The carbon vacancy pair in 4H and 6H SiC

Electron paramagnetic resonance (EPR) was used to study defects in p-type 4H and 6H SiC irradiated with 2.5 MeV electrons at elevated temperatures (400 degreesC). After irradiation, an anisotropic EPR spectrum, labeled EI4, having monoclinic symmetry (C-1h) and an effective spin S=1 was observed in both 4H and 6H SiC. The same g-tensor with the principal values, g(x)=2.0051, g(y)=2.0038 and g(z)=2.0029 was determined for the spectra in both polytypes. Here the z- and x-axis lie in the (1120)plane and the y-axis perpendicular to this plane. The angle between the principal z-axis and the c-axis is 54 degrees. The fine structure parameters were determined as D=3.28x10(-2) cm(-1) and 3.44x10(-2) cm(-1) for 6H and 4H SiC, respectively; E=0.67x10(-2) cm(-1) for both polytypes. From the obtained Si-29 hyperfine structure and spin Hamiltionian parameters, the defect can be identified as the pair of two carbon vacancies in the (1120) or equivalent planes.