Effect of Stacking Order on the Electric-Field Induced Carrier Modulation in Graphene Bilayers

When planar graphene sheets are stacked on top of each other, the electronic structure of the system varies with the position of the subsequent sublattice atoms. Here, we employ scanning photocurrent microscopy to study the disparity in the behavior of charge carriers for two different stacking configurations. It has been found that deviation from the regular Bernal stacking decouples the sheets from each other, which Imparts effective electrostatic screening of the farther layer from the underlying backgate. Electrochemical top-gating is demonstrated as a means to selectively tune the charge carrier density in the decoupled upper layer.