Plasmon-Enhanced Ultraviolet–Visible Dual-Band Photodetection in Self-Powered 2D/3D MoS2/ZnO Heterojunctions

The intrinsically weak light absorption of monolayer MoS2 limits its photoresponse and remains a major obstacle to its application in high-performance photodetectors. Here, we report a Au-grating-integrated 2D/3D MoS2/ZnO heterojunction photodetector that combines self-powered ultraviolet–visible (UV–Vis) detection with enhanced visible-light response and polarization sensitivity. The MoS2/ZnO heterojunction provides complementary UV–Vis absorption and a built-in electric field for self-powered operation. The integrated 1D Au grating induces localized surface plasmon resonance, selectively enhancing the visible-light absorption of monolayer MoS2, as confirmed by both FDTD simulations and experiments. Under 633 nm illumination, the grating-integrated device achieves a responsivity of 1.85 × 10–1 mA/W, corresponding to a nearly order-of-magnitude enhancement over the pristine heterojunction. The anisotropic grating further enables polarization-dependent photodetection, with a TM/TE responsivity ratio of 3.8. This work demonstrates that plasmonic integration is an effective strategy for enhancing light–matter interaction while enabling additional functionalities in 2D/3D heterojunction photodetectors.