Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Intrinsic ferroelectricity in Y-doped HfO2 thin films

Abstract

Ferroelectric HfO2-based materials hold great potential for the widespread integration of ferroelectricity into modern electronics due to their compatibility with existing Si technology. Earlier work indicated that a nanometre grain size was crucial for the stabilization of the ferroelectric phase. This constraint, associated with a high density of structural defects, obscures an insight into the intrinsic ferroelectricity of HfO2-based materials. Here we demonstrate that stable and enhanced polarization can be achieved in epitaxial HfO2 films with a high degree of structural order (crystallinity). An out-of-plane polarization value of 50 μC cm–2 has been observed at room temperature in Y-doped HfO2(111) epitaxial thin films, with an estimated full value of intrinsic polarization of 64 μC cm–2, which is in close agreement with density functional theory calculations. The crystal structure of films reveals the Pca21 orthorhombic phase with small rhombohedral distortion, underlining the role of the structural constraint in stabilizing the ferroelectric phase. Our results suggest that it could be possible to exploit the intrinsic ferroelectricity of HfO2-based materials, optimizing their performance in device applications.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Structure characterization and ferroelectric hysteresis.
Fig. 2: Local ferroelectric switching by PFM.
Fig. 3: Temperature dependence of ferroelectric hysteresis.
Fig. 4: Structural characterization of YHO films.
Fig. 5: Results of DFT calculations for bulk undoped and 5% Y-doped HfO2.

Similar content being viewed by others

Data availability

Source data are provided with this paper. All other data that support the findings of this study are available within the article and Supplementary Information.

References

  1. Scott, J. F. Ferroelectric Memories (Springer Press, 2000).

  2. Kushida-Abdelghafar, K., Miki, H., Torii, K. & Fujisaki, Y. Electrode-induced degradation of Pb(ZrxTi1–x)O3 (PZT) polarization hysteresis characteristics in Pt/PZT/Pt ferroelectric thin-film capacitors. Appl. Phys. Lett. 69, 3188–3190 (1996).

    Article  CAS  Google Scholar 

  3. Shimamoto, Y., Kushida-Abdelghafar, K., Miki, H. & Fujisaki, Y. H2 damage of ferroelectric Pb(Zr,Ti)O3 thin-film capacitors—the role of catalytic and adsorptive activity of the top electrode. Appl. Phys. Lett. 70, 3096–3097 (1997).

    Article  CAS  Google Scholar 

  4. Aggarwal, S. et al. Effect of hydrogen on Pb(Zr,Ti)O3-based ferroelectric capacitors. Appl. Phys. Lett. 73, 1973–1975 (1998).

    Article  CAS  Google Scholar 

  5. Ma, T. P. & Han, J.-P. Why is nonvolatile ferroelectric memory field-effect transistor still elusive? IEEE Electron Device Lett. 23, 386–388 (2002).

    Article  CAS  Google Scholar 

  6. Böscke, T. S., Müller, J., Bräuhaus, D., Schröder, U. & Böttger, U. Ferroelectricity in hafnium oxide thin films. Appl. Phys. Lett. 99, 102903 (2011).

    Article  CAS  Google Scholar 

  7. Mikolajick, T., Slesazeck, S., Park, M. H. & Schroeder, U. Ferroelectric hafnium oxide for ferroelectric random-access memories and ferroelectric field-effect transistors. MRS Bull. 43, 340–346 (2018).

    Article  CAS  Google Scholar 

  8. Wang, J., Li, H. P. & Stevens, R. Hafnia and hafnia-toughened ceramics. J. Mater. Sci. 27, 5397–5430 (1992).

    Article  CAS  Google Scholar 

  9. Park, M. H. et al. Evolution of phases and ferroelectric properties of thin Hf0.5Zr0.5O2 films according to the thickness and annealing temperature. Appl. Phys. Lett. 102, 242905 (2013).

    Article  CAS  Google Scholar 

  10. Park, M. H. et al. Surface and grain boundary energy as the key enabler of ferroelectricity in nanoscale hafnia-zirconia: a comparison of model and experiment. Nanoscale 9, 9973–9986 (2017).

