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Low-temperature, high-performance solution-processed metal oxide thin-film transistors formed by a ‘sol–gel on chip’ process

Abstract

At present there is no ‘ideal’ thin-film transistor technology for demanding display applications, such as organic light-emitting diode displays, that allows combining the low-temperature, solution-processability offered by organic semiconductors with the high level of performance achievable with microcrystalline silicon1. N-type amorphous mixed metal oxide semiconductors, such as ternary oxides Mx1My2Oz, where M1 and M2 are metals such as In, Ga, Sn, or Zn, have recently gained momentum because of their high carrier mobility and stability2,3 and good optical transparency, but they are mostly deposited by sputtering. So far no route is available for forming high-performance mixed oxide materials from solution at low process temperatures <250 °C. Ionic mixed metal oxides should in principle be ideal candidates for solution-processable materials because the conduction band states derived from metal s-orbitals are relatively insensitive to the presence of structural disorder and high charge carrier mobilities are achievable in amorphous structures2. Here we report the formation of amorphous metal oxide semiconducting thin-films using a ‘sol–gel on chip’ hydrolysis approach from soluble metal alkoxide precursors, which affords unprecedented high field-effect mobilities of 10 cm2 V−1 s−1, reproducible and stable turn-on voltages Von≈0 V and high operational stability at maximum process temperatures as low as 230 °C.

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Figure 1: Metal alkoxide molecular precursors.
Figure 2: Variation of structural and electronic properties with IZO stoichiometry.
Figure 3: Transfer curves of amorphous metal oxide TFTs fabricated at different annealing temperatures under hydrolysed and dry-annealing conditions.
Figure 4: Device uniformity and operational stress characteristics of ‘sol–gel on chip’ IZO TFTs.
Figure 5: Composition analysis of IZO devices.

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References

  1. Street, R. A. Thin-film transistors. Adv. Mater. 21, 2007–2022 (2009).

    Article  CAS  Google Scholar 

  2. Nomura, K. et al. Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors. Nature 432, 488–492 (2004).

    Article  CAS  Google Scholar 

  3. Chiang, H. Q., Wager, J. F., Hoffman, R. L., Jeong, J. & Keszler, D. A. High mobility transparent thin-film transistors with amorphous zinc tin oxide channel layer. Appl. Phys. Lett. 86, 013503 (2005).

    Article  Google Scholar 

  4. Yang, Y. H., Yang, S. S., Kao, C. Y. & Chou, K. S. Chemical and electrical properties of low-temperature solution-processed InGaZn–O thin-film transistors. IEEE Electron Device Lett. 31, 329–331 (2010).

    Article  CAS  Google Scholar 

  5. Meyers, S. T. et al. Aqueous inorganic inks for low-temperature fabrication of ZnO TFTs. J. Am. Chem. Soc. 130, 17603–17609 (2008).

    Article  CAS  Google Scholar 

  6. Park, S. K., Kim, Y. H. & Han, J. I. All solution-processed high-resolution bottom-contact transparent metal-oxide thin film transistors. J. Phys. D 42, 125102 (2009).

    Article  Google Scholar 

  7. Ryu, M. K. et al. 2009 SID International Symposium Digest of Technical Papers, Vol. Xl, 188–190 (2009).

  8. Choi, C. G., Seo, S. J. & Bae, B. S. Solution-processed indium–zinc oxide transparent thin-film transistors. Electrochem. Solid State Lett. 11, H7–H9 (2008).

    Article  CAS  Google Scholar 

  9. Koo, C. Y. et al. Sol–gel derived Ga–In–Zn–O semiconductor layers for solution-processed thin-film transistors. J. Korean Phys. Soc. 53, 218–222 (2008.).

    Article  CAS  Google Scholar 

  10. Lee, D. H., Chang, Y. J., Herman, G. S. & Chang, C. H. A general route to printable high-mobility transparent amorphous oxide semiconductors. Adv. Mater. 19, 843–847 (2007).

    Article  CAS  Google Scholar 

  11. Aoki, A., Kunitake, T. & Nakao, A. Sol–gel fabrication of dielectric HfO2 nano-films; formation of uniform, void-free layers and their superior electrical properties. Chem. Mater. 17, 450–458 (2005).

    Article  CAS  Google Scholar 

  12. Kato, K. et al. Sol-gel route to ferroelectric layer-structured Perovskite SrBi2Ta2O9 and SrBi2Nb2O9 thin films. J. Am. Ceram. Soc. 81, 1869–1875 (2005).

    Article  Google Scholar 

  13. Brinker, C. J. & Scherer, G. W. Sol–Gel Science: The Physics and Chemistry of Sol–Gel Processing (Academic, 1990).

    Google Scholar 

  14. Leedham, T. Improvements in or relating to the synthesis of gallium and indium alkoxides (UK). GB patent application No. 2,454,019 (2008).

