Nanoscale Excitonic Landscape and Quantum Confinement in Gated Monolayer Semiconductors

Engineering excitonic properties at the nanoscale is a central challenge in quantum photonics and optoelectronics. While far-field optical spectroscopy has greatly advanced our understanding of excitonic phenomena, Its diffraction-limited resolution yields only spatially averaged information. In this work, we investigate the excitonic landscape of monolayer WS2 under electrostatic gating using cathodoluminescence (CL) spectroscopy. By leveraging the high spatial resolution of CL, we reveal locally modulated changes in the energy and intensity of excitonic emission at the nanoscale. Moreover, under electron-beam excitation, we observe a peculiar gate-dependent exciton emission, attributed to beam-induced charge trapping in the hBN dielectric. This unconventional electrostatic doping mechanism under e-beam excitation enables the formation of an excitonic confinement potential, giving rise to a localized exciton channel that can be directly visualized through CL nanoscopy. Our findings elucidate the luminescence behavior of monolayer semiconductors under combined e-beam excitation and electrostatic gating. This approach provides a route for nanoscale exciton manipulation and opens opportunities for the control of quantum confined exciton transport in two-dimensional materials.