Optically detected magnetic resonance studies of intrinsic defects in 6H-SiC
Optically detected magnetic resonance (ODMR) was used for study of defects in n-type 6H-SiC. Four ODMR spectra related to spin S = 1 centres were observed. Two of these centres, labelled a and b, have a trigonal symmetry with the symmetry axis along the c-axis of the hexagonal crystal. For the other two centres, labelled c and d, the symmetry is lower (C1h) and the principal axis z of the g- and D-tensor is about 71 degrees off the c-axis. Based on the symmetry axes, the annealing behaviour and the intensity, these spectra are suggested to originate from different configurations of the paired centre between a silicon vacancy and a nearest-neighbour point defect (either a carbon vacancy or a silicon antisite), occupying different inequivalent sites in the 6H-SiC. These defects are non-radiative and act as efficient recombination channels in the material.