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Flexible CMOS integrated circuits based on carbon nanotubes with sub-10 ns stage delays

Abstract

High-performance logic circuits that are constructed on flexible or unconventional substrates are required for emerging applications such as real-time analytics. Carbon nanotube thin-film transistors (TFTs) are attractive for these applications because of their high mobility and low cost. However, flexible nanotube TFTs usually suffer from much lower performance than those built on rigid substrates, and the resulting flexible integrated circuits typically exhibit low-speed operation with logic gate delays of over 1 μs, which severely limits their practical application. Here we show that high-performance carbon nanotube TFTs and complementary circuits can be fabricated on flexible polyimide substrates using a high-yield, scalable process. Our flexible TFTs exhibit state-of-the-art performance with very high current densities (>17 μA μm−1), large current on/off ratios (>106), small subthreshold slopes (<200 mV dec−1), high field-effect mobilities (~50 cm2 V−1 s−1) and excellent flexibility. We also develop a reliable n-type doping process, which allows us to fabricate complementary logic gates and integrated circuits on flexible substrates. With our approach, we build flexible ring oscillators that have a stage delay of only 5.7 ns.

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Fig. 1: Fabrication of flexible CNT TFTs.
Fig. 2: Flexible CNT TFTs.
Fig. 3: Flexible CNT complementary logic gates.
Fig. 4: Flexible CNT CMOS ROs.

References

  1. 1.

    Qiu, C. et al. Scaling carbon nanotube complementary transistors to 5-nm gate lengths. Science 355, 271–276 (2017).

    Article  Google Scholar 

  2. 2.

    Cao, Q., Tersoff, J., Farmer, D. B., Zhu, Y. & Han, S. Carbon nanotube transistors scaled to a 40-nanometer footprint. Science 356, 1369 (2017).

    Article  Google Scholar 

  3. 3.

    Cao, Q. et al. End-bonded contacts for carbon nanotube transistors with low, size-independent resistance. Science 350, 68–72 (2015).

    Article  Google Scholar 

  4. 4.

    Tang, J., Cao, Q., Farmer, D. B., Tulevski, G. & Han, S. Carbon nanotube complementary logic with low-temperature processed end-bonded metal contacts. IEDM Tech. Dig. 2016, 5.1.1–5.1.4 (2016).

  5. 5.

    Nish, A., Hwang, J.-Y., Doig, J. & Nicholas, R. J. Highly selective dispersion of single-walled carbon nanotubes using aromatic polymers. Nat. Nanotech. 2, 640–646 (2007).

    Article  Google Scholar 

  6. 6.

    Mistry, K. S., Larsen, B. A. & Blackburn, J. L. High-yield dispersions of large-diameter semiconducting single-walled carbon nanotubes with tunable narrow chirality distributions. ACS Nano 7, 2231–2239 (2013).

    Article  Google Scholar 

  7. 7.

    Tulevski, G. S., Franklin, A. D. SpringerAmpamp; Afzali, A. High purity isolation and quantification of semiconducting carbon nanotubes via column chromatography. ACS Nano 7, 2971–2976 (2013).

    Article  Google Scholar 

  8. 8.

    Park, H. et al. High-density integration of carbon nanotubes via chemical self-assembly. Nat. Nanotech. 7, 787–791 (2012).

    Article  Google Scholar 

  9. 9.

    Han, S.-J. et al. High-speed logic integrated circuits with solution-processed self-assembled carbon nanotubes. Nat. Nanotech. 12, 861–865 (2017).

    Article  Google Scholar 

  10. 10.

    Shulaker, M. M. et al. Carbon nanotube computer. Nature 501, 526–530 (2013).

    Article  Google Scholar 

  11. 11.

    Franklin, A. D. Nanomaterials in transistors: from high-performance to thin-film applications. Science 349, 704 (2015).

    Article  Google Scholar 

  12. 12.

    Nathan, A. et al. Amorphous silicon thin film transistor circuit integration for organic LED displays on glass and plastic. IEEE J. Solid-State Circ. 39, 1477–1486 (2004).

    Article  Google Scholar 

  13. 13.

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

    Article  Google Scholar 

  14. 14.

    Forrest, S. R. The path to ubiquitous and low-cost organic electronic appliances on plastic. Nature 428, 911–918 (2004).

    Article  Google Scholar 

  15. 15.

