  We have examined the impact of charged impurity scattering on charge carrier
transport in bilayer graphene (BLG) by deposition of potassium in ultra-high
vacuum at low temperature. Charged impurity scattering gives a conductivity
which is supra-linear in carrier density, with a magnitude similar to
single-layer graphene for the measured range of carrier densities of 2-4 x
10^12 cm^-2. Upon addition of charged impurities of concentration n_imp, the
minimum conductivity Sigma_min decreases proportional to n_imp^-1/2, while the
electron and hole puddle carrier density increases proportional to n_imp^1/2.
These results for the intentional deposition of potassium on BLG are in good
agreement with theoretical predictions for charged impurity scattering.
However, our results also suggest that charged impurity scattering alone cannot
explain the observed transport properties of pristine BLG on SiO2 before
potassium doping.
