A low-temperature X-band electron paramagnetic resonance study was made of Ky1 and Ky2 centers which were attributed to a positively-charged C vacancy (VC+) in 2 quasi-cubic sites of a 6H–SiC crystal. A CS symmetry, spin S = ½ and close coincidence of the g-tensor components were revealed. The principal values of the g-tensor were determined to be gz = 2.0048, gx = 2.0022 and gy = 2.0037 for the Ky2 defect, where the z- and x-directions lay in the (11•0) plane and the z-axis made an angle of 65° with the c-axis. The same residence plane of the z- and x-axes, and an angle of 59°, were found for the Ky1 center; with gz=2.0058, gx = 2.0025 and gy = 2.0023. For the Ky2 center, the principal values and corresponding directional cosines of the hyperfine interaction tensor were determined for four Si atoms in the nearest-neighborhood of the defect. The Ky3 center

was tentatively proposed to be a VC+ defect in a quasi-hexagonal site of 6H–SiC. The results of ab initio density-functional theory calculations, using cubic C18Si16H36 and hexagonal C18Si20H40 clusters, confirmed the main features of the proposed VC+ defect models; including the point symmetry and the values of the hyperfine parameters.

Positively Charged Carbon Vacancy in 6H–SiC - EPR Study. V.Y.Bratus, I.N.Makeeva, S.M.Okulov, T.L.Petrenko, T.T.Petrenko, H.J.von Bardeleben: Physica B, 2001, 308-310, 621-4