Characterization of WO3 layers deposited on quartz and lithium niobate SAW resonators for the design of gas sensors

Surface acoustic wave (SAW) gas sensors generally require the use of a reactive layer for molecule adsorption. WO₃ has been identified for a long time as a high potential sensitive layer particularly for NH₃, NO_X, CO, etc. We report here on the characterization of elastic properties of such material using the dispersion behavior of SAW propagating under gratings passivated wich WO₃ films of various thicknesses. Quartz as well as LiNbO₃ SAW devices are used in that purpose, allowing for the derivation of a reliable data set. Complementary structural characterization using direct measurement techniques (DRX, AFM, TEM,) are reported to confirm the analysis deduced from SAW measurements. As a conclusion, the exploitation of WO₃ for SAW-based sensor is discussed.