Oxygen adsorption on Ge(111) surface: I. Atomic clean surface

Oxygen adsorption on a clean Ge(111) surface has been studied in the temperature range 300–560 K by means of Auger electron spectroscopy (AES), thermal desorption (TD), work function (WF) measurements, and electron energy loss spectroscopy (ELS). The adsorption and WF kinetics at 300 K exhibit a shape different from those observed at higher adsorption temperatures. At 300 K oxygen only removes the empty dangling bond surface state, whereas at higher temperature new loss transitions involving chemically shifted Ge 3d core levels appear. The findings imply that at 300 K only a chemisorption oxygen state exists on the Ge(111) surface whereas the formation of an oxide phase requires higher temperatures. The shapes of the TD curves show that the desorption of GeO follows $\text{1}\text{2}$ order desorption kinetics.