Influence of stoichiometry on the optical and electrical properties of chemical vapor deposition derived MoS2

In Soo Kim, Vinod K. Sangwan, Deep Jariwala, Joshua D. Wood, Spencer Park, Kan Sheng Chen, Fengyuan Shi, Francisco Ruiz-Zepeda, Arturo Ponce, Miguel Jose-Yacaman, Vinayak P. Dravid, Tobin J. Marks, Mark C. Hersam, Lincoln J. Lauhon

Research output: Contribution to journalArticlepeer-review

272 Scopus citations


Ultrathin transition metal dichalcogenides (TMDCs) of Mo and W show great potential for digital electronics and optoelectronic applications. Whereas early studies were limited to mechanically exfoliated flakes, the large-area synthesis of 2D TMDCs has now been realized by chemical vapor deposition (CVD) based on a sulfurization reaction. The optoelectronic properties of CVD grown monolayer MoS2 have been intensively investigated, but the influence of stoichiometry on the electrical and optical properties has been largely overlooked. Here we systematically vary the stoichiometry of monolayer MoS2 during CVD via controlled sulfurization and investigate the associated changes in photoluminescence and electrical properties. X-ray photoelectron spectroscopy is employed to measure relative variations in stoichiometry and the persistence of MoOx species. As MoS2-δ is reduced (increasing δ), the field-effect mobility of monolayer transistors increases while the photoluminescence yield becomes nonuniform. Devices fabricated from monolayers with the lowest sulfur content have negligible hysteresis and a threshold voltage of ∼0 V. We conclude that the electrical and optical properties of monolayer MoS2 crystals can be tuned via stoichiometry engineering to meet the requirements of various applications.

Original languageEnglish (US)
Pages (from-to)10551-10558
Number of pages8
JournalACS Nano
Issue number10
StatePublished - Oct 28 2014
Externally publishedYes


  • X-ray photoelectron spectroscopy
  • chemical vapor deposition
  • field-effect mobility
  • molybdenum disulfide
  • photoluminescence
  • stoichiometry
  • transition metal dichalcogenides

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy


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