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Compositional Analysis Of Gate Dielectric Films, Hongtao Tang
Compositional Analysis Of Gate Dielectric Films, Hongtao Tang
Digitized Theses
Oxynitride has recently drawn attention as a candidate gate dielectric material for deep sub-micron devices, e.g. MOSFET's. Since the oxide growth rates in pure oxygen are high, efforts to scale down device dimensions with high quality ultrathin ({dollar}<{dollar}100A) SiO{dollar}\sb2{dollar} films are encountering some difficulties. Recently, it has been found that oxynitride films fabricated directly by a N{dollar}\sb2{dollar}O-rapid thermal processing method exhibit improved electrical properties compared to SiO{dollar}\sb2{dollar} films. Structural analysis for such oxynitride films is necessary in order to understand the physical reasons behind the observed improvements.;Nuclear reaction analysis combined with a chemical step-etching method was performed to depth profile nitrogen quantitatively in N{dollar}\sb2{dollar}O-RTP grown oxynitride films. The oxynitride dielectric composition dependence on growth conditions in a rapid thermal processing system was also investigated by nuclear reaction analysis. It is found that most N in the oxynitride films accumulates in a region close to the interface (less than 25 A from the interface in the oxynitride). Both N concentration and film thickness increase with temperature. Furthermore, a UHV initial growth study of oxynitride films on a Si(100) substrate was carried out by nuclear reaction analysis and Auger electron spectroscopy. The results clearly confirm that the nitrogen involvement occurs primarily before an oxynitride film thickness of {dollar}\sim{dollar}25 A is developed, and the subsequent film growth is dominated by oxidation. For the first time, it is found that there is a special growth period at the very beginning during which nitridation (with no simultaneous oxidation) dominates the growth process. It is speculated that the phenomenon results from a competition between reactions of Si with O and N. The dependence of film growth on temperature is such that below 950{dollar}\sp\circ{dollar}C, there is little nitrogen incorporated in the oxide film.
The Growth And Magnetic Properties Of Metal Overlayer Systems: Palladium/Copper(100), Iron/Aluminum(100) And Iron/Sulfur/Gallium Arsenide(100), Geoffrey William Anderson
The Growth And Magnetic Properties Of Metal Overlayer Systems: Palladium/Copper(100), Iron/Aluminum(100) And Iron/Sulfur/Gallium Arsenide(100), Geoffrey William Anderson
Digitized Theses
Epitaxial growth of a metal overlayer on an appropriate substrate can be utilized to create systems which exhibit unique chemical and magnetic properties. This thesis will outline the investigation of three metal overlayer systems: Pd/Cu(100), Fe/Al(100) and Fe/S/GaAs(100). In the Pd/Cu(100) system the growth and evolution of defects were examined using re-emitted positron spectroscopy. Two changes in growth mode were observed: at 0.5 monolayer (representing the completion of the first alloy layer) and 1 monolayer Pd coverages (representing the start of bulk Pd growth). The bulk Pd film was observed to contain 1% vacancy-type defects. In the Fe/Al(100) system the …
Modelling The Motion Of Pulp Inside Wood-Chip Disc Refiners, Xiaolin Fan
Modelling The Motion Of Pulp Inside Wood-Chip Disc Refiners, Xiaolin Fan
Digitized Theses
The thesis studies the movement of wood pulp through a rotating disk refiner, by developing continuum and discrete models of the process. An existing continuum model of pulp movement for steady-state refining is first extended to include time-dependent effects, in order to study the dynamic aspects of refining operation. A system of hyperbolic P.D.E.'s is obtained, but it is shown to suffer from numerical instability. Attention is therefore shifted to a discrete model, and a stochastic model treating pulp as discontinuous flocs is developed. The prediction of the residence time distribution of pulp in a refiner is the first test …
A New Photocatalytic Reactor For The Photodegradation Of Organic Contaminants In Water, Julio E. Valladares
A New Photocatalytic Reactor For The Photodegradation Of Organic Contaminants In Water, Julio E. Valladares
Digitized Theses
The {dollar}\rm TiO\sb2{dollar} photocatalytic degradation and mineralization of organic pollutants in water has been broadly demonstrated at the laboratory level for a wide number of organic pollutants. However, there are still some problems that need to be addressed in order to make this technology more practical. The design of heterogeneous photocatalytic reactor systems, still in the infancy of their development, is facing different problems such as light scattering, oxygen starving, particle separation and mass transfer. Additionally, there have also been a lack of a general method to evaluate the performance of the different reactor systems.;The present work addresses these problems …