Synthesis and Characterization of Semiconductor Composites Gas Sensors Based on ZnO Doped TiO2 Thin Films by Laser-Induced Plasma

This work presents the development of n-type (TiO2) and p-type (ZnO) gas-sensitive materials from ZnO doped TiO2 thin films prepared by pulsed laser deposition technique (PLD) on a glass substrate as a gas sensor of CO2 gas. TiO2 gas-sensing layers have been deposited over a range of ZnO content (0, 20, and 40) wt %. The obtained thin films analysis by atomic force microscopy (AFM), and X-ray diffraction (XRD). Electrical characterization shows that TiO2:ZnO thin films were p-type conductivity and ZnO added was unable to change the composition to the n-type conductivity. There are notable gas-sensing response differences between n-type and p-type ZnO doped TiO2 thin film. The responses toward all tested oxidizing gases tend to increase with operating temperature for the n-type TiO2 films. Besides, the p-type ZnO doping results in a significant response improvement toward tested oxidizing gases such as CO2 gas at the low operating temperature of 60 °C.