Electron Transport in Graphene-Versus Al/Pd-Coated Thin Cu Films With Low-Surface Roughness: A First Principles Study

Surface scattering is a major issue in thin Cu films at reduced scales. The rise in the diffusive scattering due to the surface roughness causes the electrical resistance to increase remarkably. In this paper, graphene, as opposed to Al and Pd, is considered as a liner layer for thin Cu film with low-surface roughness using first principles calculation. The surface roughness is simulated using the nonequilibrium coherent potential approximation combined with the linear muffin-tin orbital formulation. The coherent potential approximation band structure shows that the graphene <inline-formula> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula>-bands is not significantly affected by the surface disorder at the Cu surface and that graphene acts as a parallel path to the electrons. On the other hand, the bands of Cu–Al/Pd around the Fermi level are substantially broadened due to the surface disorder. Moreover, the graphene-coated Cu shows less electrical resistance than Al/Pd-coated Cu for surface disorder <inline-formula> <tex-math notation="LaTeX">$x\lessapprox 5$ </tex-math></inline-formula>% for thin films with 0.245 nm in width, and 1.23 nm in thickness. The enhancement in the transport properties in Cu–Gr is attributed to the weak electronic interaction at the interface. The obtained results suggest that graphene is better than Al and Pd as a liner material for thin Cu films.