X-ray spectroscopy of the oxidation of 6H-SiC(0001)

Abstract

Chemically abrupt SiO 2 /6H-SiC(0001) interfaces have been obtained after thin ͑Х5 nm͒ oxide thermal growth of the Si-terminated face. The originality of the paper resides in a simultaneous use of standard technological conditions for this oxidation ͑dry O 2 oxidation at 1 atmosphere and 1000°C͒ and in control and characterization of the starting substrates taken from in situ, ultrahigh vacuum-surface techniques. The oxidation of 3ϫ3 Si-rich and 6)ϫ6)R30°C-rich reconstructed surfaces is compared. In both cases no C-C bonds or C enrichment are observed at the SiO 2 /SiC interface by x-ray photoelectron spectroscopy C 1s analysis, the C-C bonds of the initially graphitized C-rich surface being removed during the first nanometer oxide growth. The interfacial suboxide components with binding energy between the substrate and SiO 2 Si 2p features remain below our detection limit. X-ray photoelectron diffraction analyses indicate that, below the oxide layer, the ordering and polarity of the 6H-SiC͑0001͒ are maintained. These results allow us to conclude that there is probably no fundamental contraindication to obtain nearly ideal SiO 2 /SiC interfaces on flat SiC terraces. Two growth regimes are observed in the oxide growth kinetics. They are discussed to determine the possible reasons of carbon exodiffusion or previously observed C enrichments at the SiO 2 /SiC interface.

Synthesis and characterization of atomically thin graphite films on a silicon carbide substrate

“…The C 1s spectrum consists of three components, labeled as X, G, and S. In the analysis that follows we will make use of the latter two, which are assigned to the graphite overlayer (G) and the SiC bulk (S). These assignments are in agreement with previous work 21,22 . In particular, the small chemical shift of peak S relative to pure SiC by about 0.4 eV has been noted before, and was attributed to a Fermi level pinning associated with surface metallization 21,22,23 .…”

“…Peak X, broad and weak, is of a less clear origin. Previously, a similar feature was interpreted as arising from C-C bonding in a Si-depleted interfacial region between graphite and SiC 21,22 . Using the relative intensities of three peaks (Si 2p, G, and S), we obtained information on the thickness of the graphite overlayer for each of the three samples studied.…”

A Simplified Method for Patterning Graphene on Dielectric Layers

“…The NEXAFS shows no π* resonance, and the only C 1s signals present are those corresponding to the C–C and C–Si bonds of the SiC surface. 53 − 56 Inside the pattern (Region I), the graphene does not show any signs of oxidation: the π* resonances of the NEXAFS appear to be unchanged, and the energies, shapes, and intensities of the graphene core levels are well preserved. In Figure 4 b, only a small redistribution of intensity can be seen between the surface C1 and C2 peaks.…”

Atomic Structure of SiC Surfaces

“…• structure were investigated by UPS and XPS [134,135]. Atomic level experimental and theoretical investigations are now also focussing on the structural interface properties upon high pressure oxidation [136]- [142].…”