The Carbon Vacancy Pair in 4H and 6H SiC

Abstract

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 °C). After irradiation, an anisotropic EPR spectrum, labeled EI4, having monoclinic symmetry (C1h) and an effective spin S = 1 was observed in both 4H and 6H SiC. The same g-tensor with the principal values, gx = 2.0051, gy = 2.0038 and gz = 2.0029 was determined for the spectra in both polytypes. Here the z- and x-axis lie in the (1 1 2 0) plane and the y-axis perpendicular to this plane. The angle between the principal z-axis and the c-axis is 54°. The fine structure parameters were determined as D = 3.28×10-2 cm-1 and 3.44×10-2 cm-1 for 6H and 4H SiC, respectively; E = 0.67×10-2 cm-1 for both polytypes. From the obtained 29Si hyperfine structure and spin Hamiltionian parameters, the defect can be identified as the pair of two carbon vacancies in the (1 1 2 0) or equivalent planes.