Article | Published:

On-chip intercalated-graphene inductors for next-generation radio frequency electronics

Nature Electronicsvolume 1pages4651 (2018) | Download Citation


On-chip metal inductors that revolutionized radio frequency electronics in the 1990s suffer from an inherent limitation in their scalability in state-of-the-art radio frequency integrated circuits. This is because the inductance density values for conventional metal inductors, which result from magnetic inductance alone, are limited by the laws of electromagnetic induction. Here, we report inductors made of intercalated graphene that uniquely exploit the relatively large kinetic inductance and high conductivity of the material to achieve both small form-factors and high inductance values, a combination that has proved difficult to attain so far. Our two-turn spiral inductors based on bromine-intercalated multilayer graphene exhibit a 1.5-fold higher inductance density, leading to a one-third area reduction, compared to conventional inductors, while providing undiminished Q-factors of up to 12. This purely material-enabled technique provides an attractive solution to the longstanding scaling problem of on-chip inductors and opens an unconventional path for the development of ultra-compact wireless communication systems.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Evans, D. The Internet of Things - how the next evolution of the internet is changing everything. CISCO White Papers 1–11 (2011).

  2. 2.

    Nordrum, A. Popular Internet of Things forecast of 50 billion devices by 2020 is outdated. IEEE Spectrum (2016).

  3. 3.

    Manyika, J. et al. Disruptive technologies: Advances that will transform life, business, and the global economy (McKinsey Insights And Publications, 2013).

  4. 4.

    Das, R. RFID Forecasts, Players and Opportunities 2016-2026.

  5. 5.

    Lopez-Villegas, J. M., Samitier, J., Cane, C., Losantos, P. & Bausells, J. Improvement of the quality factor of RF integrated inductors by layout optimization. IEEE Trans. Microw. Theory Tech. 48, 76–83 (2000).

  6. 6.

    Yoon, J.-B., Choi, Y.-S., Kim, B.-I., Eo, Y. & Yoon, E. CMOS-compatible surface-micromachined suspended-spiral inductors for multi-GHz silicon RF ICs. IEEE Electron Device Lett. 23, 591–593 (2002).

  7. 7.

    Jiang, H., Wang, Y., Yeh, J.-L. A. & Tien, N. C. On-chip spiral inductors suspended over deep copper-lined cavities. IEEE Trans. Microw. Theory Tech. 48, 2415–2423 (2000).

  8. 8.

    Yu, X. et al. Ultra-small, high-frequency, and substrate-immune microtube inductors transformed from 2D to 3D. Sci. Rep. 5, 9661 (2015).

  9. 9.

    Yin, W.-Y. et al. Vertical topologies of miniature multispiral stacked inductors. IEEE Trans. Microw. Theory Tech. 56, 475–486 (2008).

  10. 10.

    Tang, C.-C., Wu, C.-H. & Liu, S.-I. Miniature 3-D inductors in standard CMOS process. IEEE J. Solid-State Circuits 37, 471–480 (2002).

  11. 11.

    Ahn, C. H. & Allen, M. G. Micromachined planar inductors on silicon wafers for MEMS applications. IEEE Trans. Ind. Electron. 45, 866–876 (1998).

  12. 12.

    Ikeda, K. et al. Thin-film inductor for gigahertz band with CoFeSiO-SiO2 multilayer granular films and its application for power amplifier module. IEEE Trans. Magn. 39, 3057–3061 (2003).

  13. 13.

    Li, H. & Banerjee, K. High-frequency effects in carbon nanotube interconnects and implications for on-chip inductor design. In 2008 IEEE International Electron Devices Meeting 1–4 (IEEE, 2008).

  14. 14.

    Li, H. & Banerjee, K. High-frequency analysis of carbon nanotube interconnects and implications for on-chip inductor design. IEEE Trans. Electron Devices 56, 2202–2214 (2009).

  15. 15.

    Sarkar, D., Xu, C., Li, H. & Banerjee, K. High-frequency behavior of graphene-based interconnects - Part II: impedance analysis and implications for inductor design. IEEE Trans. Electron Devices 58, 853–859 (2011).

  16. 16.

    Li, H., Xu, C., Srivastava, N. & Banerjee, K. Carbon nanomaterials for next-generation interconnects and passives: physics, status, and prospects. IEEE Trans. Electron Devices 56, 1799–1821 (2009).

  17. 17.

    Li, X. et al. Graphene inductors for high-frequency applications - design, fabrication, characterization, and study of skin effect. In IEEE International Electron Devices Meeting 5.4.1-5.4.4 (IEEE, 2014).

  18. 18.

    Jiang, J. et al. Intercalation doped multilayer-graphene-nanoribbons for next-generation interconnects. Nano Lett. 17, 1482–1488 (2017).

  19. 19.

    Dresselhaus, M. S. & Dresselhaus, G. Intercalation compounds of graphite. Adv. Phys. 51, 1–186 (2002).

  20. 20.

