Evolution of vacancy-related defects upon annealing of ion-implanted germanium

Positron annihilation spectroscopy was used to study defects created during the ion implantation and annealing of Ge. Ge and Si ions with energies from 600 keV to 2 MeV were implanted at fluences between 11012 cm−2 and 41014 cm−2. Ion channeling measurements on as-implanted samples show considerable lattice damage at a fluence of 11013 cm−2 and a fluence of 11014 cm−2 was enough to amorphize the samples. Positron experiments reveal that the average free volume in as-irradiated samples is of divacancy size. Larger vacancy clusters are formed during regrowth of the damaged layers when the samples are annealed in the temperature range 200?400 C. Evolution of the vacancy-related defects upon annealing depends noticeably on fluence of ion implantation and for the highest fluences also on ion species.