Superadditive lateral photovoltage enabled by plasmonic hot-electron transfer in MoS2/Au nanorods/Si heterojunction for ultrasensitive position detection

Plasmonics provides a compelling route to surpass the sensitivity limits of silicon position-sensitive detectors (PSDs), yet the inefficient extraction of plasmon-generated hot electrons has remained a fundamental bottleneck. Here, we report a superadditive lateral photovoltage realized in a MoS2/Au nanorods (NRs)/Si heterojunction via plasmonic hot-electron transfer, which enables ultrasensitive position detection. Owing to efficient hot-electron generation and interfacial charge separation, the heterojunction PSD exhibits a superadditive photoresponse that exceeds the sum of individual contributions of MoS2/Si and Au NRs/Si junctions. The resulting silicon PSD achieves a position sensitivity of 290.3 mV/mm, a nonlinearity below 8%, a fast temporal response of 74 μs, and a broad spectral range from 405 to 980 nm. Beyond its static position sensing, the device further enables spatially encoded free-space optical signaling by directly mapping optical positional states into digital electrical outputs. This work establishes an effective strategy for overcoming hot-electron transfer limitations in plasmon-enhanced photodetection and points toward scalable, high-performance silicon PSDs for multifunctional photoelectric sensing and information-processing applications.