Enhancement of effective electromechanical coupling factor by mass loading in layered SAW device structures

This paper describes drastic enhancement of K e 2 by mass loading in layered SAW device structures such as the ScAlN film/Si substrate. It is shown that this phenomenon is obvious even when an amorphous SiO 2 film is deposited on the top surface for temperature compensation. This enhancement is caused by SAW energy confinement to the top surface of the ScAlN layer where the IDT is placed. This K e 2 enhancement is also found when other electrode and/or substrate materials are employed.