Oxidation of 4H–SiC covered with a SmSi x surface alloy

Abstract

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 SmSi x (1 × 1) surface alloy formed on (0 0 0 1) 4H–SiC. During the initial oxidation of the SmSi x alloy, a (2 × 2)-LEED pattern is observed. Furthermore, the Sm 2+ valency observed from the clean SmSi x 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 SmSiO x 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 SiO 2 layer forms on top of the samarium silicon oxide interface layer.