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Controlled Ambipolar‐to‐Unipolar Conversion in Graphene Field‐Effect Transistors Through Surface Coating with Poly(ethylene imine)/Poly(ethylene glycol) Films
Author(s) -
Yan Zheng,
Yao Jun,
Sun Zhengzong,
Zhu Yu,
Tour James M.
Publication year - 2012
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201101528
Subject(s) - ambipolar diffusion , materials science , graphene , ethylene glycol , chemical engineering , doping , nanotechnology , field effect transistor , electron mobility , peg ratio , coating , polymer , polymer chemistry , transistor , optoelectronics , composite material , electron , physics , finance , quantum mechanics , voltage , engineering , economics
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.