Unveiling Carrier‐Mediated Acoustic Leakage as a Hidden Loss Pathway in Piezoelectric‐Semiconductor Heterostructures

Abstract

ABSTRACT Heterogeneous integration of dissimilar functional materials enables advanced micro/nano devices with unprecedented functionalities, yet the resulting interfacial multiphysics interactions can introduce hidden energy leakage pathways beyond conventional bulk systems. Here, we reveal a previously overlooked carrier‐mediated acoustic leakage mechanism in piezoelectric‐semiconductor heterostructures. By developing an electromechanical‐carrier coupling model, we demonstrate that interfacial carrier accumulation reconstructs electrical boundary conditions, causing piezoelectric fields to penetrate into non‐resonant regions. The resulting electric field distortion activates parasitic mechanical vibrations, which radiate bulk acoustic waves into the silicon substrate and degrade the quality (Q) factor. Ultrafast femtosecond laser pump‐probe spectroscopy is further employed to characterize carrier dynamics, establishing a quantitative link between carrier modulation and acoustic performance. Guided by this mechanism, multiphysics decoupling strategies based on material engineering and electric field engineering are developed to suppress carrier‐mediated acoustic leakage. By reconstructing electrical boundaries through defect‐state modulation and asymmetric electrode design, the Q factor of piezoelectric‐semiconductor devices is substantially enhanced while maintaining compatibility with standard fabrication processes. This work reveals an unconventional role of semiconductor carriers as mediators of acoustic energy redistribution and provides a mechanism‐guided strategy for designing high‐performance heterogeneously integrated micro/nano devices.