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

Abstract

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 1 x 10(12) cm(-2) and 4 x 10(14) cm(-2). Ion channeling measurements on as-implanted samples show considerable lattice damage at a fluence of 1 x 10(13) cm(-2) and a fluence of 1 x 10(14) 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 degrees 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.

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