Transmit-Receive Performance Enhancement of $\text{Sc}_{0.3}\text{AL}_{0.7}\mathrm{N}$ Pmuts Through Ferroelectric Activation

This work presents the first implementation of ferroelectric activation as a post-fabrication optimization methodology for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Sc}_{0.3} \text{Al}_{0.7} \mathrm{N}$</tex> piezoelectric micromachined ultrasonic transducers. Unlike conventional device optimization approaches that require complex structural redesign or meticulous process control during fabrication, ferroelectric activation offers a scalable post-process treatment applicable at the wafer level for mass manufacturing. Through controlled domain reorientation and intrinsic stress relaxation within the piezoelectric stack, it achieves comprehensive acoustic performance enhancement: 1.2-1.7× improvement in electromechanical coupling coefficient, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5-33 \%$</tex> increase in transmit displacement sensitivity, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$14-21 \%$</tex> increase in transmit pressure sensitivity at 10 cm, enabling simultaneous transmit and receive dual-mode performance enhancement for acoustic transducer optimization.