c-Axis parallel ZnO piezoelectric multilayer for BAW gyroscope applications

We presented a new type of gyroscope sensor using the transmission-and-detection type gyroscope sensor with the acoustic delay line. Detecting the pure shear wave can be achieved by using c-axis parallel ZnO films. c-Axis parallel ZnO films can be fabricated by using the ion beam assisted RF magnetron sputtering because c-axis in-plane detection of the top layer and bottom layer can be controlled to be vertical by the technique. In this paper, we propose that the piezoelectric thin films composed of c-axis parallel ZnO films show a shear mode electromechanical coupling coefficient $k_{15^{2}}$ of 2.0%, and especially, the pure shear wave excitation was observed in the gyroscope sensor.