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

小行星9520893 本计画的目标是在选择性磊晶成长中，达成对晶面成长的基本了解与控制，并发展出一种矽/矽锗及矽/矽锗碳奈米异质结构的原位成长技术。将研究使用基于乙硅烷的气体源分子束外延的Si基纳米结构的原位刻面生长;单个纳米结构将自隔离。该方法包括：（1）理解和控制小面生长的理论模型。该模型将考虑衬底取向、图案对准以及Si/SiGe和Si/SiGeC的异质外延。(2)将研究各种物种的表面迁移、生长速率的各向异性以及不同刻面的迁移长度。(3)光学性质将探讨大面积光致发光和光激发光谱。扫描近场光学微探针（SNOM）将用于检测来自单个纳米结构细胞的发光。此外，原子力显微镜和SNOM将被用来检查台面，并确定迁移长度和尺寸依赖的生长速率。纳米结构中的晶体质量和应变将通过X射线衍射来评估。本研究旨在了解纳米尺度的晶体小面生长和控制制造纳米结构，无表面损伤和其他影响。这些纳米结构有望表现出许多新的现象和改进的性能，这对超大规模集成电路和纳米电子学非常重要。该研究解决了传统方法遇到的两个瓶颈问题：直接干法刻蚀造成的表面损伤和光刻实现所需特征尺寸的限制。由于硅集成电路技术的普及及其巨大的经济重要性，拟议计划的技术影响可能非常大。 该计划的一个重要特点是在材料研究的基础和技术重要领域对学生进行培训。***

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. ***