CFP and Departamento de Física, Faculdade de Ciências Universidade do Porto, P-4169-007 Porto, Portugal.
J Phys Condens Matter. 2010 May 5;22(17):175503. doi: 10.1088/0953-8984/22/17/175503. Epub 2010 Apr 12.
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-a 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 four-band and two-band continuum approximations, and the four-band model is shown to always be a suitable approximation for the conditions realized in experiments. The model is applied to real biased bilayer devices, made out of either 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 for understanding the electronic properties of graphene bilayer. Also, we study the effect of electron-hole asymmetry terms, such as the second-nearest-neighbour hopping energies t' (in-plane) and γ(4) (inter-layer), and the on-site energy Δ.
我们在紧束缚近似下研究了在垂直于系统的外加电场作用下双层石墨烯的电子性质——偏置双层。通过平行板电容器模型并在哈特ree 水平进行屏蔽修正来考虑垂直电场的影响。全紧束缚描述与它的四能带和两能带连续体近似进行了比较，并且表明四能带模型始终是在实验中实现的条件的合适近似。该模型应用于由sic 或剥离石墨烯制成的实际偏置双层器件，并且与实验结果吻合良好，这表明该模型捕获了关键成分，并且有效外部控制了有限的间隙。关于电噪声和回旋共振的实验结果的分析进一步表明，该模型可以被视为理解双层石墨烯电子性质的良好起点。此外，我们研究了电子-空穴非对称项（例如，最近邻跳跃能量 t'（平面内）和γ（4）（层间）以及局域能 Δ）的影响。
