Bilayered tin oxide:zirconia thin film as a humidity sensor

Humidity sensing properties of a material having a tandem of nanoscale thin film of zirconia on tin oxide has been demonstrated. The ZrO2 film is deposited by a recently developed technique of liquid–liquid interface reaction technique (LLIRT) while SnO2 is deposited by the conventional spray pyrolysis technique. Both SnO2 and ZrO2 thin films show sensitivity towards humidity, however, during the cyclic variation of relative humidity between 30 and 90% relative humidity, hysteresis is observed in the plot of resistance versus relative humidity, which is a disadvantage of humidity sensor application. Our preliminary results suggest that the zirconation of SnO2 thin film minimises the hysteresis thus improving its scope for humidity sensor application.