Record Low Thermal Conductivity of Polycrystalline MoS<inf>2</inf> Films: Tuning the Thermal Conductivity by Grain Orientation

Marianna Sledzinska, Romain Quey, Bohayra Mortazavi, Bartlomiej Graczykowski, Marcel Placidi, David Saleta Reig, Daniel Navarro-Urrios, Francesc Alzina, Luciano Colombo, Stephan Roche, Clivia M. Sotomayor Torres

Research output: Contribution to journalArticleResearchpeer-review

12 Citations (Scopus)

Abstract

© 2017 American Chemical Society. We report a record low thermal conductivity in polycrystalline MoS2 obtained for ultrathin films with varying grain sizes and orientations. By optimizing the sulfurization parameters of nanometer-thick Mo layers, five MoS2 films containing a combination of horizontally and vertically oriented grains, with respect to the bulk (001) monocrystal, were grown. From transmission electron microscopy, the average grain size, typically below 10 nm, and proportion of differently oriented grains were extracted. The thermal conductivity of the suspended samples was extracted from a Raman laser-power-dependent study, and the lowest value of thermal conductivity of 0.27 W m-1 K-1, which reaches a similar value as that of Teflon, is obtained in a polycrystalline sample formed by a combination of horizontally and vertically oriented grains in similar proportion. Analysis by means of molecular dynamics and finite element method simulations confirm that such a grain arrangement leads to lower grain boundary conductance. We discuss the possible use of these thermal insulating films in the context of electronics and thermoelectricity.
Original languageEnglish
Pages (from-to)37905-37911
JournalACS Applied Materials and Interfaces
Volume9
Issue number43
DOIs
Publication statusPublished - 1 Nov 2017

Keywords

  • MoS 2
  • Raman thermometry
  • thermal conductivity
  • thermal insulating films
  • thermal modeling

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