Positively charged carbon vacancy in 6H–SiC: EPR study

The low-temperature X-band EPR study of Ky1 and Ky2 centers assigned to positively charged carbon vacancy (V C +) in two quasicubic sites of 6H–SiC crystal is presented. The C S symmetry, spin S=1/2 and close coincidence of the g-tensor components have been revealed. The principal values of g-tensor are determined as g z =2.0048, g x =2.0022 and g y =2.0037 for Ky2 defect, where z- and x-directions reside in the ( 1 1 2 ̄ 0 ) plane and the z-axis makes up an angle 65° with the c-axis. The same residence of z- and x-axis and an angle 59° are found for Ky1 center with g z =2.0058, g x =2.0025 and g y =2.0023. For Ky2 center, the principal values and corresponding directional cosines of the hyperfine (HF) interaction tensor A are determined for four Si atoms in the nearest neighborhood of the defect. Ky3 center is tentatively proposed as V C + defect in quasihexagonal site of 6H–SiC. The results of ab initio DFT calculations using cubic C 18Si 16H 36 and hexagonal C 18Si 20H 40 clusters corroborate the main features of proposed V C + defect models including the point symmetry and values of HF parameters.