Positively charged carbon vacancy in three inequivalent lattice sites of 6HSiC: Combined EPR and density functional theory study

V. Ya. Bratus’, T. T. Petrenko, S. M. Okulov, and T. L. Petrenko
Phys. Rev. B 71, 125202 – Published 10 March 2005

Abstract

The Ky1, Ky2, and Ky3 centers are the dominant defects produced in the electron-irradiated p-type 6HSiC crystals. The electron paramagnetic resonance study of these defects has been performed in the temperature range of 4.2300K at X, K, and Q bands. The centers are characterized by the fourfold silicon coordination established on a basis of the observed hyperfine structure. At low temperatures both Ky1 and Ky2 defects reveal the CS symmetry that only slightly deviates from the D2d one. At high temperatures, the thermally activated reorientation from one Jahn-Teller distortion to the others causes the averaging of the Ky1 and Ky2 spectra in such a manner that their spin-Hamiltonians correspond to the axial symmetry. The Ky3 center has axial symmetry in all the temperature range under investigation. Its hyperfine parameters for the first-shell silicon atoms are substantially different from those determined for the Ky1 and Ky2 centers. Based on the density functional theory, the calculations of the electronic structure of a number of fourfold silicon coordinated defects have been carried out for the unambiguous identification of the observed defects through the comparison of experimentally determined and calculated hyperfine parameters. The present study proves an assignment of the Ky1, Ky2, and Ky3 centers to the positively charged carbon vacancy located in two quasicubic and hexagonal sites of the 6HSiC lattice, respectively. The features of the VC+ defect related to the multivalley character of its potential energy surface are also discussed. It is shown that this defect can be localized in the minima of different symmetry depending on the occupied lattice site, and these minima are experimentally distinguishable by the values of hyperfine parameters.

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  • Received 6 May 2004

DOI:https://doi.org/10.1103/PhysRevB.71.125202

©2005 American Physical Society

Authors & Affiliations

V. Ya. Bratus’, T. T. Petrenko*, S. M. Okulov, and T. L. Petrenko

  • Institute of Semiconductor Physics, NASU, 45 Prospect Nauky, 03028 Kyiv, Ukraine

  • *Present address: Max-Planck-Institut fuer Bioanorganische Chemie, Stiftstr. 34-36, 45470 Muelheim a.d. Ruhr, Germany; electronic address: taras@mpi-muelheim.mpg.de

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Vol. 71, Iss. 12 — 15 March 2005

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