Morphology and Chemsitry of Lateral Composition Modulations

这个项目的目的是扩大对III-V半导体合金系统中成分同质形成的理解。该方法利用多种实验方法来检验合金层的(非)均匀性和多层膜的横向成分调制。研究的一个中心工具是一个MBE-STM组合小室，用于研究合金层中团簇的原子尺度结构和多层膜中的横向成分调制。这些信息将反馈到增长过程中，并允许完善相分离区域的组合。具体目标是：定量地了解InGaAs的表面重构、应变和局部合金成分之间的关系；从实验上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；从经验上建立利用图案化衬底可以实现的自组装程度。这项研究有望对III-V化合物半导体材料系统中合金形成和成分不均匀的来源产生重要的物理影响。结果将被应用于消除器件层中的成分不一致性。此外，这项研究还为设计半导体薄膜的成分变化和开发其纳米尺度结构所产生的新特性，如低阈值激光器奠定了基础。该项目涉及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结合。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(包括主要来自本科生机构(密歇根大学弗林特分校)的研究人员)所有级别的科学掌握的教学、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。它已经建立了包括女性、非裔美国人和西班牙裔美国人在内的代表性不足群体的成员的记录。私人投资机构将继续寻求多元化，以建立他们的研究团队。

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.***