title: Controlled ambipolar-to-unipolar conversion in graphene field-effect transistors through surface coating with poly(ethylene imine)/poly(ethylene glycol) films.
abstract: A controlled ambipolar-to-unipolar (n-type) conversion, along with a maximum fourfold increase in the electron mobility, in graphene field-effect transistors (FETs) is achieved by coating the surface of graphene with a layer of a mixed polymer system, poly(ethylene imine) (PEI) in poly(ethylene glycol) (PEG). The PEG serves as a physisorption adhesion agent for the PEI. Both unipolar and ambipolar n-type doping can be realized by adjusting the thickness of PEI films atop the graphene channel. The observed phenomena are attributed to the doping/dedoping effects of the external PEI film. The study provides a guide to engineering graphene transport properties through chemical modifications.
authors.affiliation: Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yan
authors.forename: Jun
authors.initials: J
authors.lastname: Yao
authors.forename: Zhengzong
authors.initials: Z
authors.lastname: Sun
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhu
authors.forename: James M
authors.initials: JM
authors.lastname: Tour
mesh_terms: D006108:Graphite / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D008567:Membranes, Artificial; D011092:Polyethylene Glycols / Q000737:chemistry*; D011095:Polyethylenes / Q000737:chemistry*; D014173:Transistors, Electronic
chemical_list: D007097:Imines; D008567:Membranes, Artificial; D011095:Polyethylenes; C505405:poly(ethylene imine); D011092:Polyethylene Glycols; D006108:Graphite