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

本计画主要探讨以分子束及迁移强化磊晶技术成长之第二型量子威尔斯井与超晶格中，界面结构与组成之原子尺度特性与控制。该方法强调横截面扫描隧道显微镜（STM），检查限制界面的完美性所施加的阴离子和阳离子偏析，不完整的键型选择性，和动力学限制的表面粗糙度，在各种生长条件下。完整的反卷积的界面形态（由于在生长平面中的孤岛）和不均匀的组合物（由于混合界面键类型，交叉合并，或偏析）对界面粗糙度的各自的作用是预期的。表征将用于识别和理解生长条件和相关现象，从而最大限度地控制界面结合和平面性。因此，预期可以更好地理解、控制和实现最佳II型量子阱器件所需的结构和组成完美性。该项目解决了材料科学领域的基础研究问题，具有高度的技术相关性。现在已有实验工具，可以在原子水平上观察基本表面过程，如果能更好地了解这些过程，就可以在基础科学和技术方面取得进展。从研究中获得的基本知识和理解有望通过为设计和生产改进的材料和材料组合提供基本理解和基础，有助于提高先进器械的性能和稳定性。 该计划的一个重要特点是通过在一个基本和技术上重要的领域对学生进行培训来整合研究和教育。***

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. ***