Contact Resistance Studies of Metal on HOPG and Graphene Stacks

Contact resistance is one of the major factors limiting the performance of future nanoelectronic devices. Although there has been significant progress in graphene based devices since 2004[1, 11, 13, 19, 20], there have been few studies of factors such as metal type, metal workfunction and number of layers in the graphene stack on metal/graphene contact resistance. In this work, contact resistance measurements of various metals (Cr, Ni, Pd, Pt) on Highly Oriented Pyrolytic Graphite (HOPG) and graphene (single layered and few layered) were performed. The total resistance is independent of distance indicating a contact resistance dominated system. The contact resistance is observed to be similar for a wide variety of metals although the metal workfunction varies from 4.3 eV to 5.6 eV. Similar measurements were performed for metal on single‐ and multi‐layer graphene. The electrical results are compared with XPS measurements of thin metal on HOPG. Issues regarding the characterization and interpretation of contact resistance for metal‐semimetal systems are discussed.