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Probing graphene grain boundaries with optical microscopy


Grain boundaries in graphene are formed by the joining of islands during the initial growth stage, and these boundaries govern transport properties and related device performance1,2. Although information on the atomic rearrangement at graphene grain boundaries can be obtained using transmission electron microscopy3,4 and scanning tunnelling microscopy2,5,6,7,8, large-scale information regarding the distribution of graphene grain boundaries is not easily accessible. Here we use optical microscopy to observe the grain boundaries of large-area graphene (grown on copper foil) directly, without transfer of the graphene. This imaging technique was realized by selectively oxidizing the underlying copper foil through graphene grain boundaries functionalized with O and OH radicals generated by ultraviolet irradiation under moisture-rich ambient conditions: selective diffusion of oxygen radicals through OH-functionalized defect sites was demonstrated by density functional calculations. The sheet resistance of large-area graphene decreased as the graphene grain sizes increased, but no strong correlation with the grain size of the copper was revealed, in contrast to a previous report9. Furthermore, the influence of graphene grain boundaries on crack propagation (initialized by bending) and termination was clearly visualized using our technique. Our approach can be used as a simple protocol for evaluating the grain boundaries of other two-dimensional layered structures, such as boron nitride and exfoliated clays.

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Figure 1: Observation of graphene grain boundaries (GGBs) after ultraviolet exposure under moisture-rich ambient conditions.
Figure 2: Confocal Raman mapping of GGBs.
Figure 3: Height profiles of various topological GGBs, and the oxidation mechanism.
Figure 4: The correlation between GGBs and sheet resistance.


  1. 1

    Yazyev, O. V. & Louie, S. G. Electronic transport in polycrystalline graphene. Nature Mater. 9, 806–809 (2010)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Yu, Q. et al. Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition. Nature Mater. 10, 443–449 (2011)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Huang, P. Y. et al. Grains and grain boundaries in single-layer graphene atomic patchwork quilts. Nature 469, 389–392 (2011)

    ADS  CAS  Article  Google Scholar 

  4. 4

    Kim, K. et al. Grain boundary mapping in polycrystalline graphene. ACS Nano 5, 2142–2146 (2011)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Tian, J., Cao, H., Wu, W., Yu, Q. & Chen, Y. P. Direct imaging of graphene edges: atomic structure and electronic scattering. Nano Lett. 11, 3663–3668 (2011)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Rasool, H. I. et al. Atomic-scale characterization of graphene grown on copper (100) single crystals. J. Am. Chem. Soc. 133, 12536–12543 (2011)

    CAS  Article  Google Scholar 

  7. 7

    Rasool, H. I. et al. Continuity of graphene on polycrystalline copper. Nano Lett. 11, 251–256 (2011)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Gao, L., Guest, J. R. & Guisinger, N. P. Epitaxial graphene on Cu(111). Nano Lett. 10, 3512–3516 (2010)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Kim, D. W., Kim, Y. H., Jeong, H. S. & Jung, H.-T. Direct visualization of large-area graphene domains and boundaries by optical birefringency. Nature Nanotechnol. 7, 29–34 (2012)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Blake, P. et al. Making graphene visible. Appl. Phys. Lett. 91, 063124 (2007)

    ADS  Article  Google Scholar 

  11. 11

    Li, X. et al. Large-area synthesis of high-quality and uniform graphene films on copper foils. Science 324, 1312–1314 (2009)

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  12. 12

    Han, G. H. et al. Influence of copper morphology in forming nucleation seeds for graphene growth. Nano Lett. 11, 4144–4148 (2011)

    ADS  CAS  Article  Google Scholar 

  13. 13

    Güneş, F. et al. UV-light-assisted oxidative sp3 hybridization of graphene. NANO 6, 409–418 (2011)

    Article  Google Scholar 

  14. 14

    Jin, Z. et al. Click chemistry on solution-dispersed graphene and monolayer CVD graphene. Chem. Mater. 23, 3362–3370 (2011)

    CAS  Article  Google Scholar 

  15. 15

    Malarda, L. M. Pimentaa, M. A., Dresselhaus, G. & Dresselhaus, M. S. Raman spectroscopy in graphene. Phys. Rep. 473, 51–87 (2009)

  16. 16

    Huang, M. et al. Phonon softening and crystallographic orientation of strained graphene studied by Raman spectroscopy. Proc. Natl Acad. Sci. 106, 7304–7308 (2009)

