Boron nitride substrates for high-quality graphene electronics

Journal name:
Nature Nanotechnology
Volume:
5,
Pages:
722–726
Year published:
DOI:
doi:10.1038/nnano.2010.172
Received
Accepted
Published online

Abstract

Graphene devices on standard SiO2 substrates are highly disordered, exhibiting characteristics that are far inferior to the expected intrinsic properties of graphene1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Although suspending the graphene above the substrate leads to a substantial improvement in device quality13, 14, this geometry imposes severe limitations on device architecture and functionality. There is a growing need, therefore, to identify dielectrics that allow a substrate-supported geometry while retaining the quality achieved with a suspended sample. Hexagonal boron nitride (h-BN) is an appealing substrate, because it has an atomically smooth surface that is relatively free of dangling bonds and charge traps. It also has a lattice constant similar to that of graphite, and has large optical phonon modes and a large electrical bandgap. Here we report the fabrication and characterization of high-quality exfoliated mono- and bilayer graphene devices on single-crystal h-BN substrates, by using a mechanical transfer process. Graphene devices on h-BN substrates have mobilities and carrier inhomogeneities that are almost an order of magnitude better than devices on SiO2. These devices also show reduced roughness, intrinsic doping and chemical reactivity. The ability to assemble crystalline layered materials in a controlled way permits the fabrication of graphene devices on other promising dielectrics15 and allows for the realization of more complex graphene heterostructures.

At a glance

Figures

  1. Mechanical transfer process.
    Figure 1: Mechanical transfer process.

    ac, Optical images of graphene (a) and h-BN (b) before and after (c) transfer. Scale bars, 10 µm. Inset: electrical contacts. d, Schematic illustration of the transfer process used to fabricate graphene-on-BN devices (see text for details).

  2. Atomic force microscopy.
    Figure 2: Atomic force microscopy.

    a, AFM image of monolayer graphene on BN with electrical leads. White dashed lines indicate the edge of the graphene flake. Scale bar, 2 µm. b, Histogram of the height distribution (surface roughness) measured by AFM for SiO2 (black triangles), h-BN (red circles) and graphene-on-BN (blue squares). Solid lines are Gaussian fits to the distribution. Inset: high-resolution AFM image showing a comparison of graphene and BN surfaces, corresponding to the dashed square in a. Scale bar, 0.5 µm.

  3. Transport properties.
    Figure 3: Transport properties.

    a,b, Resistance versus applied gate voltage for monolayer graphene (a) and bilayer graphene (b) on h-BN. Insets: corresponding conductivity. c,d, Temperature dependence of the conductivity minimum (c) and high-density resistivity (d) for both devices. Solid and dashed lines in d are linear fits to the data. MLG, monolayer graphene; BLG, bilayer graphene. e, Conductivity of a different monolayer graphene sample comparing the room-temperature transport characteristics measured for as-transferred-to-h-BN (blue curve) and after annealing in H2Ar (black curve).

  4. Magnetotransport.
    Figure 4: Magnetotransport.

    a, Longitudinal (left axis) and Hall conductivity (right axis) versus gate voltage at B = 14 T (solid line) and 8.5 T (dashed line) for monolayer graphene. b, Longitudinal (left axis) and Hall (right axis) resistance versus gate voltage at B = 14 T for bilayer graphene. Inset: magnetic field sweep at fixed density. Shubnikov–de Haas oscillations begin at ~0.4 T with Landau level symmetry breaking appearing at fields less than 6 T. (T  2 K in both panels).

