Fig. 1. (Color online) (a) AFM image of the CMP-treated 4H-SiC wafer, (b) distribution and (c) density of defects of the CMP-treated 4H-SiC wafer, and (d) DIC and UV-PL images of the same PL-Black defect site [the black box in (b)] of the Si-face of the CMP-treated 4H-SiC wafer.

Fig. 2. (Color online) (a) Schematic diagram showing the setup of the photo-chemical etching of 4H-SiC. (b) The current of 4H-SiC during the photo-chemical etching under the UV and sunlight illumination.

Fig. 3. (a) Differential interference contrast (DIC) optical microscopy image, (b) SEM image, (c) AFM image, and (d) height of the ridge-like defect in the photo-chemically etched Si-face of 4H-SiC.

Fig. 4. (Color online) (a) Optical microscopy image, (b) Raman spectra, and Raman mappings based on the intensity of peaks located at (c) 204, (d) 776, and (e) 984 cm^–1 across the ridge-like defect in the photo-chemically etched Si-face of 4H-SiC.

Fig. 5. (Color online) (a) Schematic diagram of molten-KOH etching of the photo-chemically etched Si-face of 4H-SiC. (b, c) DIC images obtained with the molten-KOH etching with 3 and 30 min, respectively. The insets show the local SEM images in the red dotted boxes.

Fig. 6. (Color online) Cross-section schematic diagrams showing the Si-face of 4H-SiC after the (a) fine-lapping, (b) CMP, (c) photo-chemical etching and (d) molten-KOH etching.