Propagation characteristics of surface acoustic waves in KNbO3/SrTiO3/Si layered structures

The propagation characteristics of surface acoustic waves (SAWs) in KNObO(3)/SrTiO3/Si structures were investigated theoretically. Phase velocities (v(p)) decrease when the hK value of the SrTiO3 buffer layer increases from 0.01 to 0.2 for a specified thickness of the KNbO3 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 KNbO3 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.