C-Band Lithium Niobate on Silicon Carbide SAW Resonator With Figure-of-Merit of 124 at 6.5 GHz

In this work, we demonstrate a C-band shear-horizontal surface acoustic wave (SH-SAW) resonator with high electromechanical coupling (
${k}_{\mathbf{t}}^{\mathbf{2}})$
of 22% and a quality factor (
$Q)$
of 565 based on a thin-film lithium niobate (LN) on silicon carbide (SiC) platform, featuring an excellent figure-of-merit (FoM
$=$

${k}_{\mathbf{t}}^{\mathbf{2}}\cdot Q_{{max}})$
of 124 at 6.5 GHz, the highest FoM reported in this frequency range. The resonator frequency upscaling is achieved through wavelength (
$\lambda )$
reduction and the use of thin aluminum (Al) electrodes. The LN/SiC waveguide and synchronous resonator design collectively enable effective acoustic energy confinement for a high FoM, even when the normalized thickness of LN approaches a scale of 0.5
$\lambda $
to 1
$\lambda $
. To perform a comprehensive study, we also designed and fabricated five additional resonators, expanding the
$\lambda $
studied ranging from 480 to 800 nm, in the same 500 nm-thick transferred Y-cut thin-film LN on SiC. The fabricated SH-SAW resonators, operating from 5 to 8 GHz, experimentally demonstrate a
${k}_{\mathbf{t}}^{\mathbf{2}}$
from 20.3% to 22.9% and a
$Q$
from 350 to 575, thereby covering the entire C-band with excellent performance.2024-0070