    Hu, L., Hecht, D. & Grüner, G. Carbon nanotube thin films: fabrication, properties, and applications. Chem. Rev. 110, 5790–5844 (2010).

    Article  Google Scholar 

  16. 16.

    Akinwande, D., Petrone, N. & Hone, J. Two-dimensional flexible nanoelectronics. Nat. Commun. 5, 5678 (2014).

    Article  Google Scholar 

  17. 17.

    Cai, L. & Wang, C. Carbon nanotube flexible and stretchable electronics. Nanoscale Res. Lett. 10, 320 (2015).

    Article  Google Scholar 

  18. 18.

    Chandra, B., Park, H., Maarouf, A., Martyna, G. J. & Tulevski, G. S. Carbon nanotube thin film transistors on flexible substrates. Appl. Phys. Lett. 99, 72110 (2011).

    Article  Google Scholar 

  19. 19.

    Tian, B. et al. Wafer scale fabrication of carbon nanotube thin film transistors with high yield. J. Appl. Phys. 120, 034501 (2016).

    Article  Google Scholar 

  20. 20.

    Cao, Q. et al. Medium-scale carbon nanotube thin-film integrated circuits on flexible plastic substrates. Nature 454, 495–500 (2008).

    Article  Google Scholar 

  21. 21.

    Lau, P. H. et al. Fully printed, high performance carbon nanotube thin-film transistors on flexible substrates. Nano Lett. 13, 3864–3869 (2013).

    Article  Google Scholar 

  22. 22.

    Zhao, Y. et al. Three-dimensional flexible complementary metal–oxide–semiconductor logic circuits based on two-layer stacks of single-walled carbon nanotube networks. ACS Nano 10, 2193–2202 (2016).

    Article  Google Scholar 

  23. 23.

    Honda, W., Arie, T., Akita, S. & Takei, K. Mechanically flexible and high-performance CMOS logic circuits. Sci. Rep. 5, 15099 (2015).

    Article  Google Scholar 

  24. 24.

    Wang, H. et al. Tuning the threshold voltage of carbon nanotube transistors by n-type molecular doping for robust and flexible complementary circuits. Proc. Natl Acad. Sci. USA 111, 4776–4781 (2014).

    Article  Google Scholar 

  25. 25.

    Sun, D. et al. Flexible high-performance carbon nanotube integrated circuits. Nat. Nanotech. 6, 156–161 (2011).

    Article  Google Scholar 

  26. 26.

    Chen, H., Cao, Y., Zhang, J. & Zhou, C. Large-scale complementary macroelectronics using hybrid integration of carbon nanotubes and IGZO thin-film transistors. Nat. Commun. 5, 4097 (2014).

    Google Scholar 

  27. 27.

    Ha, M. et al. Printed, sub-3V digital circuits on plastic from aqueous carbon nanotube inks. ACS Nano 4, 4388–4395 (2010).

    Article  Google Scholar 

  28. 28.

    Wang, C. et al. Extremely bendable, high performance integrated circuits using semiconducting carbon nanotube networks for digital, analog, and radio-frequency applications. Nano Lett. 12, 1527–1533 (2012).

    Article  Google Scholar 

  29. 29.

    Chen, B. et al. Highly uniform carbon nanotube field-effect transistors and medium scale integrated circuits. Nano Lett. 16, 5120–5128 (2016).

    Article  Google Scholar 

  30. 30.

    Wang, C. et al. Wafer-scale fabrication of separated carbon nanotube thin-film transistors for display applications. Nano Lett. 9, 4285–4291 (2009).

    Article  Google Scholar 

  31. 31.

    Yang, Y. et al. Carbon nanotube network film-based ring oscillators with sub 10-ns propagation time and their applications in radio-frequency signal transmission. Nano Res. 11, 300–310 (2018).

    Article  Google Scholar 

  32. 32.

    Cao, Q. et al. Arrays of single-walled carbon nanotubes with full surface coverage for high-performance electronics. Nat. Nanotech. 8, 180–186 (2013).

    Article  Google Scholar 

  33. 33.

    Brady, G. J. et al. Quasi-ballistic carbon nanotube array transistors with current density exceeding Si and GaAs. Sci. Adv. 2, e1601240 (2016).

    Article  Google Scholar 

  34. 34.

