Structural Characterization of Tin and Molybdenum Oxides Thin Films Deposited by RGTO

In this paper the oxidation process of Sn/Mo mixed oxides for sensing applications was explored with the aim of investigating the structural properties of these materials and eventually understanding possible relations with functional behaviors. The films were deposited by sputtering following the rules of RGTO (rheothaxial growth and thermal oxidation) and annealed in humid synthetic air at 500, 600, and 700 °C. This is the first time that those materials are deposited by the RGTO technique. The characterization was performed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), glancing incidence X-ray diffraction (GIXRD), and micro-Raman mapping. It is shown that because of the fabrication process, as a function of the annealing temperature, an addition of a molybdenum layer on tin films determined the formation of oxides species different from that occurring on pure tin films. The Mo content in films treated at 600 and 700 °C decreased, probably because of the molybdenum oxides evaporation.