The Au, Ge, and Ni have a homogenous distribution while Ga and As tend to diffuse to the surface. Au4f, Ga3d, Ga2p, As3d, As2p, Ni2p 3/2, Ge3d, O1s, and C1s spectral lines were recorded. The atomic concentrations of the chemical elements have been approximated. About 18 sessions of ion Ar surfaces etching and intermediate XPS measurements were performed in order to reveal the border of the metal/semiconductor interface. The fresh cleaved surfaces, supposed to be free of oxygen, were usually deposited with a 200 nm metallic layer in high vacuum conditions (better than 10 −7 torr), by thermal evaporation, and annealed at a 430–450° Celsius temperature for 5 minutes.
The depth composition of the thin layer alloy, AuGeNi, devoted to acting as an ohmic contact on n-GaAs(110) has been investigated by in situ XPS combined with Argon ion sputtering techniques.
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