title: Graphene transistors are insensitive to pH changes in solution.
abstract: We observe very small gate-voltage shifts in the transfer characteristic of as-prepared graphene field-effect transistors (GFETs) when the pH of the buffer is changed. This observation is in strong contrast to Si-based ion-sensitive FETs. The low gate-shift of a GFET can be further reduced if the graphene surface is covered with a hydrophobic fluorobenzene layer. If a thin Al-oxide layer is applied instead, the opposite happens. This suggests that clean graphene does not sense the chemical potential of protons. A GFET can therefore be used as a reference electrode in an aqueous electrolyte. Our finding sheds light on the large variety of pH-induced gate shifts that have been published for GFETs in the recent literature.
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: Wangyang
authors.initials: W
authors.lastname: Fu
authors.forename: Cornelia
authors.initials: C
authors.lastname: Nef
authors.forename: Oren
authors.initials: O
authors.lastname: Knopfmacher
authors.forename: Alexey
authors.initials: A
authors.lastname: Tarasov
authors.forename: Markus
authors.initials: M
authors.lastname: Weiss
authors.forename: Michel
authors.initials: M
authors.lastname: Calame
authors.forename: Christian
authors.initials: C
authors.lastname: Schönenberger
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D002021:Buffers; D003300:Copper / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D005464:Fluorobenzenes / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics / Q000379:methods; D013696:Temperature
chemical_list: D002021:Buffers; D005464:Fluorobenzenes; D007477:Ions; D006108:Graphite; D003300:Copper; D000537:Aluminum Oxide