Trion induced photoluminescence of a doped MoS2 monolayer

TL;DR

This paper investigates the unique temperature and doping effects on photoluminescence in doped MoS2 monolayers, highlighting the role of trion radiative decay and non-zero momentum trions in spectral features.

Contribution

It introduces a combined theoretical approach using Dirac and three-particle models to explain PL spectra, including analytical expressions for temperature dependence.

Findings

Asymmetric broadening of trion spectral peaks with temperature

Redshift of emitted light as temperature increases

Non-monotonic temperature dependence of PL intensity

Abstract

We demonstrate that the temperature and doping dependencies of the photoluminescence (PL) spectra of a doped MoS2 monolayer have several peculiar characteristics defined by trion radiative decay. While only zero-momentum exciton states are coupled to light, radiative recombination of non-zero momentum trions is also allowed. This leads to an asymmetric broadening of the trion spectral peak and redshift of the emitted light with increasing temperature. The lowest energy trion state is dark, which is manifested by the sharply non-monotonic temperature dependence of the PL intensity. Our calculations combine the Dirac model for the single-particle states, the parameters for which are obtained from the first principle calculations, and the direct solution of the three-particle problem within the Tamm-Dancoff approximation. The numerical results are well captured by a simple model that yields analytical expressions for the temperature dependencies of the PL spectra.