Electrical and multifrequency EPR study of nonstoichiometric defects in 4H-SiC

Two paramagnetic intrinsic defects P and ND1 have been studied in both C-rich n-type 4H-SiC and undoped semi-insulating (s.i.) 4H-SiC in the dark and under illumination of the s.i. sample with light at 140 and 37GHz in the temperature interval from 4.2 to 77K. Photo EPR and Hall effect measurements indicate that P is a deep donor defect localized at EC−1.15eV, while ND1 is shallow donor defect localized at EC−0.07eV. Based on the observed 13C hyperfine structure, and the C-rich growth conditions, we identify the P center with the silicon vacancy, while ND1, which exhibited a strong central hyperfine interaction with one 13C atom, is attributed to the carbon antisite CSi. Considering that the defects have spin S=12, C3V symmetry of the EPR spectrum and appear to be donor-like defects, P is attributed to the silicon vacancy in the −3 charge state (VSi3−), whereas ND1 is suggested to be the carbon antisite in the single negative charge state (CSi−).