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Journal of Nanomaterials
Volume 2010 (2010), Article ID 575472, 5 pages
http://dx.doi.org/10.1155/2010/575472
Research Article

Positioning of the Fermi Level in Graphene Devices with Asymmetric Metal Electrodes

1Department of Physics, Institute of Physics and Chemistry, Chonbuk National University, Jeonju 561-756, Republic of Korea
2Fusion-Biotechnology Research Center, Korea Research Institute of Chemical Technology, Daejeon 305-600, Republic of Korea

Received 15 June 2010; Accepted 7 July 2010

Academic Editor: Rakesh Joshi

Copyright © 2010 Bum-Kyu Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

To elucidate the effect of the work function on the position of the Dirac point, we fabricated graphene devices with asymmetric metal contacts. By measuring the peak position of the resistance for each pair of metal electrodes, we obtained the voltage of the Dirac point (V) from the gate response. We found that the position of (V) in the hybrid devices was significantly influenced by the type of metal electrode. The measured shifts in (V) were closely related to the modified work functions of the metal-graphene complexes. Within a certain bias range, the Fermi level of one of the contacts aligned with the electron band and that of the other contact aligned with the hole band.