Theoretical analysis of SAW propagation characteristics in (100) oriented AlN/diamond structure

The surface acoustic waves (SAWs) propagating in interdigital transducer (IDT)/(100) aluminum nitride (AlN)/diamond possess the greater phase velocity and coupling coefficient than those in IDT/(002) AlN/diamond. In this study, the finite element method (FEM) is employed to calculate SAW characteristics in these two layered structures with different electric interfaces; i.e., IDT/AlN/diamond, AlN/IDT/diamond, IDT/AlN/thin metal film/diamond, and thin metal film /AlN/IDT/diamond. The effects of Cu and Al electrodes on SAW characteristics are illustrated. Simulation results show that the Cu IDT/(100) AlN/diamond structure can support a SAW with a coupling coefficient of 1.71%, a phase velocity of 9705 m/s, and a reflectivity of 0.15, which is applicable for the miniaturized wideband and super high band applications.