POWRE: Role of Temperature and Morphology in the Nucleation of Misfit Dislocations in Heteroepitaxial Films

该项目的目标是加强对异质外延半导体薄膜中缺陷的了解。异质外延的一个基本问题是晶格失配引起的弹性应变随外延膜厚度的增加而松弛。应变松弛要么通过失配位错的形核，要么通过表面的形态变化，或者两者的结合。在理解温度和表面形态如何影响外延薄膜中失配位错的形核方面，仍有很大的差距。缩小这一差距是拟议研究的中心重点。提出了异质外延薄膜中失配位错成核的一种新的“温度相关”机制。它导致在一定温度以上的给定厚度的平面外延膜中许多失配位错的协同形核，而没有任何能垒。提出的研究重点是失配错位成核过程如何受到形态变化的影响。正在使用的分析方法能够预测应变松弛作为温度、生长速度、失配和形态的函数。%这是根据妇女研究和教育职业机会(POWRE)计划提供的一项研究增强拨款。这位研究人员正处于她职业生涯的关键阶段，正在从研究专家过渡到研究副教授的职位。POWRE奖将使PI能够开始一个新的研究领域，在技术上取得巨大成就。为期18个月的时间将提供一个机会来调查和测试一种新的方法的适用性，该方法是为了理解杂化外延中的一个悬而未决的问题而提出的。这项研究有望在与电子材料的行为特别相关的基础水平上贡献基本的材料科学知识。该项目由材料研究司和MPS OMA(多学科活动办公室)共同支持。***

The goal of this project is to enhance understanding of defects in heteroepitaxial semiconductor thin films. A fundamental issue in heteroepitaxy is the relaxation of the elastic strain induced by lattice mismatch with increasing thickness of the epitaxial film. Strain relaxation occurs either by nucleation of misfit dislocations or by morphological transformations of the surface, or a combi-nation of both. There remains a wide gap in understanding how temperature and surface mor-phology affect the nucleation of misfit dislocations in epitaxial films. Closing this gap is the cen-tral focus of the proposed research. A new 'temperature-dependent' mechanism for the nucleation of misfit dislocations in heteroepitaxial films is proposed. It leads to a cooperative nucleation of many misfit dislocations in a planar epitaxial film of a given thickness above a certain tempera-ture without any energy barrier. The proposed research focuses on how the process of misfit dis-location nucleation is influenced by changes in morphology. The analytical approach being pur-sued enables prediction of strain relaxation as a function of temperature, growth rate, misfit and morphology.%%% This is a research enhancement grant made under the Professional Opportunities for Women in Research and Education (POWRE) program. The investigator is at a critical stage of her career making a transition from a Research Specialist to the position of a Research Associate Professor. The POWRE award will enable the PI to begin a new area of research with promising ramifica-tions in technology. A duration of eighteen months will provide an opportunity to investigate and test the applicability of a novel approach advanced for understanding an outstanding issue in het-eroepitaxy. The research is expected to contribute basic materials science knowledge at a funda-mental level of special relevance to the behavior of electronic materials. The project is co-supported by the Division of Materials Research, and the MPS OMA(Office of Multidisciplinary Activities). ***