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Imaging strain-localized excitons in nanoscale bubbles of monolayer WSe2 at room temperature

Abstract

In monolayer transition-metal dichalcogenides, localized strain can be used to design nanoarrays of single photon sources. Despite strong empirical correlation, the nanoscale interplay between excitons and local crystalline structure that gives rise to these quantum emitters is poorly understood. Here, we combine room-temperature nano-optical imaging and spectroscopic analysis of excitons in nanobubbles of monolayer WSe2 with atomistic models to study how strain induces nanoscale confinement potentials and localized exciton states. The imaging of nanobubbles in monolayers with low defect concentrations reveals localized excitons on length scales of around 10 nm at multiple sites around the periphery of individual nanobubbles, in stark contrast to predictions of continuum models of strain. These results agree with theoretical confinement potentials atomistically derived from the measured topographies of nanobubbles. Our results provide experimental and theoretical insights into strain-induced exciton localization on length scales commensurate with exciton size, realizing key nanoscale structure–property information on quantum emitters in monolayer WSe2.

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Fig. 1: Nano-optical detection of room-temperature photoluminescence from LX states in nanobubbles in 1L-WSe2.
Fig. 2: High-resolution nanophotoluminescence imaging and spectroscopy of distinct LX states within a single nanobubble.
Fig. 3: Comparison of atomistic theory with experimental data.
Fig. 4: Comparison of experiment and theory for four nanobubbles in 1L-WSe2 with a low concentration of defects.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.

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Acknowledgements

N.J.B. and P.J.S. acknowledge support from the National Science Foundation through award NSF-1838403. P.J.S. thanks S. Strauf for stimulating and enlightening discussions. J.W.K. acknowledges support from the National Science Foundation through awards NSF-1437450 and NSF-1363093. The preparation and characterization of the nanobubbles in flux-grown low-defect-density WSe2 were partially supported as part of Programmable Quantum Materials, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Basic Energy Sciences (BES), through award DE-SC0019443. C.C., M.F. and F.J. acknowledge financial support from the German Research Foundation (RTG 2247 ‘Quantum Mechanical Materials Modelling - QM³’) as well as resources for computational time at the HLRN (Hannover/Berlin). E.Y. acknowledges partial support through a US Department of Energy, Office of Science Graduate Student Research (SCGSR) award. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by MEXT, Japan and CREST (JPMJCR15F3), JST.

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P.J.S., N.J.B. and T.P.D. conceived the nano-optical study. Experimental measurements were conducted by T.P.D., E.Y., N.J.B. and A.K. Samples for these measurements were prepared by O.A., J.A., E.Y., A.G., D.A.R., A.N.P. and J.C.H. K.W. and T.T. provided critical materials for the preparation of these samples. The experimental data were analysed by T.P.D., N.J.B. and P.J.S. with important contributions from J.W.K. Theoretical calculations were carried out by C.C., M.F. and F.J. All authors contributed to the preparation of the manuscript.

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Correspondence to Frank Jahnke or Nicholas J. Borys or P. James Schuck.

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Supplementary methods, discussion and Figs 1–7.

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Darlington, T.P., Carmesin, C., Florian, M. et al. Imaging strain-localized excitons in nanoscale bubbles of monolayer WSe2 at room temperature. Nat. Nanotechnol. 15, 854–860 (2020). https://doi.org/10.1038/s41565-020-0730-5

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