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AIP Advances / Volume 2 / Issue 1 / REGULAR ARTICLES
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AIP Advances 2, 012132 (2012); http://dx.doi.org/10.1063/1.3684617 (12 pages)

Electrical transport across metal/two-dimensional carbon junctions: Edge versus side contacts

Yihong Wu1, Ying Wang1, Jiayi Wang2, Miao Zhou3, Aihua Zhang3, Chun Zhang3,4, Yanjing Yang1,5, Younan Hua5, and Baoxi Xu6

1Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore
2NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences, #05-01, 28 Medical Drive, Singapore 117456, Singapore
3Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
4Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
5GLOBALFOUNDRIES, Singapore Pte Ltd, 60 Woodlands Industrial Park D Street 2, Singapore 738406, Singapore
6Data Storage Institute, 5 Engineering Drive 1, National University of Singapore, Singapore 117608, Singapore

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(Received 5 August 2011; accepted 10 January 2012; published online 1 February 2012)

Metal/two-dimensional carbon junctions are characterized by using a nanoprobe in an ultrahigh vacuum environment. Significant differences were found in bias voltage (V) dependence of differential conductance (dI/dV) between edge- and side-contact; the former exhibits a clear linear relationship (i.e., dI/dV ∝ V), whereas the latter is characterized by a nonlinear dependence, dI/dV ∝ V3/2. Theoretical calculations confirm the experimental results, which are due to the robust two-dimensional nature of the carbon materials under study. Our work demonstrates the importance of contact geometry in graphene-based electronic devices.

© 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License.

Article Outline

  1. INTRODUCTION
  2. EXPERIMENTS
  3. RESULTS AND DISCUSSION
    1. Structural properties of CNWs
    2. dI/dV curves for edge-contacts with bare CNWs
    3. dI/dV curves for edge-contacts with Fe-coated CNWs
    4. Comparison of edge- and side-contacts formed with CNWs
    5. Comparison of side- and edge-contact formed with HOPG and exfoliated graphene sheets
    6. Theoretical calculation of dI/dV curves
  4. CONCLUSIONS

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KEYWORDS, PACS, and IPC

Keywords

electrical conductivity, fullerene devices, graphene, metal-insulator boundaries

PACS

International Patent Classification (IPC)

ARTICLE DATA

Digital Object Identifier
http://dx.doi.org/10.1063/1.3684617

PUBLICATION DATA

ISSN

2158-3226 (online)

Publisher:

American Institute of Physics is a Member of CrossRef is a Member of CrossRef American Institute of Physics

  1. P. R. Wallace, Phys. Rev. 71, 622 (1947).
  2. J. C. Slonczewski and P. R. Weiss, Phys. Rev. 109, 272 (1958).
  3. T. Ando, J. Phys. Soc. Jpn. 74, 777 (2005).
  4. K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, Nature 438, 197 (2005). [MEDLINE]
  5. Y. B. Zhang, Y. W. Tan, H. L. Stormer, and P. Kim, Nature 438, 201 (2005). [MEDLINE]
  6. A. H. Castro Neto, F. Guinea, N. M. R. Peres, K. S. Novoselov, and A. K. Geim, Rev. Mod. Phys. 81, 109 (2009).
  7. S. Das Sarma, S. Adam, E. H. Hwang, and E. Rossi, Rev. Mod. Phys. 83, 407 (2011).
  8. P. Avouris, Z. H. Chen, and V. Perebeinos, Nature Nanotechnology 2, 605 (2007). [MEDLINE]
  9. F. N. Xia, V. Perebeinos, Y. M. Lin, Y. Q. Wu, and P. Avouris, Nature Nanotechnology 6, 179 (2011).
  10. P. Blake, R. Yang, S. V. Morozov, F. Schedin, L. A. Ponomarenko, A. A. Zhukov, R. R. Nair, I. V. Grigorieva, K. S. Novoselov, and A. K. Geim, Solid State Commun. 149, 1068 (2009).
  11. S. Russo, M. F. Craciun, M. Yamamoto, A. F. Morpurgo, and S. Tarucha, Physica E-Low-Dimensional Systems & Nanostructures 42, 677 (2010).
  12. A. Venugopal, L. Colombo, and E. M. Vogel, Appl. Phys. Lett. 96, 013512 (2010)APPLAB000096000001013512000001.
  13. K. Nagashio, T. Nishimura, K. Kita, and A. Toriumi, Appl. Phys. Lett. 97, 143514 (2010)APPLAB000097000014143514000001.
  14. Y. Matsuda, W. Q. Deng, and W. A. Goddard, Journal of Physical Chemistry C 114, 17845 (2010).
  15. Y. H. Wu, P. W. Qiao, T. C. Chong, and Z. X. Shen, Adv. Mater. 14, 64 (2002).
  16. Y. H. Wu, B. J. Yang, B. Y. Zong, H. Sun, Z. X. Shen, and Y. P. Feng, J. Mater. Chem. 14, 469 (2004).
  17. Y. H. Wu, T. Yu, and Z. X. Shen, J. Appl. Phys. 108, 071301 (2010).
  18. M. S. Xu, D. Fujita, J. H. Gao, and N. Hanagata, Acs Nano 4, 2937 (2010). [MEDLINE]
  19. M. Y. Zhu, J. J. Wang, B. C. Holloway, R. A. Outlaw, X. Zhao, K. Hou, V. Shutthanandan, and D. M. Manos, Carbon 45, 2229 (2007).
  20. S. Kondo, S. Kawai, W. Takeuchi, K. Yamakawa, S. Den, H. Kano, M. Hiramatsu, and M. Hori, J. Appl. Phys. 106, 094302 (2009)JAPIAU000106000009094302000001.
  21. E. L. Wolf , Principles of electron tunneling spectroscopy (Oxford University Press, New York, 1989).
  22. J. Taylor, H. Guo, and J. Wang, Phys. Rev. B 63, 245407 (2001).
  23. M. Brandbyge, J.-L. Mozos, P. Ordejón, J. Taylor, and K. Stokbro, Phys. Rev. B 65, 165401 (2002).

