Spectroscopic Investigations of Problems in Thin Film Materials Chemistry

这个项目是在一般地区的分析和表面 化学和薄膜材料领域。 虽然 薄膜构成了一个非常有趣和重要的类别 化学分析的材料和技术， 薄膜的厚度目前是不够的。 本研究 活动，博恩教授和他的学生将建立在他们的 在NSF赠款CHE-8508722下取得的进展， 薄介质中光谱学的非经典激发现象 薄膜的尺寸范围从5埃到5微米。 这将 通过追求两个独立的研究目标来实现。 在 一、砷化镓和铝取代砷化镓 异质结构将用作介电光波导， 在光子处进行频率调制截面测量 能量低于III-V带隙。 吸收 测量需要长的路径长度， 光波导，因为杂质的横截面 高的亚带隙能量区域中的相关跃迁 III-V族半导体的纯度极低。 在第二 分子单层中的结构-功能关系 将在电介质表面进行检查。 这一努力的一部分 将使用表面等离子体介导的光学二次谐波 高精度反射率测量 单层形成的动力学。 此外，能力 用于检查分子单层的拉曼散射， 介质表面，这是居住在博恩教授的 实验室将被用来探索之间的关系， 吸附物分子结构和膜结构 超分子水平。 这项研究对技术上重要的 III-V族半导体器件。 这些研究预计 产生表征痕量的新技术， 决定高纯度行为的杂质 半导体 此外，这项工作应导致 增强了对这些界面结构的理解， 材料和洞察这些形成的动力学 最重要的是多层分子结构 到电子工业。

This project is in the general area of analytical and surface chemistry and in the subfield of thin film materials. Although thin films comprise an extremely interesting and important class of materials, techniques for chemical analysis which are specific to thin films are currently inadequate. In this research activity, Professor Bohn and his students will build on their progress under NSF grant CHE-8508722 to extend the use of nonclassical excitation phenomena for optical spectroscopy in thin films at size scales from 5 angstroms to 5 micrometers. This will be accomplished by pursuing two separate research thrusts. In one, gallium arsenide and aluminum-substituted gallium arsenide heterostructures will be used as dielectric optical waveguides to perform frequency modulated cross section measurements at photon energies just below the III-V bandgap. The absorption measurements require the long pathlengths available only in optical waveguides, because the cross sections of the impurity related transitions in the sub-bandgap energy region of high purity III-V semiconductors is extremely weak. In the second thrust, structure-function relationships in molecular monolayers will be examined at dielectric surfaces. A portion of this effort will use surface plasmon mediated optical second harmonic generation and high precision reflectivity measurements to follow the dynamics of monolayer formation. Additionally, the capability for examining Raman scattering from molecular monolayers on dielectric surfaces that is resident in Professor Bohn's laboratory will be used to probe the relationship between adsorbate molecular structure and film architecture on the supermolecular level. This research impacts broadly on the technologically important area of III-V semiconductor devices. These studies are expected to yield new techniques for the characterization of trace impurities that determine the behavior of high purity semiconductors. Additionally, this work should lead to an enhanced understanding of the interfacial structure of these materials and to insights into the dynamics of formation of these multi-layered molecular structures which are of prime importance to the electronics industry.