Pb(Zr_0.5Ti_0.5)O₃-Based Piezoelectric Micromachined Ultrasonic Transducers for High Acoustic Transmission and Reception

Piezoelectric micromachined ultrasonic transducers (PMUTs) shows great promise in portable medical diagnostic systems and non-contact range finding owing to their miniature size, high acoustic impedance matching with human tissue, low power consumption, and easy integration with ICs. A highly transmitting and receiving PMUTs is developed in this study using Pb(Zr_0.5Ti_0.5)O₃ as the piezoelectric layer, which is fabricated through a low-temperature and high-piezoelectricity Pb(Zr_0.5Ti_0.5)O₃ thin film fabrication technique. The fabricated piezoelectric film features the lowest film-forming temperature ≤ 480°C) ever reported, excellent piezoelectric coefficient (15.5 C/m²), and lowe dielectric constant (750). Consequently, the developed PMUTs achieved a transmitting sensitivity of 4.72 kPa/V, -6 dB fractional bandwidth of 80.2 %, and high reception signal-to-noise ratio up to 37.3 and 18.9 dB, with and without any amplifier circuits, respectively. Thus, it demonstrated a higher comprehensive performance than previously reported PMUTs with the similar structure. The results of this study may accelerate the development of CMOS-compatible and high-performance PMUTs based on thin PZT film.