Morphology and Chemsitry of Lateral Composition Modulations

该项目的目标是扩大对III-V型半导体合金体系中成分不均匀性的理解。该方法利用许多实验方法来检查合金层的（非）均匀性和多层中的横向成分调制。该研究的核心工具是MBE-STM组合腔室，用于检查合金层中聚类的原子尺度结构和多层中的横向成分调制。这些信息将反馈到生长过程中，并允许完善相分离区域的组装。具体目标是：对InGaAs的表面重构、应变和局部合金成分之间的联系进行定量理解；通过实验确定自发横向成分调制的启动机制及其与表面特征和合金成分局部变化的关系；在InGaSbAs合金中形成自组装阵列；以经验建立自组装的程度，可以实现使用图案化的基板。该研究有望对III-V型化合物半导体材料体系中合金形成和成分不均匀性起源的基本物理认识产生重大影响。结果将用于消除器件层内的成分不均匀性。此外，该研究为设计半导体薄膜的成分变化和利用其纳米尺度结构（如低阈值激光器）所产生的新特性奠定了基础。该项目致力于与具有技术相关性的电子/光子材料相关的基础研究问题，并强调研究与教育的整合。该项目促进了从博士后研究人员到研究生、非传统本科生和中学女生（包括主要本科院校（密歇根大学弗林特分校）的研究人员）的各级科学精通的教学、培训和学习。该项目还将改善密歇根州的研究和教育基础设施。在吸纳女性、非洲裔美国人和西班牙裔美国人等代表性不足的群体成员方面，它已经建立了良好的记录。pi将继续寻求多元化的研究团队建设

The objective of this project is to extend understanding of the initiation of compositional inho-mogeneities in III-V semiconductor alloy systems. The approach utilizes a number of experimen-tal methods to examine the (non)homogeneity of alloy layers and lateral composition modulation in multilayers. A tool central to the investigation is a combined MBE-STM chamber to examine the atomic scale structure of clustering in alloy layers and lateral composition modulation in mul-tilayers. This information will feedback into the growth process and allow perfecting the assem-bly of the phase-separated regions. Specific goals are: To develop a quantitative understanding of the connections between surface reconstruction, strain, and local alloy composition for InGaAs; To determine experimentally the initiation mechanisms of spontaneous lateral composition modulation and how it relates to surface features and the local variations in alloy composition; To form self assembled arrays in InGaSbAs alloys; To establish empirically the degree of self-assembly that can be achieved using patterned substrates.The research is expected to have significant impact on basic physical understanding of alloy for-mation and origins of compositional inhomogeneities in III-V compound semiconductor material systems. The results will be applied to eliminate compositional nonuniformities within device layers. Additionally, the research forms the basis to design compositional variations in semicon-ductor thin films and exploit the novel properties arising from their nanometer-size scale struc-ture, such as low threshold lasers. %%% The project addresses fundamental research issues associated with electronic/photonic materials having technological relevance and emphasizes the integration of research and education. The project promotes teaching, training, and learning of all levels of scientific mastery, from post Ph.D. researchers, to graduate students, nontraditional undergraduates, and middle-school girls, including researchers from Primarily Undergraduate Institutions (University of Michigan-Flint). The project will also improve the research and education infrastructure in Michigan. It has al-ready established a track record for including members from underrepresented groups, including women, African Americans, and Hispanics. The PIs will continue to seek diversity in building their research team.***