Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 17: Quantum wires: Optical and transport properties

HL 17.4: Vortrag

Dienstag, 24. März 2009, 10:45–11:00, BEY 154

Edge-disorder-induced conduction gap in bilayer graphene nanoribbons — •Hengyi Xu¹, Thomas Heinzel¹, and Igor Zozoulenko² — ¹Heinrich-Heine Universität, Düsseldorf, Germany — ²Department of Science and Technology, Linköping University, Sweden

Graphene bilayers are interesting because they show some anomalous properties compared with single layers. We study the energy spectra of the Bernal-type bilayers with zigzag and armchair edges within the tight-binding model. Furthermore, a recursive Green's function (RGF) method for bilayer graphene nanoribbons (GNRs), which provides an efficient way to account for the effects due to the bilayer leads, is developed based on our implementation in the monolayer case. By means of the newly-developed RGF technique, the magnetoelectronic properties are examined. An important work in graphene engineering is to tune the electronic properties of GNRs by introducing an energy gap. There has been many attempts to induce an energy gap in monolayer graphene by various ways, in particular, it is shown that a modest edge disorder is sufficient to induce the conduction energy gap in the otherwise metallic graphene nanoribbons. We further study the electronic transport behaviors of bilayer GNRs with edge imperfections and discuss the possibilities of opening energy gaps by the edge disorder in bilayers. The conductance of realistic edge-disordered bilayer GNRs is calculated numerically and dependency of the gap width on the strength of the disorder is investigated systematically.