Structural modulation of bilayer graphene under an external electric field and carrier doping

Density functional theory was used to investigate the geometric structure of bilayer graphene under an external electric field with carrier doping. Our calculations revealed the crucial impact of external electric fields and the hole injection on determining the geometric structure of bilayer graphene. The bond length of graphene monotonically increased when increasing the hole doping concentration, while it remained insensitive to electron doping. Additionally, there accumulated carriers predominantly distributed in the outermost layer located just below the gate electrode. These results enabled the construction of moire superlattices in the bilayer graphene, possessing different moire periodicity depending on the carrier concentration.