Ultraviolet Photoelectron Spectroscopy Study Of Oxygen Adsorption On Rb-Covered Insb (111) Surfaces

Oxygen adsorption on Rb-covered InSb(111) surface has been studied at room temperature as a function of Rb coverage using ultraviolet photoelectron spectroscopy. At low O-2 exposures, the intensity ratio of O-2(2-) to O2- increases with nb coverage. The surfaces with low Rb coverages are mainly covered by Sb oxides, causing an increase of work function. For high Rb coverages, the Sb atoms are oxidized below a thin layer of Rb peroxide, which is related to an initial decrease of the work function. At high O-2 exposures, the intensity of O-2(-) ion increases with Rb coverage.