Weakly n-type doped germanium was irradiated with protons up to a fluence of 3 x 1014/cm2 at 35 and 100K in a unique experimental setup. Positron annihilation measurements showed a defect lifetime component of 272ps at 35K in in situ positron lifetime measurements after irradiation at 100K. This was identified as the positron lifetime in a germanium monovacancy. Annealing at 35 to 300K revealed two annealing stages. The first, at 100K, was tentatively associated with the annealing of the Frenkel pair, the second at 200K with the annealing of the monovacancy. Above 200K, it was observed that mobile neutral monovacancies form divacancies, with a positron lifetime of 315ps.

Direct Observations of the Vacancy and its Annealing in Germanium. J.Slotte, S.Kilpeläinen, F.Tuomisto, J.Räisänen, A.Nylandsted Larsen: Physical Review B, 2011, 83[23], 235212