High-Sensitivity and Fast-Response Piezotronic Pressure Sensors by Mechanical Stacking in Silicon Wafer

A CMOS-compatible pressure sensor capable of seamlessly bridging external stimuli with modern electronics is essential for advancing applications in wearable systems, human-machine interfaces, and robotics. However, the weak mechanoelectrical coupling of silicon, together with its epitaxial difficulty with piezoelectric semiconductors, has long challenged the development of high-performance Si-based sensors. Here, we report a generalizable mechanical stacking strategy that realizes epitaxial-free, wafer-scale Si/GaN pressure sensors. Both nn and pn junction architectures are constructed to yield electrically tunable pressure response due to the piezotronic effect driven by asymmetrical interfaces and carrier shielding. As a result, the device delivers high pressure sensitivity of 43.34 meV/MPa, exceptional gauge factors of 5.8 × 10⁶, and submillisecond response times. We show that these piezotronic pressure sensors can be used to detect impulsive forces with high temporal resolution, as well as monitor signals of finger rhythms. This work establishes mechanical stacking as a universal integration paradigm for epitaxial-free heterogeneous electronics, enabling high-performance, CMOS-compatible piezotronic sensors.