A La2O3 Nanoparticle SO2 Gas Sensor that Uses a ZnO Thin Film and Au Adsorption

This study uses ultrasonic wave grinding technology to produce La2O3 nanoparticles (La2O3-NPs). The TEM results show that the average diameter of these La2O3-NPs is approximately 20 nm. Au nanoparticles are adsorbed onto La2O3-NPs surfaces and integrated with a microelectromechanical systems (MEMS) structure to construct an Au/La2O3-NPs/ZnO/MEMS SO2 gas sensor. The average diameter of the Au nanoparticles is about 5 nm. In a 300-ppb SO2 gas ambience, the Au/La2O3-NPs/ZnO/MEMS gas sensor exhibits a greater sensor response than a ZnO/MEMS gas sensor or a La2O3-NPs/MEMS gas sensor. The experimental results show the ZnO thin film acts as a path for electron transport. As the concentration of the SO2 gas increases, the sensor response increases. The sensor is also more sensitive to SO2 gas than to CO2, CO or NO2 gases if 300 ppb of SO2 gas is introduced at the operating temperature of 260 °C.