Microscopic theory of exciton and trion polaritons in doped monolayers of transition metal dichalcogenides

TL;DR

This paper presents a microscopic theoretical analysis of exciton and trion polaritons in doped monolayer TMDCs within optical microcavities, revealing new hybrid modes and the influence of doping on the system's ground state.

Contribution

It introduces a comprehensive microscopic model to analyze polaritonic modes in doped TMDC monolayers, including novel bright modes and doping-dependent ground state transitions.

Findings

Identification of bright polaritonic modes due to exciton-free carrier interactions

Prediction of hybridized excited trion-cavity modes at high doping

Demonstration of doping-induced transition from dark to bright ground state

Abstract

We study a doped transition metal dichalcogenide (TMDC) monolayer in an optical microcavity. Using the microscopic theory, we simulate spectra of quasiparticles emerging due to the interaction of material excitations and a high-finesse optical mode, providing a comprehensive analysis of optical spectra as a function of Fermi energy and predicting several modes in the strong light-matter coupling regime. In addition to exciton-polaritons and trion-polaritons, we report polaritonic modes that become bright due to the interaction of excitons with free carriers. At large doping, we reveal strongly coupled modes corresponding to excited trions that hybridize with a cavity mode. We also demonstrate that rising the carrier concentration enables to change the nature of the system's ground state from the dark to the bright one. Our results offer a unified description of polaritonic modes in a wide range of free electron densities.