CAREER: Dislocation Mechanics in Strained Heteroepitaxial Layer Structures

AbstractThe拟议的研究是开发基于机制的多尺度建模和模拟，以了解应变异质外延层结构中的位错行为，这一直是在半导体工业中发展高速微电子学的核心兴趣。离散位错的形核，运动和相互作用将通过将原子的信息到一个变分边界积分方法Peierls-Nabarro框架进行研究。从完美的表面和表面异质性，如凸台，缺陷，微裂纹，和量子点的位错成核的临界条件将通过解决胚胎鞍点位错配置和它们相关的热激活能来确定。短程位错相互作用和晶格电阻对位错运动的影响也将被评估。位错的集体行为将通过将所获得的位错成核，相互作用和运动的机制纳入有限元增强位错动力学模拟，这是与劳伦斯利弗莫尔国家实验室合作开发的。重点将放在应变异质外延层结构中的穿线位错密度降低和位错图案形成的基本机制上。拟议的教育计划包括新实验室和课程的发展，强调在加州大学滨江的小规模和跨学科教育的力学和材料。我们会加倍努力，提高本科生对理工科的兴趣。我们的目标是开发一个一流的新的力学和材料教育计划，以满足纳米科学和工程的未来需求。拟议的教育和研究计划是一体化的，相互加强。

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.