Dynamic Response of Epitaxial Ferroelectric Thin Films

非技术描述：铁电薄膜在超快光通信系统和非易失性半导体存储器中有应用。 这些系统的未来应用将需要在皮秒时间制度的偏振开关动态的理解。 作为该计划的一部分，将开发一种装置来测量皮秒时间范围内的畴切换动力学。 这项工作将扩展我们对超快时间尺度下材料相变的理解。 这项研究将涉及在铁电氧化物合成、动力学过程的超快光学测量和模型开发领域对本科生和研究生进行培训。PI和研究生将参与K-12年级材料相变和复杂现象的教育模块的开发。技术要求：将在皮秒时间范围内研究BaTiO 3和KNbO 3外延铁电（FE）薄膜中畴的转变动力学。外延铁电薄膜的制备方法有金属有机物气相外延和分子束外延。 极化开关动力学将从电光效应的时间依赖性确定，这取决于铁电畴体积分数。 测量和分析失配应变、电场和温度对开关动力学的影响。静态域结构将使用透射电子显微镜、近场扫描光学显微镜和X射线衍射来确定。 动力学将分析相对于最近开发的多畴膜的动力学模型。本文将研究普适介电响应理论对铁电薄膜高频动力学的适用性。

NON-TECHNICAL DESCRIPTION:Ferroelectric thin films have applications in ultrafast optical communication systems and non-volatile semiconductor memories. Future applications of these systems will require an understanding of the polarization switching dynamics in the picosecond time regime. As part of the program an apparatus will be developed to measure the kinetics of domain switching in the picosecond time regime. This work should extend our understanding of phase transformations of materials at ultrafast time scales. The research will involve the training of undergraduate and graduate students in the area of ferroelectric oxide synthesis, ultrafast optical measurements of kinetic processes and model development. The PI and graduate students will be involved in the development of an educational module on material phase transformations and complex phenomena for grades K-12.TECHNICAL DETAILS: The transformation kinetics of domains in epitaxial ferroelectric (FE) thin films of BaTiO3 and KNbO3 will be investigated in the picosecond time regime. Epitaxial FE films will be prepared by metalorganic vapor phase epitaxy and molecular beam epitaxy. The polarization switching kinetics will be determined from the temporal dependence of the electro-optic effect, which depends on the ferroelectric domain volume fraction. The effect of mismatch strain, electric field and temperature on the switching kinetics will be measured and analyzed. The static domain structure will be determined using transmission electron microscopy, near-field scanning optical microscopy and x-ray diffraction. The kinetics will be analyzed with respect to the recently developed dynamic model for multidomain films. The applicability of the universal dielectric response theory to the dynamics of ferroelectric films at high frequencies will be investigated.