SURFACE ACOUSTIC WAVE H2 SENSOR ON SILICON SUBSTRATE

A surface acoustic wave (SAW) hydrogen sensor implemented on a silicon (Si) substrate is presented.The device is based on the changes produced in the phase velocity of SAWS propagating along a multilayered Pd/ZnO/Si02 /Si structure, by H2 absorption and desorption in the selectively sorbent Pd film. Several devices have been made and tested. The time response and the sensitivity of the devices, upon exposure to different concentration of HZ in N2 are reported for two different values of the thickness of the Pd film. The frequency of operation, the electrical performances of the device as well as the fabrication technology involved have been optimized in view of a future integration of the electroacoustic structure and of the electric signal processing circuitry on the same Si substrate.