Characterization of Electrical Properties of n-Type 4H-SiC Single Crystals by Raman Spectroscopy

N-type 4H-SiC single crystals have been grown by N-doped sublimation method. The electrical properties of 4H-SiC single crystal wafers were assessed by Raman scattering and Hall measurement system. It has been found that the carrier concentrations in whole wafer are inhomogeneous. Due to facet effect, the carrier concentration in facet region is higher than that in other region. In addition, the carrier concentration in early growth stage is higher than that in later growth stage because of desorption of nitrogen existing in crucible and raw material at high temperature. Furthermore, some approaches to the growth of n-type 4H-SiC single crystals with homogeneous carrier concentration were proposed.