Origin of interlayer exciton-phonon coupling in 2D heterostructures

TL;DR

This paper investigates the mechanism of interlayer exciton-phonon coupling in 2D heterostructures, highlighting the role of crystal symmetries and deformation potentials through first-principles calculations.

Contribution

It reveals the origin of interlayer exciton-phonon coupling in WSe$_2$@hBN heterostructures, emphasizing the importance of crystal symmetries and deformation potentials.

Findings

Crystal symmetries govern exciton-phonon scattering processes.

Deformation potential from hBN phonons interacts with WSe$_2$ excitons.

Interlayer exciton-phonon coupling explains resonant Raman intensity anomalies.

Abstract

The coupling between excitons and phonons across adjacent layers has been experimentally observed in various heterostructures of layered materials. Yet the precise mechanism underlying this phenomenon remains elusive. Using the WSe$_2$@hBN heterostructure as an example, we study the origin of the interlayer exciton-phonon coupling and its signature in resonant Raman scattering through first-principles calculations. Our study emphasizes the central role of crystal symmetries in the interlayer exciton-phonon scattering processes, which are responsible for the anomalous resonant Raman intensities of the in-plane and the out-of-plane hBN phonon modes. We find that the deformation potential induced by the hBN phonon interacts with the hybridized hole density of WSe$_2$ excitons near the hBN interface, leading to interlayer exciton-phonon coupling.