Numerical investigation of electrostatically confined excitons in monolayer $\text{MoSe}_2$

TL;DR

This paper numerically studies exciton confinement in monolayer MoSe2 using a device-inspired model, revealing quantum confinement effects, the existence of dark and bright states, and aligning with experimental observations.

Contribution

It introduces a comprehensive numerical approach to analyze exciton confinement in monolayer MoSe2, including excited states and dark states, under realistic device geometries.

Findings

Confined exciton states depend on gate voltages.

Dark states have low oscillator strengths and are not yet observed.

Bright states match recent experimental spectra.

Abstract

We investigate exciton confinement to a quantum wire in monolayer $\text{MoSe}_2$ where the confinement is achieved by a p-i-n junction. We employ an effective-mass exciton model and solve the problem numerically, reflecting device geometries found in experimental state-of-the-art set up. Our method allows us to investigate the entire spectrum of confined states. We show the emergence of quantum confinement and study the dependence of the confined states as a function of electrical gate voltages, which are experimentally tunable parameters. We find that the confined states can be divided into bright and dark states with the dark states having small but finite oscillator strengths. Their oscillator strengths are low enough that they have not yet been detected in experiments, whereas the spectrum of the bright exciton states reproduces recent experimental measurements. Our results provide insight into the theoretical background of confined exciton states beyond the ground state and pave the way for the development of new confinement schemes as well as avenues to access the previously not detected dark states.