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Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons

Nature Nanotechnology volume 12, pages 856–860 (2017)Cite this article

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Abstract

Transition metal dichalcogenide (TMD) monolayers with a direct bandgap feature tightly bound excitons, strong spin–orbit coupling and spin–valley degrees of freedom1,2,3,4. Depending on the spin configuration of the electron–hole pairs, intra-valley excitons of TMD monolayers can be either optically bright or dark5,6,7,8. Dark excitons involve nominally spin-forbidden optical transitions with a zero in-plane transition dipole moment9, making their detection with conventional far-field optical techniques challenging. Here, we introduce a method for probing the optical properties of two-dimensional materials via near-field coupling to surface plasmon polaritons (SPPs). This coupling selectively enhances optical transitions with dipole moments normal to the two-dimensional plane, enabling direct detection of dark excitons in TMD monolayers. When a WSe2 monolayer is placed on top of a single-crystal silver film10, its emission into near-field-coupled SPPs displays new spectral features whose energies and dipole orientations are consistent with dark neutral and charged excitons. The SPP-based near-field spectroscopy significantly improves experimental capabilities for probing and manipulating exciton dynamics of atomically thin materials, thus opening up new avenues for realizing active metasurfaces and robust optoelectronic systems, with potential applications in information processing and communication11.

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Figure 1: Probing out-of-plane electric dipole transitions in two-dimensional materials via near-field coupling to SPPs.
Figure 2: Gate-dependent far-field and SPP-coupled photoluminescence spectra in WSe2 and MoSe2.
Figure 3: Gate-dependent enhancement of the neutral and charged dark exciton state.
Figure 4: Band structure and optical transitions in WSe2 and MoSe2 in the presence of spin–orbit coupling.

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References

  1. Splendiani, A. et al. Emerging photoluminescence in monolayer MoS2 . Nano Lett. 10, 1271–1275 (2010).

    Article  CAS  Google Scholar 

  2. Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010).

    Article  Google Scholar 

  3. Xia, F., Wang, H., Xiao, D., Dubey, M. & Ramasubramaniam, A. Two-dimensional material nanophotonics. Nat. Photon. 8, 899–907 (2014).

    Article  CAS  Google Scholar 

  4. Xu, X., Yao, W., Xiao, D. & Heinz, T. F. Spin and pseudospins in layered transition metal dichalcogenides. Nat. Phys. 10, 343–350 (2014).

    Article  CAS  Google Scholar 

  5. Liu, G.-B., Shan, W.-Y., Yao, Y., Yao, W. & Xiao, D. Three-band tight-binding model for monolayers of group-VIB transition metal dichalcogenides. Phys. Rev. B 88, 085433 (2013).

    Article  Google Scholar 

  6. Kośmider, K., González, J. W. & Fernández-Rossier, J. Large spin splitting in the conduction band of transition metal dichalcogenide monolayers. Phys. Rev. B 88, 245436 (2013).

    Article  Google Scholar 

  7. Zhang, X.-X., You, Y., Zhao, S. Y. F. & Heinz, T. F. Experimental evidence for dark excitons in monolayer WSe2 . Phys. Rev. Lett. 115, 257403 (2015).

    Article  Google Scholar 

  8. Kormányos, A. et al. K·p theory for two-dimensional transition metal dichalcogenide semiconductors. 2D Mater. 2, 022001 (2015).

    Article  Google Scholar 

  9. Echeverry, J. P., Urbaszek, B., Amand, T., Marie, X. & Gerber, I. C. Splitting between bright and dark excitons in transition metal dichalcogenide monolayers. Phys. Rev. B 93, 121107 (2016).

    Article  Google Scholar 

  10. High, A. A. et al. Visible-frequency hyperbolic metasurface. Nature 522, 192–196 (2015).

    Article  CAS  Google Scholar 

  11. Poem, E. et al. Accessing the dark exciton with light. Nat. Phys. 6, 993–997 (2010).

    Article  CAS  Google Scholar 

  12. Chance, R. R., Prock, A. & Silbey, R. in Advances in Chemical Physics Vol. 37 (eds Prigogine, I. & Rice, S. A.) 1–65 (Wiley, 1978).

    CAS  Google Scholar 

  13. Gontijo, I. et al. Coupling of InGaN quantum-well photoluminescence to silver surface plasmons. Phys. Rev. B 60, 11564–11567 (1999).

    Article  CAS  Google Scholar 

  14. Wang, G. et al. Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2 . Phys. Rev. B 90, 075413 (2014).

    Article  Google Scholar 

  15. Schuller, J. A. et al. Orientation of luminescent excitons in layered nanomaterials. Nat. Nanotech. 8, 271–276 (2013).

    Article  CAS  Google Scholar 

  16. Ross, J. S. et al. Electrical control of neutral and charged excitons in a monolayer semiconductor. Nat. Commun. 4, 1474 (2013).

    Article  Google Scholar 

  17. Wang, Z., Shan, J. & Mak, K. F. Valley- and spin-polarized Landau levels in monolayer WSe2 . Nat. Nanotech. 12, 144–149 (2017).

    Article  CAS  Google Scholar 

  18. Zhang, Y. et al. Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2 . Nat. Nanotech. 9, 111–115 (2014).

    Article  CAS  Google Scholar 

  19. Zhu, Z. Y., Cheng, Y. C. & Schwingenschlögl, U. Giant spin–orbit-induced spin splitting in two-dimensional transition-metal dichalcogenide semiconductors. Phys. Rev. B 84, 153402 (2011).

