Love-mode surface acoustic wave devices based on multilayers of TeO2/ZnO(112¯0)/Si(1 0 0) with high sensitivity and temperature stability

A multilayer structure of TeO2/interdigital transducers (IDTs)/ZnO(112¯0)/Si(1 0 0) was proposed and investigated to achieve both high sensitivity and temperature-stability for bio-sensing applications. Dispersions of phase velocities, electromechanical coupling coefficients K2, temperature coefficient of delay (TCD) and sensitivity in the multilayer structures were simulated as functions of normalized thicknesses of ZnO (hZnO/λ) and TeO2 (hTeO2/λ) films. The fundamental mode of Love mode (LM) - surface acoustic wave (SAW) shows a larger value of K2 and higher sensitivity compared with those of the first mode. TeO2 film with a positive TCD not only compensates the temperature effect induced due to the negative TCD of ZnO(112¯0)/Si(1 0 0), but also enhances the sensitivity of the love mode device. The optimal normalized thickness ratios were identified to be hTeO2/λ = 0.021 and hZnO/λ = 0.304, and the devices with such structures can which generate a normalized sensitivity of −1.04 × 10−3 m3/kg, a TCD of 0.009 ppm/°C, and a K2 value of 2.76%.