Interface-Strain Engineering Enables High-Performance Silicon-Integrated Piezoelectric Thin Films

High-performance piezoelectric thin films are pivotal to microelectromechanical systems (MEMS), enabling diverse applications from precision sensing to mid-air haptic interfaces for virtual and augmented reality. However, achieving large piezoelectric responses on silicon remains challenging owing to lattice and thermal mismatches that generate substantial interfacial strain, leading to defect formation, mixed-phase growth, and poorly aligned ferroelectric domains. Herein, we present an interfacial strain–engineering epitaxial strategy that, using lead zirconate titanate (PZT) as an exemplar, enables deterministic control over thin-film growth and crystallographic orientation on silicon. By tailoring the interfacial strain of Pt bottom electrodes, we realize highly uniform (001)-PZT films exhibiting superior maximum polarization (P_max ∼ 111.55 µC cm⁻²) with remnant polarization (P_r ∼ 89.08 µC cm⁻²), yielding an ultrahigh transverse piezoelectric coefficient (e₃₁) of 15.99 C·m⁻² that surpasses the performance of previously reported silicon-integrated ferroelectric systems. Furthermore, integration of these films into piezoelectric micromachined ultrasonic transducer (PMUT) arrays enables mid-air haptic feedback, demonstrating their functional viability for immersive tactile interfaces. This work establishes a universal pathway for strain-mediated epitaxy of piezoelectric thin films on silicon, paving the way toward high-performance tactile and MEMS technologies.