Electronic properties of a biased graphene bilayer

Abstract

We study, within the tight-binding approximation, the electronic properties of a graphene bilayer in the presence of an external electric field applied perpendicular to the system -biased bilayer. The effect of the perpendicular electric field is included through a parallel plate capacitor model, with screening correction at the Hartree level. The full tight-binding description is compared with its 4-band and 2-band continuum approximations, and the 4-band model is shown to be always a suitable approximation for the conditions realized in experiments. The model is applied to real biased bilayer devices, either made out of SiC or exfoliated graphene, and good agreement with experimental results is found, indicating that the model is capturing the key ingredients, and that a finite gap is effectively being controlled externally. Analysis of experimental results regarding the electrical noise and cyclotron resonance further suggests that the model can be seen as a good starting point to understand the electronic properties of graphene bilayer. Also, we study the effect of electron-hole asymmetry terms, as the second-nearest-neighbor hopping energies t ′ (in-plane) and γ4 (inter-layer), and the on-site energy ∆.

Strain and electric field modulation of the electronic structure of bilayer graphene

“…While the freestanding BLG is a zero band-gap semiconductor 3,4 like the single layer graphene ͑SLG͒, an applied electric field through an external gate induces an asymmetric potential between the graphene layers, which in turn opens a gap between the valence and the conduction bands in the Bernal structure. [4][5][6][7][8] It has been recently noted 10 that graphene exhibits the hexagonal stacking surprisingly often, surprising because of the higher energy of the hexagonal structure. In the hexagonal structure, the two graphene layers are stacked vertically on top of one another, while in the Bernal structure, one layer is rotated with respect to the other as indicated in Fig.…”

Quantum Hall effect in bilayer graphene: Disorder effect and quantum phase transition

“…[3][4][5][6][7][8][9][10][11][12][13] Recently, bilayer graphene is found to show an anomalous behavior in its spectral and transport properties, which has attracted much experimental and theoretical interest. Theoretical studies 4,5 show that interlayer coupling modifies the intralayer relativistic spectrum to yield a quasiparticle spectrum with a parabolic energy dispersion, which implies that the quasiparticles in bilayer graphene cannot be treated as massless but have a finite mass.…”

Analytical device model for graphene bilayer field-effect transistors using weak nonlocality approximation

“…In the GBL-FET the energy gap is electrically induced by the back gate voltage [32][33][34] (see also [18]). Thus in GBL-FETs, the back gate plays the dual role: it provides the formation of the electron channel and the energy gap.…”

“…-31]. However, some important features of GBL-FETs, * Electronic mail: v-ryzhii@u-aizu.ac.jp in particular, the dependence of both the electron density and the energy gap in different sections of the GBL-FET channel on the gate and drain voltages should be considered [32][33][34], as well as the "short-gate" effect and the drain-induced barrier lowering [29].…”