Response to oxygen and chemical properties of SnO2 thin-film gas sensors

The measurements of the response—in terms of the conductance changes—to oxygen adsorption of tin dioxide (SnO2) thin-film-based gas sensors were performed. The sensing SnO2 layers were obtained by means of the rheotaxial growth and thermal oxidation (RGTO) method. The sensor responses were measured under a dry gas flow containing oxygen in nitrogen, within the range of temperature from 25 to 540 °C. For comparison, similar studies were performed for a commercial SnO2 thick-film (TGS 812) gas sensor.The in-depth profiles of the chemical composition of the RGTO SnO2 layers were determined from the scanning Auger microprobe experiment. The changes in concentration ratios [O]/[Sn] and [C]/[Sn] from the near-surface region towards the grain bulk were shown.