    Article  CAS  Google Scholar 

  11. Park, M. H. et al. Understanding the formation of the metastable ferroelectric phase in hafnia-zirconia solid solution thin films. Nanoscale 10, 716–725 (2018).

    Article  CAS  Google Scholar 

  12. Materlik, R., Künneth, C. & Kersch, A. The origin of ferroelectricity in Hf1−xZrxO2: a computational investigation and a surface energy model. J. Appl. Phys. 117, 134109 (2015).

    Article  CAS  Google Scholar 

  13. Batra, R., Tran, H. D. & Ramprasad, R. Stabilization of metastable phases in hafnia owing to surface energy effects. Appl. Phys. Lett. 108, 172902 (2016).

    Article  CAS  Google Scholar 

  14. Liu, S. & Hanrahan, B. M. Effects of growth orientations and epitaxial strains on phase stability of HfO2 thin films. Phys. Rev. Mater. 3, 054404 (2019).

    Article  CAS  Google Scholar 

  15. Xu, X. et al. Kinetically stabilized ferroelectricity in bulk single-crystalline HfO2:Y. Nat. Mater. 20, 826–832 (2021).

    Article  CAS  Google Scholar 

  16. Katayama, K. et al. Growth of (111)-oriented epitaxial and textured ferroelectric Y-doped HfO2 films for downscaled devices. Appl. Phys. Lett. 109, 112901 (2016).

    Article  CAS  Google Scholar 

  17. Katayama, K. et al. Orientation control and domain structure analysis of {100}-oriented epitaxial ferroelectric orthorhombic HfO2-based thin films. J. Appl. Phys. 119, 134101 (2016).

    Article  CAS  Google Scholar 

  18. Shimizu, T. et al. The demonstration of significant ferroelectricity in epitaxial Y-doped HfO2 film. Sci. Rep. 6, 32931 (2016).

    Article  CAS  Google Scholar 

  19. Wei, Y. F. et al. A rhombohedral ferroelectric phase in epitaxially strained Hf0.5Zr0.5O2 thin films. Nat. Mater. 17, 1095–1100 (2018).

    Article  CAS  Google Scholar 

  20. Yoong, H. Y. et al. Epitaxial ferroelectric Hf0.5Zr0.5O2 thin films and their implementations in memristors for brain-inspired computing. Adv. Funct. Mater. 28, 1806037 (2018).

    Article  CAS  Google Scholar 

  21. Estandia, S. et al. Engineering ferroelectric Hf0.5Zr0.5O2 thin films by epitaxial stress. ACS Appl. Electron. Mater. 1, 1449–1457 (2019).

    Article  CAS  Google Scholar 

  22. Lyu, J., Fina, I., Solanas, R., Fontcuberta, J. & Sanchez, F. Growth window of ferroelectric epitaxial Hf0.5Zr0.5O2 thin films. ACS Appl. Electron. Mater. 1, 220–228 (2019).

    Article  CAS  Google Scholar 

  23. Bégon-Lours, L. et al. Stabilization of phase-pure rhombohedral HfZrO4 in pulsed laser deposited thin films. Phys. Rev. Mater. 4, 043401 (2020).

    Article  Google Scholar 

  24. Park, M. H. et al. Ferroelectricity and antiferroelectricity of doped thin HfO2-based films. Adv. Mater. 27, 1811–1831 (2015).

    Article  CAS  Google Scholar 

  25. Song, T. et al. Epitaxial ferroelectric La-doped Hf0.5Zr0.5O2 thin films. ACS Appl. Electron. Mater. 2, 3221–3232 (2020).

    Article  CAS  Google Scholar 

  26. Chouprik, A., Negrov, D., Tsymbal, E. Y. & Zenkevich, A. Defects in ferroelectric HfO2. Nanoscale 13, 11635–11678 (2021).

