Initial oxidation of 6H–SiC(0 0 0 1)-3×3 surface studied by ion scattering combined with photoemission induced by synchrotron-radiation-light

Initial oxidation of the 6H–SiC(0 0 0 1)-3×3 surface was analyzed in situ by medium energy ion scattering coupled with photoemission using synchrotron-radiation-light. The former determined the absolute quantity of adsorbed oxygen and the latter provided the fraction of each oxidation state of Si together with the surface band structure. Oxidation was performed at room temperature (RT) and 500 °C under O2-pressure of 1×10−8 and 1×10−5 Torr, respectively. The absolute quantity of oxygen adsorbed was saturated with 1.07±0.05 ML (monolayer) (1 ML: 1.22×1015 atoms/cm2) at O2-exposure of 10 L (1 L: 10−6 Torr s) for RT and with 1.80±0.05 ML at 100 L for 500 °C. The Si-2p and C-1s core level analysis considering the absolute amount of oxygen adsorbed has revealed that all the adatoms are easily oxidized at RT and a small amount of oxygen (10–15%) is inserted into the Si–C bond and the oxidation at 500 °C proceeds inhomogeneously not in a layer-by-layer fashion and leads to formation of SiO2-like domains accompanied by some silicate (SiCxOy) with a C–O bond.