Charged exciton kinetics in monolayer MoSe$_2$ near ferroelectric domain walls in periodically poled LiNbO$_3$

TL;DR

This study investigates how monolayer MoSe$_2$ interacts with ferroelectric domain walls in LiNbO$_3$, revealing large electric fields that influence exciton behavior and charge routing, with implications for optoelectronic device design.

Contribution

We demonstrate the impact of ferroelectric domain walls on exciton dynamics in monolayer MoSe$_2$, providing a detailed model that explains exciton dissociation and charge routing at these boundaries.

Findings

Large in-plane electric fields of 3000 kV/cm at domain walls.

Spatial sorting of neutral and charged excitons across boundaries.

Qualitative agreement between experimental data and drift-diffusion modeling.

Abstract

Monolayers of semiconducting transition metal dichalcogenides are a strongly emergent platform for exploring quantum phenomena in condensed matter, building novel opto-electronic devices with enhanced functionalities. Due to their atomic thickness, their excitonic optical response is highly sensitive to their dielectric environment. In this work, we explore the optical properties of monolayer thick MoSe$_2$ straddling domain wall boundaries in periodically poled LiNbO$_3$. Spatially-resolved photoluminescence experiments reveal spatial sorting of charge and photo-generated neutral and charged excitons across the boundary. Our results reveal evidence for extremely large in-plane electric fields of 3000\,kV/cm at the domain wall whose effect is manifested in exciton dissociation and routing of free charges and trions toward oppositely poled domains and a non-intuitive spatial intensity dependence. By modeling our result using drift-diffusion and continuity equations, we obtain excellent qualitative agreement with our observations and have explained the observed spatial luminescence modulation using realistic material parameters.