Charged impurity scattering in bilayer graphene
Abstract
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 1012 cm-2. Upon addition of charged impurities of concentration nimp, the minimum conductivity Sigmamin decreases proportional to nimp-1/2, while the electron and hole puddle carrier density increases proportional to nimp1/2. 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.