Ferroelectricity mediated by ferroelastic domain switching in HfO2-based epitaxial thin films

Takao Shimizu, Takanori Mimura, Takanori Kiguchi, Takahisa Shiraishi, Toyohiko Konno, Yoshio Katsuya, Osami Sakata, Hiroshi Funakubo

Research output: Contribution to journalArticlepeer-review

60 Citations (Scopus)


Herein, ferroelastic domain switching from the nonpolar b-axis to the polar c-axis oriented domain in 7%-YO1.5-substituted HfO2 (YHO-7) epitaxial ferroelectric films is demonstrated. Scanning transmission electron microscopy (STEM) indicates that the polarization of a pristine film deposited on a Sn-doped In2O3/(001)YSZ substrate by the pulsed laser deposition method tends to be along the in-plane direction to avoid a strong depolarization field with respect to the out-of-plane direction. Applying an electric field aids in ferroelastic domain switching in YHO-7 films. Such films exhibit ferroelectric characteristics with a relatively large saturated polarization around 30 μC/cm2 by polarization reorientation from the in-plane to the out-of-plane directions and an increased dielectric constant. The synchrotron X-ray diffraction measurements with a focused beam for the pristine and poled area indicate ferroelastic 90° domain switching as the odd number reflection disappears, which is only allowed in the nonpolar b-axis orientation. STEM observations also show a significant increase in the c-axis oriented domain. This observation of ferroelastic domain switching strongly supports the conclusion that the ferroelectricity of HfO2 originates from the non-centrosymmetric orthorhombic phase.

Original languageEnglish
Article number212901
JournalApplied Physics Letters
Issue number21
Publication statusPublished - 2018 Nov 19


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