Isolated acoustic wave based on AlN/ZnO/diamond structure for sensor applications

We present a theoretical calculation and experimental results for an isolated acoustic wave. The experimental device is modeled by finite element method (FEM) for the structure AlN/ZnO/diamond. The phase velocity in the AlN/ZnO/diamond structure was investigated by theoretical calculations. It was found that the AlN thickness must be at least more than 3lambda/2 to obtain a negligible surface displacement. In the same way the ZnO thickness for a fixed value of AlN at 2lambda must be higher than lambda/4 to confine the acoustic wave. The coupling of the wave presents an optimum around lambda/2 for the ZnO layer thichness.