Tip-induced excitonic luminescence nanoscopy of an atomically-resolved van der Waals heterostructure

TL;DR

This study employs low-temperature scanning tunneling microscopy to achieve atomic-scale imaging of excitonic luminescence in a van der Waals heterostructure, revealing how nanoscale environment influences emission properties.

Contribution

It demonstrates atomic-resolution imaging of excitonic luminescence and links emission variability to local nanoscale environment effects in heterostructures.

Findings

Identification of sharp emission lines from various excitons

Emission energies and intensities depend on local environment

Insights into optoelectronic phenomena in moiré superlattices

Abstract

Low-temperature scanning tunneling microscopy is used to probe, with atomic-scale spatial resolution, the intrinsic luminescence of a van der Waals heterostructure, made of a transition metal dichalcogenide monolayer stacked onto a few-layer graphene flake supported by an Au(111) substrate. Sharp emission lines arising from neutral, charged and localised excitons are reported. Their intensities and emission energies vary as a function of the nanoscale environment of the van der Waals heterostructure, explaining the variability of the emission properties observed with diffraction-limited approaches. Our work paves the way towards understanding and control of optoelectronic phenomena in moir\'e superlattices with atomic-scale resolution.