Atomic-Scale Spectroscopy of Gated Monolayer MoS2

Xiaodong Zhou, Kibum Kang, Saien Xie, Ali Dadgar, Nicholas R. Monahan, X. Y. Zhu, Jiwoong Park, Abhay N. Pasupathy

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

The electronic properties of semiconducting monolayer transition-metal dichalcogenides can be tuned by electrostatic gate potentials. Here we report gate-tunable imaging and spectroscopy of monolayer MoS2 by atomic-resolution scanning tunneling microscopy/spectroscopy (STM/STS). Our measurements are performed on large-area samples grown by metal-organic chemical vapor deposition (MOCVD) techniques on a silicon oxide substrate. Topographic measurements of defect density indicate a sample quality comparable to single-crystal MoS2. From gate voltage dependent spectroscopic measurements, we determine that in-gap states exist in or near the MoS2 film at a density of 1.3 × 1012 eV-1 cm-2. By combining the single-particle band gap measured by STS with optical measurements, we estimate an exciton binding energy of 230 meV on this substrate, in qualitative agreement with numerical simulation. Grain boundaries are observed in these polycrystalline samples, which are seen to not have strong electronic signatures in STM imaging.

Original languageEnglish (US)
Pages (from-to)3148-3154
Number of pages7
JournalNano Letters
Volume16
Issue number5
DOIs
StatePublished - May 11 2016
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

Keywords

  • exciton binding energy
  • grain boundary
  • Monolayer molybdenum disulfide
  • scanning tunneling microscopy/spectroscopy
  • single-particle band gap

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