Depth profile analysis of native oxide layer on GaAs (100) surface

Ar + ion etching and X-ray photoelectron spectroscopy (XPS)depth profile analysis have been performed on the native oxide layerof GaAs(100) surface. The composition of the native oxide layer,that isthe oxide phases of gallium and arsenic, was characterized precisely. It is indicated that native oxide phases on extreme surface of GaAs(100) consist of a mixture of Ga 2 O 3 , As 2 O 3 and As 2 O 5 . Furthermore, the respective distribution of oxide phases of gallium and arsenic along the depthwere compared and analyzed.A seemingly contradictory phenomenon was found, that is As enrichment exist in total oxide layer, but the content of Ga oxide was greater than that of As oxide in the oxide layer except for the outmost surface layer.Based on the comprehensive influence of oxidation process, etching, segregation and growth process, the intrinsic mechanism of the change of oxides along etching depth was discussed. According to the analyzed results, the oxide layer of GaAs (100) surface should be divided to two layers,that is the outmost layer containing oxides of Ga and As and the intermediate layer including only oxide of Ga.The concentration of As oxides in the outmost layer and the enrichment of As in total oxide layer are derived from surface structure inhomogeneity. The throughout total oxide layer of Ga oxide is attributed to its stronger oxidability.In the present work, the system study for native oxide layer of GaAs surface provides the powerful foundation for understanding surface state of GaAs and surface treatment.