Trion-Induced Negative Photoconductivity in Monolayer MoS[subscript 2]
Author(s)
Lee, Y.-H.; Ling, X.; Akselrod, Gleb Markovitch; Lui, Chun Hung; Frenzel, Alex James; Pilon, Daniel Victor; Kong, Jing; Gedik, Nuh; ... Show more Show less
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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 (MoS[subscript 2]), 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.
Date issued
2014-10Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science; Massachusetts Institute of Technology. Department of PhysicsJournal
Physical Review Letters
Publisher
American Physical Society
Citation
Lui, C. H., et al. "Trion-Induced Negative Photoconductivity in Monolayer MoS[subscript 2]." Phys. Rev. Lett. 113, 166801 (October 2014). © 2014 American Physical Society
Version: Final published version
ISSN
0031-9007
1079-7114