Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

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

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.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: SAM growth.
Figure 2: SAM microstructure.
Figure 3: Spatially resolved connectivity.
Figure 4: Visualization of the SAM.
Figure 5: Electrical transport versus monolayer coverage.
Figure 6: Scaling of extracted linear and saturated device mobility.

References

  1. Horowitz, G., Hajlaoui, R. & Delannoy, P. Temperature dependence of the field-effect mobility of sexithiophene. Determination of the density of traps. J. Phys. III 5, 355–371 (1995).

    CAS  Google Scholar 

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

    CAS  Article  Google Scholar 

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

    CAS  Article  Google Scholar 

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

    CAS  Article  Google Scholar 

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

    Article  Google Scholar 

  6. Ruiz, R., Papadimitratos, A., Mayer, A. C. & Malliaras, G. G. Thickness dependence of mobility in pentacene thin-film transistors. Adv. Mater. 17, 1795–1798 (2005).

    CAS  Article  Google Scholar 

  7. Park, B.-N., Seo, S. & Evans, P. G. Channel formation in single-monolayer pentacene thin film transistors. J. Phys. D 40, 3506–3511 (2007).

    CAS  Article  Google Scholar 

  8. Whitesides, G. M. & Grzybowski, B. Self-assembly at all scales. Science 295, 2418–2421 (2002).

    CAS  Article  Google Scholar 

  9. Smits, E. C. P. et al. Bottom-up organic integrated circuits. Nature 455, 956–959 (2008).

    CAS  Article  Google Scholar 

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

    CAS  Article  Google Scholar 

  11. Onclin, S., Ravoo, B. J. & Reinhoudt, D. N. Engineering silicon oxide surfaces using self-assembled monolayers. Angew. Chem. Int. Ed. 44, 6282–6304 (2005).

    CAS  Article  Google Scholar 

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

    Article  Google Scholar 

  13. Puntambekar, K. P., Pesavento, P. V. & Frisbie, C. D. 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).

    CAS  Article  Google Scholar 

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

    Article  Google Scholar 

  15. Sze, S. M. Physics of Semiconductor Devices 2nd edn (Wiley, 1981).

    Google Scholar 

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

    CAS  Article  Google Scholar 

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

    Article  Google Scholar 

  18. Grimmett, G. Percolation (Springer-Verlag, 1989).

    Google Scholar 

  19. Stauffer, D. & Aharony, A. Introduction to Percolation Theory (CRC Press, 1985).

    Book  Google Scholar 

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

    Article  Google Scholar 

  21. Huang, J., Sun, J. & Katz, H. E. Monolayer-dimensional 5,5′-bis(4-hexylphenyl)-2,2′-bithiophene transistors and chemically responsive heterostructures. Adv. Mater. 20, 2567–2572 (2008).

    CAS  Article  Google Scholar 

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

    CAS  Article  Google Scholar 

  23. Dato, A., Radmilovic, V., Lee, Z., Phillips, J. & Frenklach, M. Substrate-free gas-phase synthesis of graphene sheets. Nano Lett. 8, 2012–2016 (2008).

    CAS  Article  Google Scholar 

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.

Author information

Authors and Affiliations

Authors

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.

Supplementary information

Supplementary information

Supplementary information (PDF 481 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Mathijssen, S., Smits, E., van Hal, P. et al. Monolayer coverage and channel length set the mobility in self-assembled monolayer field-effect transistors. Nature Nanotech 4, 674–680 (2009). https://doi.org/10.1038/nnano.2009.201

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

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

Further reading

Search

Quick links

Find nanotechnology articles, nanomaterial data and patents all in one place. Visit Nano by Nature Research