Broadband transient THz conductivity of the transition-metal dichalcogenide MoS2

J. H. Buss, R. P. Smith, G. Coslovich, R. A. Kaindl

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Scopus citations

Abstract

The transient dynamics of transition-metal dichalcogenides is of significant interest for clarifying fundamental manyparticle interactions at the nanoscale as well as for novel applications. We report an ultrafast terahertz study up to 7 THz of the lamellar semiconductor MoS2 to access the non-equilibrium conductivity of photo-excited indirect e-h pairs in this multi-layered parent compound. While the equilibrium transport is Drude-like, near-IR optical excitation results in a complex photo-induced conductivity that consists of two components. Mobile charge carriers dominate the low frequency response below 2 THz, while at low temperatures an additional excess conductivity is observed that is enhanced around 4 THz. Two time scales appear in the dynamics: a slow ns relaxation due to non-radiative recombination and a faster sub-100 ps decay connected to the high-frequency THz feature. We discuss the broad THz peak within a model of intra-excitonic transitions in MoS2. It agrees well with the expected binding energy and oscillator strength, yet results in an anomalous temperature dependence of the exciton fraction requiring an electronically inhomogeneous phase.

Original languageEnglish (US)
Title of host publicationUltrafast Phenomena and Nanophotonics XIX
EditorsMarkus Betz, Abdulhakem Y. Elezzabi, Kong-Thon Tsen
PublisherSPIE
ISBN (Electronic)9781628414516
DOIs
StatePublished - 2015
Externally publishedYes
EventUltrafast Phenomena and Nanophotonics XIX - San Francisco, United States
Duration: Feb 8 2015Feb 11 2015

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9361
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceUltrafast Phenomena and Nanophotonics XIX
CountryUnited States
CitySan Francisco
Period2/8/152/11/15

Keywords

  • electron-hole pairs
  • many-particle interactions
  • molybdenum disulfide
  • MoS
  • non-equilibrium charge transport
  • THz spectroscopy
  • transition-metal dichalcogenides
  • ultrafast dynamics

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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