Contact Resistance Studies of Metal on HOPG and Graphene Stacks

Abstract

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.

WITHDRAWN: Utilizing a single silica nanospring as an insulating support to characterize the electrical transport and morphology of nanocrystalline graphite

“…The total resistance (R T ) obtained from the two-point I SD -V SD measurement is the sum of the resistance of the single G-NS (R G−NS ) and of the two contact resistances (R C ) at the GUITAR-Ti/Au interface on each end: R T = R G−NS + 2R C . Previous studies on the contact resistance of single-and multilayered graphene to Ti/Au metal contacts have reported contact resistances of <250 Ω for multilayered graphene (~50 layers) [51], and~165 Ω for single-layered graphene [52]. A comparison of the contact resistances for Ni contacts on graphene and highly ordered pyrolytic graphite (HOPG) has shown that the measurements are approximately two orders of magnitude higher for Ni contacts on graphene than on HOPG.…”

Utilizing a Single Silica Nanospring as an Insulating Support to Characterize the Electrical Transport and Morphology of Nanocrystalline Graphite

“…The total resistance (RT) obtained from the two-point I SD – V SD measurement is the sum of the resistance of the single G-NS (RnormalG−NS) and of the two contact resistances (RCfalse) at the GUITAR–Ti/Au interface on each end: RT=RnormalG−NS+2RC. Previous studies on the contact resistance of single- and multilayered graphene to Ti/Au metal contacts have reported contact resistances of <250 Ω for multilayered graphene (~50 layers) [51], and ~165 Ω for single-layered graphene [52]. A comparison of the contact resistances for Ni contacts on graphene and highly ordered pyrolytic graphite (HOPG) has shown that the measurements are approximately two orders of magnitude higher for Ni contacts on graphene than on HOPG.…”

“…A comparison of the contact resistances for Ni contacts on graphene and highly ordered pyrolytic graphite (HOPG) has shown that the measurements are approximately two orders of magnitude higher for Ni contacts on graphene than on HOPG. This greater contact resistance is attributed to the higher charge density in HOPG [51]. Additionally, Venugopal et al have shown that the contact resistance for metal contacts on multilayered graphene decreases as the number of graphene layers increases [51]; this is because increasing the number of graphene layers results in increased carrier concentration, until the structure approaches that of HOPG, i.e., becomes more metallic.…”

“…This greater contact resistance is attributed to the higher charge density in HOPG [51]. Additionally, Venugopal et al have shown that the contact resistance for metal contacts on multilayered graphene decreases as the number of graphene layers increases [51]; this is because increasing the number of graphene layers results in increased carrier concentration, until the structure approaches that of HOPG, i.e., becomes more metallic. Since the GUITAR coating is characteristic of a disordered multilayered graphitic material, it must have a high charge density, representative of multilayered graphene and HOPG.…”

High performance multi-purpose nanostructured thin films by inkjet printing: Au micro-electrodes and SERS substrates

“…S16 †). 54,55 Regarding pAuNP_PVA samples, two relevant differences with respect to pAuNP_Cys LT and pAuNP_Cys HT appear: (i) pAuNP_PVA LT cannot be operated as an electrode (viz. monotasking substrate) because of the insulating properties of PVA; (ii) pAuNP_PVA HT shows the lowest sheet resistance (i.e.…”