  Graphene is an attractive material for microelectronics applications, given
such favourable electrical characteristics as high mobility, high operating
frequency, and good stability. If graphene is to be implemented in electronic
devices on a mass scale, then it must be compatible with existing semiconductor
industry fabrication processes. Unfortunately, such processing introduces
defects and impurities to the graphene, which cause scattering of the charge
carriers and changes in doping level. Scattering results in degradation of
electrical performance, including lower mobility and Dirac point shifts. In
this paper, we review methods by which to mitigate the effects of charged
impurities and defects in graphene devices. Using capping layers such as
fluoropolymers, statistically significant improvement of mobility, on/off
ratio, and Dirac point voltage for graphene FETs have been demonstrated. These
effects are also reversible and can be attributed to the presence of highly
polar groups in these capping layers such as carbon-fluoride bonds in the
fluoropolymer acting to electrostatically screen charged impurities and defects
in or near the graphene. In other experiments, graphene FETs were exposed to
vapour-phase, polar, organic molecules in an ambient environment. This resulted
in significant improvement to electrical characteristics, and the magnitude of
improvement to the Dirac point scaled with the dipole moment of the delivered
molecule type. The potential profile produced in the plane of the graphene
sheet by the impurities was calculated to be significantly reduced by the
presence of polar molecules. We present strong evidence that the polar nature
of capping layers or polar vapour molecules introduced to the surface of a
graphene FET act to mitigate detrimental effects of charged impurities/defects.
