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In situ studies of the electronic and vibrational properties of thin films and novel materials.

机译：薄膜和新型材料的电子和振动特性的原位研究。

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摘要

The electronic and vibrational properties of several novel materials were investigated in an in situ ultra high vacuum (UHV) environment. The novel materials included thin films of laser-modified fullerenes, believed to be photopolymerized; rubidium fulleride, a fullerene polymer in a slow-cooled phase; the zinc selenide (100) surface which reconstructs into (2 x 1) and c(2 x 2) forms; and silicon nanoparticles which exhibit size-dependent effects. Interference enhanced Raman scattering (IERS) and high resolution electron energy loss spectroscopy (HREELS) in reflection were employed to study the vibrational spectra of the materials. Ultraviolet photoemission spectroscopy (UPS) and electron energy loss spectroscopy (EELS) provided spectral information related to the electronic states of these systems.; Ultra-thin layers of silicon were grown by dc magnetron sputtering in ultra high vacuum on amorphous MgO and Ag buffer layers. The average thickness of the layers ranged from monolayer coverage to 200 angstroms. Transmission electron microscopy (TEM) has been used to determine the size and shape of the silicon nanoparticles. Changes in the crystallization process have been studied by interference enhanced Raman scattering (IERS). Marked size dependences in the phonon spectra of amorphous silicon nanoparticles were detected. A relaxation of the k-vector conservation condition occurs in silicon nanocrystals as they decrease in size. The nanocrystal transition between crystalline-like and amorphous-like behavior takes place films with average thickness less than or equal to 10 angstroms. TEM micrographs indicate that the silicon nanoparticles exhibiting this transition have an average number of silicon atoms equal to 700 (+/−200). The electronic spectra as measured by EELS continue to be differentiable even at considerably thinner coverages.
机译：在原位超高真空（UHV）环境下研究了几种新型材料的电子和振动特性。新材料包括被认为是光聚合的激光改性富勒烯薄膜。富勒er，慢冷相中的富勒烯聚合物；硒化锌（100）表面重构为（2 x 1）和 （2 x 2）形式；以及具有尺寸依赖性效应的硅纳米粒子。采用反射干涉增强拉曼散射（IERS）和高分辨率电子能量损失谱（HREELS）来研究材料的振动光谱。紫外光发射光谱法（UPS）和电子能量损失光谱法（EELS）提供了与这些系统的电子状态有关的光谱信息。通过直流磁控溅射在超高真空下在非晶MgO和Ag缓冲层上生长硅的超薄层。层的平均厚度范围从单层覆盖到200埃。透射电子显微镜（TEM）已用于确定硅纳米粒子的大小和形状。已经通过干涉增强拉曼散射（IERS）研究了结晶过程的变化。检测到非晶硅纳米粒子的声子光谱中明显的尺寸依赖性。随着硅纳米晶体尺寸的减小，k矢量守恒条件的松弛发生。纳米晶体在类晶体和类晶体之间的转变发生在平均厚度小于或等于10埃的薄膜上。 TEM显微照片表明，表现出这种转变的硅纳米颗粒的平均硅原子数等于700（+/- 200）。即使在相当薄的覆盖范围内，通过EELS测量的电子光谱仍然可以区分。

著录项

  • 作者

    Fox, Jon Raymond.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Physics Condensed Matter.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 174 p.
  • 总页数 174
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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