Investigation of Mechanisms of Facet Growth and In-Situ Fabrication of Si-Based Nanostructures

点击翻译按钮获取中文摘要

9520893 Wang The objectives of this project are to achieve fundamental understanding and control of facet growth in selective epitaxial growth, and to develop an in-situ growth technique of nanometer scale heterostructures of Si/SiGe and Si/SiGeC. In-situ facet growth of Si-based nanostructures using disilane based gas source molecular beam epitaxy will be studied; individual nanostructures will be self-isolated. The approach includes: (1) A theoretical model for understanding and control of facet growth. The model will take substrate orientations, pattern alignments, and heteroepitaxy of Si/SiGe and Si/SiGeC will be included into account. (2) Surface migration of various species, anisotropy of growth rate, and migration lengths for different facets will be studied. (3) Optical properties will be explored with large area photoluminescence and photoexcitation spectroscopy. A Scanning Near-field Optical Microprobe (SNOM) will be used to detect the luminescence from a single nanostructure cell. In addition, atomic force microscope and SNOM will be used to examine mesas and to determine migration length, and size dependent growth rate. Crystalline quality and strain in the nanostructures will be assessed by X-ray diffraction. %%% This research aims toward gaining an understanding of crystal facet growth in the nanometer scale and the control of fabricating nanostructures, free of surface damage and other effects. These nanostructures are expected to exhibit many new phenomena and improved properties, which are very important for ultra-large scale integrated circuits and nanoelectronics. The research addresses two bottleneck problems encountered with conventional methods: surface damage caused by direct dry etching and the limitation of lithography for achieving a desired feature size. Because of the pervasiveness of silicon integrated circuit technology and its enormous economic importance, the technological impact of the proposed program is potentially very large. An important feature of the program is the training of students in a fundamentally and technologically significant area of materials research. ***