Atomically Thin MoS2: A New Direct-Gap Semiconductor

Phys. Rev. Lett. 105, 136805 – Published 24 September 2010
Kin Fai Mak, Changgu Lee, James Hone, Jie Shan, and Tony F. Heinz

Abstract

The electronic properties of ultrathin crystals of molybdenum disulfide consisting of N=1,2,,6 S-Mo-S monolayers have been investigated by optical spectroscopy. Through characterization by absorption, photoluminescence, and photoconductivity spectroscopy, we trace the effect of quantum confinement on the material’s electronic structure. With decreasing thickness, the indirect band gap, which lies below the direct gap in the bulk material, shifts upwards in energy by more than 0.6 eV. This leads to a crossover to a direct-gap material in the limit of the single monolayer. Unlike the bulk material, the MoS2 monolayer emits light strongly. The freestanding monolayer exhibits an increase in luminescence quantum efficiency by more than a factor of 104 compared with the bulk material.

DOI: http://dx.doi.org/10.1103/PhysRevLett.105.136805

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  • Received 2 April 2010
  • Published 24 September 2010

© 2010 The American Physical Society

Authors & Affiliations

Kin Fai Mak1, Changgu Lee2, James Hone3, Jie Shan4, and Tony F. Heinz1,*

  • 1Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA
  • 2SKKU Advanced Institute of Nanotechnology (SAINT) and Department of Mechanical Engineering, Sungkyunkwan University, Suwon 440-746, Korea
  • 3Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA
  • 4Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA

  • *Corresponding author.tony.heinz@columbia.edu

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