CAREER: Dislocation Mechanics in Strained Heteroepitaxial Layer Structures

摘要为了了解应变异质外延层结构中的位错行为，发展基于机理的多尺度建模和模拟是半导体工业发展高速微电子学的核心问题。离散位错的形核、运动和相互作用将通过在Peierls-Nabarro框架下的变分边界积分方法中结合原子信息来研究。通过求解胚胎鞍点位错组态及其相关的热激活能，可以确定理想表面位错成核的临界条件，以及由台阶、缺陷、微裂纹和量子点等表面异质性形成位错的临界条件。短程位错相互作用和晶格阻力对位错运动的影响也将被评估。通过将已获得的位错成核、相互作用和运动机制纳入与劳伦斯利弗莫尔国家实验室合作开发的有限元增强位错动力学模拟中，将研究位错的集体行为。重点将放在应变异质外延层结构中螺纹位错密度降低和位错图案形成的基本机制上。建议的教育计划包括开发新的实验室和课程，强调小规模的力学和材料以及加州大学河滨分校的跨学科教育。将加大力度，提高本科生对理工科的兴趣。目标是开发一流的新的力学和材料教育计划，以满足未来纳米科学和工程的需求。拟议的教育和研究计划相互结合，相辅相成。

AbstractThe proposed research is to develop mechanism-based multiscale modeling and simulation to understand dislocation behavior in strained heteroepitaxial layer structures, which has been of central interest in developing high-speed microelectronics in the semiconductor industry. Discrete dislocation nucleation, motion, and interaction will be studied by incorporating atomistic information into a variational boundary integral method in the Peierls-Nabarro framework. Critical conditions for dislocation nucleation from the perfect surface and surface heterogeneities such as ledges, defects, microcracks, and quantum dots will be determined by solving the embryonic saddle-point dislocation configurations and their associated thermal activation energies. Short-range dislocation interactions and the effect of lattice resistance to dislocation motion will be evaluated as well. Collective behavior of dislocations will be investigated by incorporating the obtained mechanisms of dislocation nucleation, interaction, and motion into a finite element enhanced dislocation dynamics simulation, which has been developed in collaboration with the Lawrence Livermore National Laboratory. The emphasis will be placed on fundamental mechanisms of threading dislocation density reduction and dislocation pattern formation in strained heteroexpitaxial layer structures.The proposed education plan consists of the development of the new laboratory and curriculum that emphasize mechanics and materials at the small scale and interdisciplinary education at UC Riverside. Extra efforts will be made to enhance undergraduate students' interest in science and engineering. The objective is to develop a first-rate new mechanics and materials education program that meets the future demands of nanoscale science and engineering. The proposed education and research plans are integrated to reinforce each other.