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\n(SH-SAW) resonator with high electromechanical coupling (kt2) of 22% and a\nquality factor (Q) of 565 based on a thin-film lithium niobate (LN) on silicon\ncarbide (SiC) platform, featuring an excellent figure-of-merit (FoM = kt2*Q )\nof 124 at 6.5 GHz, the highest FoM reported in this frequency range. The\nresonator frequency upscaling is achieved through wavelength ($\\lambda$)\nreduction and the use of thin aluminum (Al) electrodes. The LN/SiC waveguide\nand synchronous resonator design collectively enable effective acoustic energy\nconfinement for a high FoM, even when the normalized thickness of LN approaches\na scale of 0.5$\\lambda$ to 1$\\lambda$. To perform a comprehensive study, we\nalso designed and fabricated five additional resonators, expending the\n$\\lambda$ studied ranging from 480 to 800 nm, in the same 500 nm-thick\ntransferred Y-cut thin-film LN on SiC. The fabricated SH-SAW resonators,\noperating from 5 to 8 GHz, experimentally demonstrate a kt2 from 20.3% to 22.9%\nand a Q from 350 to 575, thereby covering the entire C-band with excellent\nperformance.\n