Bi- and trilayer graphene solutions


Bilayer and trilayer graphene with controlled stacking is emerging as one of the most promising candidates for post-silicon nanoelectronics. However, it is not yet possible to produce large quantities of bilayer or trilayer graphene with controlled stacking, as is required for many applications. Here, we demonstrate a solution-phase technique for the production of large-area, bilayer or trilayer graphene from graphite, with controlled stacking. The ionic compounds iodine chloride (ICl) or iodine bromide (IBr) intercalate the graphite starting material at every second or third layer, creating second- or third-stage controlled graphite intercolation compounds, respectively. The resulting solution dispersions are specifically enriched with bilayer or trilayer graphene, respectively. Because the process requires only mild sonication, it produces graphene flakes with areas as large as 50 µm2. Moreover, the electronic properties of the flakes are superior to those achieved with other solution-based methods; for example, unannealed samples have resistivities as low as 1 kΩ and hole mobilities as high as 400 cm2 V–1 s–1. The solution-based process is expected to allow high-throughput production, functionalization, and the transfer of samples to arbitrary substrates.

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Figure 1: Graphene dispersions from ionic graphite intercalation compounds (GIC).
Figure 2: On-chip separation method based on graphene size, using the ‘coffee-ring effect’.
Figure 3: Characterization of graphene flakes.
Figure 4: Evidence for layer- and size-controlled graphene dispersions from different GICs.
Figure 5: Electronic characteristics of bilayer and 3–4-layer graphene devices in the presence of a perpendicular electric field at room temperature.


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The authors acknowledge fundings from the 2009 US Office of Naval Research Multi University Research Initiative (MURI) on Graphene Advanced Terahertz Engineering (GATE) at MIT, Harvard and Boston University. M.S.S. is also grateful for a 2008 Young Investigator Program Award (YIP) from the US Office of Naval Research. D.B. and S.L. are grateful for financial support from the DuPont/MIT Alliance. C.J.S. is grateful for partial financial support from the David H. Koch Fellowship. The authors acknowledge support from the Institute for Soldier Nanotechnologies at MIT, funded by a grant from the Army Research Office. XRD and TEM analyses were performed at the MIT Center of Materials Science and Engineering (CMSE), supported by S. Speakman and Y. Zhang. Fruitful discussions with D.D.L Chung, J. Kong, A. Hsu and J.H. Kim are also gratefully acknowledged.

Author information

C.J.S, A.V., R.K. and M.S.S. conceived and designed the dispersion experiments. C.J.S. and R.K. implemented the dispersion method. C.J.S., A.V., R.S., G.P. and M.H.H. fabricated FET devices. C.J.S. and M.S.S. developed the mathematical model. A.V., R.S., Z.J. and J.H.H. performed the TEM and AFM analysis. C.J.S. performed the XRD and Raman analysis. Q.H.W., S.L. and N.F.R. did additional experiments for revising the manuscript. C.J.S., D.B. and M.S.S. wrote the manuscript with input from A.V. All authors discussed the results and commented on the manuscript.

Correspondence to Michael S. Strano.

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Shih, C., Vijayaraghavan, A., Krishnan, R. et al. Bi- and trilayer graphene solutions. Nature Nanotech 6, 439–445 (2011) doi:10.1038/nnano.2011.94

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