Reactivity of Contact Metals on Monolayer WS2

Incorporating two-dimensional transition metal dichalcogenides (TMDs) into electronic and optoelectronic applications requires a fundamental understanding of metal/TMD interactions. This work applies a fast and easy approach to observe reactivity between metal contacts and monolayer (1L) WS2 via Raman spectroscopy using both destructive and non-destructive methods. We compare findings from Raman spectra collected via a backside geometry, and also from mechanically exfoliated metal/WS2 films after annealing, with our previously published thermodynamic predictions for reactivity of bulk materials. The disappearance of the Raman-active phonon modes for WS2 suggests consumption of WS2 through reaction with the continuous metal film, as observed completely for Ti upon deposition and nearly completely for Al after annealing at and above 100 degrees C. On the other hand, the persistence of multiple Raman-active phonon modes for WS2 confirms that Au, Cu, and Pd are unreactive with WS2 upon deposition and after cumulatively annealing for 1 h at 100, 200, and 300 degrees C, even though unreactive metal overlayers can shift some of the peaks in the spectrum. The metal/WS2 reactivity observed in this study is in excellent agreement with predictions from bulk thermodynamics, which can provide good guidance for studies of other metal/TMD systems. In addition, using a backside geometry for collecting Raman spectra can aid in fundamental studies of interfaces with TMDs.

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Work Title Reactivity of Contact Metals on Monolayer WS2
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Open Access
Creators
  1. Suzanne Mohney
  2. Ama Duffie Agyapong
  3. Kayla Anne Cooley
Keyword
  1. Contact
  2. Transition Metal Dichalcogenide
  3. Tungsten Disulfide
  4. Raman spectroscopy
License In Copyright (Rights Reserved)
Work Type Article
Acknowledgments
  1. This work was primarily supported by the National Science Foundation (NSF) under No. DMR 1410334. Ama D. Agyapong acknowledges PPG for providing fellowship support and NSF EFRI 2-DARE Grant No. 1433378 for allowing her to complete the work. Kayla A. Cooley acknowledges the NSF Graduate Research Fellowship Program under No. DGE1255832. The monolayer WS2 was provided through the NSF-supported 2DCC-MIP at the Penn State (No. DMR-1539916). We also thank Maxwell Wetherington for training and assistance with Raman spectroscopy and Kirstin Schauble and Humberto Terrones for comments.
Publisher
  1. Journal of Applied Physics
Publication Date 2020
Subject
  1. Reactivity of contact metals on monolayer WS2
Language
  1. English
Publisher Identifier (DOI)
  1. https://doi.org/10.1063/5.0014005
Deposited March 02, 2021

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  • Updated Acknowledgments Show Changes
    Acknowledgments
    • This work was primarily supported by the National Science Foundation (NSF) under No. DMR 1410334. Ama D. Agyapong acknowledges PPG for providing fellowship support and NSF EFRI 2-DARE Grant No. 1433378 for allowing her to complete the work. Kayla A. Cooley acknowledges the NSF Graduate Research Fellowship Program under No. DGE1255832. The monolayer WS2 was provided through the NSF-supported 2DCC-MIP at the Penn State (No. DMR-1539916). We also thank Maxwell Wetherington for training and assistance with Raman spectroscopy and Kirstin Schauble and Humberto Terrones for comments.
  • Added Creator Suzanne Mohney
  • Added Creator Ama Duffie Agyapong
  • Added Creator Kayla Anne Cooley
  • Added Accepted Manuscript.pdf
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