High-Performance MEMS Oxygen Sensors Based on Au/TiO2 Films

High-performance microelectromechanical system (MEMS) oxygen sensors were realized by successful preparation of Au nanofilms over TiO2 thin films through successive sputtering on commercial MEMS microhotplates. Oxygen sensing performance of 3 and 6 nm thick Au over TiO2 thin films were compared with that of pure TiO2 thin films. It was shown that 6 nm thick Au over TiO2 thin films have the best sensitivity toward oxygen. The prepared TiO2 thin films were characterized using SEM, EDS, XPS, and a gas testing instrument. The results show that Au decoration has little influence on the surface morphologies of TiO2 thin films. However, Au decoration has a strong influence on the surface properties of the composite films. The favorable performance of 6 nm Au-doped TiO2 thin films is attributed to factors such as catalytical performance, height of Schottky contact, and number of oxygen vacancies. This work makes contributions to low power consumption and high-performance oxygen sensors for Internet of Things applications.