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Grains and grain boundaries in highly crystalline monolayer molybdenum disulphide

Nature Materials volume 12, pages 554561 (2013) | Download Citation

Abstract

Recent progress in large-area synthesis of monolayer molybdenum disulphide, a new two-dimensional direct-bandgap semiconductor, is paving the way for applications in atomically thin electronics. Little is known, however, about the microstructure of this material. Here we have refined chemical vapour deposition synthesis to grow highly crystalline islands of monolayer molybdenum disulphide up to 120 μm in size with optical and electrical properties comparable or superior to exfoliated samples. Using transmission electron microscopy, we correlate lattice orientation, edge morphology and crystallinity with island shape to demonstrate that triangular islands are single crystals. The crystals merge to form faceted tilt and mirror twin boundaries that are stitched together by lines of 8- and 4-membered rings. Density functional theory reveals localized mid-gap states arising from these 8–4 defects. We find that mirror twin boundaries cause strong photoluminescence quenching whereas tilt boundaries cause strong enhancement. Meanwhile, mirror twin boundaries slightly increase the measured in-plane electrical conductivity, whereas tilt boundaries slightly decrease the conductivity.

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Acknowledgements

Overall project coordination, sample growth, and electrical and optical characterization were supported as part of the Center for Re-Defining Photovoltaic Efficiency Through Molecular-Scale Control, an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Award DE-SC0001085. A.M.v.d.Z was supported by the EFRC as a research fellow. Electron microscopy was performed at and supported by the Cornell Center for Materials Research, an NSF MRSEC (NSF DMR-1120296). P.Y.H. was supported under the National Science Foundation Graduate Research Fellowship Grant No. DGE-0707428. D.A.C. was supported by a Columbia University Presidential fellowship and a GEM PhD Fellowship sponsored by the Center for Functional Nanomaterials at Brookhaven National Lab. T.C.B. was supported under the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), administered by ORISE-ORAU under Contract No. DE-AC05-06OR23100. The authors thank S. Gondarenko, R. Hovden, I. Meric, J. Ravichandran, L. Wang, J. Richmond-Decker and P. Kim for helpful discussions.

Author information

Author notes

    • Arend M. van der Zande
    • , Pinshane Y. Huang
    •  & Daniel A. Chenet

    These authors contributed equally to this work

Affiliations

  1. Energy Frontier Research Center, Columbia University, New York, New York 10027, USA

    • Arend M. van der Zande
    • , Tony F. Heinz
    • , David R. Reichman
    •  & James C. Hone
  2. Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA

    • Arend M. van der Zande
    • , Daniel A. Chenet
    • , Gwan-Hyoung Lee
    •  & James C. Hone
  3. School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA

    • Pinshane Y. Huang
    •  & David A. Muller
  4. Department of Chemistry, Columbia University, New York, New York 10027, USA

    • Timothy C. Berkelbach
    •  & David R. Reichman
  5. Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA

    • YuMeng You
    •  & Tony F. Heinz
  6. Samsung-SKKU Graphene Center (SSGC), Suwon, 440-746, Korea

    • Gwan-Hyoung Lee
  7. Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA

    • David A. Muller

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Contributions

A.M.v.d.Z. supervised and coordinated all aspects of the project. MoS2 growth was carried out by D.A.C. and A.M.v.d.Z. Electrical characterization and analysis was carried out by A.M.v.d.Z., D.A.C. and G-H.L. under the supervision of J.C.H. Electron microscopy and data analysis were carried out by P.Y.H. with D.A.M.’s supervision. Optical spectroscopy and data analysis were carried out by A.M.v.d.Z. and Y.Y. under T.F.H.’s supervision. DFT simulations were carried out by T.C.B. under D.R.R.’s supervision. A.M.v.d.Z., P.Y.H., D.A.C., T.C.B., Y.Y., T.F.H., D.A.M. and J.C.H. wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Arend M. van der Zande.

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DOI

https://doi.org/10.1038/nmat3633

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