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

点击翻译按钮获取中文摘要

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.***