标题：High Q-Factor Pure Thickness Shear Mode Film Bulk Acoustic Resonator Working in Liquids
作者：Da Chen;Jingjing Wang;Hongwei Song;Shilin Xu;Dehua Li
作者机构：Qingdao Key Laboratory of Terahertz Technology, Department of Applied Physics, School of Science, Shandong University of Science
来源：Sensor Letters: A Journal Dedicated to all Aspects of Sensors in Science, Engineering, and Medicine
关键词：Film Bulk Acoustic Resonator;Thickness Shear Mode;Q-Factors;Biochemical Sensors
摘要：We present a design of the pure thickness shear mode film bulk acoustic resonator with high Q-factor working in liquids. The device consists of the c-axis oriented AlN film, the electrodes parallel to the film surface, and the Bragg reflector of SiO_2/W. The pure shear mode wave is excited by the lateral electric field. The responses of the device were tested in air and liquids. The results show that the resonance of thickness shear mode wave can be excited near 2 GHz with the Q_s of 550 in air. There is no obvious longitudinal resonance in the frequency response due to the weak vertical electric field component generated by the parallel electrodes and the high frequency selectivity of the acoustic reflector. Importantly for the sensor applications, the immersion into de-ionized water and glycerol still allow for the high Q_s of 485 and Q_p of 467, respectively. The resonance frequencies are decreased in the liquids due to the loading effect on the device surface. This device shows the potential as mass loading sensors for biochemical application.