Initial stages of GaP(1 1 0) oxidation

The initial phases of the oxidation of the GaP(1 1 0) cleaved surface have been studied, by photoemission with synchrotron radiation. A first stage in which an increase in band bending occurs and a second stage in which complete saturation of dangling bonds occurs are distinguished. This result accounts for previous surface reflectance data on the same surface. The processes of band bending variation and dangling bond saturation with oxygen exposure are very similar in GaP(1 1 0) and GaAs(1 1 0).