G. Will, N. Masciocchi, et al.
Zeitschrift fur Kristallographie - New Crystal Structures
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 [Phys. Rev. B 79, 195425 (2009)]10.1103/ PhysRevB.79.195425, we predict the boundary potential and junction type for different metal contacts. © 2010 The American Physical Society.