Electron paramagnetic resonance was used to study defects in 4H-type and 6H-type samples which had been irradiated with 2.5MeV electrons at room temperature. An electron paramagnetic resonance spectrum appeared when the irradiation dose reached about 5 x 1017/cm2. In both materials, the defect which was associated with this spectrum had C1h symmetry, with an effective electron spin of S = 1 and an isotropic g-value of 2.0063. The crystal-field parameter was determined to be 1.65 and 1.67GHz for 4H- and 6H-type material, respectively. The principal crystal-field axis lay in the (11•0) plane and made an angle of about 46º with respect to the c-axis in both polytypes. A clear hyperfine structure from 29Si, due to the interaction with 4 nearest-neighbour Si atoms, was observed; thus confirming that the defect was related to the C vacancy. A similarity of all of the features, including the annealing behaviour of the spectrum, of both polytypes suggested that it belonged to the same defect. On the basis of its formation and electronic structure, the defect was suggested to be a complex, of which one of the components was the C vacancy.

A Complex Defect Related to the Carbon Vacancy in 4H and 6H SiC. N.T.Son, W.M.Chen, J.L.Lindström, B.Monemar, E.Janzén: Physica Scripta T, 1999, 79, 46-9