WO3 SPUTTERED THIN-FILMS FOR NOX MONITORING

We present in this paper preliminary results concerning the preparation of tungsten trioxide thin films by reactive sputtering, the characterization either of their structural properties by means of XRD measurements or of the film morphology with the AFM microscope and the electrical response of the films towards toxic and pollutant gases. WO3 thin films showed a good sensitivity towards low NOx concentrations (1-10 ppm) in the temperature interval 200-500 degrees C and they were also sensitive to 10 ppm NH3. These films were also selective to NOx with respect to interfering gases like CH4, CO and SO2 in the same temperature range.