Using nanoscale thermocapillary flows to create arrays of purely semiconducting single-walled carbon nanotubes


Among the remarkable variety of semiconducting nanomaterials that have been discovered over the past two decades, single-walled carbon nanotubes remain uniquely well suited for applications in high-performance electronics, sensors and other technologies. The most advanced opportunities demand the ability to form perfectly aligned, horizontal arrays of purely semiconducting, chemically pristine carbon nanotubes. Here, we present strategies that offer this capability. Nanoscale thermocapillary flows in thin-film organic coatings followed by reactive ion etching serve as highly efficient means for selectively removing metallic carbon nanotubes from electronically heterogeneous aligned arrays grown on quartz substrates. The low temperatures and unusual physics associated with this process enable robust, scalable operation, with clear potential for practical use. We carry out detailed experimental and theoretical studies to reveal all of the essential attributes of the underlying thermophysical phenomena. We demonstrate use of the purified arrays in transistors that achieve mobilities exceeding 1,000 cm2 V−1 s−1 and on/off switching ratios of 10,000 with current outputs in the milliamp range. Simple logic gates built using such devices represent the first steps toward integration into more complex circuits.

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Figure 1: Process for exploiting thermocapillary effects in the purification of arrays of SWNTs.
Figure 2: Thermal origins and power scaling in behaviour of the thermocapillary resists.
Figure 3: Nanoscale thermocapillary flows in thermocapillary resists induced by Joule heating in SWNTs.
Figure 4: Description of two alternative approaches to scale thermocapillary separation for large-area applications.
Figure 5: Thermocapillary purification process performed with a reusable bottom split gate structure.
Figure 6: Short channel transistors and logic gates that use s-SWNT arrays created by thermocapillary purification.


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The authors thank C. Lee, M. Losego and D. Cahill for their help with materials characterization. The work at University of Illinois was supported by a grant from the Materials Structures and Devices (MSD) program of the Semiconductor Research Corporation and Northrop Grumman. The facilities were supported by the US Department of Energy, Division of Materials Sciences (award no. DEFG02-91ER45439), through the Frederick Seitz MRL and Center for Microanalysis of Materials at the University of Illinois at Urbana-Champaign. S.N.D. acknowledges support from a National Science Foundation Graduate Research Fellowship.

Author information

S.H.J., S.N.D. and J.A.R. conceived and designed the experiments. S.H.J., S.N.D., X.X., A.I., J.K., F.D., J.S., J.F., M.M., E.C. and K.G. performed the experiments. J.S., C.L., Y.L., F.X., M.A.W., M.A.A. and Y.H. performed modelling and simulations. E.P., M.A.A., B.K., Y.H. and J.A.R. provided technical guidance. S.H.J., S.N.D., X.X., J.S., Y.H. and J.A.R. analysed the experiments and simulations. S.H.J., S.N.D., J.S. and J.A.R. wrote the manuscript.

Correspondence to John A. Rogers.

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Jin, S., Dunham, S., Song, J. et al. Using nanoscale thermocapillary flows to create arrays of purely semiconducting single-walled carbon nanotubes. Nature Nanotech 8, 347–355 (2013).

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