Synchrotron-induced photoemission of GaAs electrodes after electrochemical treatment in aqueous electrolytes

Electrochemically-induced oxidation and reduction reactions of UHV-cleaved GaAs(110) surfaces have been studied after emersion under potential control using high resolution synchrotron-induced photoelectron spectroscopy. High quality spectra of the As and Ga core 3d lines and the valence band region have been obtained. The spectra of the anodic oxide show strong emission of bulk-like Ga(2)O(3) and some As(2)O(3) with the admixture of suboxides and hydroxides. Ga(2)O(3) and As(2)O(3) are cathodically reduced leaving the GaAs surface covered mostly with elemental As, some As-H and remnants of Ga-suboxides and -hydroxides.