Sub-10 nm Visualization of Trions in Ultralow-Strained Monolayer MoSe₂

Understanding and manipulating the nanoscale behavior of excitonic quasiparticles in low-dimensional semiconductors is critical for advancing nanoexcitonic devices and next-generation integrated circuits. However, the direct nanoscale visualization of trions under ultralow strain remains experimentally challenging due to their intrinsically weak emission and the limited resolution of far-field techniques. In this work, we present a simple hybrid structure that integrates a plasmonic-SNOM (p-SNOM) system, enabling both a high local electron density and efficient exciton funneling. Using hyperspectral tip-enhanced photoluminescence (TEPL) nanoimaging with sub-10 nm resolution, we investigate the exciton and trion distributions in monolayer MoSe₂ on a gold nanostar (AuNS) particle. The results show that the integrated PL intensity can be enhanced by up to 190%, and the trion population reaches 20% at an ultralow strain threshold of just 0.05%. This platform offers a powerful route for efficient exciton-to-trion conversion and high-resolution trion visualization in TMD materials under ultralow strain.