Design and fabrication of TiO2 thin films oxygen sensors

In this paper, we investigated the sensing properties of oxygen gas sensors in which the nanostructured TiO₂ thin films buried with Pd layer serve as the semiconducting materials. The nanostructured titania thin films for O₂ sensors were prepared with the sol-gel process by using the Ti butoxide-derived sol and were processed by heat-treatment at 500 °C. The TiO₂ square board with an area of 350 μm × 350 μm was prepared by wet etching. On the square board, 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer were fabricated by lift-off process. X-ray diffraction(XRD) analysis of TiO₂ film results indicated the crystal phase of TiO₂ thin films was anatase, and SEM observation showed the average size of TiO₂ thin films buried with Pd layer crystals were decreased compared with the pure TiO₂ thin films. Electric resistance of the O₂ sensor was monitored to evaluate its performance and the results showed that the sensor outputs stable signal with good response properties.