Properties of LiNbOs₃ thin film deposited by chemical vapor deposition and frequency characteristics of film bulk acoustic wave resonator

We have realized the fabrication of a film bulk acoustic wave resonator (FBAR) using a thin LiNbOs film deposited by chemical vapor deposition (CVD) for the first time. As a result, a 2.9 GHz FBAR with an impedance ratio of 40 dB at resonant (fr) and antiresonant (f_a) frequencies was realized. The LiNbO₃ film has a mixed polarity. As a result of scanning nonlinear dielectric microscopy (SNDM), -c domains and +c domains occupy 82 and 18% of the LiNbO₃ film, respectively. A shear mode was not excited on the fabricated FABR. According to a calculation, it is found that the shear wave mode can be suppressed by selecting the thickness of electrodes without any changes in the main responses of the longitudinal mode wave. It is important to deposit another oriented LiNbO₃ film with a larger coupling factor to realize a wider-band device.