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

Chemically abrupt SiO2/6H-SiC(0001) interfaces have been obtained after thi n (congruent to 5 nm) oxide thermal growth of the Si-terminated face. The o riginality of the paper resides in a simultaneous use of standard technolog ical conditions for this oxidation (dry O-2 oxidation at I atmosphere and 1 000 degrees C) and in control and characterization of the starting substrat es taken from in situ, ultrahigh vacuum-surface techniques. The oxidation o f 3x3 Si-rich and 6 root 3x6 root 3R30 degrees C-rich reconstructed surface s is compared. In both cases no C-C bonds or C enrichment are observed at t he SiO2/SiC interface by x-ray photoelectron spectroscopy Cls 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 SiO2 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-SiC(0001) are maintained. These results allow us to conclude that there is probably no fu ndamental contraindication to obtain nearly ideal SiO2/SiC interfaces on fl at SiC terraces. Two growth regimes are observed in the oxide growth kineti cs. They are discussed to determine the possible reasons of carbon exodiffu sion or previously observed C enrichments at the SiO2/SiC interface. [S0163 -1829(99)12431-7].