Theorectical Investigation Of Longitudinal Surface Acoustic Waves In Rotated Y-Cut Linbo3/Sic Heterostructures

A longitudinal surface acoustic wave (LSAW) mode with higher phase velocity and without energy leakage is found in Y-cut LiNbO3/SiC heterostructure when both short-circuit phase velocity (Vsc) and open-circuit phase velocity (Voc) are lower than the phase velocity of slow shear bulk wave (SSBW) in SiC. The excitation and characteristics of the LSAW mode are influenced by the LiNbO3 cut angles, the LiNbO3 thickness, the electrode thickness and the electrode metallization. High K-2 of 18.75% and phase velocity of 6320m/s for the LSAW is obtained when the Euler angle of LiNbO3 thin film is (0 degrees, -53 degrees, 47 degrees), the thickness of LiNbO3 is 0.32X, the Al electrode thickness is 0.06X, and the electrode metallization ratio is 0.5. The proposed LSAW mode in Y-cut LiNbO3/SiC structure shows great potential in high-frequency and wide-band SAW filters application.