6H- and 4H- SiC crystals grown on the Si-face were chemically etched on the as-grown (virgin) surface and the C-face (sliced side). The etching of both the surfaces revealed a strong relationship between a variety of etch pits and the morphological features of the grown boule surface. Several types of etched patterns were revealed. On the Si face, we observed small, medium, and large hexagonal shaped pits and a linear array of small etch pits. However, the C face contained only small pits and a linear array of small pits.
We observed individual or group of dislocations that were connected from the Si face to the opposite C face of the wafer. Also, etch pit lines oriented along specific crystallographic directions were seen.
Our experimental observations have provided a physical basis to explain the generation of defects in SiC. An analysis of our observations show that a correlation exists between the distribution of different size etch pits and the condition of the crystal growth process.