Impedance-matched high-overtone bulk acoustic resonator

作者：Megumi Kurosu, Daiki Hatanaka, Ryuichi Ohta, Hiroshi Yamaguchi, Yoshitaka Taniyasu, Hajime Okamoto · 发表于：Applied Physics Letters · 年份：2023 · DOI：10.1063/5.0141405 · 被引用次数：12 · 研究领域：Acoustic Wave Resonator Technologies、GaN-based semiconductor devices and materials、Mechanical and Optical Resonators

We demonstrated a nearly impedance-matched high-overtone bulk acoustic resonator (HBAR) operating at super high frequency ranges using an epitaxial AlN piezoelectric layer directly grown on a conductive SiC cavity substrate with no metal layer insertion. The small impedance mismatch was verified from the variation in the free spectral range (FSR); the experimentally obtained FSR spectra were greatly reproduced using the Mason model. Broadband phonon cavity modes up to the K-band (26.5 GHz) were achieved at an AlN layer thickness of 200 nm. The high figure of merit of f×Q=1.3×1013 Hz at 10 GHz was also obtained. Our nearly impedance-matched high-quality HBAR will enable the development of microwave signal processing devices for 5G and future 6G communication systems, such as low-phase noise oscillators and acoustic filters, as well as research on high-frequency acoustic systems hybridized with electric, optical, and magnetic systems.