GAS-SENSING APPLICATIONS OF W-TI-O-BASED NANOSIZED THIN-FILMS PREPARED BY RF REACTIVE SPUTTERING

Thin films were obtained by r.f. reactive sputtering from a T-0.1-W-0. 9 target followed by heating in dry air. Their morphological and struc tural characteristics were studied by means of electron-microscopy tec hniques. Annealing at 600 degrees C of a sample leads to a WO3 polycry stalline thin-film. A solution of Ti ions in the WO3 lattice causes th e film to have higher surface-to-volume ratio and thereby higher gas-s ensitivity with respect to pure WO3, sputtered thin films. This layer is highly sensitive to NO2 as concentrations lower than I ppm of NO2 a re detected. Annealing the film at 800 degrees C results in a TiO2-ana tase nanostructured layer which is capable to detect few ppm of NO2 in dry air within the temperature range of 350-800 degrees C. (C) 1997 E lsevier Science S.A.