Intervalley electron-hole exchange interaction and impurity-assisted recombination of indirect excitons in WS$_2$ and WSe$_2$ monolayers

TL;DR

This paper investigates the electron-hole exchange interaction and impurity-assisted recombination mechanisms of indirect excitons in tungsten-based monolayers, enhancing understanding of their energy and polarization properties.

Contribution

It provides a detailed analysis of the short-range exchange interaction and impurity-mediated recombination in indirect excitons, which was not thoroughly understood before.

Findings

Characterization of energy and polarization of indirect exciton resonance

Identification of impurity-assisted recombination pathways

Insight into the role of exchange interaction in exciton behavior

Abstract

The variety of excitonic states in tungsten-based dichalcogenide monolayers stems from unique interplay between the spin and valley degrees of freedom. One of the exciton species is the indirect exciton (momentum or valley dark), which is responsible to a series of resonances when the monolayer is charge neutral. We investigate the short-range electron-hole exchange interaction of the indirect exciton, as well as its recombination mechanism mediated by impurities. The analysis provides thorough understanding of the energy and polarization of the zero-phonon indirect exciton resonance in the emission spectrum.