Morphological and optical characterization of porous silicon carbide

In this communication, we report on the morphological and optical character izations of porous silicon carbide prepared by electrochemical etching meth od. AFM images show that the etched surface is constituted by three kinds o f structures: porous, spherical nanostructures and islands. The latest stru ctures show very low density. Photoluminescence spectrum shows a blue-red e mission line with a 320 meV of FWHM. This line does not show any change und er etching conditions and compared with the intrinsic 6H-SiC, apart from th e 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 d ensity of nitrogen in the crystal and to C-H bonds on the surface. (C) 2001 Elsevier Science B.V. All rights reserved.