2009/02/28 by Paola Gava, Michele Lazzeri, A. Marco Saitta +1 · 1 citation
Chemistry · Materials Science · Physics and Astronomy · #2D Materials and Applications #Band gap #Bilayer #Bilayer graphene #Brillouin zone #Chemistry #Condensed matter physics #Density functional theory #Doping #Electric field #Electronic band structure #Graphene #Graphene research and applications #Materials science #Nanotechnology #Physics #Quantum and electron transport phenomena #Quantum mechanics #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.79.165431
15 pages 20 figures, accepted for publication in Physical Review B
arxiv created 2009/04/24 · openalex publication_date 2009/04/24 · arxiv updated 2015/05/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The electronic properties of doped bilayer graphene in presence of bottom and top gates have been studied and characterized by means of density-functional theory (DFT) calculations. Varying independently the bottom and top gates it is possible to control separately the total doping charge on the sample and the average external electric field acting on the bilayer. We show that, at fixed doping level, the band gap at the K point in the Brillouin zone depends linearly on the average electric field, whereas the corresponding proportionality coefficient has a nonmonotonic dependence on doping. We find that the DFT-calculated band gap at K, for small doping levels, is roughly half of the band gap obtained with standard tight-binding (TB) approach. We show that this discrepancy arises from an underestimate, in the TB model, of the screening of the system to the external electric field. In particular, on the basis of our DFT results we observe that, when bilayer graphene is in presence of an external electric field, both interlayer and intralayer screenings occur. Only the interlayer screening is included in TB calculations, while both screenings are fundamental for the description of the band-gap opening. We finally provide a general scheme to obtain the full band structure of gated bilayer graphene for an arbitrary value of the external electric field and of doping.