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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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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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.
The authors declare no competing interests.
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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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