XPS STUDY OF RESIDUAL OXIDE LAYERS ON P-GAAS SURFACES

The total thickness and composition of a residual oxide layer after ch emical etching of p-GaAs:Zn + In has been studied by X-ray photoelectr on spectroscopy (XPS). The variation of the Ga to As oxides ratio alon g the depth has been determined. A concentration correlation of doping isovalent impurity and the dislocation density with the composition o f residual oxides is looked for. The total thickness of the residual o xide layer on p- and semi-insulating GaAs is about 5-6 Angstrom. It is found that the Ga2O3 quantity in the oxide bulk is greater than the s ame value of As2O3 in highly In-doped samples. In-doping in concentrat ions over 1.5 x 10(19) cm(-3) increases the Ga2O3 content and the dens ity of the residual oxide. This influence is determined by reducing th e dislocation density and changing the point defect environment. The p resence of As-rich precipitates on the dislocations and in the matrix decreases the sputtering time and changes the composition of the resid ual oxide. The correlation between the type of high temperature disloc ations 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 proc esses of semiconductor device and ICs fabrication. (C) 1997 Elsevier S cience B.V.