    Article  Google Scholar 

  20. Slobodeniuk, A. O. & Basko, D. M. Spin–flip processes and radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers. 2D Mater. 3, 035009 (2016).

    Article  Google Scholar 

  21. Wang, G. et al. Spin–orbit engineering in transition metal dichalcogenide alloy monolayers. Nat. Commun. 6, 10110 (2015).

    Article  CAS  Google Scholar 

  22. Zhang, X.-X. et al. Magnetic brightening and control of dark excitons in monolayer WSe2 . Nat. Nanotech. http://dx.doi.org/10.1038/nnano.2017.105 (2017).

  23. Molas, M. R. et al. Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides. 2D Mater. 4, 021003 (2017).

    Article  Google Scholar 

  24. Komsa, H.-P. & Krasheninnikov, A. V. Effects of confinement and environment on the electronic structure and exciton binding energy of MoS2 from first principles. Phys. Rev. B 86, 241201 (2012).

    Article  Google Scholar 

  25. Chernikov, A. et al. Exciton binding energy and nonhydrogenic Rydberg series in monolayer WS2 . Phys. Rev. Lett. 113, 076802 (2014).

    Article  Google Scholar 

  26. Mak, K. F. et al. Tightly bound trions in monolayer MoS2 . Nat. Mater. 12, 207–211 (2013).

    Article  CAS  Google Scholar 

  27. Ganchev, B., Drummond, N., Aleiner, I. & Fal'ko, V. Three-particle complexes in two-dimensional semiconductors. Phys. Rev. Lett. 114, 107401 (2015).

    Article  Google Scholar 

  28. Sidler, M. et al. Fermi polaron–polaritons in charge-tunable atomically thin semiconductors. Nat. Phys. 13, 255–261 (2017).

    Article  CAS  Google Scholar 

  29. Yu, H., Liu, G.-B., Gong, P., Xu, X. & Yao, W. Dirac cones and Dirac saddle points of bright excitons in monolayer transition metal dichalcogenides. Nat. Commun. 5, 3876 (2014).

    Article  CAS  Google Scholar 

  30. Rivera, P. et al. Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures. Nat. Commun. 6, 6242 (2015).

    Article  CAS  Google Scholar 

  31. Jin, C. et al. Interlayer electron–phonon coupling in WSe2/hBN heterostructures. Nat. Phys. 13, 127–131 (2017).

    Article  CAS  Google Scholar 

  32. Nandi, D., Finck, A. D. K., Eisenstein, J. P., Pfeiffer, L. N. & West, K. W. Exciton condensation and perfect Coulomb drag. Nature 488, 481–484 (2012).

    Article  CAS  Google Scholar 

  33. Fogler, M. M., Butov, L. V. & Novoselov, K. S. High-temperature superfluidity with indirect excitons in van der Waals heterostructures. Nat. Commun. 5, 4555 (2014).

    Article  CAS  Google Scholar 

  34. Zomer, P. J., Guimarães, M. H. D., Brant, J. C., Tombros, N. & van Wees, B. J. Fast pick up technique for high quality heterostructures of bilayer graphene and hexagonal boron nitride. Appl. Phys. Lett. 105, 013101 (2014).

    Article  Google Scholar 

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Acknowledgements

The authors acknowledge support from the DoD Vannevar Bush Faculty Fellowship (N00014-16-1-2825), AFOSR MURI (FA9550-12-1-0024 and FA9550-17-1-0002), the NSF (PHY-1506284), NSF CUA (PHY-1125846), the Gordon and Betty Moore Foundation and Samsung Electronics. All film deposition and device fabrication was carried out at the Harvard Center for Nanoscale Systems.

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Author notes

  1. You Zhou, Giovanni Scuri, Dominik S. Wild and Alexander A. High: These authors contributed equally to this work.

Authors and Affiliations

  1. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, 02138, Massachusetts, USA

    You Zhou, Alexander A. High, Alan Dibos, Kristiaan De Greve & Hongkun Park

  2. Department of Physics, Harvard University, Cambridge, 02138, Massachusetts, USA

    You Zhou, Giovanni Scuri, Dominik S. Wild, Alexander A. High, Luis A. Jauregui, Chi Shu, Kristiaan De Greve, Kateryna Pistunova, Andrew Y. Joe, Philip Kim, Mikhail D. Lukin & Hongkun Park

  3. National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan

    Takashi Taniguchi & Kenji Watanabe

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Contributions

H.P., P.K., M.D.L., A.A.H., Y.Z., A.D. and L.A.J. conceived the study and Y.Z., G.S., A.A.H., A.D., L.A.J., K.P. and A.Y.J. developed the fabrication procedure. Y.Z., G.S., A.A.H., A.D., C.S. and K.D.G. performed experiments and T.T. and K.W. performed hBN growth. D.S.W. and A.A.H. performed computational analyses and simulations. D.S.W., M.D.L. and H.P. contributed to theoretical descriptions. Y.Z., G.S., D.S.W., A.A.H., P.K., M.D.L. and H.P. wrote the manuscript, with extensive input from all authors.

Corresponding authors

Correspondence to Philip Kim, Mikhail D. Lukin or Hongkun Park.

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Zhou, Y., Scuri, G., Wild, D. et al. Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons. Nature Nanotech 12, 856–860 (2017). https://doi.org/10.1038/nnano.2017.106

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