Cooperative kinetics of defects and domain structures in ferroelectrics

铁电体中缺陷和畴结构的协同动力学

• 批准号: 405631895
• 负责人: Professor Dr. Yuri A. Genenko
• 金额: --
• 依托单位: Institute of Physics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/405631895?language=en
• 关键词: Cooperative; kinetics; defects; domain; structures

The general objective of the project is to establish the main features of the formation and cooperative evolution of domain structures in ferroelectrics in the presence of mobile – ionic or electronic – charge carriers in bulk or at the surface. Specifically, we will (a) develop a self-consistent description of domain structure evolution driven by the kinetics of charged defects (oxygen vacancies, ions, etc); (b) devise a theory of cooperative phenomena driven by electro-neutral elastic defects in ferroelectrics; (c) establish the impact of nonlinear surface screening on the spontaneous polarization reversal; and (d) elaborate a self-consistent description of domain structure kinetics in ferroelectric structures with 2D-semiconducting electrodes.The proposed methodology will use 3D finite element modeling and analytical calculations in the framework of the Landau-Ginzburg-Devonshire approach including, beyond polarization and electric field, chemical strain, piezoelectric, electrostrictive and flexoelectric coupling. Theoretical predictions will be verified by comparison with observed phenomena and specially designed measurements of electro-physical, polar and dielectric hysteresis properties in a wide temperature range, X-ray and spectroscopic characterization of generic ferroelectrics (Pb,Zr)TiO3, BaTiO3, BiFeO3, (Cu,In)P2(S,Se)6 and Sn2P2(S,Se)6 with intrinsic or introduced point defects.The combined methodologies will allow us to establish the influence of bulk and surface defects and related screening phenomena on the cooperative domain structure kinetics and polarization reversal mechanisms in ferroelectric thin films. Moreover, we will analyze the hysteresis loops of ferroelectric polarization, space and surface charge distributions, as well as relaxation dynamics of corresponding domain and charge states. Analytical and numerical calculations will be performed for generic models describing charged and electro-neutral elastic defects, bulk screening by free carriers (electrons and holes, as well as ionic transport) and nonlinear surface screening by e.g. Bardeen surface states, Fermi-Dirac 2D-electron gas or Stephenson-Highland absorbed ions and vacancies. As a result the regions of single- and poly-domain ferroelectric, mixed and non-ferroelectric states will be delineated as a function of defect concentration, formation energy and ionization degree, film thickness, applied voltage and temperature. We further will establish the interaction between domain structure and the charge transport in ferroelectrics with 2D-semiconducting electrodes. The proposed approach will allow us exploring the general features, specifics of switching kinetics and domain evolution in various ferroelectric films with bulk and surface defects, and open opportunities to use ferroelectric films in next generation field effect transistors, modulators, memory elements, electrical transducers and piezo-resistive elements.

该项目的总体目标是建立铁电体中存在体中或表面的移动的离子或电子电荷载流子时畴结构的形成和合作演化的主要特征。具体来说，我们将（a）发展一个自洽的描述域结构的演变驱动的动力学的带电缺陷（B）提出了铁电体中电中性弹性缺陷驱动的协同现象理论，（c）建立了非线性表面屏蔽对自发极化反转的影响，（d）建立了非线性表面屏蔽对自发极化反转的影响模型，（e）建立了非线性表面屏蔽对自发极化反转的影响模型。以及（d）阐述具有二维半导体电极的铁电结构中的畴结构动力学的自洽描述。所提出的方法将在Landau-Ginzburg-Devonshire方法的框架内使用三维有限元建模和分析计算，包括，超越极化和电场、化学应变、压电、电致伸缩和挠曲电耦合。理论预测将通过与观察到的现象和专门设计的在宽温度范围内的电物理、极性和介电滞后特性的测量、一般铁电体（Pb，Zr）TiO 3、BaTiO 3、BiFeO 3、（Cu，In）P2（S，Se）6和Sn 2 P2（S，Se）结合的方法将使我们能够建立体缺陷和表面缺陷以及相关的屏蔽现象对协同畴结构动力学和极化反转机制的影响在铁电薄膜中。此外，我们将分析铁电极化的磁滞回线，空间和表面电荷分布，以及相应的域和电荷态的弛豫动力学。分析和数值计算将进行通用模型描述带电和电中性的弹性缺陷，散装屏蔽自由载流子（电子和空穴，以及离子传输）和非线性表面屏蔽，如Barclay表面状态，费米-狄拉克二维电子气或斯蒂芬森-高地吸收离子和空缺。因此，单畴和多畴铁电、混合和非铁电状态的区域将被描绘为缺陷浓度、形成能和电离度、膜厚度、施加电压和温度的函数。我们将进一步建立二维半导体电极铁电体中畴结构与电荷输运之间的相互作用。所提出的方法将使我们能够探索的一般功能，具体的开关动力学和域的演变，在各种铁电薄膜的体积和表面缺陷，并打开机会，使用铁电薄膜在下一代场效应晶体管，调制器，存储元件，电换能器和压阻元件。