title: Water-gated charge doping of graphene induced by mica substrates.
abstract: We report on the existence of water-gated charge doping of graphene deposited on atomically flat mica substrates. Molecular films of water in units of ~0.4 nm thick bilayers were found to be present in regions of the interface of graphene/mica heterostacks prepared by micromechanical exfoliation of kish graphite. The spectral variation of the G and 2D bands, as visualized by Raman mapping, shows that mica substrates induce strong p-type doping in graphene with hole densities of (9 ± 2) × 10(12) cm(-2). The ultrathin water films, however, effectively block interfacial charge transfer, rendering graphene significantly less hole-doped. Scanning Kelvin probe microscopy independently confirmed a water-gated modulation of the Fermi level by 0.35 eV, which is in agreement with the optically determined hole density. The manipulation of the electronic properties of graphene demonstrated in this study should serve as a useful tool in realizing future graphene applications.
authors.affiliation: Department of Applied Chemistry, Kyung Hee University, Yongin, Gyeonggi 446-701, Korea.
authors.forename: Jihye
authors.initials: J
authors.lastname: Shim
authors.forename: Chun Hung
authors.initials: CH
authors.lastname: Lui
authors.forename: Taeg Yeoung
authors.initials: TY
authors.lastname: Ko
authors.forename: Young-Jun
authors.initials: YJ
authors.lastname: Yu
authors.forename: Philip
authors.initials: P
authors.lastname: Kim
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz
authors.forename: Sunmin
authors.initials: S
authors.lastname: Ryu
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D008567:Membranes, Artificial; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D008567:Membranes, Artificial; D014867:Water; D006108:Graphite; C011934:mica