Stresses, Deformation, and Dislocations in Thin Films: Combining Modeling and Simulations with Experiments

在这项资助下，位错动力学模拟和透射电子显微镜将用于研究衬底上薄金属膜中位错的行为。该计划的一个主要目标是模拟边界和界面附近的位错合奏的细观尺度的行为与使用基板曲率和X射线方法测量的整体力学行为进行比较。该计划包括一个“自下而上”的研究，其中通过相互作用对位错和这些相互作用的强度所采取的配置进行检查，和一个“自上而下”的研究，其中许多位错的行为进行模拟，以寻找控制机制。这种实验和建模的结合，预计将提供直接的证据机制，导致非散装的行为在薄膜。本工作的目标是详细研究导致金属薄膜中高应力和非块体行为的位错机制。这种薄膜是各种纳米制造器件中不可或缺的元素，但通常会受到非常高的应力，这可能会导致变形、空隙形成或断裂。薄膜的机械行为与体材料不同，目前还没有很好的理解。在这个程序中，位错动力学模拟将进行研究薄膜的尺寸约束如何影响位错行为和机械性能。模拟中看到的位错配置将与使用透射电子显微镜实验观察到的进行比较。这种独特的实验和建模的结合将提供一个更好的理解薄膜金属化的机械行为。该项目将支持以高中教师和学生为重点的外联工作，并将吸引本科生参与研究。

Under this grant, dislocation dynamics simulations and transmission electron microscopy will be used to study the behavior of dislocations in thin metal films on substrates. A major objective of the program is to simulate meso-scale behavior of ensembles of dislocation near boundaries and interfaces for comparison with the overall mechanical behavior measured using substrate curvature and x-ray methods. The program includes both a 'bottom-up' study in which the configurations adopted by interacting pairs of dislocations and the strength of those interactions are examined, and a 'top down' study in which the behavior of many dislocations is simulated to search for controlling mechanisms. This combination of experiments and modeling is expected to provide direct evidence of mechanisms that lead to non-bulk-like behavior in thin films. The goal of this work is to study the dislocation mechanisms that lead to high stresses and non-bulk-like behavior in thin metal films in detail. Such films are indispensable elements in a wide range of nanofabricated devices, but typically suffer from very high stresses, which may lead to failure by deformation, void formation, or fracture.The mechanical behavior of thin films is not like that of bulk materials and is not well understood. In this program, dislocation dynamics simulations will be conducted to study how the dimensional constraints of a thin film affect dislocation behavior and mechanical properties. Dislocation configurations seen in simulations will be compared with those observed experimentally using transmission electron microscopy. This unique combination of experiments and modeling will provide a better understanding of the mechanical behavior of thin film metallizations. The project will support outreach efforts focused on high school teachers and students, and will engage undergraduates in research.