The Origin of Residual Carriers in CVD-Grown 3C-SiC

PL and ESR spectra were measured for unintentionally doped and N-doped 3C-SiC epilayers grown on Si by CVD in order to clarify the origin of residual carriers in the SiC films. PL spectra of lightly N-doped samples show broad peaks in addition to the sharp peaks observed for unintentionally doped ones. The intensities of these broad peaks increase with the N2 partial pressure during growth. ESR signals of the 3C-SiC films consist of a sharp triplet and a broad structure. The spin densities of the unintentionally doped samples at 4.2 K are estimated to be much lower than the carrier densities at room temperature. From these experimental results, we can conclude that the main origin of the residual carriers in unintentionally doped 3C-SiC is not attributed to simple nitrogen donors.