Morphological and optical characterization of porous silicon carbide

In this communication, we report on the morphological and optical characterizations of porous silicon carbide prepared by electrochemical etching method. AFM images show that the etched surface is constituted by three kinds of structures: porous, spherical nanostructures and islands. The latest structures show very low density. Photoluminescence spectrum shows a blue-red emission line with a 320 meV of FWHM. This line does not show any change under etching conditions and compared with the intrinsic 6H–SiC, apart from the intensity which increases by 100 times. The band gap edge of the PSC and crystalline SiC by optical absorption does not show any change, whereas the absorption constant increases drastically. The visible luminescence could not be attributed to the quantum size effects but could be related to the density of nitrogen in the crystal and to CH bonds on the surface.