Love-mode surface acoustic wave devices based on multilayers of TeO 2 /ZnO(112¯0)/Si(100) with high sensitivity and temperature stability.

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 (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(100), 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 0.009ppm/°C, and a K2 value of 2.76%.