Novel selective ethanol sensors: W/TiO2 thin films by sol–gel spin-coating

TiO2 and W-doped TiO2 thin films have been obtained by a chemically modified sol–gel technique, that implies hydrolysis and condensation of Titanium(VI) ethoxide (TEOT) (and tungsten(V) ethoxide) in the presence of a polymer dissolved in ethanol. Dopant was added in concentration that led to nominal W/Ti atomic ratio of 5/33 and 10/33. Film deposition by spin-coating was performed onto allumina substrates. Annealing at 500 °C produced nanosized structurally stable oxides films. Structural characterization of these films was made by means of glancing incidence X-ray diffraction (GIXRD). Scanning electron microscopy (SEM) cross-section images were collected and an estimation of the films thickness was obtained. W/Ti atomic ratio was determined by Rutherford back scattering (RBS) analysis. The electrical response towards ethanol and methanol (100–500 ppm) have been tested in the temperature range of 300–500 °C. Doping effects on structural and sensing properties were investigated. A comparison with the previous obtained dip-coated W/TiO2 thin films have been reported.