Holes distribution in bilayer graphene

Abstract

Layer-resolved charge distribution in bilayer graphene is crucial for understanding new physics in van der Waals stacked 2D crystals and related electronics applications. Here, we report the hole distribution in Bernal-stacked and twisted bilayer graphene (AB-BLG and t-BLG) labeled by carbon isotopes prepared by chemical vapor deposition. Raman spectroscopy identifies the isotope components and stacking orientation and further characterizes the hole concentration (nh) by monitoring the shift of ωG and ω2D. This study reveals that, for both AB-BLG and t-BLG, the nh in the top and bottom layers are close, leaving negligible differences smaller than their standard deviation of experimental data. The redshift of ωG in each layer of BLG relative to that of single-layer graphene implies the extra layer reduces the degree of charge exchange at the graphene/dopant interface. Moreover, the hole distribution behavior is rotational-angle independent despite a distinct electronically coupling degree between AB-BLG and t-BLG.