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.