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 3lambda/2 to obtain negligible surface displacement. In the same way, the ZnO thickness for a fixed value of AlN thickness at 2lambda must be larger than lambda/4 to confine the acoustic wave. The electromechanical coupling of the wave presents an optimum around lambda/2 for the ZnO layer thickness. A first experimental AlN/ZnO/diamond device has been developed and shows the WLAW at 412 MHz.