Denis-Rotella Lyndsey M, Esteves Giovanni, Walker Julian, Zhou Hanhan, Jones Jacob L, Trolier-McKinstry Susan
IEEE Trans Ultrason Ferroelectr Freq Control. 2021 Feb;68(2):259-272. doi: 10.1109/TUFFC.2020.2987438. Epub 2021 Jan 26.
Ferroelectric films are often constrained by their substrates and subject to scaling effects, including suppressed dielectric permittivity. In this work, the thickness dependence of intrinsic and extrinsic contributions to the dielectric properties was elucidated. A novel approach to quantitatively deconstruct the relative permittivity into three contributions (intrinsic, reversible extrinsic, and irreversible extrinsic) was developed using a combination of X-ray diffraction (XRD) and Rayleigh analysis. In situ synchrotron XRD was used to understand the influence of residual stress and substrate clamping on the domain state, ferroelastic domain reorientation, and electric field-induced strain. For tetragonal {001} textured Pb(ZrTi)NbO thin films clamped to an Si substrate, a thickness-dependent in-plane tensile stress developed during processing, which dictates the domain distribution over a thickness range of 0.27- [Formula: see text]. However, after the films were partially declamped from the substrate and annealed, the residual stress was alleviated. As a result, the thickness dependence of the volume fraction of c -domains largely disappeared, and the out-of-plane lattice spacings ( d ) for both a - and c -domains increased. The volume fraction of c -domains was used to calculate the intrinsic relative permittivity. The reversible Rayleigh coefficient was then used to separate the intrinsic and reversible extrinsic contributions. The reversible extrinsic response accounted for ~50% of the overall relative permittivity (measured at 50 Hz and alternating current (ac) field of 0.5·E ) and was thickness dependent even after poling and upon release.
铁电薄膜常常受到其衬底的限制，并受到包括介电常数抑制在内的尺寸效应的影响。在这项工作中，阐明了本征和非本征对介电性能贡献的厚度依赖性。利用X射线衍射（XRD）和瑞利分析相结合的方法，开发了一种将相对介电常数定量解构为三种贡献（本征、可逆非本征和不可逆非本征）的新方法。利用原位同步辐射XRD来理解残余应力和衬底夹持对畴态、铁弹畴重取向和电场诱导应变的影响。对于夹在Si衬底上的四方{001}织构的Pb(ZrTi)NbO薄膜，在加工过程中会产生与厚度相关的面内拉伸应力，该应力决定了在0.27 - [公式：见原文]厚度范围内的畴分布。然而，在薄膜从衬底上部分松开并退火后，残余应力得到缓解。结果，c畴体积分数的厚度依赖性基本消失，a畴和c畴的面外晶格间距（d）均增大。利用c畴的体积分数来计算本征相对介电常数。然后使用可逆瑞利系数来分离本征和可逆非本征贡献。可逆非本征响应占总相对介电常数（在50 Hz和0.5·E的交流（ac）场下测量）的~50%，并且即使在极化和释放后仍与厚度有关。
