Propagation Characteristics of Surface Acoustic Waves in KNbO₃/SrTiO₃/Si Layered Structures

The propagation characteristics of surface acoustic waves (SAWs) in KNObO 3 /SrTiO 3 /Si structures were investigated theoretically. Phase velocities ( v p ) decrease when the h K value of the SrTiO 3 buffer layer increases from 0.04 to 0.2 for a specified thickness of the KNbO 3 film. The value of the coupling coefficient ( K 2 ) can be as high as 10%. A layered structure with the interdigital transducer (IDT) located on top of the KNbO 3 film is a better choice for device fabrication if we select a coupling coefficient of 1% as a reference for comparison. The results could provide useful information for combining optical devices, semiconductor devices and SAW devices on the same Si substrate.