Savchenko D. Electronic structure and kinetic properties of the paramagnetic impurities and defects in silicon carbide

The work deals with study of the electronic structure of nitrogen (N) donors and their complexes in n-type 4H, 6H-SiC as well as defects and their kinetic properties in semi-insulating (SI) 4H, 6H-SiC by electron paramagnetic resonance (EPR) echo detected EPR (ED EPR), pulse electron nuclear double resonance (ENDOR) and photo EPR. The triplet lines with S = 1 were found in N ED EPR spectrum in 4H, 6H SiC which was attributed to the distant NkSikNh pairs formed between N on quasicubic (Nk) and hexagonal (Nh) sites. The parameters of Nh in 4H SiC and quadrupole interaction constants for N were determined from the study of N pulse ENDOR spectrum. The superhyperfine interaction constants of the N with nearest neighborhood were determined. It was concluded that N in 6H SiC substitutes carbon atoms. From photo EPR data the electronic model of the defects responsible for the SI properties in 6H SiC were established. The long persistent relaxation (LPR) of the minority carriers trapped on the defects and impurities was found and theoretically described in SI 4H SiC. The kinetic properties of the defects, impurities and type of the electronic process responsible for the LPR were determined.