Love-mode surface acoustic wave devices based on multilayers of TeO₂/ZnO(112¯0)/Si(100) with high sensitivity and...

A multilayer structure of TeO₂/interdigital transducers (IDTs)/ZnO(112¯0)/Si(100) 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 (h_ZnO/λ) and TeO₂ (h_TeO2/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(100), but also enhances the sensitivity of the love mode device. The optimal normalized thickness ratios were identified to be h_TeO2/λ=0.021 and h_ZnO/λ=0.304, and the devices with such structures can which generate a normalized sensitivity of -1.04×10^-3m³/kg, a TCD of 0.009ppm/°C, and a K² value of 2.76%.