Thermal treatment stabilization processes in SnO2 thin films catalyzed with Au and Pt

We examined the thermal treatment stabilization processes in SnO 2-based thin films for gas-sensing applications in order to understand their influence on structural properties and possible relations with functional behavior of the sensors. The films of SnO2 were deposited by magnetron sputtering, following the rules of the rheothaxial growth and thermal oxidation (RGTO) technique and annealed in humid synthetic air at 600 °C. Afterward, a thin overlayer of gold or platinum was deposited on the oxidized films. The samples were characterized soon after catalyzer deposition and after one-hour aging process at 400 °C, in order to evaluate stabilization process influence as a function of catalyzer. The experiments of X-ray photoelectron spectroscopy (XPS) and scanning tunnelling microscopy (STM) demonstrated that a short aging affects the microstructure of gold-catalyzed samples, while it does not influence platinum catalyzed ones. The results of the microstructural characterization were confirmed by electrical measurements of gas-sensitivity: the short-aging influences the stability of gas-sensing parameters only in gold-catalyzed samples.