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Trion-Induced Negative Photoconductivity in Monolayer MoS2

C. H. Lui, A. J. Frenzel, D. V. Pilon, Y.-H. Lee, X. Ling, G. M. Akselrod, J. Kong, and N. Gedik
Phys. Rev. Lett. 113, 166801 – Published 16 October 2014
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Abstract

Optical excitation typically enhances electrical conduction and low-frequency radiation absorption in semiconductors. We, however, observe a pronounced transient decrease of conductivity in doped monolayer molybdenum disulfide (MoS2), a two-dimensional (2D) semiconductor, using ultrafast optical-pump terahertz-probe spectroscopy. In particular, the conductivity is reduced to only 30% of its equilibrium value at high pump fluence. This anomalous phenomenon arises from the strong many-body interactions in the 2D system, where photoexcited electron-hole pairs join the doping-induced charges to form trions, bound states of two electrons and one hole. The resultant increase of the carrier effective mass substantially diminishes the conductivity.

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  • Received 19 June 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.166801

© 2014 American Physical Society

Authors & Affiliations

C. H. Lui1, A. J. Frenzel1,2, D. V. Pilon1, Y.-H. Lee3,4, X. Ling3, G. M. Akselrod1, J. Kong3, and N. Gedik1,*

  • 1Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  • 2Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
  • 3Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  • 4Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

  • *gedik@mit.edu

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Issue

Vol. 113, Iss. 16 — 17 October 2014

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