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Lookup NU author(s): Dr Jose Coutinho,
Professor Patrick Briddon
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We present a comprehensive spin-density functional modeling study of the structural and electronic properties of donor-vacancy complexes (PV, AsV, SbV, and BiV) in Ge crystals. Special attention is paid to spurious results which are related to the choice of the boundary conditions (supercell-cluster approach), the resulting band-gap width, and the choice of the points to sample the Brillouin zone. The underestimated energy gap, resulting from the periodic conditions together with the local-density approximation to the exchange-correlation energy, leads to defect-related gap states that are strongly coupled to crystalline states within the center of the zone. This is shown to produce a strong effect even on relative energies. Our results indicate that in all E centers the donor atom occupies a nearly substitutional site, as opposed to the split-vacancy form adopted by the SnV complex in Si. The E centers can occur in four charge states, from positive to double negative, and produce occupancy levels at E(0 +)= Ev +0.1 eV, E(- 0)= Ev +0.3 eV, and E(= -)= Ec -0.3 eV. © 2006 The American Physical Society.
Author(s): Coutinho J, Oberg S, Torres VJB, Barroso M, Jones R, Briddon PR
Publication type: Article
Publication status: Published
Journal: Physical Review B
ISSN (print): 1098-0121
ISSN (electronic): 1550-235X
Publisher: American Physical Society
Notes: Article no. 235213
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