Thermal Etching of 4H-SiC(0001) Si Faces in the Mixed Gas of Chlorine and Oxygen

4H-SiC (0001)Si faces have been thermally etched at atmospheric pressure in a mixed gas of oxygen (O 2 ) and chlorine (Cl 2 ). Etch pits with definite shapes appeared independently of the conduction type and doping level of SiC. The types of dislocation can be easily identified from the shape of etch pits. Facets in etch pits of screw and edge dislocations consist of specific {110 n } pyramidal planes. In dislocation-free areas, etching rate depended on Cl 2 flow rate, temperature and the off-angle of the substrate. The activation energy from the Arrhenius plots of etching rate was about 54 kcal/mol, which did not change at O 2 /Cl 2 =0-1. After the thermal etching in dislocation-free areas, many concavities were formed. On the basis of these results, etching mechanisms are discussed.