Figure 3
Analysis of the electrostatic potential in the case of the Ni medium structure. (a) Atomistic and (b) schematic representation of graphene-metal contact. The electrostatic potential (V(R)) analysis is also shown. (c) 1-D plot of V(R) between nearest neighbors carbon atoms of the graphene fragment; (e) 1-D plot of V(R) between nearest neighbors metal atoms of the metal fragment. From (c,e), the difference between the V(R) in the middle of the (c) C-C or (e) M-M bond and the Fermi energies of the fragments is extracted as \({\rm{\Delta }}{E}_{F}^{G}\) and \({\rm{\Delta }}{E}_{F}^{M}\), respectively. (d,f) 1-D plot of V(R) between nearest neighbors (d) carbon atoms or (f) metal atoms of the component system, respectively. Using the \({\rm{\Delta }}{E}_{F}^{G}\), \({\rm{\Delta }}{E}_{F}^{M}\) values from (c,e), the local Dirac point E D (loc) and the local Fermi energy in the metal E F (loc) are determined. Hence, the local Fermi energies are substracted to the appropriate vacuum levels to obtain in (b) the local Work Functions: W G (loc) = V A − E D (loc) and W M (loc) = V D − E F (loc) of graphene and metal components, respectively. (g) 2D-plot of V(R) on a (x, z) plane containing both metal and graphene atoms.
