Electronic properties of O₂ on Cs or Na overlayers adsorbed on Si(100)21 from room temperature to 650°C

Valence-band and core-level photoemission spectroscopy experiments using synchrotron radiation were performed at various temperatures to study the effect of oxygen on cesium or sodium overlayers adsorbed on a Si(100)2×{}1 surface. At room temperature, a large enhancement of the silicon oxidation was observed with formation of high oxidation states such as Si³⁺. Thermal annealing to low temperatures resulted in the formation of a SiO₂-Si interface with subsequent complete desorption of the alkali metal.