High-field pulsed and continuous-wave electron paramagnetic resonance techniques at 95GHz were used to investigate radiation defects in neutron-irradiated SiC. In the temperature range between 1.2 and 300K, 3 types of electron paramagnetic resonance spectra were observed in 4H-and 6H-SiC crystals, and were attributed to the neutral Si vacancy, the negatively charged Si vacancy, and the C vacancy. In the electron paramagnetic resonance spectra of VSi- in 4H- and 6H-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 (k) and hexagonal (h) sites. The g-factor for the k site, g (k), was found to be isotropic, with g(k) = 2.0032, and the g-

factor of the h-site was found to be slightly anisotropic, with g||(h) = g(k)-0.00004 and g(h) = g(k)-0.00002. The 95GHz electron paramagnetic resonance spectra at 1.4K showed that the ground state of VSi0 was a triplet state. Additional 9.5GHz electron paramagnetic resonance experiments revealed signals that were attributed to the C vacancy, on the basis of the observed hyperfine splitting. The results demonstrated that VSi-,VSi0 and Vc were dominant defects after the neutron irradiation of SiC to doses of up to 1019/cm2.

Neutral and Negatively Charged Silicon Vacancies in Neutron-Irradiated SiC - a High-Field Electron Paramagnetic Resonance Study. P.G.Baranov, E.N.Mokhov, S.B.Orlinskii, J.Schmidt: Physica B, 2001, 308-310, 680-3