Fig. 1. (Color online) (a) Schematic diagram showing the experimental setup of molten-KOH etching, and the oxide-removal mechanism of 4H-SiC. The surface morphologies of the molten-KOH-etched 4H-SiC samples: (b) Exposed Si face, (c) protected C face, (d) protected Si face, and (e) exposed C face.

Fig. 2. (Color online) Temperature dependence of the etch rates of the Si face and C face of HPSI 4H-SiC.

Fig. 3. (Color online) XPS high-resolution spectra of molten-KOH etched 4H-SiC wafer. (a) Si 2p spectrum fitting of Si face, (b) Si 2p spectrum fitting of the C face, (c) C 1s spectrum fitting of the Si face, (d) C 1s spectrum fitting of the C face.

Fig. 4. (Color online) (a) Surface energies of the Si face and C face with different surface reconstructions, and (b) oxidation energies of the C face (1×1) and Si face (3×3), as functions of the chemical potential of Si.