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Exploiting dimensionality and defect mitigation to create tunable microwave dielectrics



Nathan D. Orloff, C H. Lee, T Birol, J A. Mundy, V. Goian, R. Haislmaier, E. Vlahos, Y. Kim, J. D. Brock, Y Zhu, R. Uecker, V. Gopalan, S. Kamba, X X. Xi, D A. Muller, I. Takeuchi, James C. Booth, C. J. Fennie


The miniaturization and integration of frequency-agile microwave circuits—tunable filters, resonators, phase shifters and more—with microelectronics offers tantalizing device possibilities, yet requires thin films whose dielectric constant at GHz frequencies can be tuned by applying a quasi-static electric field 1. Appropriate systems, e.g., BaxSr1–xTiO3, have a paraelectric-to- ferroelectric transition just below ambient temperature, providing high tunability 1–3, Unfortunately such films suffer significant losses arising from defects. Recognizing that progress is stymied by dielectric loss, we start with a system with exceptionally low loss— Srn+1TinO3n+1 phases 4,5 —where in-plane crystallographic shear 6,7 (SrO)2 faults provide an alternative to point defects for accommodating non-stoichiometry 8,9. Here, we report the experimental realization of the emergence of a ferroelectric and highly tunable ground state in biaxially strained Srn+1TinO3n+1 phases with n ≥ 3 at frequencies up to 40 GHz. With increasing n the (SrO)2 faults are separated further than the ferroelectric coherence length perpendicular to the in-plane polarization, enabling tunability with a figure of merit at room temperature that rivals all known tunable microwave dielectrics3.


Orloff, N. , Lee, C. , Birol, T. , Mundy, J. , Goian, V. , Haislmaier, R. , Vlahos, E. , Kim, Y. , Brock, J. , Zhu, Y. , Uecker, R. , Gopalan, V. , Kamba, S. , Xi, X. , Muller, D. , Takeuchi, I. , Booth, J. and Fennie, C. (2013), Exploiting dimensionality and defect mitigation to create tunable microwave dielectrics, Nature, [online], (Accessed July 22, 2024)


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Created October 23, 2013, Updated January 27, 2020