Uncovering the effects of metal contacts on monolayer MoS2

Kirstin Schauble, Dante Zakhidov, Eilam Yalon, Sanchit Deshmukh, Ryan W. Grady, Kayla A. Cooley, Connor J. McClellan, Sam Vaziri, Donata Passarello, Suzanne E. Mohney, Michael F. Toney, A. K. Sood, Alberto Salleo, Eric Pop

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Metal contacts are a key limiter to the electronic performance of two-dimensional (2D) semiconductor devices. Here, we present a comprehensive study of contact interfaces between seven metals (Y, Sc, Ag, Al, Ti, Au, Ni, with work functions from 3.1 to 5.2 eV) and monolayer MoS2 grown by chemical vapor deposition. We evaporate thin metal films onto MoS2 and study the interfaces by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and electrical characterization. We uncover that (1) ultrathin oxidized Al dopes MoS2 n-type (>2 × 1012 cm−2) without degrading its mobility, (2) Ag, Au, and Ni deposition causes varying levels of damage to MoS2 (e.g. broadening Raman E′ peak from <3 to >6 cm−1), and (3) Ti, Sc, and Y react with MoS2. Reactive metals must be avoided in contacts to monolayer MoS2, but control studies reveal the reaction is mostly limited to the top layer of multilayer films. Finally, we find that (4) thin metals do not significantly strain MoS2, as confirmed by X-ray diffraction. These are important findings for metal contacts to MoS2 and broadly applicable to many other 2D semiconductors.

Original languageEnglish (US)
Pages (from-to)14798-14808
Number of pages11
JournalACS nano
Volume14
Issue number11
DOIs
StatePublished - Nov 24 2020

All Science Journal Classification (ASJC) codes

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

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