XPS study of residual oxide layers on p-GaAs surfaces

The total thickness and composition of a residual oxide layer after chemical etching of p-GaAs:Zn + In has been studied by X-ray photoelectron spectroscopy (XPS). The variation of the Ga to As oxides ratio along the depth has been determined. A concentration correlation of doping isovalent impurity and the dislocation density with the composition of residual oxides is looked for. The total thickness of the residual oxide layer on p- and semi-insulating GaAs is about 5–6 Å. It is found that the Ga₂O₃ quantity in the oxide bulk is greater than the same value of As₂O₃ in highly In-doped samples. In-doping in concentrations over 1.5 × 10¹⁹ cm^?3 increases the Ga₂O₃ content and the density of the residual oxide. This influence is determined by reducing the dislocation density and changing the point defect environment. The presence of As-rich precipitates on the dislocations and in the matrix decreases the sputtering time and changes the composition of the residual oxide. The correlation between the type of high temperature dislocations revealed by Abrahams-Buiocchi (AB) etching and the oxide layer composition is shown. The results obtained could be used in the first stages of epitaxial growth, metallization and other technological processes of semiconductor device and ICs fabrication.