Berlin 2008 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 16: Functional Oxides
DS 16.8: Vortrag
Dienstag, 26. Februar 2008, 19:30–19:45, H 2032
Density functional investigation of the dielectric constant for bilayer graphene under electric field — •Ruijuan Xiao, Manfred Taut, Ferenc Tasnadi, and Manuel Richter — IFW Dresden, Germany
Single and bilayer graphene have attracted much current interest not only because of their novel electronic structure but also for their potential application in future electronic devices. Several methods have been reported to open an energy gap in bilayer graphene, including application of gate-voltage, which may allow to switch off the electric conduction in bilayer graphene devices. In the present work, we evaluated the gap width and the dielectric constant of bilayer graphene in an external electric field (Eext) using the full-potential local-orbital (FPLO) code. We obtain a dielectric constant reaching a minimal of 2.76 when the Eext=0.3 V/Å, then increasing with the Eext, reaching 2.84 when the Eext=0.8V/Å. The calculated gap width increases with the Eext, reaching a saturated value of 0.26eV when the Eext=0.8V/Å. We also studied the effect of layer distance on the gap and dielectric constant of this system. The calculations indicate that the dielectric constant decreases linearly with the reduction of distance between the two graphene layers.