Enhanced coupling factor of surface acoustic wave devices employing ScAlN/diamond layered structure with embedded electrodes

• We model the layered structure ScAlN/diamond configured with embedded electrodes, which offers dramatically enhanced coupling factor.
• The influences of various ScAlN thickness and different electrode thickness as well as electrode materials on K2 are investigated.

A layered structure ScAlN/diamond configured with embedded electrodes is studied for high frequency and wide band SAW devices. Theoretical studies are performed to calculate the phase velocity and K2 dispersion curves of the Rayleigh mode and its higher modes. The influences of various ScAlN film thickness and electrode thickness as well as different electrode materials on K2 are also investigated. The maximum electromechanical coupling factor (K2) of surface acoustic wave (SAW) resonator based on such structure has been theoretically shown up to be 14.5%, which is about 2.5 times larger than the previously reported. Such an enhancement of K2 makes this layered structure great potential application to ultrawide band SAW filters operating in 2–3 GHz range.

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