The Restorative Effect of Fluoropolymer Coating on Electrical Characteristics of Graphene Field-Effect Transistors

We report on the improvement of the electronic characteristics of mono-layered graphene field-effect transistors by an interacting capping layer of a suitable fluoropolymer. Favorable shifts in the Dirac voltage toward zero with shift magnitudes in excess of 60 V are observed. Furthermore, the field-effect mobility is increased and the on–off current ratio is improved by up to a factor of 2. The residual carrier concentration is reduced to ${\sim}4.8\times 10^{11}~{\rm cm}^{-2}$ . We hypothesize that this improvement is due to the strongly polar nature of the C-F chemical bond in the fluoropolymer. Significantly, these results have been achieved in graphene grown by wafer-scale chemical vapor deposition process and lift-off transfer.