    Enoki, T., Suzuki, M. & Endo, M. Graphite Intercalation Compounds and Applications. (Oxford University Press, NY, 2003).

  21. 21.

    Liu, W., Kang, J. & Banerjee, K. Characterization of FeCl3 intercalation doped CVD few-layer graphene. IEEE Electron Device Lett. 37, 1246–1249 (2016).

  22. 22.

    Plombon, J. J., O’Brien, K. P., Gstrein, F., Dubin, V. M. & Jiao, Y. High-frequency electrical properties of individual and bundled carbon nanotubes. Appl. Phys. Lett. 90, 63106 (2007).

  23. 23.

    Lee, T. H. The Design of CMOS Radio-Frequency Integrated Circuits. (Cambridge University Press, Cambridge, 2004).

  24. 24.

    Tongay, S. et al. Supermetallic conductivity in bromine-intercalated graphite. Phys. Rev. B 81, 115428 (2010).

  25. 25.

    Jiang, J., Kang, J. & Banerjee, K. Characterization of self-heating and current-carrying capacity of intercalation doped graphene-nanoribbon interconnects. In IEEE International Reliability Physics Symposium 6B.1.1–6B.1.6 (2017).

  26. 26.

    Xu, C., Li, H. & Banerjee, K. Modeling, analysis, and design of graphene nano-ribbon interconnects. IEEE Trans. Electron Devices 56, 1567–1578 (2009).

  27. 27.

    Steinhögl, W., Schindler, G., Steinlesberger, G., Traving, M. & Engelhardt, M. Comprehensive study of the resistivity of copper wires with lateral dimensions of 100 nm and smaller. J. Appl. Phys. 97, 23706 (2005).

  28. 28.

    Ueno, K. et al. Bromine doping of multilayer graphene for low-resistance interconnects. Jpn. J. Appl. Phys. 53, 05GC02 (2014).

Download references


This work was supported in part by the UC Lab Fees Research Program (grant LFR-17-477237), the UC MRPI (MRP-17-454999), the Systems on Nanoscale Information fabriCs (SONIC), one of the six SRC STARnet Centres, sponsored by MARCO and DARPA, as well as by the Air Force Office of Scientific Research, Arlington, VA, USA (grant FA9550-14-1-0268). X.L. and J.M. were supported by the National Natural Science Foundation of China (grant 61331004). Y.M., K.K., M.K. and K.U. received support from the SIT Research Centre for Green Innovation, Japan. The authors would like to thank W. Cao, A. Pal of the Nanoelectronics Research Lab ( at University of California, Santa Barbara (UCSB), M. Guidry at UCSB and C. Xu at Maxim Integrated for useful technical discussions.

Author information

Author notes

  1. Yuji Matsumoto, Xiang Li and Junkai Jiang contributed equally to this work.


  1. Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA, USA

    • Jiahao Kang
    • , Junkai Jiang
    • , Xuejun Xie
    • , Jae Hwan Chu
    • , Wei Liu
    •  & Kaustav Banerjee
  2. Graduate School of Engineering and Science, Shibaura Institute of Technology, Tokyo, Japan

    • Yuji Matsumoto
    • , Keisuke Kawamoto
    • , Munehiro Kenmoku
    •  & Kazuyoshi Ueno
  3. Key Laboratory of Ministry of Education for Design and Electromagnetic Compatibility of High-Speed Electronic Systems, Shanghai Jiao Tong University, Shanghai, China

    • Xiang Li
    •  & Junfa Mao


  1. Search for Jiahao Kang in:

  2. Search for Yuji Matsumoto in:

  3. Search for Xiang Li in:

  4. Search for Junkai Jiang in:

  5. Search for Xuejun Xie in:

  6. Search for Keisuke Kawamoto in:

  7. Search for Munehiro Kenmoku in:

  8. Search for Jae Hwan Chu in:

  9. Search for Wei Liu in:

  10. Search for Junfa Mao in:

  11. Search for Kazuyoshi Ueno in:

  12. Search for Kaustav Banerjee in:


K.B. conceived the idea and led the research. J.K., X.L. and J.J. performed the modelling and simulations guided by K.B. and J.M. J.K., X.L. and X.X. designed the inductor layouts. J.J., Y.M., K.K., M.K. and K.U. performed the doping process. J.H.C., K.K., M.K. and K.U. performed the Raman, XPS, ultraviolet photoelectron spectroscopy, EDX, STEM and Hall measurements. X.X. and J.J. performed the AFM measurements. J.K., J.J., X.X. and W.L. fabricated the devices and performed electrical measurements. X.L. and J.K. analysed the data. J.K. and K.B. wrote the main paper and the Supplementary Information Sections with input from all other authors.

Competing Interest

The authors declare no competing financial interests.

Corresponding author

Correspondence to Kaustav Banerjee.

Supplementary information

  1. Supplementary Information

    Supplementary Sections 1–15.

About this article

Publication history





Further reading Further reading