An investigation was made of irradiated 6H–SiC and of 15R–SiC via the magnetic circular dichroism of the absorption and MCDA-detected electron paramagnetic resonance. In neutron- and electron-irradiated 6H–SiC, two MCDA transitions were observed at photon energies of 1.435 and 1.369eV. Photoluminescence lines at these photon energies (so-called V1 and V3 lines) were currently attributed to the neutral Si vacancy at the 2 quasi-cubic lattice sites in 6H–SiC. In electron-irradiated 15R–SiC, which had 3 inequivalent quasi-cubic lattice sites, 3 MCDA lines were observed at 1.442, 1.438 and 1.373eV. At the photon energy expected for the hexagonal site in 6H–SiC (so-called V2 photoluminescence line), no MCDA signal was observed. From the temperature and field dependence of the magnetic circular dichroism of the absorption, a spin S = ½ of the quasi-cubic sites was determined. Electron paramagnetic resonance spectra detected via these MCDA lines consisted of single electron paramagnetic resonance lines at g = 2.005(2). It was concluded that the ground state of VSi giving rise to these optical transitions was paramagnetic with S = ½, which was predicted theoretically for the ground state of the triply-negative charge state. The previous attribution of the optical transitions to the neutral charge state therefore had to be corrected.

The Ground State of Silicon Vacancies in 6H–SiC and 15R–SiC. T.Lingner, S.Greulich-Weber, J.M.Spaeth: Physica B, 2001, 308-310, 649-51