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首页> 外文学位 >Textured ferroelectric thin films: Synthesis, characterization, and influence of compositional grading on the dielectic behavior.
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Textured ferroelectric thin films: Synthesis, characterization, and influence of compositional grading on the dielectic behavior.

机译：织构铁电薄膜：合成，表征以及成分分级对介电行为的影响。

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摘要

This dissertation focuses on two topics concerning the connections between structure and property in ferroelectric thin films. First, the synthesis of highly oriented ferroelectric thin films is addressed, where the texture is needed to generate high strains that rely on electromechanical domain switching. The ferroelectric films are integrated with oxide electrodes onto single crystal MgO and Si substrates using biaxially-textured MgO as buffer layers. The second topic focuses on modeling the dielectric behavior of compositionally graded ferroelectrics.; The functional ferroelectric PbxBa1- xTiO3 films are deposited by metalorganic chemical vapor deposition (MOCVD). SrRuO3, grown by pulsed laser deposition (PLD), is a lattice-matching electrode. Both the ferroelectric and oxide electrode layers are found to inherit the biaxial texture of the underlying MgO template, which can be deposited by ion beam assisted deposition (IBAD) directly on Si-based substrates. In addition, we demonstrated control of the ferroelectric film stoichiometry using a spectroscopic control loop that monitors the ultraviolet spectra of the gas-phase MOCVD precursors during growth. Detailed studies of the microstructural details of these films will be presented.; The second topic of this thesis explores the dielectric behavior of functionally graded ferroelectric thin films. Homogenous ferroelectrics offer the possibility of engineering a tunable dielectric response for components in microwave circuits. However, this approach often leads to an undesired temperature sensitivity. Compositionally-graded BaxSr1- xTO3 ferroelectric films have been explored as a means of redressing this sensitivity, but experimental observations vary depending on geometry and other details. A continuum model is presented to calculate the capacitive response of graded ferroelectric films with realistic electrode geometries by accurately accounting for the polarization distribution and long-range electrostatic interactions. We show preferred designs that are extremely effective in obtaining high and temperature-stable dielectric properties.
机译：本文主要研究铁电薄膜的结构与性能之间的联系。首先，解决了高取向铁电薄膜的合成问题，其中需要纹理来生成依赖于机电域切换的高应变。使用双轴纹理化的MgO作为缓冲层，将铁电薄膜与氧化物电极集成到单晶MgO和Si衬底上。第二个主题集中于对成分渐变铁电体的介电行为进行建模。通过金属有机化学气相沉积（MOCVD）沉积功能性铁电PbxBa1-xTiO3膜。通过脉冲激光沉积（PLD）生长的SrRuO3是晶格匹配电极。发现铁电和氧化物电极层都继承了下面的MgO模板的双轴织构，可以通过离子束辅助沉积（IBAD）将其直接沉积在Si基衬底上。另外，我们展示了使用光谱控制环对铁电薄膜化学计量的控制，该控制环在生长过程中监测气相MOCVD前体的紫外光谱。将介绍这些薄膜的微观结构细节的详细研究。本文的第二个主题探讨了功能梯度铁电薄膜的介电性能。均质铁电体提供了对微波电路中的组件进行可调介电响应的可能性。但是，这种方法经常导致不希望的温度敏感性。人们已经探索了成分分级的BaxSr1-xTO3铁电薄膜作为纠正这种灵敏度的一种方法，但是实验观察结果随几何形状和其他细节而变化。提出了一个连续模型，通过精确考虑极化分布和远距离静电相互作用，计算出具有实际电极几何形状的梯度铁电薄膜的电容响应。我们展示了在获得高且温度稳定的介电特性方面极为有效的首选设计。

著录项

  • 作者

    El-Naggar, Mohamed Y.;

  • 作者单位

    California Institute of Technology.;

  • 授予单位 California Institute of Technology.;
  • 学科 Engineering Mechanical.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 113 p.
  • 总页数 113
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;工程材料学;
  • 关键词

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