    Article  CAS  Google Scholar 

  27. Lee, H. J. et al. Scale-free ferroelectricity induced by flat phonon bands in HfO2. Science 369, 1343–1347 (2020).

    Article  CAS  Google Scholar 

  28. Qi, Y. et al. Stabilization of competing ferroelectric phases of HfO2 under epitaxial strain. Phys. Rev. Lett. 125, 257603 (2020).

    Article  CAS  Google Scholar 

  29. Cao, J., Shi, S., Zhu, Y. & Chen, J. An overview of ferroelectric hafnia and epitaxial growth. Phys. Status Solidi Rapid Res. Lett. 15, 2100025 (2021).

    Article  CAS  Google Scholar 

  30. Kashir, A., Kim, H., Oh, S. & Hwang, H. Large remnant polarization in a wake-up free Hf0.5Zr0.5O2 ferroelectric film through bulk and interface engineering. ACS Appl. Electron. Mater. 3, 629–638 (2021).

    Article  CAS  Google Scholar 

  31. Nukala, P. et al. Reversible oxygen migration and phase transitions in hafnia-based ferroelectric devices. Science 372, 630–635 (2021).

    Article  CAS  Google Scholar 

  32. Adkins, J. W., Fina, I., Sánchez, F., Bakaul, S. R. & Abiade, J. T. Thermal evolution of ferroelectric behavior in epitaxial Hf0.5Zr0.5O2. Appl. Phys. Lett. 117, 142902 (2020).

    Article  CAS  Google Scholar 

  33. Nukala, P. et al. Guidelines for the stabilization of a polar rhombohedral phase in epitaxial Hf0.5Zr0.5O2 thin films. Ferroelectrics 569, 148–163 (2020).

    Article  CAS  Google Scholar 

  34. Mimura, T., Shimizu, T., Uchida, H., Sakata, O. & Funakubo, H. Thickness-dependent crystal structure and electric properties of epitaxial ferroelectric Y2O3-HfO2 films. Appl. Phys. Lett. 113, 102901 (2018).

    Article  CAS  Google Scholar 

  35. Mimura, T., Shimizu, T. & Funakubo, H. Ferroelectricity in YO1.5-HfO2 films around 1 μm in thickness. Appl. Phys. Lett. 115, 032901 (2019).

    Article  CAS  Google Scholar 

  36. Shimura, R. et al. Preparation of near-1-µm-thick {100}-oriented epitaxial Y-doped HfO2 ferroelectric films on (100)Si substrates by a radio-frequency magnetron sputtering method. J. Ceram. Soc. Jpn 128, 539–543 (2020).

    Article  CAS  Google Scholar 

  37. Vasudevan, R. K., Balke, N., Maksymovych, P., Jesse, S. & Kalinin, S. V. Ferroelectric or non-ferroelectric: why so many materials exhibit ‘ferroelectricity’ on the nanoscale. Appl. Phys. Rev. 4, 021302 (2017).

    Article  CAS  Google Scholar 

  38. Lee, J. S., Lee, S. & Noh, T. W. Resistive switching phenomena: a review of statistical physics approaches. Appl. Phys. Rev. 2, 031303 (2015).

    Article  CAS  Google Scholar 

  39. Buragohain, P. et al. Fluid imprint and inertial switching in ferroelectric La:HfO2 capacitors. ACS Appl. Mater. Interfaces 11, 35115–35121 (2019).

    Article  CAS  Google Scholar 

  40. Estandía, S., Dix, N., Chisholm, M. F., Fina, I. & Sánchez, F. Domain-matching epitaxy of ferroelectric Hf0.5Zr0.5O2(111) on La2/3Sr1/3MnO3(001). Cryst. Growth Des. 20, 3801–3806 (2020).

    Article  Google Scholar 

  41. Sang, X., Grimley, E. D., Schenk, T., Schroeder, U. & LeBeau, J. M. On the structural origins of ferroelectricity in HfO2 thin films. Appl. Phys. Lett. 106, 162905 (2015).

