Investigation of lateral-field-excitation on LiTaO3 single crystal

Lateral field excitation (LFE) acoustic wave devices, which employ two electrodes on the same surface of a piezoelectric substrate, have been found attractive in sensing applications. However, up to now, the cut for the pure-LFE mode of LiTaO3 is still unknown, which has hindered the application of LiTaO3 pure-LFE mode device in liquid phase sensing. In this work, pure-LFE on LiTaO3 was investigated both theoretically and experimentally. The calculated results showed that when the driving electric field direction is parallel to the crystallographic X-axis of the piezoelectric substrate, (yxl)90° LiTaO3 LFE device works on pure-LFE mode with a piezoelectric coupling factor of 44.52% for slow shear c mode of LFE. The devices' impedance curves were measured. The experimental results agreed with the theoretical prediction well.