Electric-Field-Driven Trion Drift and Funneling in MoSe₂ Monolayer

Excitons, electron-hole pairs in semiconductors,can beutilized as information carriers with a spin or valley degree of freedom.However, manipulation of excitons' motion is challenging becauseof their charge-neutral characteristic and short recombination lifetimes.Here we demonstrate electric-field-driven drift and funneling of chargedexcitons (i.e., trions) toward the center of a MoSe2 monolayer.Using a simple bottom-gate device, we control the electric fieldsin the vicinity of the suspended monolayer, which increases the triondensity and pulls down the layer. We observe that locally excitedtrions are subjected to electric force and, consequently, drift towardthe center of the stretched layer. The exerting electric force onthe trion is estimated to be 10(2)-10(4) timesstronger than the strain-induced force in the stretched monolayer,leading to the successful observation of trion drift under continuous-waveexcitation. Our findings provide a new route for manipulating trionsand achieving new types of optoelectronic devices.