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

• Published in: Journal of microelectromechanical systems Vol. 33; no. 5; pp. 604 - 609
• Main Authors: Hsu, Tzu-Hsuan, Campbell, Joshua, Kramer, Jack, Cho, Sinwoo, Li, Ming-Huang, Lu, Ruochen
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Admittance; C band; Figure of merit; Frequency ranges; Lithium niobate; Lithium niobates; piezoelectric; Piezoelectric devices; Resonant frequency; Resonators; Silicon carbide; Surface acoustic wave; Surface acoustic wave devices; Surface acoustic waves; thin film; Thin films; Waveguides
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2024.3423768

In this work, we demonstrate a C-band shear-horizontal surface acoustic wave (SH-SAW) resonator with high electromechanical coupling (<inline-formula> <tex-math notation="LaTeX">{k}_{\mathbf {t}}^{\mathbf {2}} </tex-math></inline-formula>) 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 <inline-formula> <tex-math notation="LaTeX">= {k}_{\mathbf {t}}^{\mathbf {2}}\cdot Q_{max} </tex-math></inline-formula>) of 124 at 6.5 GHz, the highest FoM reported in this frequency range. The resonator frequency upscaling is achieved through wavelength (<inline-formula> <tex-math notation="LaTeX">\lambda </tex-math></inline-formula>) 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 <inline-formula> <tex-math notation="LaTeX">0.5\lambda </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">1\lambda </tex-math></inline-formula>. To perform a comprehensive study, we also designed and fabricated five additional resonators, expanding the <inline-formula> <tex-math notation="LaTeX">\lambda </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">{k}_{\mathbf {t}}^{\mathbf {2}} </tex-math></inline-formula> from 20.3% to 22.9% and a Q from 350 to 575, thereby covering the entire C-band with excellent performance. [2024-0070]