Two paramagnetic intrinsic defects, P and ND1, were studied in C-rich n-type 4H-SiC and in undoped semi-insulating 4H-SiC; in the dark, or under illumination of the semi-insulating sample with light (140 and 37GHz) at 4.2 to 77K. Photo-electron paramagnetic resonance and Hall-effect measurements indicated that P was a deep donor defect localized at Ec-1.15eV, while ND1 was a shallow donor defect that was localized at Ec-0.07eV. Based upon the observed 13C hyperfine structure, and the C-rich growth conditions, the P center was identified with a Si vacancy. Meanwhile, ND1 (which exhibited a strong central hyperfine interaction with one 13C atom) was attributed to the C antisite, CSi. Since the defects had spin S = ½, C3V symmetry of the electron paramagnetic resonance spectrum and appeared to be donor-like defects, P was attributed to a Si vacancy in the -3 charge state (VSi3-), whereas ND1 was suggested to be a C antisite in the single negative charge state, CSi-.

Electrical and Multifrequency EPR Study of Non-Stoichiometric Defects in 4H-SiC. E.N.Kalabukhova, S.N.Lukin, D.V.Savchenko, W.C.Mitchel: Physica B, 2003, 340-342, 156-9