Nanoscale cobalt oxides thin films obtained by CVD and sol-gel routes

The effect of the preparation procedure on the structure and properties of nanoscale systems constitutes an interesting starting point for the preparation of advanced materials for functional applications. In this work, cobalt oxides nanocrystalline thin films were synthesized by the Chemical Vapor Deposition and sol-gel routes. In the first case, a Co(II) β-diketonate was employed as source compound in an oxygen atmosphere, whereas the sol-gel films were obtained by dip-coating from alcoholic solutions of cobalt acetate. The films were deposited on glassy substrates (SiO2, Indium Tin Oxide) and subsequently annealed in different conditions in order to tailor their composition from CoO to Co3O4 by a proper combination of the synthesis parameters and thermal treatments. The microstructure of the samples was studied by X-ray Diffraction (XRD) and optical absorption, while their surface and in-depth chemical composition was analyzed by X-ray Photoelectron (XPS) and (XE-AES) techniques. Atomic Force Microscopy (AFM) was employed to analyze the surface morphology of the films. Particular emphasis was given to the influence of the preparation route on the system features by a comparison of the results obtained by the two synthetic approaches.