Abstract
The desirable electrical properties of InOX thin films and their response towards oxidizing gases has promoted InOX to be recognized as a promising material for gas sensors. In this study, InOX films in the thickness range of 10-1000 nm were deposited onto Coming 7059 glass substrates by dc magnetron sputtering. Their structural, electrical, and O-3 and NO2 sensing properties were analyzed. Structural investigations carried out by XRD and AFM showed a strong correlation between crystallinity, surface topology and gas sensitivity. Moreover, the electrical conductivity exhibited a change of over six orders of magnitude during the processes of photoreduction and oxidation. The films deposited on alumina transducers were calibrated towards O-3 and NO2 at temperatures from 50-300 degreesC. The sensors show promising characteristics as they exhibited reproducible and stable responses. The 50 run thin film had a response of over 10 towards 50 ppb of ozone operating at 50degreesC, while the 20 rim film had a response of over 22 towards 0.1 ppm of NO2 at 100degreesC.