Polarization-Driven Asymmetric Electronic Response of Monolayer Graphene to Polymer Zwitterions Probed from Both Sides

Nicholas Hight-Huf, Yehiel Nagar, Adi Levi, James Nicolas Pagaduan, Avdhoot Datar, Reika Katsumata, Todd Emrick, Ashwin Ramasubramaniam, Doron Naveh, Michael D. Barnes

Research output: Contribution to journalArticlepeer-review

Abstract

We investigated the nature of graphene surface doping by zwitterionic polymers and the implications of weak in-plane and strong through-plane screening using a novel sample geometry that allows direct access to either the graphene or the polymer side of a graphene/polymer interface. Using both Kelvin probe and electrostatic force microscopies, we observed a significant upshift in the Fermi level in graphene of ∼260 meV that was dominated by a change in polarizability rather than pure charge transfer with the organic overlayer. This physical picture is supported by density functional theory (DFT) calculations, which describe a redistribution of charge in graphene in response to the dipoles of the adsorbed zwitterionic moieties, analogous to a local DC Stark effect. Strong metallic-like screening of the adsorbed dipoles was observed by employing an inverted geometry, an effect identified by DFT to arise from a strongly asymmetric redistribution of charge confined to the side of graphene proximal to the zwitterion dipoles. Transport measurements confirm n-type doping with no significant impact on carrier mobility, thus demonstrating a route to desirable electronic properties in devices that combine graphene with lithographically patterned polymers.

Original languageEnglish
Pages (from-to)47945-47953
Number of pages9
JournalACS applied materials & interfaces
Volume13
Issue number40
DOIs
StatePublished - 13 Oct 2021

Keywords

  • EFM
  • FET
  • KPFM
  • charge transfer
  • graphene
  • hybrid 2D materials
  • lithography
  • polarizability
  • screening
  • zwitterion

All Science Journal Classification (ASJC) codes

  • General Materials Science

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