Ferroelectricity mediated by ferroelastic domain switching in HfO2-based epitaxial thin films
Ferroelectricity mediated by ferroelastic domain switching in HfO2-based epitaxial thin films
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DOI：
10.1063/1.5055258
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发表时间：
2018-11
影响因子：
4
通讯作者：
Takao Shimizu;T. Mimura;T. Kiguchi;T. Shiraishi;T. Konno;Y. Katsuya;O. Sakata;H. Funakubo
中科院分区：
文献类型：
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作者：
Takao Shimizu;T. Mimura;T. Kiguchi;T. Shiraishi;T. Konno;Y. Katsuya;O. Sakata;H. Funakubo
在此，铁弹畴切换从非极性的b轴到极性的c轴取向的畴在7%-YO 1.5取代的HfO 2（YHO-7）外延铁电薄膜被证明。扫描透射电子显微镜（STEM）结果表明，采用脉冲激光沉积方法在掺Sn的In 2 O 3/（001）YSZ衬底上沉积的原始薄膜的极化倾向于沿着面内方向，从而避免了相对于面外方向的强退极化场。施加电场有助于YHO-7薄膜中的铁弹畴变。这种薄膜表现出铁电特性，通过从面内到面外方向的极化重取向，具有相对大的饱和极化（约30 μC/cm 2）和增加的介电常数。用聚焦光束对原始和极化区域进行的同步加速器X射线衍射测量表明，随着奇数反射消失，铁弹90°畴变，这仅在非极性b轴取向中允许。STEM观察还显示c轴定向域的显著增加。这一铁弹畴变的观测结果有力地支持了HfO 2的铁电性起源于非中心对称正交相的结论，并证明了在7%YO 1.5取代的HfO 2（YHO-7）外延铁电薄膜中，铁弹畴从非极性的b轴向向转变为极性的c轴向取向畴。扫描透射电子显微镜（STEM）结果表明，采用脉冲激光沉积方法在掺Sn的In 2 O 3/（001）YSZ衬底上沉积的原始薄膜的极化倾向于沿着面内方向，从而避免了相对于面外方向的强退极化场。施加电场有助于YHO-7薄膜中的铁弹畴变。这种薄膜表现出铁电特性，通过从面内到面外方向的极化重取向，具有相对大的饱和极化（约30 μC/cm 2）和增加的介电常数。同步辐射X射线衍射测量结果表明，在极化区和原始区，由于奇数反射消失，铁弹90°畴变，这只在非极化区才允许。
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.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 non...