A complex defect related to the carbon vacancy in 4H and 6H SiC

Electron paramagnetic resonance (EPR) was used to study defects in 4H and 6H SiC irradiated with 2.5 MeV electrons at room temperature. When the dose of irradiation reaches similar to 5 x 10(17) electrons/cm(2), an EPR spectrum appears. In both 4H and 6H SiC, the defect associated with this spectrum has C-1h symmetry with an effective electron spin S = 1 and an isotropic g-value of 2.0063 +/- 0.0002. The crystal;field parameter was determined as D = 1.65 and D = 1.67 GHz for 4H and 6H SiC, respectively. The principal crystal-field axis lies in the (11 (2) over bar 0) plane and makes an angle of similar to 46 degrees with the c-axis for both polytypes. A clear hyperfine structure from Si-29 due to the interaction with four nearest silicon neighbours was observed, confirming that the defect is related to the carbon vacancy. The similarity in all respects including the annealing behaviour of the spectrum in both polytypes suggests that it belongs to the same defect. Based on the formation and its electronic structure, the defect is suggested to be a complex with one of the components being the carbon vacancy.