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基底上金属薄膜中的位错行为。该程序的主要目标是模拟边界和界面附近位错集合的中尺度行为，以便与使用衬底曲率和x射线方法测量的整体力学行为进行比较。该程序既包括“自下而上”的研究，其中检查了相互作用的位错对所采用的配置和这些相互作用的强度，也包括“自上而下”的研究，其中模拟了许多位错的行为以寻找控制机制。这种实验和模型的结合有望为导致薄膜非块状行为的机制提供直接证据。本工作的目的是详细研究导致金属薄膜中高应力和非块状行为的位错机制。这种薄膜是广泛的纳米制造器件中不可缺少的元素，但通常会受到非常高的应力，这可能导致变形、空洞形成或断裂。薄膜的力学行为与块状材料的力学行为不同，目前还没有得到很好的理解。在这个项目中，位错动力学模拟将进行，以研究薄膜的尺寸约束如何影响位错行为和力学性能。在模拟中看到的位错构型将与用透射电子显微镜观察到的实验结果进行比较。这种实验和建模的独特结合将更好地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推广工作，并将让本科生参与研究。

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.