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.

Formation and morphological evolution of self-similar 3D nanostructures on weakly interacting substrates

“…Such approaches may, for example, be relevant for achieving 2D metal film growth on 2D crystals, including graphene and Mo 2 S, and thereby synthesize low-resistivity electrical contacts on nanoelectronic devices [4,5,[7][8][9][10][11][12][13][14] or fabricate catalytic devices that exhibit enhanced turnover frequencies [6].…”

“…A notable example is the deposition of metal films on twodimensional (2D) crystals (e.g., graphene and MoS 2 ) [4][5][6] for which the tendency toward the formation of 3D agglomerates imposes technological obstacles for the use of 2D materials in a wide range of switching and, in some cases, catalytic devices [4][5][6][7][8][9][10][11][12][13][14]. Thus, understanding atomistic mechanisms that govern 3D island formation and shape evolution is a key step toward controlling film morphology and, by extension, the functionality of devices based on weakly interacting film/substrate materials systems.…”

A coarse-grained Monte Carlo approach to diffusion processes in metallic nanoparticles

“…The largest discrepancy between our prediction and the ab initio value occurs for nickel, which might be related to a reduced image contrast for the lighter Ni atoms and due to more pronounced oxidation effects. Furthermore, nickel is known as a wetting electrode on graphene at higher temperatures, forming carbides at the contact surface [60][61][62].…”

Substrate-dependent plasmonic properties of supported graphene

“…GR-metal contacts [4][5][6][7][8][9][10][11][12][13] are unavoidable components of each GR-based device. Therefore, the investigation of the nature and dispersion of plasmon modes at GR/metal interfaces is a critical step toward engineering plasmonic applications of GR.…”