    Article  CAS  Google Scholar 

  42. Mimura, T. et al. Effects of heat treatment and in situ high-temperature X-ray diffraction study on the formation of ferroelectric epitaxial Y-doped HfO2 film. Jpn J. Appl. Phys. 58, SBBB09 (2019).

    Article  CAS  Google Scholar 

  43. Tashiro, Y., Shimizu, T., Mimura, T. & Funakubo, H. Comprehensive study on the kinetic formation of the orthorhombic ferroelectric phase in epitaxial Y-doped ferroelectric HfO2 thin films. ACS Appl. Electron. Mater. 3, 3123–3130 (2021).

    Article  CAS  Google Scholar 

  44. Shimizu, T. et al. Growth of epitaxial orthorhombic YO1.5-substituted HfO2 thin film. Appl. Phys. Lett. 107, 032910 (2015).

    Article  CAS  Google Scholar 

  45. Giannozzi, P. et al. QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials. J. Phys. Condens. Matter 21, 395502 (2009).

    Article  Google Scholar 

  46. Burton, J. D. & Tsymbal, E. Y. Prediction of electrically induced magnetic reconstruction at the manganite/ferroelectric interface. Phys. Rev. B 80, 174406 (2009).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

This work was primarily supported by the National Science Foundation (NSF), Division of Electrical, Communications and Cyber Systems (ECCS), under grant no. ECCS-1917635 (Y.Y., X.L., X.X., P.B., A.G., M.L, L.T. and E.Y.T.). J.L. acknowledges support from the US Department of Energy’s (DOE) (DE-SC0019173) for interdigital device fabrication. Y.Z. and Haiyan Wang acknowledge support from the NSF (DMR-2016453 and DMR-1565822) for the microscopy effort at Purdue University. The research was performed in part at the Nebraska Nanoscale Facility, National Nanotechnology Coordinated Infrastructure and the Nebraska Center for Materials and Nanoscience, which are supported by the NSF under grant no. ECCS- 2025298, as well as the Nebraska Research Initiative through the Nebraska Center for Materials and Nanoscience and the Nanoengineering Research Core Facility at the University of Nebraska–Lincoln. Sandia National Laboratories is a multimission laboratory managed and operated by the National Technology and Engineering Solutions of Sandia, a wholly owned subsidiary of Honeywell International for the US DOE’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the US DOE or the US Government.

Author information

Authors and Affiliations

Authors

Contributions

The thin films were synthesized by Y.Y. with assistance from X.X. and Haohan Wang. Structure distortion and symmetry were investigated by Y.Y. and X.X. The thin-film structures with in-plane interdigital electrodes were fabricated by X.L. and J.L. Time-resolved RHEED was studied by Y.Y. and X.L. Local switching and temperature-dependent polarization were studied and analysed by P.B. under the supervision of A.G. M.L. carried out the DFT calculations under the supervision of L.T. and E.Y.T. (S)TEM experiments were conducted by Z.A. and Y.Z. under the supervision of J.S., P.L. and Haiyan Wang. The study was conceived by Y.Y., P.B. and X.X. Y.Y., P.B., M.L., E.Y.T., A.G. and X.X. co-wrote the manuscript. All the authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Evgeny Y. Tsymbal, Alexei Gruverman or Xiaoshan Xu.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Materials thanks Jeffrey Eastman, Hiroshi Funakubo and Jun Hee Lee for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–21 and refs. 1–15.

Supplementary Data 1

Atomic coordinates of the HfO2 unit cell.

Source data

Source Data Fig. 1

Source data for Fig. 1b–f.

Source Data Fig. 2

Source data for Fig. 2d.

Source Data Fig. 3

Source data for Fig. 3.

Source Data Fig. 4

Source data for Fig. 4a,d,e,g–i.

Source Data Fig. 5

Source data for Fig. 5a,b.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yun, Y., Buragohain, P., Li, M. et al. Intrinsic ferroelectricity in Y-doped HfO2 thin films. Nat. Mater. 21, 903–909 (2022). https://doi.org/10.1038/s41563-022-01282-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41563-022-01282-6

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing