Exciton confinement in one-dimensional potentials in monolayer transition metal dichalcogenide crystals

Excitons in transition metal dichalcogenide (TMDC) semiconductors have emerged as a widely studied platform for exploring many-body physics and light-matter interactions. Achieving precise control of exciton confinement will facilitate further advances in the field. In this work, we employ static in-plane electric fields to define tunable trapping potentials for intralayer excitons in monolayer MoSe₂. The trapping mechanism relies on the in-plane polarizability of the excitons, which causes them to be attracted to regions with strong in-plane electric fields. By engineering patterned 1D metal wire electrodes separated from the monolayer by thin hBN spacers, we can create periodic 1D potential landscapes for intralayer excitons with controllable geometry and strength. In particular, electrostatic simulations indicate the presence of strong and highly localized fields near the edge of the metal lines, suggesting the possibility of one-dimensional exciton confinement in this region.

Low-temperature measurements of the optical absorption of these devices reveal sharp transitions lying below the energy of the unconfined excitons. These transitions, characterized by tunable energies and splittings as a function of the applied trapping potentials, are attributed to confined exciton states, whose properties also depend on the engineered dimensions of the metal lines. The trapped excitons produce pairs of optical transitions with linear and mutually orthogonal polarization. This behavior is expected from 1D confinement of the LO and TO exciton modes.