Inexpensive radio-frequency devices that can meet the ultrahigh-frequency needs of fifth- and sixth-generation wireless telecommunication networks are required. However, combining high performance with cost-effective scalable manufacturing has proved challenging. Here, we report the fabrication of solution-processed zinc oxide Schottky diodes that can operate in microwave and millimetre-wave frequency bands. The fully coplanar diodes are prepared using wafer-scale adhesion lithography to pattern two asymmetric metal electrodes separated by a gap of around 15 nm, and are completed with the deposition of a zinc oxide or aluminium-doped ZnO layer from solution. The Schottky diodes exhibit a maximum intrinsic cutoff frequency in excess of 100 GHz, and when integrated with other passive components yield radio-frequency energy-harvesting circuits that are capable of delivering output voltages of 600 mV and 260 mV at 2.45 GHz and 10 GHz, respectively.
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The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.
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D.G.G., J.S. and T.D.A. acknowledge financial support from the European Union Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement 706707, the European Research Council (ERC) project AMPRO under grant no. 280221, the Engineering and Physical Sciences Research Council (EPSRC) grant no. EP/P505550/1 and the EPSRC Centre for Innovative Manufacturing in Large Area Electronics (CIM-LAE) grant no. EP/K03099X/1. A.S., K.L., H.F. and T.D.A. acknowledge support by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no. OSR-2018-CARF/CCF-3079. A.A.S. thanks SERB for an Early Research Career Award (ECR/2017/1562) and SRM IST for financial support. We also thank S. Kano for helpful discussion on the nanogap size analysis.
The authors declare no competing interests.
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Georgiadou, D.G., Semple, J., Sagade, A.A. et al. 100 GHz zinc oxide Schottky diodes processed from solution on a wafer scale. Nat Electron 3, 718–725 (2020). https://doi.org/10.1038/s41928-020-00484-7