Characterization and Control of Interfacial Structure in Type-II Superlattices and Quantum Wells

本项目致力于研究分子束(MBE)和迁移增强型(MEE)外延生长的第二类量子阱和超晶格中界面结构和成分的原子尺度表征和控制。这种方法强调横截面扫描隧道显微镜(STM)，在各种生长条件下，检查阴阳离子分离对界面完整性的限制、不完全键类型的选择性和动力学限制的表面粗糙度。界面形态(由于生长平面上的孤岛)和不均匀成分(由于混合的界面键类型、交叉结合或分离)对界面粗糙度的各自作用有望完全反卷积。表征将被用来识别和理解生长条件和相关现象，这些现象提供了对界面结合和平面性的最大控制。因此，可以预期，可以更好地理解、控制和实现优化的第二类量子阱器件所需的结构和组成的完美性。%该项目解决了材料科学中具有高度技术相关性的主题领域的基础研究问题。现在可以使用实验工具对基本的表面过程进行原子水平的观察，如果更好地了解这些过程，就可以推动基础科学和技术的进步。从研究中获得的基本知识和理解有望为改进材料和材料组合的设计和生产提供基本认识和基础，从而有助于提高先进器件的性能和稳定性。该计划的一个重要特点是通过在一个具有根本意义和技术意义的领域对学生进行培训，将研究和教育结合起来。***

This project addresses atomic-scale characterization and control of interface structure and composition in type-II quantum wells and superlattices grown by molecular-beam (MBE), and migration-enhanced (MEE), epitaxy. The approach emphasizes cross-sectional scanning tunneling microscopy (STM), examining limitations to interfacial perfection imposed by anion and cation segregation, incomplete bond type selectivity, and kinetically limited surface roughness, under a variety of growth conditions. Complete deconvolution of the respective roles of interface morphology (due to islanding in the growth plane) and inhomogeneous composition (due to mixed interface bond types, cross incorporation, or segregation) on interface roughness is expected. Characterization will be used to identify and understand growth conditions and associated phenomena which afford maximal control over interface bonding and planarity. Accordingly it is anticipated that structural and composition perfection needed for optimal type-II quantum well devices may be better understood, controlled and realized. %%% The project addresses basic research issues in a topical area of materials science with high technological relevance. Experimental tools are now available to allow atomic level observation of elementary surface processes which when better understood allow advances in fundamental science and technology. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance and stability of advanced devices by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. ***