Three-particle Complexes in Two-Dimensional Semiconductors

TL;DR

This paper develops a boundary-matching-matrix method to analyze three-particle complexes in 2D semiconductors, calculating their binding energies and revealing that trions are more resilient to heating than other excitonic complexes.

Contribution

It introduces a novel computational approach for three-body problems in 2D materials and provides detailed binding energy evaluations for various excitonic complexes.

Findings

Trions have higher dissociation energies than localized exciton complexes.

Trions are more resilient to thermal dissociation.

Optical recombination lines of trions are less red-shifted than those of donor/acceptor bound excitons.

Abstract

We map the three-body problem in two dimensions onto one particle in a three dimensional potential treatable by a purposely-developed boundary-matching-matrix method. We evaluate binding energies of trions $X^{\pm}$, excitons bound by a donor/acceptor charge $X^{D/A}$, and overcharged acceptors/donors in two-dimensional atomic crystals of transition metal dichalcogenides, where interaction between charges features logarithmic behavior at intermediate distances. We find that dissociation energy of $X^{\pm}$ is, typically, much larger than that of localised exciton complexes, so that trions are more resilient to heating, despite that their recombination line in optics is much less red-shifted from the exciton line, as compared to $X^{D/A}$