The preparation and characterization of In2O3 gas sensor sensitive to CO gas

In2O3 thin films were successfully grown on glass substrates at 20, 30, 40 and 50 SILAR cycles at room temperature by the Successive Ionic Layer Adsorption and Reaction (SILAR) method. The effect of SILAR cycle on the structural, morphological, compositional and CO gas sensing properties of the thin films were investigated by XRD, SEM, EDAX and gas measurement system, respectively. The XRD and SEM studies indicated that the thin films had polycrystalline nature with cubic phase of In2O3 and the structural and morphological properties of the thin films depended on the SILAR cycle. CO gas sensing measurements were carried out as a function of temperature and gas concentration. The sensing responses of the thin film sensors increased with operating temperature and reached to the maximum at 222 °C. The In2O3 thin film sensors exhibited high sensing responses when exposed to CO gas concentration in the range of 1-100 ppm at operating temperature of 222 °C. At the optimal operating temperature (222 °C) and 50 ppm CO gas concentration, the sensing responses of In2O3 thin film sensors with 20, 30, 40 and 50 SILAR cycle were calculated to be 47 %, 84 %, 74 % and 63 %, respectively. It was seen that the gas sensing properties of the thin film with 30 SILAR cycle were better than others.