References

  1. Geim, A. & Novoselov, K. The rise of graphene. Nature Mater. 6, 183191 (2007).
  2. Neto, A., Guinea, F., Peres, N. M. R., Novoselov, K. S. & Geim, A. K. The electronic properties of graphene. Rev. Mod. Phys. 81, 109162 (2009).
  3. Ando, T. Screening effect and impurity scattering in monolayer graphene. J. Phys. Soc. Jpn 75, 074716 (2006).
  4. Nomura, K. & MacDonald, A. H. Quantum transport of massless dirac fermions. Phys. Rev. Lett. 98, 076602 (2007).
  5. Hwang, E. H., Adam, S. & Das Sarma, S. Carrier transport in two-dimensional graphene layers. Phys. Rev. Lett. 98, 186806 (2007).
  6. Hwang, E. H., Adam, S. & Das Sarma, S. Carrier transport in two-dimensional graphene layers. Phys. Rev. Lett. 98, 1839218397 (2007).
  7. Fratini, S. & Guinea, F. Substrate-limited electron dynamics in graphene. Phys. Rev. B 77, 195415 (2008).
  8. Chen, J.-H., Jang, C., Xiao, S., Ishigami, M. & Fuhrer, M. S. Intrinsic and extrinsic performance limits of graphene devices on SiO2. Nature Nanotech. 3, 206209 (2008).
  9. Ishigami, M., Chen, J. H., Cullen, W. G., Fuhrer, M. S. & Williams, E. D. Atomic structure of graphene on SiO2. Nano Lett. 7, 16431648 (2007).
  10. Katsnelson, M. I. & Geim, A. K. Electron scattering on microscopic corrugations in graphene. Phil. Trans. R. Soc. A 366, 195204 (2007).
  11. Morozov, S. V. et al. Giant intrinsic carrier mobilities in graphene and its bilayer. Phys. Rev. Lett. 100, 016602 (2008).
  12. Martin, J. et al. Observation of electron–hole puddles in graphene using a scanning single-electron transistor. Nature Phys. 4, 144148 (2008).
  13. Bolotin, K. I., Sikes, K. J., Hone, J., Stormer, H. L. & Kim, P. Temperature-dependent transport in suspended graphene. Phys. Rev. Lett. 101, 096802 (2008).
  14. Du, X., Skachko, I., Barker, A. & Andrei, E. Y. Approaching ballistic transport in suspended graphene. Nature Nanotech. 3, 491495 (2008).
  15. Hong, X. et al. High-mobility few-layer graphene field effect transistors fabricated on epitaxial ferroelectric gate oxides. Phys. Rev. Lett 102, 136808 (2009).
  16. Ponomarenko, L. A. et al. Effect of a high-kappa environment on charge carrier mobility in graphene. Phys. Rev. Lett. 102, 206603 (2009).
  17. Lafkioti, M. et al. Graphene on a hydrophobic substrate: doping reduction and hysteresis suppression under ambient conditions. Nano Lett. 10, 11491153 (2010).
  18. Liao, L., Bai, J., Qu, Y., Huang, Y. & Duan, X. Single-layer graphene on Al2O3/Si substrate: better contrast and higher performance of graphene transistors. Nanotechnology 21, 015705 (2010).
  19. Watanabe, K., Taniguchi, T. & Kanda, H. Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal. Nature Mater. 3, 404409 (2004).
  20. Giovannetti, G., Khomyakov, P., Brocks, G., Kelly, P. & Brink, J. V. D. Substrate-induced band gap in graphene on hexagonal boron nitride: ab initio density functional calculations. Phys. Rev. B 76, 073103 (2007).
  21. Lui, C. H., Liu, L., Mak, K. F., Flynn, G. W. & Heinz, T. F. Ultraflat graphene. Nature 462, 339341 (2009).
  22. Young, A. F. et al. Electronic compressibility of gapped bilayer graphene. preprint at arXiv:1004.5556v2 (2010).
  23. Meric, I. et al. Current saturation in zero-bandgap, top-gated graphene field-effect transistors. Nature Nanotech. 3, 654659 (2008).
  24. Schwierz, F. Graphene transistors. Nature Nanotech. 5, 487496 (2010).
  25. Taniguchi, T. & Watanabe, K. Synthesis of high-purity boron nitride single crystals under high pressure by using Ba–Bn solvent. J. Cryst. Growth 303, 525529 (2007).
  26. Lee, C. et al. Frictional characteristics of atomically thin sheets. Science 328, 7680 (2010).
  27. Reina, A. et al. Large area, few-layer graphene films on arbitrary substrates by chemical vapor deposition. Nano Lett. 9, 3035 (2009).
  28. Hong, X., Zou, K. & Zhu, J. The quantum scattering time and its implications on scattering sources in graphene. Phys. Rev. B 80, 241415 (2009).
  29. Bolotin, K. I. et al. Ultrahigh electron mobility in suspended graphene. Solid State Commun. 146, 351355 (2008).
  30. Feldman, B. E., Martin, J. & Yacoby, A. Broken-symmetry states and divergent resistance in suspended bilayer graphene. Nature Phys. 5, 889893 (2009).
  31. Adam, S. & Sarma, S. D. Boltzmann transport and residual conductivity in bilayer graphene. Phys. Rev. B 77, 115436 (2007).
  32. McCann, E. Asymmetry gap in the electronic band structure of bilayer graphene. Phys. Rev. B 74, 161403 (2006).
  33. Castro, E. V. et al. Biased bilayer graphene: semiconductor with a gap tunable by the electric field effect. Phys. Rev. Lett. 99, 216802 (2007).
  34. Zhang, Y. et al. Landau-level splitting in graphene in high magnetic fields. Phys. Rev. Lett. 96, 136806 (2006).
  35. Zhao, Y. et al. Symmetry breaking in the zero-energy Landau level in bilayer graphene. Phys. Rev. Lett. 104, 066801 (2010).

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Author information

Affiliations

  1. Department of Electrical Engineering, Columbia University, New York, New York, 10027, USA

    • C. R. Dean,
    • I. Meric,
    • S. Sorgenfrei &
    • K. L. Shepard
  2. Department of Mechanical Engineering, Columbia University, New York, New York, 10027, USA

    • C. R. Dean,
    • L. Wang &
    • J. Hone
  3. Department of Physics, Columbia University, New York, New York, 10027, USA

    • A. F. Young &
    • P. Kim
  4. SKUU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwa University, Suwon 440-746, Korea

    • C. Lee
  5. Department of Mechanical Engineering, Sungkyunkwa University, Suwon 440-746, Korea

    • C. Lee
  6. Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan

    • K. Watanabe &
    • T. Taniguchi

Contributions

C.R.D. and A.F.Y. performed the experiments, including sample fabrication, measurement, characterization and development of the transfer technique. I.M. contributed to sample fabrication, measurement and development of the transfer technique. C.L. and W.L. contributed to sample fabrication. S.S. contributed to development of the transfer technique. K.W. and T.T. synthesized the h-BN samples. P.K., K.L.S., and J.H. provided advice on the experiments.

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The authors declare no competing financial interests.

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