Electrically active defects introduced into Ge crystals co-doped with tin and phosphorus atoms by irradiation with 6MeV electrons were studied by means of transient capacitance techniques and ab initio density functional modelling. It was shown that Sn atoms were effective traps for vacancies (V) in the irradiated Ge:Sn+P crystals. The electronic structure of Sn-V was unravelled on the basis of hybrid states from a Sn atom and a divacancy. Unlike the case for Si, Sn-V in Ge was not a donor. A hole trap with 0.19eV activation energy for hole emission to the valence band was assigned to an acceptor level of the Sn-V complex. The Sn-V complex anneals out upon heat-treatments in the temperature range 50–100C. Its disappearance was accompanied by the formation of phosphorus-vacancy centers.

Tin-Vacancy Complex in Germanium. V.P.Markevich, A.R.Peaker, B.Hamilton, V.V.Litvinov, Y.M.Pokotilo, S.B.Lastovskii, J.Coutinho, A.Carvalho, M.J.Rayson, P.R.Briddon: Journal of Applied Physics, 2011, 109[8], 083705