Electronic structure and Jahn–Teller instabilities in a single vacancy in Ge

• Published in: Journal of physics. Condensed matter Vol. 17; no. 48; pp. L521 - L527
• Main Authors: Coutinho, J, Jones, R, Torres, V J B, Barroso, M, Öberg, S, Briddon, P R
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.12.2005; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Elemental semiconductors; Exact sciences and technology; Impurity and defect levels; Physics; Scientific Computing; Teknisk-vetenskapliga beräkningar; Defect states; Electronic structure; Vacancies; Acceptor center; Electron affinity; Density functional method; Germanium; Instability; Modelling; Jahn-Teller effect
• ISSN: 0953-8984; 1361-648X; 1361-648X
• DOI: 10.1088/0953-8984/17/48/L02

Density functional modelling studies of the single vacancy in large Ge clusters are presented. We take a careful look at the origin of Jahn-Teller instabilities as a function of the vacancy net charge, resulting in a variety of structural relaxations. By comparing electron affinities of the vacancy with those from defects with well established gap states, we were able to estimate three acceptor states for the vacancy at E(-/0) = Ev+0.2eV, E(=/-) = Ec-0.5eV and &E({equiv }{/}{=})=E_{{c}}-0.3 in Ge is not a donor. We also show that these dissimilarities have fundamental consequences for the electronic/atomic picture of other centres, such as transition metals in germanium crystals.