The occurrence of polytype domains in the central region decreases the yield of wafers, when large diameter 6H-, 4H-silicon carbide(SiC) single crystals are grown by a sublimation method. Accordingly, the suppression of polytype domains is very important. Previous studies revealed that polytype domains occur in SiC crystals during the growth process and the domains were based on the root of micropipes and macro-defects. However, in spite of many studies and much development, the suppression of polytype domains has not been perfectly solved. In this study, we verified the systematic experimental results that the relationship between ΔTB-U (vertical temperature gradient) and ΔTF-I (the temperature difference between initial temperature and final temperature at bottom of crucible) has an important effect on the occurrence of polytype domains. It was found that the optimization of ΔTF-I was more important than that of ΔTB-U in order to reduce the macro-defects and polytype domains.

Keywords: Silicon carbide, single crystal, polytype domain, sublimation, temperature gradient