An irradiation-induced photoluminescence band in 4H- and 6H-type material, and the corresponding optically detected magnetic resonance signals from this band, were studied. The deep photoluminescence band had the same number of no-phonon lines as the number of inequivalent sites in the respective polytype. These lines were located at 1.352 and 1.438eV in the case of 4H-type samples, and at 1.366, 1.398 and 1.433eV in the case of 6H-type samples. The intensity of the photoluminescence lines was reduced by short-term annealing at 750C. Optically detected magnetic resonance measurements, using above-bandgap excitation, showed that 2 spin-triplet (S = 1) states with weak axial character were detected via each photoluminescence line in the bands. One of these 2 triplet states could be selectively excited with the excitation energy of the corresponding photoluminescence line. These triplet signals could then be detected separately, and only then could the well-known and characteristic hyperfine interaction of the Si vacancy be resolved. After considering the correlation between the irradiation dose and the signal strength, the well-established annealing temperature and the characteristic hyperfine pattern, it was concluded that this photoluminescence band was related to the isolated Si vacancy in 4H- and 6H-material. The spin state (S = 1) implied a charge state of the vacancy, with an even number of electrons.

Silicon Vacancy Related Defect in 4H and 6H SiC E.Sörman, N.T.Son, W.M.Chen, O.Kordina, C.Hallin, E.Janzén: Physical Review B, 2000, 61[4], 2613-20