Microstructure and electrical properties of RuO2–CeO2 composite thin films

RuO2–CeO2 composite thin films are deposited on various Si substrates by a radiofrequency magnetron sputtering technique. Compacted polycrystalline pellets of the nanostructured CeO2–RuO2 composite system are used as standard samples for comparative electrical analyses. All films and composite samples are analyzed by X-ray diffraction and transmission electron microscopy. Electrical measurements of radiofrequency sputtering of thin films are performed as a function of the RuO2 fraction and of the temperature (between 25 and 400 °C). A nonlinear variation in the electrical conductivity of the RuO2–CeO2 composite thin films as a function of the RuO2 volume fraction (Φ) is observed and discussed. It is interpreted in terms of a power law (in (Φ − Φc)m ), where m and Φc are parameters characteristic of the distribution of the conducting phase in a composite medium.