Gaseous etching for characterization of structural defects in silicon carbide single crystals

Single crystal SiC substrates were subjected to high temperature (1575 degrees C) H-2/C3H8 gaseous etches. The etches resulted in a variety of surface features on 4H-SiC substrates that included elongated hillocks from 10 to > 100 mu m in length by a few mu m in width. In some 4H- and 6H-SiC substrates, the etches resulted in a, continuous coverage of macrosteps. We conclude that the morphology observed after the etching process is influenced by the local Si-C bilayer stacking sequence on the surface of off-(0001) oriented substrates. A model is presented for the formation of the hillocks, based on localized transformations of the 4H substrates during the high temperature etch process.