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Supercell and cluster density functional calculations of the thermal stability of the divacancy in germanium

Lookup NU author(s): Professor Patrick Briddon

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Abstract

Large vacancy clusters, or voids, formed during crystal growth have been reported in Ge. The divacancy is a precursor to such clusters, and is believed to be stable up to 150 or 180°C. It is also believed to form in Ge irradiated at room temperature where single vacancies are mobile. Density functional theory (DFT) cluster calculations have been performed to calculate the energy barriers for migration and dissociation of the divacancy. We find that the binding energy in the neutral charge state is ∼1.5 eV and increases for negatively charged states. The migration energies were found to vary from 1.0 to 1.3 eV from the singly positive to the doubly negative charge states. These results line up well with an estimate of a migration barrier of 1.0 eV for the divacancy from experimental data. Therefore, we conclude that the divacancy in germanium will anneal by migration to trapping centers. © 2007 The American Physical Society.

Publication metadata

Author(s): Janke C, Jones R, Oberg S, Briddon PR

Publication type: Article

Publication status: Published

Journal: Physical Review B - Condensed Matter and Materials Physics

Year: 2007

Volume: 75

Issue: 19

Pages: -

Print publication date: 16/05/2007

ISSN (print): 1098-0121

ISSN (electronic): 1550-235X

Publisher: American Physical Society

URL: http://dx.doi.org/10.1103/PhysRevB.75.195208

DOI: 10.1103/PhysRevB.75.195208

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