A CORRELATION BETWEEN ELECTROCHEMICAL-BEHAVIOR, COMPOSITION AND SEMICONDUCTING PROPERTIES OF NATURALLY GROWN OXIDE-FILMS ON COPPER

Copper(I) oxide films formed under open-circuit potential in neutral a queous solutions have been characterized, using coulometry, photocurre nt spectroscopy and X-ray photo-electron spectroscopy (XPS). The reduc tion potential of the oxide layer was found to depend on the presence in the electrolyte of chloride ions, Cu(II) or Cu(I) ionic species or of a corrosion inhibitor. XPS analyses were performed on these oxide l ayers, and showed in some cases an evolution of the oxidation state of copper from +2 to +1 state throughout the film. Different conducting properties of the cuprous oxides could be demonstrated through photo-e lectrochemical measurements, and the formation of a duplex Cu2O layer with two semiconducting components of different stoichiometries was di scussed.