Nature of electrically detected magnetic resonance in highly nitrogen-doped 6<i>H</i>-SiC single crystals

Abstract

This work focuses on unraveling electron paramagnetic resonance (EPR) and electrically detected magnetic resonance (EDMR) properties of n-type 6H silicon carbide (SiC) single crystals with high concentrations of uncompensated nitrogen (N) donors, which is essential for fundamental understanding of spin-related phenomena, developing spin-based devices, optimizing materials and devices, and advancing research in quantum information and spintronics. Utilizing low-temperature multifrequency EPR spectroscopy (9.4-395.12 GHz), we identified two intense signals labeled as S line and S1 line in the 6H-SiC crystals with N D - N A approximate to 8 x 1018 and 4 x 1019 cm-3. In addition, in 6H-SiC crystals with N D - N A approximate to 8 x 1018 cm-3, a low-intensity triplet from N donors substituting the quasicubic "k2" nonequivalent position (Nk2) was observed. The S line [g perpendicular to = 2.0029(2), g|| = 2.0038(2)] was assigned to the exchange interaction of conduction electrons and Nk2, while the S1 line [g perpendicular to = 2.0030(2), g|| = 2.0040(2)] is caused by the exchange spin coupling of localized N donors at the "k1" and "k2" positions. The S1 line was observed in high-frequency EDMR spectra of 6H-SiC with N D - N A approximate to 8 x 1018 cm-3, and its emergence was explained by an enhancement of the hopping conductivity due to the EPR-induced temperature increase mechanism. No EDMR spectra were found to occur in the 6H-SiC crystals with N D - N A approximate to 4 x 1019 cm-3, which is close to the critical donor concentration value for a semiconductor-metal transition. Thus it can be concluded that this N donor concentration is too high for the appearance of spin-dependent scattering and too low for the emergence of EPR-induced hopping mechanisms in 6H-SiC.This work focuses on unraveling electron paramagnetic resonance (EPR) and electrically detected magnetic resonance (EDMR) properties of n-type 6H silicon carbide (SiC) single crystals with high concentrations of uncompensated nitrogen (N) donors, which is essential for fundamental understanding of spin-related phenomena, developing spin-based devices, optimizing materials and devices, and advancing research in quantum information and spintronics. Utilizing low-temperature multifrequency EPR spectroscopy (9.4-395.12 GHz), we identified two intense signals labeled as S line and S1 line in the 6H-SiC crystals with N D - N A approximate to 8 x 1018 and 4 x 1019 cm-3. In addition, in 6H-SiC crystals with N D - N A approximate to 8 x 1018 cm-3, a low-intensity triplet from N donors substituting the quasicubic "k2" nonequivalent position (Nk2) was observed. The S line [g perpendicular to = 2.0029(2), g|| = 2.0038(2)] was assigned to the exchange interaction of conduction electrons and Nk2, while the S1 line [g perpendicular to = 2.0030(2), g|| = 2.0040(2)] is caused by the exchange spin coupling of localized N donors at the "k1" and "k2" positions. The S1 line was observed in high-frequency EDMR spectra of 6H-SiC with N D - N A approximate to 8 x 1018 cm-3, and its emergence was explained by an enhancement of the hopping conductivity due to the EPR-induced temperature increase mechanism. No EDMR spectra were found to occur in the 6H-SiC crystals with N D - N A approximate to 4 x 1019 cm-3, which is close to the critical donor concentration value for a semiconductor-metal transition. Thus it can be concluded that this N donor concentration is too high for the appearance of spin-dependent scattering and too low for the emergence of EPR-induced hopping mechanisms in 6H-SiC.