The Effect of Catalytic Metal Contact and Surface Modification on Hydrogen Sensing Performance of Nano WO3/SiO2/Si Sensor

A sol–gel derived nano WO3/SiO2/Si device has been fabricated. Pure and Pd-surface modified Tungsten trioxide (WO3) sensors have been investigated for hydrogen sensing. The device with three different contact metals (Pd–Ag contacts on WO3 side and Au contacts on WO3 side, Al contacts on WO3 side) has been studied at different operating temperatures (150°C-300 °C) for varying concentrations of hydrogen (0.01%, 0.05%, 0.1%, 0.5%, 1.0%). The material properties of the sensor have been investigated by the X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. The Stability curve of Pd-surface modified WO3 thin film hydrogen sensor with suitable contacts has also been studied. Pd-surface modified sensor presents much lower operating temperature than that of unmodified ones. It has been examined that the Pd-surface modified device with Pd–Ag (70%) contacts presents higher response magnitudecompared to unmodified WO3 sensor.