High-Frequency Lamb Wave Device Composed of LiNbO3Thin Film

It has been considered that it is difficult to realize a high-frequency device of 3 GHz or more, for instance, for a fourth generation mobile phone system in Japan, using a conventional surface acoustic wave (SAW) substrate. In this study, we attempted to fabricate a high-frequency resonator using Lamb waves, which has a high velocity and consists of a thin LiNbO3 film deposited by chemical vapor deposition (CVD). As a result, a 1-port Lamb wave resonator composed of an electrode/thin epitaxial LiNbO3 film/air-gap/base substrate was fabricated. The measured resonator has a high resonant frequency of 4.5 GHz, which corresponds to a very high velocity of 14,000 m/s, a large impedance ratio of 52 dB, and a relatively wide bandwidth of 7.2%.