Lateral-field-excitation properties of LiNbO3 single crystal

LiNbO₃ has been found attractive for lateral field excitation (LFE) applications due to its high piezoelectric coupling. In this paper, bulk acoustic wave propagation properties for LiNbO₃ single crystal excited by a lateral electric field have been investigated using the extended Christoffel--Bechmann method. It is found that the LFE piezoelectric coupling factor for c mode reaches its maximum value of 95.46% when ψ = 0° for both (yxl)-58° and (yxwl)± 60°/58° LiNbO₃. The acoustic wave phase velocity of c mode TSM (thickness shear mode) changes from 3456m/s to 3983 m/s as a function of ψ. Here ψ represents the angle between the lateral electric field and the crystallographic X-axis in the substrate major surface. A 5MHz LFE device of (yxl)-58° LiNbO₃ with ψ=0° was designed and tested in air. A major resonance peak was observed with the motional resistance as low as 17Ω and the Q-factor value up to 10353. The test result is well in agreement with the theoretical analysis, and suggests that the LFE LiNbO₃ device can be a good platform for high performance resonator or sensor applications.