Search

Abstract: D-band EPR, X-band FS ESE and pulsed ENDOR studies of the additional nitrogen (N) related centers observed in highly compensated n-type 6H-SiC wafers are presented. The D-band EPR and X-band FS ESE spectrum consists of the 14N hyperfine (hf) triplet lines of the N donors incorporated at the two quasi-cubic (Nc1, Nc2) sites with the intensity ratio of I Nc1/I Nc2=0.7 and three additional triplet lines. X-band pulsed ENDOR spectra have shown intense 14N ENDOR signals of Nc1, Nc2 centers and new 14N lines due to the N related centers N1, N2, N3 with the isotropic hf splitting: 21.04, 26.43, 29.77MHz, respectively. It was found that the g-tensors of the N2 and N3 triplet lines coincide with those of N on quasi-cubic Nc2 site. The g-tensor of the third N1 triplet lines corresponds to the average value of the Nc1 and Nc2 spectrum: . It was suggested that N1 center with A iso=21.04MHz is due to the spin coupling between N on two quasi-cubic Nc1 and Nc2 sites while two others are tentatively attributed to the N pairs formed between N atoms on one quasi-cubic Nc2 site. [Copyright &y& Elsevier]

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 37 GHz in the temperature interval from 4.2 to 77 K. Photo EPR and Hall effect measurements indicate that P is a deep donor defect localized at EC−1.15 eV, while ND1 is shallow donor defect localized at EC−0.07 eV.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=1/2, 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−). [Copyright &y& Elsevier]