Exciton localization in two-dimensional semiconductors through modification of the dielectric environment

TL;DR

This study explores how modifying the dielectric environment around monolayer semiconductors can create potential traps that fully confine excitons, leading to quantized energy levels with potential applications in quantum technologies.

Contribution

It demonstrates the feasibility of engineering dielectric surroundings to achieve complete exciton confinement and energy quantization in two-dimensional semiconductors.

Findings

Complete exciton energy discretization of tens of meV is achievable.

Dielectric environment modifications can significantly alter exciton binding and bandgap.

Potential for new optoelectronic and quantum device applications.

Abstract

Monolayer semiconductors, given their thickness at the atomic scale, present unique electrostatic environments due to the sharp interfaces between the semiconductor film and surrounding materials. These interfaces significantly impact both the quasiparticle band structure and the electrostatic interactions between charge carriers. Akey area of interest in these materials is the behavior of bound electron-hole pairs (excitons) within the ultra-thin layer, which plays a crucial role in its optoelectronic properties. In this work, we investigate the feasibility of generating potential traps that completely confine excitons in the thin semiconductor by engineering the surrounding dielectric environment. By evaluating the simultaneous effects on bandgap renormalization and modifications to the strength of the electron-hole Coulomb-interaction, both associated to the modulation of the screening by the materials sandwiching the monolayer, we anticipate the existence of low-energy regions in which the localization of the exciton center of mass may be achieved. Our results suggest that for certain dielectric configurations, it is possible to generate complete discretization of exciton eigenenergies in the order of tens of meV. Such quantization of energy levels of two-dimensional excitons could be harnessed for applications in new-generation optoelectronic devices, which are necessary for the advancement of technologies like quantum computing and quantum communication.