Distortion of atoms around the neutral vacancy in a Si crystal
Physikalisch-Technische Bundesanstalt, P.O. Box 3345, 38023 Braunschweig, Germany
2 Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
Published online: 15 April 1999
The single-particle electronic structure of a neutral lattice vacancy in a Si crystal is treated theoretically within the 16-atom supercell using the conventional tight-binding approximation. The physical mechanism leading to a spontaneous symmetric and tetragonal displacement of atoms surrounding a vacancy is discussed in detail. The elastic response of the lattice is calculated using the Keating valence force model applied to the cluster contained 441 atoms. The directions and amplitudes of atomic displacements are strongly symmetry-dependent. The amplitudes decrease with the distance R from the vacancy, approximately, as R-2, independently of the distortion symmetry. The influence of the vacancy defects on the lattice parameter is considered and estimated.
PACS: 61.72.Ji – Point defects (vacancies, interstitials, color centers, etc.) and defect clusters / 71.55.Cn – Elemental semiconductors
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999