Photoelectron Spectroscopic Study of Coadsorption of O₂ and Rb on InSb(111) Surface

Photoelectron spectroscopy（XPS and UPS） technique has been used to study coadsorption of O₂ and Rb on InSb（111） surface at room temperature. The bonding state between Rb atoms and InSb surface and the catalytic effect of Rb adsorbate on the substrate oxidation were investigated. The results show that the Rb adsorbate reacts with the Sb atom of the InSb surface enhancing the oxidation rate of the In and Sb atoms on the InSb surface. Two kinds of Rb oxides （Rb₂O₂ and RbO₂） have been observed during oxygen adsorption. The spectra of core-level and valenceband reveal the existence of three oxygen ion states（O^2-, ₂^2- and ₂^- ）.