Electron paramagnetic resonance and electron-nuclear double resonance methods were used to identify the negatively charged Si vacancy in neutron-irradiated 4H-type material. The identification was based upon resolved ligand hyperfine interactions with C and Si nearest-neighbors and next-nearest neighbors, and upon the determination of the spin state (S = 3/2). The magnetic resonance parameters of VSi- were found to be almost identical for 3C, 4H and 6H samples. The experimental data were supported by theoretical ligand hyperfine interaction data that were based upon a total-energy calculation which involved the standard local-density approximation of density-functional theory.

T.Wimbauer, B.K.Meyer, A.Hofstaetter, A.Scharmann, H.Overhof: Physical Review B, 1997, 56[12], 7384-8