Highly sensitive SnO2 thin film with low operating temperature prepared by sol–gel technique

Sol–gel dip coating technique was employed to prepare Cu-doped SnO2 thin films, which were able to detect H2S gas at room temperature with high sensitivity and revealed fast response characteristics. The highest sensor response (the ratio of resistance in air versus in H2S) was 3648 under H2S concentration of 68.5 ppm at room temperature. Recoverability of the thin films appeared when the temperature raised to 50 °C. The films were analyzed by means of XRD and the dried gel powder was studied by TG-DTA test. Influences of sintering temperature and doping level on the H2S response are discussed. The average grain size of the SnO2 was about 25 nm.