Connecting Small-Angle Diffraction With Real-Space Images by Quantitative TEM of Amorphous Thin Films

76 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1998.Amorphous solids are a technologically important class of materials whose structure is not yet well-described. High resolution structural probes such as neutron or x-ray scattering give limited information, restricted mainly to near-neighbor bond lengths and bond angles, but these probes become less useful when trying to examine structure on "medium" length scales, roughly 1 nm in size. Small-angle scattering is used to study structure on this scale, but data analysis is limited by free parameters and the need to probe a macroscopic sample volume. Until now, progress using transmission electron microscopy (TEM) has been limited by instrumental difficulties, but recent technological advances have made quantitative TEM studies of amorphous solids possible. We have used TEM to examine microscopic areas of ultrathin $\rm SiO\sb2$ layers, directly correlating small-angle scattering with real-space images. Our studies have allowed us to pinpoint medium range structures which gives rise to small angle scattering, and we have gained insight into structural questions regarding both native oxides and ultrathin gate oxides used in microelectronic devices.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD