▎ 摘　　要

We demonstrate that a hydrophobic layer between substrate and graphene largely eliminates Coulomb interaction between the graphene monolayer and charged impurities on the substrate, significantly reducing short-range scattering. At high carrier concentrations the mobilities thus obtained, deliver a ratio of Coulomb scattering mean free path to average charge carrier separation comparable to that of the highest mobility samples that exhibit the fractional quantum Hall effect (FQHE). We observe the FQHE in the lowest mobility samples reported up to now and conclude that increasing the ratio of Coulomb scattering mean free path to charge carrier separation overcomes the limitations for the observation of the FQHE imposed by overall mobility. ((c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)