    ADS  CAS  Article  Google Scholar 

  17. 17

    Chae, S. J. et al. Synthesis of large-area graphene layers on poly-nickel substrate by chemical vapor deposition: wrinkle formation. Adv. Mater. 21, 2328–2333 (2009)

    CAS  Article  Google Scholar 

  18. 18

    Liu, Y. & Yakobson, B. I. Cones, pringles, and grain boundary landscapes in graphene topology. Nano Lett. 10, 2178–2183 (2010)

    ADS  CAS  Article  Google Scholar 

  19. 19

    Lee, G., Lee, B., Kim, J. & Cho, K. Ozone adsorption on graphene: ab initio study and experimental validation. J. Phys. Chem. C 113, 14225–14229 (2009)

    CAS  Article  Google Scholar 

  20. 20

    Jandhyala, S. et al. Atomic layer deposition of dielectrics on graphene using reversibly physisorbed ozone. ACS Nano 6, 2722–2730 (2012)

    CAS  Article  Google Scholar 

  21. 21

    Feiyan, C., Pehkonen, S. O. & Ray, M. B. Kinetics and mechanisms of UV-photodegradation of chlorinated organics in the gas phase. Wat. Res. 36, 4203–4214 (2002)

    Article  Google Scholar 

  22. 22

    Wang, J. H. & Ray, M. B. Application of ultraviolet photooxidation to remove organic pollutants in the gas phase. Separ. Purif. Tech. 19, 11–20 (2000)

    Article  Google Scholar 

  23. 23

    Chen, J.-H., Jang, C., Xiao, S., Ishigami, M. & Fuhrer, M. S. Intrinsic and extrinsic performance limits of graphene devices on SiO2 . Nature Nanotechnol. 3, 206–209 (2008)

    CAS  Article  Google Scholar 

  24. 24

    Jeong, C., Nair, P., Khan, M., Lundstrom, M. & Alam, M. A. Prospects for nanowire-doped polycrystalline graphene films for ultratransparent, highly conductive electrodes. Nano Lett. 11, 5020–5025 (2011)

    ADS  CAS  Article  Google Scholar 

  25. 25

    Regan, W. et al. A direct transfer of layer-area graphene. Appl. Phys. Lett. 96, 113102 (2010)

    ADS  Article  Google Scholar 

  26. 26

    Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996)

    ADS  CAS  Article  Google Scholar 

  27. 27

    Delley, B. An all electron numerical method for solving the local density functional for polyatomic molecules. J. Chem. Phys. 92, 508–518 (1990)

    ADS  CAS  Article  Google Scholar 

  28. 28

    Tkatchenko, A. & Scheffler, M. Accurate molecular Van Der Waals interactions from ground-state electron density and free-atom reference data. Phys. Rev. Lett. 102, 073005 (2009)

    ADS  Article  Google Scholar 

  29. 29

    Monkhorst, H. J. & Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B 13, 5188–5192 (1976)

    ADS  MathSciNet  Article  Google Scholar 

  30. 30

    Halgren, T. A. & Lipscomb, W. N. The synchronous-transit method for determining reaction pathways and locating molecular transition states. Chem. Phys. Lett. 49, 225–232 (1977)

    ADS  CAS  Article  Google Scholar 

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This work was supported by the Star Faculty programme (2010-0029653), the International Research and Development programme (2011-00242) and the WCU programme (R31-2008-10029) of the NRF of Korea funded by MEST.

Author information




D.L.D. and G.H.H. contributed equally to this work in experiment planning, experiment measurements, data analysis and manuscript preparation. S.M.L. performed the theoretical calculations. F.G. prepared the samples for TEM measurements. The copper grain size was characterized by H.K. SEM and EDS were performed by E.S.K. and J.W.J. S.H.C. and S.C.L. designed the ultraviolet chamber and humidity controller. S.T.K. and S.C.L. performed conductance AFM. K.P.S. designed and performed the bending test. Graphene on nickel was prepared by S.J.C. S.J.Y. performed recovery of sheet resistance after ultraviolet exposure. Q.H.T. prepared the graphene samples for all the experiments. The TEM images were taken by M.H.P. S.M.L. and J.Y.C. contributed to the manuscript preparation. Y.H.L. contributed to experiment planning, data analysis and manuscript preparation.

Corresponding author

Correspondence to Young Hee Lee.

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The authors declare no competing financial interests.

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Duong, D., Han, G., Lee, S. et al. Probing graphene grain boundaries with optical microscopy. Nature 490, 235–239 (2012).

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