Spatially resolved photoexcited charge-carrier dynamics in phase-engineered monolayer MoS2

Hisato Yamaguchi, Jean Christophe Blancon, Rajesh Kappera, Sidong Lei, Sina Najmaei, Benjamin D. Mangum, Gautam Gupta, Pulickel M. Ajayan, Jun Lou, Manish Chhowalla, Jared J. Crochet, Aditya D. Mohite

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

A fundamental understanding of the intrinsic optoelectronic properties of atomically thin transition-metal dichalcogenides (TMDs) is crucial for its integration into high performance semiconductor devices. Here, we investigate the transport properties of chemical vapor deposition (CVD) grown monolayer molybdenum disulfide (MoS2) under photoexcitation using correlated scanning photocurrent microscopy and photoluminescence imaging. We examined the effect of local phase transformation underneath the metal electrodes on the generation of photocurrent across the channel length with diffraction-limited spatial resolution. While maximum photocurrent generation occurs at the Schottky contacts of semiconducting (2H-phase) MoS2, after the metallic phase transformation (1T-phase), the photocurrent peak is observed toward the center of the device channel, suggesting a strong reduction of native Schottky barriers. Analysis using the bias and position dependence of the photocurrent indicates that the Schottky barrier heights are a few millielectron volts for 1T- and ∼200 meV for 2H-contacted devices. We also demonstrate that a reduction of native Schottky barriers in a 1T device enhances the photoresponsivity by more than 1 order of magnitude, a crucial parameter in achieving high-performance optoelectronic devices. The obtained results pave a way for the fundamental understanding of intrinsic optoelectronic properties of atomically thin TMDs where ohmic contacts are necessary for achieving high-efficiency devices with low power consumption.

Original languageEnglish
Pages (from-to)840-849
Number of pages10
JournalACS Nano
Volume9
Issue number1
DOIs
Publication statusPublished - Jan 27 2015

Fingerprint

Charge carriers
Photocurrents
photocurrents
charge carriers
Monolayers
Optoelectronic devices
Transition metals
phase transformations
electric contacts
Phase transitions
transition metals
molybdenum disulfides
Ohmic contacts
Photoexcitation
Semiconductor devices
optoelectronic devices
photoexcitation
semiconductor devices
Transport properties
Molybdenum

Keywords

  • contact resistance
  • monolayer
  • MoS
  • optoelectronic
  • phase conversion
  • scanning photocurrent microscopy
  • transition-metal dichalcogenide

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Physics and Astronomy(all)

Cite this

Yamaguchi, H., Blancon, J. C., Kappera, R., Lei, S., Najmaei, S., Mangum, B. D., ... Mohite, A. D. (2015). Spatially resolved photoexcited charge-carrier dynamics in phase-engineered monolayer MoS2 . ACS Nano, 9(1), 840-849. https://doi.org/10.1021/nn506469v

Spatially resolved photoexcited charge-carrier dynamics in phase-engineered monolayer MoS2 . / Yamaguchi, Hisato; Blancon, Jean Christophe; Kappera, Rajesh; Lei, Sidong; Najmaei, Sina; Mangum, Benjamin D.; Gupta, Gautam; Ajayan, Pulickel M.; Lou, Jun; Chhowalla, Manish; Crochet, Jared J.; Mohite, Aditya D.

In: ACS Nano, Vol. 9, No. 1, 27.01.2015, p. 840-849.

Research output: Contribution to journalArticle

Yamaguchi, H, Blancon, JC, Kappera, R, Lei, S, Najmaei, S, Mangum, BD, Gupta, G, Ajayan, PM, Lou, J, Chhowalla, M, Crochet, JJ & Mohite, AD 2015, 'Spatially resolved photoexcited charge-carrier dynamics in phase-engineered monolayer MoS2 ', ACS Nano, vol. 9, no. 1, pp. 840-849. https://doi.org/10.1021/nn506469v
Yamaguchi H, Blancon JC, Kappera R, Lei S, Najmaei S, Mangum BD et al. Spatially resolved photoexcited charge-carrier dynamics in phase-engineered monolayer MoS2 . ACS Nano. 2015 Jan 27;9(1):840-849. https://doi.org/10.1021/nn506469v
Yamaguchi, Hisato ; Blancon, Jean Christophe ; Kappera, Rajesh ; Lei, Sidong ; Najmaei, Sina ; Mangum, Benjamin D. ; Gupta, Gautam ; Ajayan, Pulickel M. ; Lou, Jun ; Chhowalla, Manish ; Crochet, Jared J. ; Mohite, Aditya D. / Spatially resolved photoexcited charge-carrier dynamics in phase-engineered monolayer MoS2 . In: ACS Nano. 2015 ; Vol. 9, No. 1. pp. 840-849.
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