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arXiv · 1003.5404

Scanning Gate Microscopy on Graphene: Charge Inhomogeneity and Extrinsic Doping

Romaneh Jalilian·Luis A. Jauregui·Gabriel Lopez·Jifa Tian·Caleb Roecker·Mehdi M. Yazdanpanah·Robert W. Cohn·Igor Jovanovic·Yong P. Chen
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Abstract

We have performed scanning gate microscopy (SGM) on graphene field effect transistors (GFET), using a biased metallic nanowire coated with a dielectric layer as a contact mode tip and local top gate. Electrical transport through graphene at various back gate voltages is monitored as a function of tip voltage and tip position. Near the Dirac point, the dependence of graphene resistance on tip voltage shows a significant variation with tip position. SGM imaging reveals mesoscopic domains of electron-doped and hole-doped regions. Our measurements indicate a substantial spatial fluctuation (on the order of 10^12/cm^2) in the carrier density in graphene due to extrinsic local doping. Important sources for such doping found in our samples include metal contacts, edges of graphene, structural defects, and resist residues.

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Romaneh Jalilian, Luis A. Jauregui, Gabriel Lopez, Jifa Tian, Caleb Roecker, Mehdi M. Yazdanpanah, Robert W. Cohn, Igor Jovanovic, Yong P. Chen. 2010-03-28. Scanning Gate Microscopy on Graphene: Charge Inhomogeneity and Extrinsic Doping. https://doi.org/10.1088/0957-4484%2F22%2F29%2F295705

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