Surface acoustic wave characteristics of a (100) ZnO/(100) AlN/diamond structure

Abstract Propagation characteristics of surface acoustic waves (SAWs) in the (100) ZnO/interdigital transducer (IDT)/(100) AlN/diamond structure are investigated in this study. The temperature coefficient of delay (TCD), the phase velocity, and the coupling coefficient of the first three modes of SAWs for different thicknesses of (100) ZnO and (100) AlN are theoretically analyzed. Results show that the second mode (Sezawa mode) exhibits the largest coupling coefficient. In the second mode, the largest coupling coefficient of 6.05% associated with a phase velocity of 6234 m/s and a TCD of 20.9 ppm/°C can be found; for a zero TCD case, a large coupling coefficient of 5.35% associated with a phase velocity of 6460 m/s can be obtained. Those coupling coefficients and phase velocities are better than the ones in the IDT/(100) ZnO/diamond structure that possesses a large positive TCD. Simulation results indicate that the (100) ZnO/IDT/(100) AlN/diamond structure exhibits a high phase velocity, a large coupling coefficient, and a small TCD, which can be used to design the wideband and temperature-compensated SAW devices for gigahertz-band applications.