Cs-Promoted Oxidation on GaAs（100） Surface

The adsorption behavior of oxygen on Cs-covered and clean GaAs（100） surface are studied with XPS, UPS and work function measurement. The experimental results show that the drastic enhancement of the oxidation of substrate has been observed on Cs covered GaAs（100） surface with deposition of 0.6ML. The oxygen may be located on As atoms beneath or between alkali metal atoms. With increasing the amount of exposure, the oxygen may be located on both Ga and As atoms and Ga and As could be oxided by forming Ga₂O₃ and As₂O₃.