SAW-based gas sensors with RF sputtered InOx and PECVD SiNx films: response to H2 and O3 gases

Surface acoustic wave (SAW)-based sensors, with InOx and SiNx layers on 36 degrees YX LiTaO3 substrates were investigated for the detection of hydrogen (H-2) and ozone (O-3) gases at different operating temperatures. SiNx films with different thicknesses were deposited using the plasma enhanced chemical vapour deposition (PECVD) method. The InOx sensing layer was deposited using an rf magnetron sputterer. The sensors' performance was analyzed in terms of their frequency shifts as a function of different gas concentrations. The chemical-physical characterization of the deposited films was carried out by X-ray photoelectron spectroscopy (XPS). High sensitivities and excellent repeatabilities were observed towards both gases.