Department of Physics, Northwest University, Xi'an, People's Republic of China.
J Phys Condens Matter. 2010 Nov 24;22(46):465301. doi: 10.1088/0953-8984/22/46/465301. Epub 2010 Oct 29.
Recent experiments have confirmed that the electron-hole inhomogeneity in graphene is a new type of charge disorder. Motivated by such confirmation, we theoretically study the transport properties of a monolayer graphene (MLG) based p-n junction and a bilayer graphene (BLG) p-n junction in the quantum Hall regime where electron-hole puddles are considered. By using the non-equilibrium Green function method, both the current and conductance are obtained. We find that, in the presence of the electron-hole inhomogeneity, the lowest quantized conductance plateau at e(2)/h emerges in the MLG p-n junction under very small charge puddle disorder strength. For a BLG p-n junction, however, the conductance in the p-n region is enhanced with charge puddles, and the lowest quantized conductance plateau emerges at 2e(2)/h. Besides, when an ideal quantized conductance plateau is formed for a MLG p-n junction, the universal conductance fluctuation is found to be 2e(2)/3h. Furthermore, we also investigate the influence of Anderson disorder on such p-n junctions and the comparison and discussion are given accordingly. To compare the two models with different types of disorder, we investigate the conductance distribution specially. Finally the influence of disorder strength on the conductance of a MLG p-n junction is investigated.
最近的实验证实，石墨烯中的电子-空穴非均匀性是一种新型的电荷无序。受此证实的启发，我们理论研究了量子霍尔效应中考虑电子-空穴微滴的情况下，基于单层石墨烯（MLG）的 p-n 结和双层石墨烯（BLG）p-n 结的输运性质。通过使用非平衡格林函数方法，我们得到了电流和电导。我们发现，在存在电子-空穴非均匀性的情况下，在非常小的电荷微滴无序强度下，在 MLG p-n 结中出现了最低量子化电导平台 e(2)/h。然而，对于 BLG p-n 结，随着电荷微滴的存在，p-n 区的电导增强，并且在 2e(2)/h 处出现了最低量子化电导平台。此外，当 MLG p-n 结形成理想的量子化电导平台时，发现通用电导涨落为 2e(2)/3h。此外，我们还研究了安德森无序对这些 p-n 结的影响，并进行了相应的比较和讨论。为了比较这两种具有不同类型无序的模型，我们特别研究了电导分布。最后，研究了 MLG p-n 结中无序强度对电导的影响。
