WO3 SPUTTERED THIN-FILMS FOR NOX MONITORING

We present in this paper preliminary results concerning the preparatio n of tungsten trioxide thin films by reactive sputtering, the characte rization either of their structural properties by means of XRD measure ments or of the film morphology with the AFM microscope and the electr ical 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 r espect to interfering gases like CH4, CO and SO2 in the same temperatu re range.