Surface Acoustic Wave Devices Using Lithium Niobate on Silicon Carbide

• Published in: IEEE transactions on microwave theory and techniques Vol. 68; no. 9; pp. 3653 - 3666
• Main Authors: Zhang, Shibin, Lu, Ruochen, Zhou, Hongyan, Link, Steffen, Yang, Yansong, Li, Zhongxu, Huang, Kai, Ou, Xin, Gong, Songbin
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Chemical bonds; Diamond; Electric arcs; Figure of merit; Figure of merit (FoM); Frequency ranges; Group delay; impedance ratio; Insertion loss; Lithium niobate; Lithium niobates; MEMS; piezoelectric filters; piezoelectric resonators; power handling; Q factors; Resonant frequency; Resonators; shear horizontal (SH0) modes; Silicon; Silicon carbide; Silicon substrates; Single crystals; Slicing; Substrates; Surface acoustic wave devices; Surface acoustic waves; temperature of frequency (TCF); Thin films
• DOI: 10.1109/TMTT.2020.3006294
• ISSN: 0018-9480

This work demonstrates a group of shear horizontal (SH0) mode resonators and filters using lithium niobate (LiNbO 3 ) thin films on silicon carbide (SiC). The single-crystalline X-cut LiNbO 3 thin films on 4H-SiC substrates have been prepared by ion-slicing and wafer-bonding processes. The fabricated resonator has demonstrated a large effective electromechanical coupling (<inline-formula> <tex-math notation="LaTeX">{k}^{2} </tex-math></inline-formula>) of 26.9% and a high-quality factor (Bode-<inline-formula> <tex-math notation="LaTeX">Q </tex-math></inline-formula>) of 1228, hence resulting in a high figure of merit (FoM <inline-formula> <tex-math notation="LaTeX">= {k}^{2}\,\,\cdot </tex-math></inline-formula> Bode-<inline-formula> <tex-math notation="LaTeX">Q </tex-math></inline-formula>) of 330 at 2.28 GHz. Additionally, these fabricated resonators show scalable resonances from 1.61 to 3.05 GHz and impedance ratios between 53.2 and 74.7 dB. Filters based on demonstrated resonators have been demonstrated at 2.16 and 2.29 GHz with sharp roll-off and spurious-free responses over a wide frequency range. The filter with a center frequency of 2.29 GHz shows a 3-dB fractional bandwidth of 9.9%, an insertion loss of 1.38 dB, an out-of-band rejection of 41.6 dB, and a footprint of 0.75 mm 2 . Besides, the fabricated filters also show a temperature coefficient of frequency of −48.2 ppm/°C and power handling of 25 dBm. Although the power handling is limited by arc discharge and migration-induced damage of the interdigital electrodes and some ripples in insertion loss and group delay responses are still present due to the transverse spurious modes, the demonstrations still show that acoustic devices on the LiNbO 3 -on-SiC platform have great potential for radio-frequency applications.