Manipulation of Surface Reactions for Growth of Ultra-Thin Films (1-20ML)

该项目的重点是获得更多的了解表面化学的新方法来生长的多层膜，即第三族金属或半导体双层的单层。范围包括衬底和外延覆盖层之间的潜在过渡层，以及两个外延膜之间的过渡层。该项目建立在基础半导体热和非平衡化学的最新进展之上。材料化学研究涉及到传统的基于分子的增长和新的增长方法。超高真空探针将用于了解表面化学细节，包括例如表面配体的组成、键合和排序以及前体分子和表面物种的反应途径。此外，操纵表面配位体的方法将被检查，包括用光学和电子束照射，并通过衬底中的快速温度变化。超高真空系统将配备剂量器、原位探针和变温衬底保持器。将研究用于形成单个氮化物双层和用于在两个外延薄膜系统（例如Si/ZnS等）之间形成过渡单层的化学。进一步的研究将检查新的诊断工具的应用，例如用于确定基于分子的外延生长系统中的表面化学的近边X射线吸收精细结构（NEXAFS）。该项目涉及材料科学专题领域的基础研究问题，具有很高的潜在技术相关性。该研究将为电子/光子器件的新方面提供基础材料科学知识。 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，预计将有助于提高先进器件和电路的性能和稳定性，为设计和生产改进的材料和材料组合提供基本的理解和基础。 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。

The focus of this project is gaining greater understanding of surface chemistry for new approaches to the growth of ultrathin layers, i.e. a monolayer of Group III metals or semiconductor bilayers. The scope includes both potential transition layers between substrate and epitaxial overlayers, and ultrathin layers between two epitaxial films. The project builds on recent advances in fundamental semiconductor thermal and nonequilibrium chemistry. The materials chemistry studied relates to both conventional molecular-based growth and new approaches to growth. Ultrahigh vacuum probes will be used to understand surface chemistry details, including, for example, the composition, bonding, and ordering of surface ligands and the reaction pathways of precursor molecules and surface species. In addition, ways of manipulating surface ligands will be examined, including irradiation with optical and electron beams, and by rapid temperature changes in the substrate. The UHV system will be equipped with dosers, in situ probes, and a variable-temperature substrate holder. Chemistries for forming single nitride bilayers and for forming a transition monolayer between two epitaxial thin-film systems, e.g. Si/ZnS, etc. will be studied. Additional research will examine the application of new diagnostic tools, such as near edge x--ray absorption fine structure (NEXAFS) for determining the surface chemistry in molecule-based epitaxial growth systems.%%%The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new aspects of electronic/photonic devices. 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 and circuits 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.***