ULTRATHIN FE FILMS ON TIO2(110) - GROWTH AND REACTIVITY

As part of a systematic study of metals on oxides, we report here a study of the growth of Fe films on TiO2(110) surfaces using low-energy ion scattering and x-ray photoelectron spectroscopy (XPS). Our studies reveal that Fe grows initially in an island growth mode, and completely covers the TiO2 substrate for thicknesses of a few monolayers. XPS shows evidence for a strong interaction between Fe films and the oxide substrate, i.e., oxidation of Fe overlayers and reduction of the oxide substrate, at submonolayer thickness. Comparing the wetting ability of Fe with that of Cu, a less reactive metal, and with that of Cr, a more reactive metal, we observe a relation between the wetting ability of the metal films and the reactivity of metal with oxygen. Complete coverage of the TiO2 substrate can be obtained for a 1 monolayer Fe film following oxidation of the film. Studies of Fe film growth on sputtered TiO2 surfaces indicate that surface roughness also plays an important role in the morphology of the metal films.