Vibration Analysis and Transmission Characteristics of Piezoelectric Micromachined Ultrasonic Transducers Using Epitaxial Pb(Zr,Ti)O3 Thin Films on ?-Al2O3/Si Substrate

Low-voltage (< 12 V)-operation piezoelectric micromachined ultrasonic transducers (pMUTs) are hoped to be integrated with Si-LSI. Realizing this requires not only improving the piezoelectric properties, but also clarifying the vibration modes of transducers. In this study, we experimentally investigated the vibration mode and transmission ultrasonic waves by pMUTs using epitaxial Pb(Zr,Ti)O-3 thin films on the epitaxial gamma-Al2O3/Si substrates to radiate ultrasonic waves effectively. Five resonance vibration modes appeared in 100-mu m-diameter circular pMUTs at frequencies in the range from 1 to 10MHz in air. The frequency of mode (0,1) was 2.2 MHz, and this mode radiates ultrasonic waves very effectively. Ultrasonic transmission was also achieved in water using the above vibration mode, applying voltage of less than 10 Vp-p. These results show the potential for high-frequency pMUT integration with Si devices. (C) 2012 The Japan Society of Applied Physics