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.
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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 (http://nrl.ece.ucsb.edu/) at University of California, Santa Barbara (UCSB), M. Guidry at UCSB and C. Xu at Maxim Integrated for useful technical discussions.
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Nature Electronics (2018)