High frequency Lamb wave device composed of LiNbO3 thin film

The Lamb wave type of high frequency resonator was proposed. But any Lamb wave resonator operating really above 3 GHz, which is difficult to be realized with conventional surface acoustic wave (SAW), have been not reported. Authors have tried to realize the high frequency device by using A₁ mode of Lamb wave propagating in the X-axis direction on Z-cut thin LiNbO₃ film deposited by chemical vapor deposition system (CVD) having high velocity and high electromechanical coupling factor. As the result, authors have realized a 4.5 GHz high frequency Lamb wave resonator with high velocity of 14,000 m/s, large impedance ratio of 52 dB, and wide bandwidth of 7.2 % composed of thin LiNbO₃ epitaxial film/air-gap/substrate for the first time. Also it is found that the thin LiNbO₃ film is twined crystal. It is confirmed theoretically and experimentally that the spurious responses such as SH₀ mode can not be excited because of twined crystal effect.