Figures (click on thumbnails to view enlargements)

FIG.1
Setup of differential conductance measurement: a) illustration of edge-contact between of W probe and 2D carbon; b) SEM image showing experimental realization of edge-contact between W probe and edge of CNW; c) SEM image showing experimental realization of edge-contact between W probe and graphene sheets obtained by in-situ exfoliation of HOPG inside the UHV chamber.

FIG.1 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.2
a) SEM images of CNWs grown on SiO2/Si substrate (also seen in the image is the W tip used for conductance measurement of edge-contact); b) SEM image of CNW coated with a thin layer of iron with a nominal thickness of 30 nm; c) HRTEM image of a piece of CNW, which demonstrates the high-degree of graphitization of the sample. The inset shows the image of a CNW with a thickness of 2-3 layers.

FIG.2 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.3
a) SEM image of CNWs grown on Cu substrate. A portion of CNW has been peeled off by a tweezers. The darker region (ii) near the unpeeled portion is covered by a thin layer of carbon; b) Auger mapping of carbon using peaks associated with graphene sheets of the sample whose SEM image is shown in (a). Graphene sheets were found to exist in both regions (i) and (ii); c) copper mapping of the same sample; d) SEM image of CNW sample (B) with a piece of flipped over CNW (A). Auger mapping confirms that region A consists of flat graphene sheets. Portions A and B were used to form side- and edge-contacts, respectively.

FIG.3 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.4
a) dI/dV curves as a function of bias voltage for CNW edge-contacts, at different ZBR values (4.6 - 26.1kΩ); b) dI/dV curves as a function of bias voltage for Fe-coated CNW contacted at the edge by W probe, at different values of ZBR (3.7 - 21.9kΩ). The Fe-coating was performed in-situ in the same UHV system. For clarity, all the curves other than the one with highest ZBR are shifted upward (same for Figures 5 , 6 , 7). The ZBR values (resistance at the lowest point of the dI/dV curve) for different contacts are listed at the top of the figure in unit of kΩ.

FIG.4 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.5
a) dI/dV curves as a function of bias voltage for the back surface of CNWs [region A of Figure 3d], at different ZBR values (9.41 - 20.1kΩ), which corresponds to a side-contact. The CNWs were peeled off and flipped over in-situ in the same UHV system; b) dI/dV curves as a function of bias voltage for CNW edge-contacts [region B of Figure 3d], at different ZBR values (8.35 - 13.1kΩ).

FIG.5 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.6
a) dI/dV curves as a function of bias voltage for HOPG surface-contact, at different ZBR values (5.15 - 21.7kΩ). The top layer of HOPG was peeled off in situ using one of the probes to avoid the influence of surface contamination; b) dI/dV curves as a function of bias voltage for HOPG edge-contact, at different values of ZBR (4.71 - 13.1 kΩ).

FIG.6 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.7
Differential conductance curves of edge-contacts formed with exfoliated graphene sheets in the low contact resistance regime (ZBR ranges from 256 to 476 Ω).

FIG.7 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.8
dI/dV curves as a function of bias voltage for Fe-coated HOPG surface, at different ZBR values (0.82 – 1.67kΩ).

FIG.8 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.9
Schematic of relative orientation of graphene Fermi surface with respect to the current direction: a) surface-contact, and b) edge-contact. For simplicity, the Fermi surface of metal probe is assumed to have a spherical shape, whereas that of graphene under finite bias is denoted by a circular disk.

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FIG.10
a) Theoretical model of graphene sandwiched between two metal electrodes (shadowed areas L and R denote two contact regions); b) calculated dI/dV curve as a function of bias voltage for the in-plane transport with two semi-infinite contact regions. Calculations were done using first principles methods combining DFT and Green's functions’ techniques.

FIG.10 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.11
Model of vertical electron transport (side-contact): left panel, the sketch of the system for which the axis of the STM tip is normal to graphene plane; right panel, the sketch of the transport process. Electrons with a vertical momentum can enter graphene, and every state in graphene can accept electrons from the probe without scattering.

FIG.11 Download High Resolution Image (.zip file) | Export Figure to PowerPoint





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