Rb/β-SiC(100) surface and catalytic oxidation of the substrate

Abstract

We investigate the Rb/β-SiC(100) surface and the subsequent promoted SiC oxidation using photoemission spectroscopy with the AlKα (1486.6 eV) and ZrMζ (151.4 eV) X-ray lines at Si 2p, C 1s, O 1s and Rb 3p core levels, and work-function measurements. Clean and stoichiometric β-SiC(100) surfaces are obtained by thermal annealing procedures only. Rb deposition on the clean β-SiC(100) surface induces a large decrease of the work function reaching a minimum at Δф = − 3.3 eV. The Rb layer enhances the room temperature oxygen uptake by 4 orders of magnitude. Upon subsequent annealing, high silicon oxidation states are formed, leading to SiO2/β-SiC(100) interface formation with no apparent carbon atoms present on the surface and/or in the oxide layer. Further heating below 800°C removes the Rb atoms completely by thermal desorption.