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A ferroelectric-gate fin microwave acoustic spectral processor

Nature Electronics volume 7, pages 147–156 (2024)Cite this article

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Abstract

Wireless communication through dynamic spectrum allocation is essential to accommodate increasing data traffic. This requires massive arrays of radiofrequency filters for adaptive signal shaping at arbitrary frequencies. However, it is difficult to create massively integrated arrays using conventional filters based on planar acoustic resonators due to their large footprint and limited on-chip frequency scalability or intrinsic configurability. Here, we report a three-dimensional ferroelectric-gate fin nano-acoustic resonator that can be used to make spectral processors with high-frequency tailorability, large-scale and dense integrability, and intrinsic switchability. The ferroelectric-gate fins are created by growing atomic-layered ferroelectric hafnia-zirconia transducers on silicon nano-fins. The resonator generates bulk acoustic modes with scalable frequencies over 3–28 GHz (defined lithographically by the fin width) and provides a frequency–quality–electromechanical coupling product (f × Q × kt2) of 19.4 × 1010 Hz (at around 11 GHz). The voltage-controlled tuneability of the gate-transducer polarization also enables intrinsic configurability without the need for external switches. We used the approach to create a monolithic filter array, created by electrical coupling of ferroelectric-gate fins implemented on a single die, covering 9–12 GHz, providing dynamic configurability of the active passband and an isolation as large as 17 dB.

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Fig. 1: FGF nano-acoustic resonator concept and scaling characteristics.
Fig. 2: Three-dimensional and cross-sectional images of FGF acoustic resonators.
Fig. 3: Measured admittance of intrinsically switchable FGF nano-acoustic resonators.
Fig. 4: Images of implemented FGF filter array.
Fig. 5: Measured transmission response of intrinsically switchable FGF filter array.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

We thank T. Hancock for technical discussions and support of this effort, and the University of Florida Nanoscale Research Facility cleanroom staff for fabrication support. F.H., T.T. and R.T. acknowledge the financial support from the Defense Advanced Research Projects Agency through the Young Faculty Award (grant no. D19AP00044) and National Science Foundation through the CAREER award (grant no. ECCS-1752206). The Herbert Wertheim College of Engineering Research Service Centers is acknowledged for use of the FEI Helios G4 CXe dual plasma focused ion beam–scanning electron microscope and FEI Themis Z scanning-transmission electron microscope.

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Authors and Affiliations

  1. Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, USA

    Faysal Hakim, Troy Tharpe & Roozbeh Tabrizian

  2. Research Service Centers, University of Florida, Gainesville, FL, USA

    Nicholas G. Rudawski

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Contributions

F.H. and R.T. designed, fabricated and measured FGF resonators and filters. T.T. and F.H. fabricated and characterized the ferroelectric transducer. N.G.R. prepared samples for imaging and performed STEM characterization. N.G.R., F.H. and T.T. characterized crystallinity and structure of the ferroelectric transducer. R.T. supervised the project and provided guidance throughout the process. All authors participated in analysing the results and contributed to writing the paper. All authors have given approval to the final version of the paper.

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Correspondence to Roozbeh Tabrizian.

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Nature Electronics thanks Shuji Tanaka, Yao Zhu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Sections 1–8, Figs. 1–8 and Tables 1–4.

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Hakim, F., Rudawski, N.G., Tharpe, T. et al. A ferroelectric-gate fin microwave acoustic spectral processor. Nat Electron 7, 147–156 (2024). https://doi.org/10.1038/s41928-023-01109-5

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