Electron paramagnetic resonance and electron spin-echo studies were performed that showed that isolated VSi–, VSi0 and VC vacancies were the predominant intrinsic paramagnetic defects in SiC which had been subjected to room-temperature neutron irradiation to doses of up to 1019/cm2. This conclusion was supported by observations of high concentrations of all of these defects, in 4H- and 6H-SiC, that were almost proportional to the irradiation dose. The 95GHz electron paramagnetic resonance spectra at 1.2K proved that the ground state of VSi0 corresponded to S = 1 and that the zero-field splitting parameter was positive. A possible energy-level scheme and optical pumping process was presented which induced spin polarization of the ground triplet state of the VSi0 vacancy in SiC. In the electron paramagnetic resonance spectra of VSi– in 4H-SiC, an anisotropic splitting of the electron paramagnetic resonance lines was observed. This splitting was assumed to arise from small differences in the g-tensor of the quasi-cubic and hexagonal sites. Anisotropic electron paramagnetic resonance spectra with S = ½, that were related to the C vacancy, had also been observed in the neutron-irradiated SiC crystals. The hyperfine interaction with the first shell of Si atoms was almost identical to that observed in electron-irradiated SiC crystals. An observed additional 6.8G hyperfine splitting, with 12 C-atoms in the second shell, was considered to confirm the isolated C vacancy model.

Silicon and Carbon Vacancies in Neutron-Irradiated SiC - a High-Field Electron Paramagnetic Resonance Study. S.B.Orlinski, J.Schmidt, E.N.Mokhov, P.G.Baranov: Physical Review B, 2003, 67[12], 125207 (8pp)