Microstructural Analysis and Electrical Property Studies on BaxSr1-xTiO3 Ferroelectric Thin Films

9711044 McKittrick高品质铁电薄膜的发展是实现动态随机存取存储器（DRAM）设备上的千兆位存储容量的主要挑战之一。 体铁电体，如钛酸钡是很好的特点;然而，薄膜的铁电性能没有理解在一个基本的，甚至技术水平。 微观结构特征，如晶粒尺寸，晶粒取向（多晶与外延），化学计量，膜的厚度，残余应力，掺杂剂浓度和表面粗糙度尚未进行系统的研究或表征。 为了使用铁电薄膜，它们必须夹在导电电极之间。 已发现这些电极是电流泄漏的来源，增加了疲劳和老化损伤。 为了充分利用优化的薄膜结构，对电极的基本理解也是必要的。 这个为期两年的提案旨在系统地研究用于兆字节DRAM应用的顺电TiO_3_xTiO_3的微结构-电性能依赖性。 这项工作有四个目标：（A）优化用于沉积铁电膜的导电氧化物电极，（B）量化化学计量、晶粒尺寸、厚度和残余应力在薄膜铁电体中的作用并优化电性能，（C）研究将施主掺杂剂添加到Sr 1-xTiO 3中的效果，目的是改善电性能，以及（D）制备BaTiO 3和SrTiO 3的超晶格结构，并将微结构特征与电学性质相关联。 这项工作将在加州大学圣地亚哥分校和墨西哥恩塞纳达物理研究所进行，这两个机构的设施不同但互补。 ***

9711044 McKittrick The development of high quality ferroelectric thin films is one of the main challenges to achieving giga-bit storage capacity on dynamic random access memory (DRAM) devices. Bulk ferroelectrics such as BaTiO3 are well characterized; however, the ferroelectric properties of thin films are not understood at a fundamental or even technical level. The microstructural features such as grain size, grain orientation (polycrystalline vs. epitaxial), stoichiometry, thickness of the film, residual stress, dopant concentrations and surface roughness have not been systematically studied or characterized. In order to use ferroelectric thin films, they must be sandwiched between conductive electrodes. These electrodes have been found to be the source of current leakage, increasing fatigue and aging damage. To fully exploit the optimized thin film structures, a basic understanding of the electrode is also necessary. This two year proposal seeks to systematically investigate the microstructure-electrical property dependence of paraelectric BaxS l-xTiO3, for megabyte DRAM applications. The objectives of this work are fourfold: (A) to optimize a conductive oxide electrode for the deposition of the ferroelectfic films, (B) to quantify the role of stoichiometry, grain size, thickness, and residual stress in thin film ferroelectrics and optimize the electrical properties, (C) investigate the effect of adding donor dopants to BaxSrl-xTiO3 with the goal of improving the electrical properties and (D) to fabricate superlattice structures of BaTiO3 and SrTiO3 and correlate the microstructural features with the electrical properties. This work will be performed at UC-San Diego and the Institute of Physics in Ensenada, Mexico which have different but complementary facilities. ***