Electrochemical and Surface Characteristics of Tin Oxide and Indium Oxide Electrodes

The electrochemical characteristics of heavily doped tin oxide and indium oxide thin film electrodes have been correlated with results of surface analyses by x-ray photoelectron (ESCA) and Auger spectroscopy. From measurement of current, capacitance, and surface conductance as a function of the applied electrode potential, regions of potential where surface reactions were possibly occurring could be delineated. ESCA/Auger analyses of these electrodes, which were poised in various potential regions, confirmed the changes in the stoichiometry of the metal oxides at the surface. Similar analyses were performed on tin oxide surfaces which had been modified by derivatization of the surface. Such modifications resulted in the lowering of the effective carrier density of the surface. Depth and extent of coverage of these modified electrodes could be inferred from the Auger analysis coupled with argon ion sputtering of the surface.