| Abstrakt: |
Perovskite BaTiO3 has been widely studied and utilized in various applications owing to its high permittivity, ferroelectricity, and stability. However, its low ferroelectric-paraelectric phase transition temperature (TC, 120 °C) limits its application. The TC can be increased by applying an epitaxial strain provided by a latticemismatched substrate. However, applying large tensile strain on BaTiO3 is difficult, especially when a bottom electrode is present. In this study, we successfully fabricated large tensile-strained BaTiO3 films using La-doped BaSnO3 bottom electrodes. A tensile strain of 2% was achieved, which is three times larger than that previously reported for BaTiO3 films grown on bottom electrodes. By adjusting the thickness of the BaTiO3 layer between 20 and 300 nm, tensile strain can be varied within the range of 0.6-2%. Remarkably, the TC of the obtained films exceeds 400 °C. In addition, although it was considered that tensile-strained BaTiO3 films have ferroelectric polarization in the in-plane direction, the 0.6% tensilestrained film showed ferroelectric polarization in the out-of-plane direction. This finding reveals that the ferroelectric polarization direction was slightly tilted away from the predominant in-plane direction of the film. [ABSTRACT FROM AUTHOR] |
