The electronic and optical properties of van der Waals heterostructures are strongly influenced by the structuration and homogeneity of their nano- and atomic-scale environments. Unravelling this intimate structure–property relationship is a key challenge that requires methods capable of addressing the light–matter interactions in van der Waals materials with ultimate spatial resolution. Here we use a low-temperature scanning tunnelling microscope to probe—with atomic-scale resolution—the excitonic luminescence of a van der Waals heterostructure, made of a transition metal dichalcogenide monolayer stacked onto a few-layer graphene flake supported by a Au(111) substrate. Sharp emission lines arising from neutral, charged and localized excitons are reported. Their intensities and emission energies vary as a function of the nanoscale topography 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 controlling optoelectronic phenomena in moiré superlattices with atomic-scale resolution.
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Source data necessary to reproduce the results shown in the Article and Supplementary Information are available via figshare at https://doi.org/10.6084/m9.figshare.21913017. Additional data are available from the corresponding authors upon reasonable request. Source data are provided with this paper.
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We thank M. Chong, B. Doppagne, G. Froehlicher, A. Gloppe, E. Le Moal, E. Lorchat and T. Neuman for fruitful discussions. We are grateful to the IPCMS mechanical workshop, particularly H. Sumar, as well as V. Speisser, M. Romeo and the STnano cleanroom staff for technical support. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 771850) and the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 894434. We acknowledge financial support from the Agence Nationale de la Recherche under grant ATOEMS ANR-20-CE24-0010. This work of the Interdisciplinary Thematic Institute QMat, as part of the ITI 2021 2028 program of the University of Strasbourg, CNRS and Inserm, was supported by IdEx Unistra (ANR 10 IDEX 0002), as well as by SFRI STRAT’US project (ANR 20 SFRI 0012) and EUR QMAT ANR-17-EURE-0024 under the framework of the French Investments for the Future Program. S.B. acknowledges support from the Indo-French Centre for the Promotion of Advanced Research (CEFIPRA) and from the Institut Universitaire de France (IUF).
The authors declare no competing interests.
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López, L.E.P., Rosławska, A., Scheurer, F. et al. Tip-induced excitonic luminescence nanoscopy of an atomically resolved van der Waals heterostructure. Nat. Mater. (2023). https://doi.org/10.1038/s41563-023-01494-4