Polytype Transformation in 4H-SiC single crystals grown on on-axis Seeds

Polytype destabilization at the periphery of 4H-SiC single crystals during the initial stage of 4H-SiC bulk crystals grown on on-axis seeds by sublimation method were investigated. Optical microscopy and Raman spectroscopy, were used to study the distribution of polytypism. Three regions with different Raman peak intensity ratio (I150/I204) at the outer parts of the grown layer are distinctly observed, indicating the increase in parasitic polytype component towards the edge. The higher probability of 6H or 15R-SiC nucleation due to the higher supersaturation at the periphery could be responsible for the polytype transformation.