AlN/ZnO/diamond waveguiding layer acoustic wave structure: Theoretical and experimental results

We present a theoretical calculation and experimental results for a waveguiding layer acoustic wave (WLAW). The experimental device is modeled by the finite element method (FEM) for the AlN/ZnO/diamond structure. It was found that the AlN thickness must be at least larger than 3λ/2 to obtain negligible surface displacement. In the same way, the ZnO thickness for a fixed value of AlN thickness at 2λ must be larger than λ/4 to confine the acoustic wave. The electromechanical coupling of the wave presents an optimum around λ/2 for the ZnO layer thickness. A first experimental AlN/ZnO/diamond device has been developed and shows the WLAW at 412 MHz.