TiO2 thin film gas sensor for monitoring ammonia

Systematic development and mechanistic studies of sensing materials are critical to the design of higher performance gas sensing elements and arrays. Polycrystalline metal-oxide semiconductors such as SnO2 and TiO2 are among the most widely used materials for thin film-based conductometric gas sensors. The mechanistic steps responsible for the gas-induced conductance changes of polycrystalline metal-oxide sensors have been investigated. Results are presented for TiO2 gas sensing films. The TiO2 films experience an increase in conductance upon exposure to ammonia. Reduction of surface oxygen is proposed as the dominant mechanism for the increase in conductance in TiO2 sensing films upon exposure to ammonia. Here TiO2 films of low thickness prepared using DC magnetron sputtering were employed for sensing applications. A suitable operating temperature, sensitivity, response and recovery time of the TiO2 thin film gas sensor was studied for sensing ammonia.