Chemical Reactivity at the Ti/CoO Interface as Investigated by X-ray Photoelectron Spectroscopy

The chemical reactivity at the Ti/CoO interface has been investigated. Thin films of cobalt deposited on silicon substrate were oxidized in vacuum. Such an oxidation results in the formation of the CoO phase. Thin films of titanium were then deposited on such CoO substrates kept at room temperature. The technique of X-ray photoelectron spectroscopy has been used for the characterization of the constituents present at the interface. The 2p core levels of cobalt and titanium have been investigated. Chemical reactivity has been found to occur at the interface. The cobalt oxide was observed to get reduced to elemental cobalt, while the titanium overlayer was observed to get oxidized. A mixture of titanium dioxide and titanium-suboxides were found to be present at the interface. An increasing amount of unreacted titanium was observed as the thickness of the overlayer was increased. The results on the chemical reactivity as a function of the thickness of the titanium overlayer and the substrate temperature will be presented.