Nonlinear screening of charges induced in graphene by metal contacts

P.A. Khomyakov, A.A. Starikov, G. Brocks, P.J. Kelly

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105 Citations (Scopus)
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To understand the band bending caused by metal contacts, we study the potential and charge density induced in graphene in response to contact with a metal strip. We find that the screening is weak by comparison with a normal metal as a consequence of the ultrarelativistic nature of the electron spectrum near the Fermi energy. The induced potential decays with the distance from the metal contact as x −1/2 and x−1 for undoped and doped graphene, respectively, breaking its spatial homogeneity. In the contact region, the metal contact can give rise to the formation of a p−p′, n−n′, and p−n junction (or with additional gating or impurity doping, even a p−n−p′ junction) that contributes to the overall resistance of the graphene sample, destroying its electron-hole symmetry. Using the work functions of metal-covered graphene recently calculated by Khomyakov et al. [Phys. Rev. B 79, 195425 (2009)], we predict the boundary potential and junction type for different metal contacts.
Original languageEnglish
Article number115437
Number of pages6
JournalPhysical review B: Condensed matter and materials physics
Issue number11
Publication statusPublished - 2010


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