Surface electrical charge and field analysis of single-electrode type interdigital transducers with bus-bar

摘要

A single-electrode type interdigital transducer (SIDT) is extensively used to excite surface acoustic waves (SAWs) on piezoelectric substrates because of its simple structure and fabrication process. In a SIDT a bus-bar is used for feeding in electrical voltage. However, systematic analyses about bus-bar effects of SIDT are still sparse among the existing studies concerning the propagation of acoustic wave of SIDT. In this paper, a two-dimensional interface Green's function method is adopted for calculating the electrical charge density on the electrode surfaces and acoustic wave fields in a Y-cut Z-propagation LiNbO3 substrate excited by SIDTs with a bus-bar. The computation results show that the charge density associated with SAW cannot be neglected; the bus-bar has essential effects on the excited SAW fields and the SAW field generally diverges strongly due to the influence of the bus-bar. Approaches for reducing this effect are discussed.