Surface chemistry of porous silicon carbide

Abstract

The anodization reaction of SiC using HF solution makes a porous silicon carbide (PSC) layer develop. The luminescence behavior of PSC, however, is somewhat different from that of porous Si in that the so-called blue shift is not observed. Though the quantum confinement effect is said to be responsible for light emission in porous SiC, the surface state of PSC plays an important role. The effects of thermal annealing under various atmospheres on the luminescence properties were studied. Some spectroscopic analyses were adopted to elucidate the surface chemistry of PSC. The surface of PSC, which seems to be an origin of the luminescence, had C-H termination but Si-H or Si-O bonds were not detected. X-ray photoelectron spectroscopy analysis also showed that the Si-O bond that usually exists on the surface of bulk SiC was depressed and a strong peak assigned to -CH- appeared. The oxidation treatment reconstructed the Si-O bonds on the PSC surface, and this surface depressed the luminescence. Two other thermal treatments also depressed the PL spectra from the higher energy region, which is due to alternation from C-H to C-C on the surface.