title: Realistic metal-graphene contact structures.
abstract: The contact resistance of metal-graphene junctions has been actively explored and exhibited inconsistencies in reported values. The interpretation of these electrical data has been based exclusively on a side-contact model, that is, metal slabs sitting on a pristine graphene sheet. Using in situ X-ray photoelectron spectroscopy to study the wetting of metals on as-synthesized graphene on copper foil, we show that side-contact is sometimes a misleading picture. For instance, metals like Pd and Ti readily react with graphitic carbons, resulting in Pd- and Ti-carbides. Carbide formation is associated with C-C bond breaking in graphene, leading to an end-contact geometry between the metals and the periphery of the remaining graphene patches. This work validates the spontaneous formation of the metal-graphene end-contact during the metal deposition process as a result of the metal-graphene reaction instead of a simple carbon diffusion process.
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States.
authors.forename: Cheng
authors.initials: C
authors.lastname: Gong
authors.forename: Stephen
authors.initials: S
authors.lastname: McDonnell
authors.forename: Xiaoye
authors.initials: X
authors.lastname: Qin
authors.forename: Angelica
authors.initials: A
authors.lastname: Azcatl
authors.forename: Hong
authors.initials: H
authors.lastname: Dong
authors.forename: Yves J
authors.initials: YJ
authors.lastname: Chabal
authors.forename: Kyeongjae
authors.initials: K
authors.lastname: Cho
authors.forename: Robert M
authors.initials: RM
authors.lastname: Wallace