title: Electronic structure of Zn, Cu and Ni impurities in germanium.
abstract: We present a density functional modelling study of Zn, Cu and Ni impurities in hydrogen-terminated germanium clusters. Their electronic structure is 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 are estimated semi-empirically with the help of the measured formation energy of the single Ge vacancy. We find that while Zn is a double shallow acceptor, Cu and Ni are deep acceptors with levels close to the available experimental data. Donor levels were only found for interstitial Cu and Zn.
authors.affiliation: Department of Physics and I3N, University of Aveiro, Campus Santiago, 3810-193 Aveiro, Portugal. elora@ua.pt
authors.forename: E L
authors.initials: EL
authors.lastname: Silva
authors.forename: J
authors.initials: J
authors.lastname: Coutinho
authors.forename: A
authors.initials: A
authors.lastname: Carvalho
authors.forename: V J B
authors.initials: VJ
authors.lastname: Torres
authors.forename: M
authors.initials: M
authors.lastname: Barroso
authors.forename: R
authors.initials: R
authors.lastname: Jones
authors.forename: P R
authors.initials: PR
authors.lastname: Briddon