Polarization-inverted multilayered pure shear mode AlN film resonator

c-axis parallel AlN film is suitable for pure shear mode devices. Polarization-inverted multilayered structure can excite high order mode resonance. The film thickness of high order mode resonator is thicker than that of fundamental mode resonator in same operating frequency. Therefore, the multilayered resonator is expected to have high power handling capability. c-axis parallel polarization-inverted multilayered AlN films were fabricated by ion beam assisted deposition (IBAD). caxis parallel orientation was formed under the 3 kV accelerated ion beam irradiation. Shear mode resonator was prepared to investigate piezoelectric properties of the film. Only pure shear wave without any longitudinal wave was excited in the resonators. k15 was determined to be 0.05 and this value is 71 % of the single crystalline AlN. We considered that in-plane crystal growth direction should to be determined by the ion beam irradiation direction. c-axis parallel multilayer AlN film was fabricated by inverting in-plane beam irradiation direction. High order mode resonance was observed in the resonators, showing that polarization was inverted in the multilayer AlN films.