Excitons in strain-induced one-dimensional moiré potentials at transition metal dichalcogenide heterojunctions

Abstract

The possibility of confining interlayer excitons in interfacial moiré patterns has recently gained attention as a strategy to form ordered arrays of zero-dimensional quantum emitters and topological superlattices in transition metal dichalcogenide heterostructures. Strain is expected to play an important role in the modulation of the moiré potential landscape, tuning the array of quantum dot-like zero-dimensional traps into parallel stripes of one-dimensional quantum wires. Here, we present real-space imaging of unstrained zero-dimensional and strain-induced one-dimensional moiré patterns along with photoluminescence measurements of the corresponding excitonic emission from WSe2/MoSe2 heterobilayers. Whereas excitons in zero-dimensional moiré traps display quantum emitter-like sharp photoluminescence peaks with circular polarization, the photoluminescence emission from excitons in one-dimensional moiré potentials shows linear polarization and two orders of magnitude higher intensity. These results establish strain engineering as an effective method to tailor moiré potentials and their optoelectronic response on demand.

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Fig. 1: Hexagonal vs quasi-1D moiré patterns and the associated PL spectra.
Fig. 2: Transformation of moiré patterns and strain analysis.
Fig. 3: Direct correlation between 1D moiré patterns and linearly polarized PL emission.
Fig. 4: Evolution of PL peak shape with exciton density for interlayer excitons in the 1D moiré potential.

Data availability

The data represented in Figs. 14 are provided with the article source data. All data that support the results in this article are available from the corresponding author upon reasonable request. Source data are provided with this paper.

Change history

  • 20 July 2020

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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Acknowledgements

The PFM imaging experiments and PL measurements were supported by the Center for Programmable Quantum Materials, an Energy Frontier Research Center funded by the US Department of Energy through grant DE-SC0019443. Sample preparation and SHG characterization were supported by the Center for Precision Assembly of Superstratic and Superatomic Solids, a Materials Science and Engineering Research Center (MRSEC) through National Science Foundation (NSF) grant DMR-1420634. The power-dependent measurements on many-body effects (Supplementary Figs. 1214) were supported by the NSF through grant DMR-1809680. Building of the confocal PL spectrometer was supported in part by the Office of Naval Research under grant N00014-16-1-2921. D.H. acknowledges the generous support from the Simons Foundation (579913).

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X.Y.Z., Y.B. and L.Z. conceived this work. Y.B., L.Z., J.W. and W.W. performed the experiments. L.M., J.A., F.L., P.R. and N.R.F. participated in various stages of sample preparation and characterization. D.H. and C.F.B.L. carried out strain field analysis, with supervision from D.N.B. X.C.Y. and W.Y. carried out model Hamiltonian analysis. X.Y.Z. supervised the project, with inputs from A.P., J.H. and X.X. X.Y.Z, W.Y., X.X., J.H. and A.P. participated in the interpretation of experimental findings. X.Y.Z. and Y.B. wrote the manuscript, with inputs from all coauthors. All authors read and commented on the manuscript.

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Correspondence to Abhay N. Pasupathy or X.-Y. Zhu.

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Supplementary information

Supplementary Information

Supplementary Text 1–3 and Figs. S1–S24.

Source data

Source Data Fig. 1

Experimental data points of PL spectra shown in Fig. 1e.

Source Data Fig. 2

Fitting data points of the strain field shown in Fig. 2k–l.

Source Data Fig. 3

Experimental data points of PL spectra shown in Fig. 3a–e, experimental and fitting data points of linear polarization responses shown in Fig. 3f–j.

Source Data Fig. 4

Experimental and fitting data points shown in Fig. 4a–c.

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Bai, Y., Zhou, L., Wang, J. et al. Excitons in strain-induced one-dimensional moiré potentials at transition metal dichalcogenide heterojunctions. Nat. Mater. (2020). https://doi.org/10.1038/s41563-020-0730-8

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