Investigation of layered SAW sensors based on a WO3/ZNO/64° YX LiNbO3 structure with gold catalytic layer

A layered Surface Acoustic Wave (SAW) hydrogen gas sensor, based on a delay line structure with 64 finger pairs on input and output port, is fabricated on 64 degrees Y-cut, X-propagating, LiNbO3 substrate. A guiding layer of ZnO is used to increase the sensitivity of the structure. A WO3 selective layer is employed to H-2 gas sensing applications at different operating temperatures between room temperature and 300 degrees C. In this paper, the fabrication process of WO3/ZnO/64 degrees YX LiNbO3 sensor is described and the sensor's response features are analyzed. The improvement of the response with the addition of a gold catalytic layer on the sensor surface is also investigated.