High speed surface acoustic wave and laterally excited bulk wave resonator based on single-crystal non-polar AlN film

作者：Tongxin Lu, Xiaoli Fang, Shibin Zhang, Ye Yuan, Yanda Ji, Hongmeng Zhang, Anli Yang, Hengyi Yin, Pengcheng Zheng, Liping Zhang, Jinbo Wu, Tai Li, Wei Luo, Tiangui You, Xin Ou, Xinqiang Wang · 发表于：Applied Physics Letters · 年份：2023 · DOI：10.1063/5.0181087 · 被引用次数：13 · 研究领域：Acoustic Wave Resonator Technologies、GaN-based semiconductor devices and materials、Mechanical and Optical Resonators

One approach to extend the acoustic applications of aluminum nitride (AlN) in the GHz frequency range is to take advantage of the piezoelectric performance and high acoustic velocity (∼11 350 m/s) along the c-axis of this material. In particular, in the case of high-frequency micro-electromechanical systems, it should be possible to simplify the construction of resonators by using a-plane AlN-based structures. In the work described in this Letter, a single-crystalline a-plane AlN layer on an r-plane sapphire substrate is obtained by combining sputtering and high-temperature annealing. Based on this non-polar AlN, a resonator with only planar interdigital transducer electrodes is fabricated. Experiments on this resonator reveal simultaneous excitation of an anisotropic Rayleigh surface acoustic wave (SAW) at 2.38 GHz and a laterally excited bulk acoustic wave (LBAW) at 4.00 GHz. It is found that the Rayleigh SAW exhibits outstanding performance, with a quality factor as high as 2458 and great stability under variations in temperature. The LBAW at 4.00 GHz is excited by pure planar interdigitated electrodes without the need for any cavity or bottom electrode structure, thus demonstrating a promising approach to the construction of high-frequency resonators with a relatively simple structure.