EPR, ESE and pulsed ENDOR study of the nitrogen donor pairs on quasi-cubic lattice sites in 6H SiC

摘要

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 ~(14)N hyperfine (hf) triplet lines of the N donors incorporated at the two quasi-cubic (N_(c1), N_(c2) 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 N_(c1), N_(c2) centers and new 14N lines due to the N related centers N_1, N_2, N_3 with the isotropic hf splitting: 21.04, 26.43, 29.77MHz,respectively. It was found that the g-tensors of the N_2 and N_3 triplet lines coincide with those of N on quasi-cubic N_(c2) site. The g-tensor of the third N1 triplet lines corresponds to the average value of the N_(c1) and N_(c2)spectrum: g(N_1)≈1/2[g(N_(c1)+g(N_c2)]. It was suggested that N1 center with A_(iso)=21.04MHz is due to the spin coupling between N on two quasi-cubic N_(c1) and N_(c2) sites while two others are tentatively attributed to the N pairs formed between N atoms on one quasi-cubic N_(c2) site.