Determination of quantum capacitance and band filling potential in graphene transistors with dual electrochemical and field-effect gates

Chang Hyun Kim, C. Daniel Frisbie

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

We report here an investigation of graphene field-effect transistors (G-FETs) in which the graphene channel is in contact with an electrolyte phase. The electrolyte and the ultrathin nature of graphene allow direct measurement of the channel electrochemical potential versus a reference electrode also in contact with the electrolyte. In addition, the electrolyte can be used to gate the graphene; i.e., a dual-gate structure is realized. We employ this electrolyte modified G-FET architecture to (1) track the Fermi level of the graphene channel as a function of gate bias, (2) determine the density of states (i.e., the quantum capacitance CQ) of graphene, and (3) separate the gate induced band filling potential δ from the electrochemical double-layer charging potential ΔøEDL. Additionally, we are able to determine the electric double-layer capacitance CEDL for the graphene/electrolyte interface, which is ∼5 μF/cm2, the same order of magnitude as CQ. Overall, the electrolyte modified G-FETs provide an excellent model system for probing the electronic structure and transport properties of graphene and for understanding the differences between the two gating mechanisms.

Original languageEnglish (US)
Pages (from-to)21160-21169
Number of pages10
JournalJournal of Physical Chemistry C
Volume118
Issue number36
DOIs
StatePublished - Sep 11 2014

Bibliographical note

Publisher Copyright:
© 2014 American Chemical Society.

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