Investigation of Carbon Inclusions in SiC Crystals Grown by PVT Method

The carbon inclusions in SiC bulk crystals were studied by using optical microscope. The carbon inclusions were classified into three types, namely Type Ⅰ (100~1000 μm), Type Ⅱ (20~50 μm), Type Ⅲ (~5 μm) carbon inclusions based on their different morphologies. In addition, the evolution of these three type carbon inclusions with crystal growth process was traced. It was found that the number of Type Ⅰ and Type Ⅱ carbon inclusions showed declined tendency with crystal growth, while the number of Type Ⅲ carbon inclusions exhibited less dependence on crystal growth. Furthermore, the formation mechanism of carbon inclusions was clarified. This study would give out a better understanding of carbon inclusions, thus contribute to reducing or eliminating carbon inclusions in SiC crystals.