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Monolayer coverage and channel length set the mobility in self-assembled monolayer field-effect transistors

Nature Nanotechnology volume 4, pages 674680 (2009) | Download Citation

Abstract

The mobility of self-assembled monolayer field-effect transistors (SAMFETs) traditionally decreases dramatically with increasing channel length. Recently, however, SAMFETs using liquid-crystalline molecules have been shown to have bulk-like mobilities that are virtually independent of channel length. Here, we reconcile these scaling relations by showing that the mobility in liquid crystalline SAMFETs depends exponentially on the channel length only when the monolayer is incomplete. We explain this dependence both numerically and analytically, and show that charge transport is not affected by carrier injection, grain boundaries or conducting island size. At partial coverage, that is when the monolayer is incomplete, liquid-crystalline SAMFETs thus form a unique model system to study size-dependent conductance originating from charge percolation in two dimensions.

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References

  1. 1.

    , & Temperature dependence of the field-effect mobility of sexithiophene. Determination of the density of traps. J. Phys. III 5, 355–371 (1995).

  2. 2.

    et al. Chemoresponsive monolayer transistors. Proc. Natl Acad. Sci. USA 103, 11452–11456 (2006).

  3. 3.

    et al. Attaching organic semiconductors to gate oxides: in situ assembly of monolayer field effect transistors. J. Am. Chem. Soc. 126, 15048–15050 (2004).

  4. 4.

    et al. Low-operating-voltage organic transistors made of bifunctional self-assembled monolayers. Adv. Funct. Mater. 17, 597–604 (2007).

  5. 5.

    et al. Spatially correlated charge transport in organic thin film transistors. Phys. Rev. Lett. 92, 116802 (2004).

  6. 6.

    , , & Thickness dependence of mobility in pentacene thin-film transistors. Adv. Mater. 17, 1795–1798 (2005).

  7. 7.

    , & Channel formation in single-monolayer pentacene thin film transistors. J. Phys. D 40, 3506–3511 (2007).

  8. 8.

    & Self-assembly at all scales. Science 295, 2418–2421 (2002).

  9. 9.

    et al. Bottom-up organic integrated circuits. Nature 455, 956–959 (2008).

  10. 10.

    & New insights for self-assembled monolayers of organothiols on Au(111) revealed by scanning tunneling microscopy. J. Phys. Chem. B 107, 8746–8759 (2003).

  11. 11.

    , & Engineering silicon oxide surfaces using self-assembled monolayers. Angew. Chem. Int. Ed. 44, 6282–6304 (2005).

  12. 12.

    Anomalous surface reflection of X-rays. Phys. Rev. 131, 2010–2013 (1963).

  13. 13.

    , & Surface potential profiling and contact resistance measurements on operating pentacene thin-film transistors by Kelvin probe force microscopy. Appl. Phys. Lett. 83, 5539–5541 (2003).

  14. 14.

    et al. Unified description of potential profiles and electrical transport in unipolar and ambipolar organic field-effect transistors. Phys. Rev. B 76, 125202 (2007).

  15. 15.

    Physics of Semiconductor Devices 2nd edn (Wiley, 1981).

  16. 16.

    et al. Scaling behavior and parasitic series resistance in disordered organic field-effect transistors. Appl. Phys. Lett. 82, 4576–4578 (2003).

  17. 17.

    Percolation and conduction. Rev. Mod. Phys. 45, 574–588 (1973).

  18. 18.

    Percolation (Springer-Verlag, 1989).

  19. 19.

    & Introduction to Percolation Theory (CRC Press, 1985).

  20. 20.

    Speculations on the cluster radius below the percolation threshold. Z. Physik B 30, 173–176 (1978).

  21. 21.

    , & Monolayer-dimensional 5,5′-bis(4-hexylphenyl)-2,2′-bithiophene transistors and chemically responsive heterostructures. Adv. Mater. 20, 2567–2572 (2008).

  22. 22.

    et al. Contact-induced crystallinity for high-performance soluble acene-based transistors and circuits. Nature Mater. 7, 216–221 (2008).

  23. 23.

    , , , & Substrate-free gas-phase synthesis of graphene sheets. Nano Lett. 8, 2012–2016 (2008).

Download references

Acknowledgements

The authors acknowledge financial support from the Dutch Technology Foundation STW, the EU project ONE-P (no. 212311), the Austrian Nanoinitiative and H. C. Starck GmbH. We thank M. Kaiser for FIB-TEM imaging. We thank the Cornell High Energy Synchrotron Source for provision of synchrotron radiation facilities and D. Smilgies for his assistance in using beamline G2.

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Affiliations

  1. Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven, The Netherlands

    • Simon G. J. Mathijssen
    • , Edsger C. P. Smits
    • , Paul A. van Hal
    • , Harry J. Wondergem
    •  & Dago M. de Leeuw
  2. Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands

    • Simon G. J. Mathijssen
    • , Peter A. Bobbert
    • , Martijn Kemerink
    •  & René A. J. Janssen
  3. Holst Centre/TNO, High Tech Campus 34, 5656 AE Eindhoven, The Netherlands

    • Edsger C. P. Smits
  4. Enikolopov Institute of Synthetic Polymer Materials of Russian Academy of Sciences, Profsoyuznaya 70, 117393 Moscow, Russia

    • Sergei A. Ponomarenko
  5. Institute of Solid State Physics, Graz University of Technology, Petersgasse 16A, 8010 Graz, Austria

    • Armin Moser
    •  & Roland Resel
  6. Molecular Electronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

    • Dago M. de Leeuw

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Contributions

S.M., E.S., P.H., P.B. M.K., R.J. and D.L. conceived and designed the experiments. S.M., E.S., P.H., H.W., A.M., R.R. and M.K. performed the experiments. S.P. synthesized the materials. All authors discussed the results, commented on the manuscript and co-wrote the paper.

Corresponding author

Correspondence to Dago M. de Leeuw.

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DOI

https://doi.org/10.1038/nnano.2009.201

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