-Related Defects upon Annealing of Ion-Implanted Germanium. J.Slotte, M.Rummukainen, F.Tuomisto, V.P.Markevich, A.R.Peaker, C.Jeynes, R.M.Gwilliam: Physical Review B, 2008, 78[8], 085202 (5pp)