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

该项目的重点是为生长超薄层的新方法，即第三类金属或半导体双层的单分子层，更好地了解表面化学。范围既包括衬底和外延层之间的潜在过渡层，也包括两个外延膜之间的超薄层。该项目建立在基础半导体、热化学和非平衡化学的最新进展基础上。所研究的材料化学既涉及传统的基于分子的生长，也涉及新的生长方法。超高真空探头将被用来了解表面化学细节，例如，包括表面配体的组成、成键和有序性以及前体分子和表面物种的反应路径。此外，还将研究操纵表面配体的方法，包括用光学和电子束照射，以及通过基质中的快速温度变化。UHV系统将配备剂量计、原位探头和变温衬底固定器。将研究在两个外延薄膜系统之间形成单一氮化物双层膜和形成过渡单分子膜的化学方法，如Si/ZnS等。其他研究将检查新诊断工具的应用，如近边缘X射线吸收精细结构(NEXAFS)，用于确定基于分子的外延生长系统中的表面化学。%该项目解决具有高潜在技术相关性的材料科学主题领域的基础研究问题。这项研究将在基础水平上为电子/光子器件的新方面贡献基本的材料科学知识。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认识和基础。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。

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.***