Localized interlayer complexes in heterobilayer transition metal dichalcogenides

TL;DR

This paper theoretically investigates localized interlayer excitonic complexes in twisted heterobilayer transition metal dichalcogenides, analyzing radiative decay, doping effects, and phonon-assisted recombination with implications for optoelectronic properties.

Contribution

It provides a detailed theoretical analysis of localized interlayer excitonic complexes, including radiative rates and phonon effects, supported by quantum Monte Carlo calculations.

Findings

Radiative decay rates are in the microsecond inverse range for aligned layers.

Strong twist angle dependence of radiative rates, scaling as θ^{-8}.

Phonon-assisted recombination introduces additional emission lines.

Abstract

We present theoretical results for the radiative rates and doping-dependent photoluminescence spectrum of interlayer excitonic complexes localized by donor impurities in MoSe$_2$/WSe$_2$ twisted heterobilayers, supported by quantum Monte Carlo calculations of binding energies and wave-function overlap integrals. For closely aligned layers, radiative decay is made possible by the momentum spread of the localized complexes' wave functions, resulting in few $\mu$s$^{-1}$ radiative rates. For strongly misaligned layers, the short-range interaction between the carriers and impurity provides a finite radiative rate with a strong asymptotic twist angle dependence $\propto \theta^{-8}$. Finally, phonon-assisted recombination is considered, with emission of optical phonons in both layers resulting in additional weaker emission lines, redshifted by the phonon energy.