A density functional modelling study was made of Zn, Cu and Ni impurities in hydrogen-terminated germanium clusters. Their electronic structure was investigated in detail, especially their Jahn–Teller instabilities and electrical levels. Interstitial and substitutional defects were considered and the latter were found to be the most stable defect form for nearly all Fermi level positions. Relative formation energies were estimated semi-empirically with the help of the measured formation energy of the single Ge vacancy. It was found that, while Zn was a double shallow acceptor, Cu and Ni were deep acceptors with levels close to the available experimental data. Donor levels were only found for interstitial Cu and Zn.

Electronic Structure of Zn, Cu and Ni Impurities in Germanium. E.L.Silva, J.Coutinho, A.Carvalho, V.J.B.Torres, M.Barroso, R.Jones, P.R.Briddon: Journal of Physics - Condensed Matter, 2011, 23[6], 065802