Thermal etching of SiC

Thermal etching of SiC or its decomposition at high temperatures is of significance because of the many industrial applications of SiC at high temperatures. The effect of vacuum annealing at relatively high temperatures (1200–1800 °C) on the surface microstructure of 6H-SiC and polycrystalline SiC was investigated using a modern high resolution scanning electron microscope (FEG-SEM) with an in-lens detector. Crystal defects such as stacking faults and twins on the SiC surfaces were easily observed in this system. Thermal etching of SiC already started at 1200 °C with evidence of step bunching and grain boundary grooving. Preferred etching occurred on certain crystal surfaces of polycrystalline SiC. Significant decomposition of SiC occurred at 1800 °C. The resulting decomposition structures have possible nanotechnological applications.