Optical Investigation of Electronic Properties in Bulk and Surface Region of Sublimation-Grown 3C-SiC Crystals

Abstract

We applied a picosecond dynamic grating technique for studies of nonequilibrium carrier dynamics in a 0.8 mm thick bulk 3C-SiC crystal grown by the continuous feed physical vapor transport (CF-PVT) on 6H-SiC (0001) substrate. Investigation of carrier dynamics at surface or bulk excitation conditions was performed for excess carrier density in range from ~ 1017 cm-3 to ~ 1020 cm3 using for excitation weakly or strongly absorbed illumination. In DPBs free domains, the bipolar diffusion coefficient and carrier lifetime value at 300K were found gradually increasing with carrier density. The bipolar mobility vs. temperature dependence, μ. ~ T -k, provided a value k = 1.2 - 2 in range T < 100 K, thus indicating a negligible scattering by point and extended defects. These data indicated strong contribution of the carrier-density dependent but not defect-density governed scattering mechanisms, thus indicating high quality of the CF-PVT grown bulk cubic SiC. These studies were found in good correlation with the structural and photoluminescence characterization of the given crystal.