Enabling ultra-low-voltage switching in BaTiO3

Y Jiang; E Parsonnet; A Qualls; W Zhao; S Susarla; D Pesquera; A Dasgupta; M Acharya; H Zhang; T Gosavi; C-C Lin; D E Nikonov; H Li; I A Young; R Ramesh; L W Martin

doi:10.1038/s41563-022-01266-6

Enabling ultra-low-voltage switching in BaTiO₃

Nat Mater. 2022 Jul;21(7):779-785. doi: 10.1038/s41563-022-01266-6. Epub 2022 May 26.

Authors

Y Jiang^{1

2}, E Parsonnet³, A Qualls³, W Zhao¹, S Susarla⁴, D Pesquera^{1

5}, A Dasgupta¹, M Acharya^{1

2}, H Zhang¹, T Gosavi⁶, C-C Lin⁶, D E Nikonov⁶, H Li⁶, I A Young⁶, R Ramesh^{1

2

3}, L W Martin^{7

8}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Berkeley, CA, USA.
² Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
³ Department of Physics, University of California, Berkeley, CA, USA.
⁴ National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁵ Catalan Institute of Nanoscience and Nanotechnology, CSIC and BIST, Barcelona, Spain.
⁶ Components Research, Intel Corporation, Hillsboro, OR, USA.
⁷ Department of Materials Science and Engineering, University of California, Berkeley, CA, USA. lwmartin@berkeley.edu.
⁸ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. lwmartin@berkeley.edu.

PMID: 35618823
DOI: 10.1038/s41563-022-01266-6

Abstract

Single crystals of BaTiO₃ exhibit small switching fields and energies, but thin-film performance is considerably worse, thus precluding their use in next-generation devices. Here, we demonstrate high-quality BaTiO₃ thin films with nearly bulk-like properties. Thickness scaling provides access to the coercive voltages (<100 mV) and fields (<10 kV cm^-1) required for future applications and results in a switching energy of <2 J cm^-3 (corresponding to <2 aJ per bit in a 10 × 10 × 10 nm³ device). While reduction in film thickness reduces coercive voltage, it does so at the expense of remanent polarization. Depolarization fields impact polar state stability in thicker films but fortunately suppress the coercive field, thus driving a deviation from Janovec-Kay-Dunn scaling and enabling a constant coercive field for films <150 nm in thickness. Switching studies reveal fast speeds (switching times of ~2 ns for 25-nm-thick films with 5-µm-diameter capacitors) and a pathway to subnanosecond switching. Finally, integration of BaTiO₃ thin films onto silicon substrates is shown. We also discuss what remains to be demonstrated to enable the use of these materials for next-generation devices.