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Tunable Fröhlich polarons in organic single-crystal transistors

Nature Materials volume 5, pages 982986 (2006) | Download Citation

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Abstract

In organic field-effect transistors (FETs), charges move near the surface of an organic semiconductor, at the interface with a dielectric. In the past, the nature of the microscopic motion of charge carriers—which determines the device performance—has been related to the quality of the organic semiconductor. Recently, it was discovered that the nearby dielectric also has an unexpectedly strong influence. The mechanisms responsible for this influence are not understood. To investigate these mechanisms, we have studied transport through organic single-crystal FETs with different gate insulators. We find that the temperature dependence of the mobility evolves from metallic-like to insulating-like with increasing dielectric constant of the insulator. The phenomenon is accounted for by a two-dimensional Fröhlich polaron model that quantitatively describes our observations and shows that increasing the dielectric polarizability results in a crossover from the weak to the strong polaronic coupling regime. This represents a considerable step forward in our understanding of transport through organic transistors, and identifies a microscopic physical process with a large influence on device performance.

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References

  1. 1.

    & Organic thin-film transistors for large area electronics. Adv. Mater. 14, 99–117 (2002).

  2. 2.

    , , , & Low-k insulators as the choice of dielectrics in organic field-effect transistors. Adv. Funct. Mater. 13, 199–204 (2003).

  3. 3.

    , , & Influence of the gate dielectric on the mobility of rubrene single-crystal field-effect transistors. Appl. Phys. Lett. 85, 3899–3901 (2004).

  4. 4.

    et al. Elastomeric transistor stamps: Reversible probing of charge transport in organic crystals. Science 303, 1644–1646 (2004).

  5. 5.

    et al. Intrinsic charge transport on the surface of organic semiconductors. Phys. Rev. Lett. 93, 086602 (2004).

  6. 6.

    , , & Hall effect in the accumulation layers on the surface of organic semiconductors. Phys. Rev. Lett. 95, 226601 (2005).

  7. 7.

    Many-Particle Physics 2nd edn (Plenum, New York, 1990).

  8. 8.

    & Self-trapping of electrons at the field-effect junction of a molecular crystal. Phys. Rev. B 68, 235312 (2003).

  9. 9.

    , , & Organic single-crystal field-effect transistors. Phys. Status Solidi A 201, 1302–1331 (2004).

  10. 10.

    , , , & Dielectric properties of CVD grown SiON thin films on Si for MOS microelectronic devices. Semicond. Sci. Technol. 19, 50–53 (2004).

  11. 11.

    et al. Switch-on voltage in disordered organic field-effect transistors. Appl. Phys. Lett. 80, 3838–3840 (2002).

  12. 12.

    et al. General observation of n-type field-effect behaviour in organic semiconductors. Nature 434, 194–199 (2005).

  13. 13.

    , , , & Hall effect of quasi-hole gas in organic single-crystal transistors. Jpn J. Appl. Phys. 44, L1393–L1396 (2005).

  14. 14.

    & Polarons in crystalline and non-crystalline materials. Adv. Phys. 50, 757–812 (1969).

  15. 15.

    Semiclassical small-polaron hopping in a generalized molecular-crystal model. Phys. Rev. B 43, 11720–11724 (1991).

  16. 16.

    Formation and hopping motion of molecular polarons. Phys. Rev. B 61, 14543–14553 (2000).

  17. 17.

    & Electron-optical-phonon interaction in single and double heterostructures. Phys. Rev. B 40, 6175–6188 (1989).

  18. 18.

    , & The impact of molecular polarization on the electronic properties of molecular semiconductors. Europhys. Lett. 66, 392–398 (2004).

  19. 19.

    , & Transport properties in the rubrene crystal: electronic coupling and vibrational reorganization energy. Adv. Mater. 17, 1072–1076 (2005).

  20. 20.

    , , & Polarization effects in the channel of an organic field-effect transistor. J. Appl. Phys. 100, 023702 (2006).

  21. 21.

    , , & Mobility of slow electrons in a polar crystal. Phys. Rev. 127, 1004–1017 (1962).

  22. 22.

    et al. High-performance n- and p-type single-crystal organic transistors with free-space gate dielectrics. Adv. Mater. 16, 2097–2101 (2004).

  23. 23.

    , , , & Single-crystal organic field effect transistors with the hole mobility 8 cm2/Vs. Appl. Phys. Lett. 83, 3504–3506 (2003).

  24. 24.

    , & Field-effect transistors on rubrene single crystals with parylene gate insulator. Appl. Phys. Lett. 82, 1739–1741 (2003).

  25. 25.

    , & Field-effect transistors on tetracene single crystals. Appl. Phys. Lett. 84, 4345–4347 (2004).

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Acknowledgements

We gratefully acknowledge V. Podzorov for discussions and for letting us use his temperature-dependent measurements on FETs with a parylene gate dielectric. We thank R. W. I. de Boer and A. F. Stassen for contributing to the initial part of this work. Useful discussions with J. van den Brink are also acknowledged. This work was supported by FOM and by NWO through the Vernieuwingsimpuls 2000 program.

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Affiliations

  1. Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands

    • I. N. Hulea
    • , H. Xie
    • , C. L. Mulder
    • , N. N. Iossad
    •  & A. F. Morpurgo
  2. Laboratoire d’Etudes des Propriétés Electroniques des Solides, CNRS, BP 166-25, Avenue des Martyrs, F-38042 Grenoble Cedex 9, France

    • S. Fratini
    •  & G. Rastelli
  3. INFM-CNR SMC and Dipartimento di Fisica, Università dell’Aquila, via Vetoio, I-67010 Coppito-L’Aquila, Italy

    • G. Rastelli
    •  & S. Ciuchi

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The authors declare no competing financial interests.

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Correspondence to A. F. Morpurgo.

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https://doi.org/10.1038/nmat1774

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