Film thickness dependence of ferroelectric properties in polar-axis-oriented epitaxial tetragonal (Bi,K)TiO3 films prepared by hydrothermal method
Film thickness dependence of ferroelectric properties in polar-axis-oriented epitaxial tetragonal (Bi,K)TiO3 films prepared by hydrothermal method
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水热法制备的极轴取向外延四方(Bi,K)TiO3薄膜中铁电性能的膜厚依赖性
DOI：
10.1063/5.0084170
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发表时间：
2022-03
期刊：
影响因子：
1.6
通讯作者：
Rurika Kubota;Akinori Tateyama;T. Shiraishi;Yoshiharu Ito;M. Kurosawa;H. Funakubo
中科院分区：
文献类型：
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作者：
Rurika Kubota;Akinori Tateyama;T. Shiraishi;Yoshiharu Ito;M. Kurosawa;H. Funakubo
采用水热法在（100）cSrRuO 3//（100）SrTiO 3衬底上生长了四方（00 l）取向的（Bi，K）TiO 3外延薄膜。以KOH水溶液、Bi（NO3）3 ·5 H2O和TiO 2粉体为原料，采用XRD、SEM、SEM等方法对样品进行了表征。通过改变沉积时间将膜厚度控制在33至1200 nm，并且对于所有膜厚度，钙钛矿ABO 3的A位中的Bi/（Bi+K）比几乎是恒定的。在所有厚度范围内，获得了极轴（00 l）取向的外延（Bi，K）TiO 3薄膜，而没有第二相和/或其他取向。对于厚度低至33 nm的（Bi，K）TiO 3薄膜，观察到约84 µC/cm 2的反射极化（Pr）的大铁电性，与先前报道的铅基铁电薄膜相当。另一方面，Ec随着膜厚度的减小而增加，但不像其他钙钛矿铁电膜那样表现出强烈的膜厚度依赖性。这些数据对于理解铁电薄膜的退化机理是非常有用的。
Tetragonal (00l)-oriented epitaxial (Bi,K)TiO3 films were grown at 240 °C on (100) cSrRuO3//(100)SrTiO3 substrates by the hydrothermal method. KOH aqueous solutions and Bi(NO3)3 · 5H2O and TiO2 powders were used as the starting materials. Film thickness was controlled from 33 to 1200 nm by changing the deposition time, and the Bi/(Bi+K) ratio in the A-site of perovskite ABO3 was almost constant for all film thicknesses. Polar-axis (00l)-oriented epitaxial (Bi,K)TiO3 films were obtained without a secondary phase and/or other orientation for all thickness ranges. Large ferroelectricity with the remanent polarization ( Pr) of about 84 µC/cm2, comparable to previously reported lead-based ferroelectric films, was observed for (Bi,K)TiO3 films down to 33 nm in thickness. On the other hand, Ec increased with decreasing film thickness, but did not show strong film thickness dependence like other perovskite ferroelectric films. These data are very useful for understanding the degradation mechanism of ferroelectric thin films.