Exploring the Impact of Sr(Zr,Ti)O₃ Buffer Layers for Controlling Domain Structure of Ferroelectric Thin Films.

In recent years, ferroelectrics have been used as important components in many devices such as nonvolatile memory, sensors, and energy harvesters. This study focuses on ferroelectric thin films with domain structures affected by the strain induced from the substrate. It is known that the misfit strain caused by the difference in lattice constants between the substrate and ferroelectric thin film is important in controlling the stress in epitaxial thin films. However, there are limits to the range of lattice constants that can be achieved with single-crystal substrates. In this study, Sr(Zr,Ti)O₃ solid solution (SZTO), which has cubic-like structure and a wide lattice parameter selection range of 0.39~0.41 nm, was employed as a new buffer layer to overcome this problem.^[1] It can be expected to change the lattice constant continuously and control the amount of strain precisely by using SZTO with various compositions as a buffer layer. We prepared SZTO buffer layers on (100) LSAT substrates and Pb(Zr,Ti)O₃ (PZT) films on them by pulsed laser deposition (PLD).<br/>XRD 2<i>θ</i>-<i>θ</i> measurement results indicated that buffer layer lattice parameters could be effectively manipulated by altering Zr content of SZTO. This study reveals a strong dependence of crystal structure and thickness in SZTO films with different composition, and the domain structure of PZT films is found to be significantly influenced by the lattice constant of the buffer layer. These findings underline the potential of SZTO in controlling lattice constants and strain in ferroelectric thin films.