    Cao, Q. et al. Gate capacitance coupling of singled-walled carbon nanotube thin-film transistors. Appl. Phys. Lett. 90, 2–4 (2007).

    Google Scholar 

  35. 35.

    Yang, Y., Ding, L., Han, J., Zhang, Z. & Peng, L.-M. High-performance complementary transistors and medium-scale integrated circuits based on carbon nanotube thin films. ACS Nano 11, 4124–4132 (2017).

    Article  Google Scholar 

  36. 36.

    Geier, M. L. et al. Solution-processed carbon nanotube thin-film complementary static random access memory. Nat. Nanotech. 10, 944–948 (2015).

    Article  Google Scholar 

  37. 37.

    Ha, T. et al. Highly uniform and stable n-type carbon nanotube transistors by using positively charged silicon nitride thin films. Nano Lett. 15, 392–397 (2015).

    Article  Google Scholar 

  38. 38.

    Li, G. et al. Fabrication of air-stable n-type carbon nanotube thin-film transistors on flexible substrates using bilayer dielectrics. Nanoscale 7, 17693–17701 (2015).

    Article  Google Scholar 

  39. 39.

    Wei, H., Chen, H. Y., Liyanage, L., Wong, H. S. P. & Mitra, S. Air-stable technique for fabricating n-type carbon nanotube FETs. IEDM Tech. Dig. 2011, 23.2.1–23.2.4 (2011).

    Google Scholar 

  40. 40.

    Zhang, J., Wang, C., Fu, Y., Che, Y. & Zhou, C. Air-stable conversion of separated carbon nanotube thin-film transistors from p-type to n-type using atomic layer deposition of high-κ oxide and its application in CMOS logic circuits. ACS Nano 5, 3284–3292 (2011).

    Article  Google Scholar 

  41. 41.

    Tang, J. et al. Contact engineering and channel doping for robust carbon nanotube NFETs. 2017 Int. Symp. VLSI Tech. Syst. Appl. https://doi.org/10.1109/VLSI-TSA.2017.7942478 (2017).

  42. 42.

    Ha, M. et al. Aerosol jet printed, low voltage, electrolyte gated carbon nanotube ring oscillators with sub-5 μs stage delays. Nano Lett. 13, 954–960 (2013).

    Article  Google Scholar 

  43. 43.

    Sun, D.-M. et al. Mouldable all-carbon integrated circuits. Nat. Commun. 4, 2302 (2013).

    Google Scholar 

  44. 44.

    Myny, K. et al. Organic RFID transponder chip with data rate compatible with electronic product coding. Org. Electron. 11, 1176–1179 (2010).

    Article  Google Scholar 

  45. 45.

    Zschieschang, U. et al. Flexible low-voltage organic transistors and circuits based on a high-mobility organic semiconductor with good air stability. Adv. Mater. 22, 982–985 (2010).

    Article  Google Scholar 

  46. 46.

    Kim, D. K., Lai, Y., Diroll, B. T., Murray, C. B. & Kagan, C. R. Flexible and low-voltage integrated circuits constructed from high-performance nanocrystal transistors. Nat. Commun. 3, 1216 (2012).

    Article  Google Scholar 

  47. 47.

    Zhao, D., Mourey, D. A. & Jackson, T. N. Fast flexible plastic substrate ZnO circuits. IEEE Electron Device Lett. 31, 323–325 (2010).

    Article  Google Scholar 

  48. 48.

    Kim, Y.-H. et al. Flexible metal-oxide devices made by room-temperature photochemical activation of sol–gel films. Nature 489, 128–132 (2012).

    Article  Google Scholar 

Download references

Acknowledgements

The authors thank B. Ek for technical assistance with metal deposition. The authors also acknowledge H. Riel and Z. Lemnios for management support.

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J.T. conceived and designed the experiments. G.T. prepared the purified CNT solution and deposited CNT thin films. J.T. fabricated the devices and performed the measurements with help from Q.C., K.A.J., L.N., D.B.F. and S.-J.H. J.T. wrote the manuscript. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Jianshi Tang or Shu-Jen Han.

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Supplementary Figures 1–9

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Tang, J., Cao, Q., Tulevski, G. et al. Flexible CMOS integrated circuits based on carbon nanotubes with sub-10 ns stage delays. Nat Electron 1, 191–196 (2018). https://doi.org/10.1038/s41928-018-0038-8

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