The effect of extrinsic defects in pyrolytic graphite on the a-axis resistivity

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.

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“…Four Point Probe measurements on HOPG yield a sheet resistance value ~ O.OIQ/D and bulk resistivity values consistent with literature [8,9].…”

Section: Resultssupporting

confidence: 68%

Contact Resistance Studies of Metal on HOPG and Graphene Stacks

Venugopal¹,

Pirkle

Wallace

et al. 2009

AIP Conference Proceedings

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“…The conductivity of graphite is highly anisotropic, with the caxis conductivity over 10 3 less than the in-plane value [30]. Therefore the predicted conductivity based on the composite values will be a smaller (averaged) value since only tubes aligned with the exciting voltage contribute to the conductivity measurement.…”

Section: Discussionmentioning

confidence: 99%

Effect of purification of the electrical conductivity and complex permittivity of multiwall carbon nanotubes

Grimes

Dickey

Mungle

et al. 2001

Journal of Applied Physics

126

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In this work we report on the complex permittivity spectra and electrical conductivity of both as-fabricated and graphitized multiwall carbon nanotubes (MWNTs). The high-temperature annealing removes the Fe3C catalyst particles present in the as-fabricated material, enabling the intrinsic MWNT properties to be measured. The permittivity spectra of 1 wt % MWNT-polystyrene composite films are measured from 75 to 1875 MHz. Comparison of measurements with an appropriate effective medium model shows that the residual catalyst inclusions in the core of the nanotube increase the average electrical conductivity by approximately a factor of 3.5.

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“…After it was confirmed that the resistivity of HOPG (4 × 10 −5 cm) 16 was accurately measured, the HOPG plate was immersed in alkane by pouring alkane into the laboratory dish. The accurate resistivity measurement of HOPG provides confirmation that there are no problems with the resistance measurement.…”

Section: Fig 3 (A)mentioning

confidence: 99%

“…5, a broken line indicates the resistivity of HOPG (4 × 10 −5 cm). 16 Figure 5(a) shows that the resistance of the sample suddenly dropped to zero ∼160 s after the HOPG plate was immersed in n-heptane. Figure 5(b) shows that the resistance of the sample suddenly dropped to zero ∼270 s after the HOPG plate was immersed in n-octane.…”

Section: Fig 3 (A)mentioning

confidence: 99%

Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

Kawashima

2013

AIP Advances

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In 1986, a cuprate superconductor (Ba-La-Cu-O system) having a critical temperature which goes over the BCS limit (~30 K) was discovered and then a cuprate superconductor (Y-Ba-Cu-O system) with a critical temperature higher than 77 K was discovered. Furthermore, a Hg-based cuprate with a critical temperature of 133 K was found. The 133 K is still the highest critical temperature of conventional superconductors under atmospheric pressure. We have shown that materials obtained by bringing n-alkanes into contact with graphite are capable of conducting electricity with almost no energy loss at room temperature. We here report that the sudden jump in resistance showing a phase transition is observed in the materials during heating by two-probe resistance measurement. The measured critical temperatures of the materials consisting of pitch-based graphite fibers and n-alkanes having 7-16 carbon atoms range from 363.08 to 504.24 K and the transition widths range between 0.15 and 3.01 K. We also demonstrate that superconductors with critical temperatures beyond 504 K are obtained by alkanes with 16 or more carbon atoms.

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The effect of extrinsic defects in pyrolytic graphite on the a-axis resistivity

Cited by 18 publications

References 10 publications

Contact Resistance Studies of Metal on HOPG and Graphene Stacks

Contact Resistance Studies of Metal on HOPG and Graphene Stacks

Effect of purification of the electrical conductivity and complex permittivity of multiwall carbon nanotubes

Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

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