Oxidation of 4H-SiC covered with a SmSix surface alloy

Oxidation of Sm/4H-SiC is studied by X-ray photoemission spectroscopy (XPS) and low energy electron diffraction (LEED). In particular, we report kinetic information from the oxidation of a SmSix (1 × 1) surface alloy formed on (0 0 0 1) 4H-SiC. During the initial oxidation of the SmSix alloy, a (2 × 2)-LEED pattern is observed. Furthermore, the Sm 2+ valency observed from the clean SmSix surface alloy, which is related to surface samarium atoms, disappear at 15 L oxygen exposure. The oxygen atom is consequently deduced to be located at bridge or hollow sites involving one Sm atom. The initial oxidation result in an oxygen deficit SmSiOx interface oxide, probably as a consequence of the high oxidation temperatures in this work (900-1050 °C). We report that in a prolonged oxidation (longer than 10 kL) a SiO2 layer forms on top of the samarium silicon oxide interface layer.