  15. Bradley, D. C., Chudzynska, H., Frigo, D. M., Hursthouse, M. B. & Mazid, M. A. A penta-indium oxo alkoxide cluster with a central 5-co-ordinate oxygen. Preparation and X-ray crystal structure of (InOPri)5(μ2-OPri)4(μ3-OPri)4(μ5-O). J. Chem. Soc.-Chem. Commun. 1258–1259 (1988).

  16. Kageyama, H. et al. Molecular-structure of [Zn(OCH2CH2OMe)2·(EtZnOCH2CH2OMe)6]. An enantiomorphic catalyst for the stereoselective polymerization of methyloxirane. Makromolekulare Chem.-Rapid Commun. 3, 947–951 (1982).

    Article  CAS  Google Scholar 

  17. Han, S-Y., Lee, D-H., Herman, G. S. & Chang, C-H. Inkjet-printed high mobility transparent-oxide semiconductors. J. Display Techn. 5, 520–524 (2009).

    Article  CAS  Google Scholar 

  18. Keszler, D. A., Anderson, J. T. & Meyers, S. T. in Solution Processing of Inorganic Materials (ed. Mitzi, D.) 109–129 (Wiley, 2009).

    Google Scholar 

  19. Dehuff, N. L. et al. Transparent thin-film transistors with zinc indium oxide channel layer. J. Appl. Phys. 97, 064505 (2005).

    Article  Google Scholar 

  20. Fung, T. C. et al. Two-dimensional numerical simulation of radio frequency sputter amorphous In–Ga–Zn–O thin-film transistors. J. Appl. Phys. 106, 084511 (2009).

    Article  Google Scholar 

  21. Jeong, J. H. et al. Origin of subthreshold swing improvement in amorphous indium gallium zinc oxide transistors. Electrochem. Solid State Lett. 11, H157–H159 (2008).

    Article  CAS  Google Scholar 

  22. Park, J. S., Jeong, J. K., Chung, H. J., Mo, Y. G. & Kim, H. D. Electronic transport properties of amorphous indium–gallium–zinc oxide semiconductor upon exposure to water. Appl. Phys. Lett. 92, 072104 (2008).

    Article  Google Scholar 

  23. Jackson, W. B. & Moyer, M. D. Creation of near-interface defects in hydrogenated amorphous-silicon silicon-nitride heterojunctions—the role of hydrogen. Phys. Rev. B 36, 6217–6220 (1987).

    Article  CAS  Google Scholar 

  24. Lee, J. M., Cho, I. T., Lee, J. H. & Kwon, H. I. Bias-stress-induced stretched-exponential time dependence of threshold voltage shift in InGaZnO thin film transistors. Appl. Phys. Lett. 93, 093504 (2008).

    Article  Google Scholar 

  25. Fan, J. C. C. & Goodenough, J. B. X-ray photoemission spectroscopy studies of Sn-doped indium-oxide films. J. Appl. Phys. 48, 3524–3531 (1977).

    Article  CAS  Google Scholar 

  26. Janotti, A. & Van de Walle, C. G. Fundamentals of zinc oxide as a semiconductor. Rep. Prog. Phys. 72, 126501 (2009).

    Article  Google Scholar 

  27. Janotti, A. & Van de Walle, C. G. Hydrogen multicentre bonds. Nature Mater. 6, 44–47 (2007).

    Article  CAS  Google Scholar 

  28. Ramesh, R. & Schlom, D. G. Whither oxide electronics? MRS Bull. 33, 1006–1014 (2008).

    Article  Google Scholar 

  29. Bradley, D. C., Methrotra, R. C. & Kaur, D. P. Metal Alloxides (Academic, 1978).

    Google Scholar 

Download references

Acknowledgements

This work was supported by a grant from Panasonic Corporation. We would like to thank W. Jennings (Swagelok Center for Surface Analysis of Materials, OH USA) for XPS analysis, A. Chew and D. Sykes (Loughborough Surface Analysis, UK) for SIMS analysis, and D. Morgan (XPS Analysis Centre Cardiff University) for valuable discussions on XPS analysis. TEM cross-sectional analysis was conducted at Loughborough University, by J. Bates. We would also like to thank G. Nikiforov for help with SEM imaging.

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Contributions

The metal oxide solution process development was carried out by K.K.B., K.M., Y.Y. and R.L.P. T.L. prepared the chemical precursors. Thin-film transistor and device performance was recorded by K.K.B. and Y.Y using protocols provided by R.L.P, K.M. and Y.Y. Constant current bias stress tests were developed by R.L.P., with contributions from Y.Y. J.R. recorded TEM and SEM images. The manuscript was prepared by K.K.B. and H.S. All authors examined and commented on the manuscript. The project was guided by H.S.

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Correspondence to H. Sirringhaus.

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Banger, K., Yamashita, Y., Mori, K. et al. Low-temperature, high-performance solution-processed metal oxide thin-film transistors formed by a ‘sol–gel on chip’ process. Nature Mater 10, 45–50 (2011). https://doi.org/10.1038/nmat2914

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