We report a novel water-gated charge doping in graphene supported on atomically flat mica substrates studied with Raman spectroscopy and scanning Kelvin probe microscopy (SKPM). Thin water molecular films in units of ~0.4 nm-thick bilayers were randomly generated at the interface of graphene/mica hetero-stacks prepared by micromechanical exfoliation of kish graphite. The spectral variation of the G and 2D bands visualized by Raman mapping shows that mica substrates induce strong and virtually constant p-type doping in graphene with hole density of 9x1012 cm-2. The atom-thick interfacial water films, however, effectively block the interfacial charge transfer making graphene almost charge-neutral. SKPM independently confirmed the water-gated modulation of the Fermi level by 0.35 eV, which matches well with the optically determined hole density. The manipulation of the electronic properties of graphene shown in this study should serve as a useful tool in realizing future graphene applications.

Water-gated charge doping of graphene induced by mica substrates

244th National Meeting (2012)

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