XPS in-situ investigation of GaAs oxidation in glow discharge plasma

The work is devoted to investigation of early stages of GaAs oxidation in glow discharge plasma, using X-ray photoelectron spectroscopy (XPS) in-situ. The chemical composition and oxide film thickness were measured at different stages of oxidation without exposition of the sample to laboratory atmosphere. After plasma activation a two layer oxide film is formed on the preliminary cleaned GaAs surface. The down layer consists of a superposition of As and In oxides and is characterized by complex dependence of film thickness on plasma oxidation time. The upper layer is a cathode material (aluminum) oxide. Its thickness rises quasilinear on the time with the rate 0.03 nm/min. The growing aluminum oxide film is a barrier for oxygen diffusion to the GaAs substrate. This film prevents the semiconductor oxidation in the following time of plasma treatment.