Characterization of multi- and single-layer structure SAW sensor [gas sensor]

The design of CMOS compatible thin ZnO film base, and LiNbO/sub 3/ wafer base, surface acoustics wave (SAW) gas sensors, that are highly selective and sensitive, is described. Furthermore, design and post-CMOS processing fabrication steps that utilises micro-electro-mechanical systems (MEMS) techniques to implement the SAW gas sensor are presented. The Rayleigh wave velocity for various ZnO film thicknesses is simulated and results are presented. The velocity calculation is based on a computer simulation of a multilayer (ZnO/SiO/sub 2//Si) structure that uses wave equations. Simulation results and experimental measurements of SAW sensors with a single layer bulk LiNbO/sub 3/ wafer are shown, and compared. Moreover, results of experimentation and simulation of wave velocity for a yz-cut LiNbO/sub 3/ wafer are shown.