Impact of mechanical stress on ferroelectricity in (Hf0.5Zr0.5)O2 thin films

Takahisa Shiraishi, Kiliha Katayama, Tatsuhiko Yokouchi, Takao Shimizu, Takahiro Oikawa, Osami Sakata, Hiroshi Uchida, Yasuhiko Imai, Takanori Kiguchi, Toyohiko Konno, Hiroshi Funakubo

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Abstract

To investigate the impact of mechanical stress on their ferroelectric properties, polycrystalline (Hf0.5Zr0.5)O2 thin films were deposited on (111)Pt-coated SiO2, Si, and CaF2 substrates with thermal expansion coefficients of 0.47, 4.5, and 22 × 10-6/ °C, respectively. In-plane X-ray diffraction measurements revealed that the (Hf0.5Zr0.5)O2 thin films deposited on SiO2 and Si substrates were under in-plane tensile strain and that their volume fraction of monoclinic phase decreased as this strain increased. In contrast, films deposited on CaF2 substrates were under in-plane compressive strain, and their volume fraction of monoclinic phase was the largest among the three kinds of substrates. The maximum remanent polarization of 9.3 μC/cm2 was observed for Pt/(Hf0.5Zr0.5)O2/Pt/TiO2/SiO2, while ferroelectricity was barely observable for Pt/(Hf0.5Zr0.5)O2/Pt/TiO2/SiO2/CaF2. This result suggests that the in-plane tensile strain effectively enhanced the ferroelectricity of the (Hf0.5Zr0.5)O2 thin films.

Original languageEnglish
Article number262904
JournalApplied Physics Letters
Volume108
Issue number26
DOIs
Publication statusPublished - 2016 Jun 27

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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    Shiraishi, T., Katayama, K., Yokouchi, T., Shimizu, T., Oikawa, T., Sakata, O., Uchida, H., Imai, Y., Kiguchi, T., Konno, T., & Funakubo, H. (2016). Impact of mechanical stress on ferroelectricity in (Hf0.5Zr0.5)O2 thin films. Applied Physics Letters, 108(26), [262904]. https://doi.org/10.1063/1.4954942