Toward ambient-stable molecular gated graphene-FET: A donor/acceptor hybrid architecture to achieve bandgap in bilayer graphene

摘要

In this work we report a technique to improve the Ion/Ioff ratio in bilayer graphene FET by asymetrical doping of layers. Doping is achived by n-doping the bottom layer by depositing bilayer graphene flakes on NH_2-SAM modified SiO_2 substrate and hole doping the top layer via coating the device with a film of F_4TCNQ-containing polystyrene. Asymmetric surface doping of bilayer graphene can induce an electric field between both layers which results in opening of an electronic bandgap due to symmetry breaking. DFT modelling shows an effective electric field of ～1.5 V/nm between the layers and field effect measurements show an increase of Ion/Ioff ratio in bilayer FET up to 135 due to opening of the bandgap also, a Schottky barrier of ～60 meV at the interface of the semiconducting bilayer graphene and the electric contact is observed.