No description available.

[No abstract available] / Science, Faculty of / Chemistry, Department of / Graduate

As the present trend to larger scales of integration of chips continues an increasing demand on reliability must be met. One source of premature device failure is contamination by mobile sodium ions. This thesis is a study of some of the effects of sodium contamination in silicon dioxide using internal photoemission and self healing breakdown. Lateral inhomogeneities in the barrier height at the Si-Si02 interface were probed by scanning a focussed beam of ultraviolet light along a MOS capacitor. It was found that barrier height was uniform unless highly contaminated samples were subjected both to a high temperature and also to a positive bias on the field plate for a short time at moderate temperatures. Qualitative features of lateral inhomogeneities in the surface potential were characterized by high frequency capacitance-voltage measurements showing similar effects. A model for the photoemission process was proposed. The effect of illumination while measuring photoemission was found to affect the band bending substantially so that a relatively simple model neglecting band bending in the silicon was used. Barrier height lowering caused by sodium contamination was measured on samples having a uniform photocurrent. By measuring samples at different contamination levels an experimental relationship between sodium concentration and barrier height lowering was found. A simple model taking into account Schottky barrier lowering resulting from the dipole field was found to be in good agreement with the results for low levels of surface concentration. Good experimental agreement was found with previous work. Self healing breakdown of the sample was also performed showing a convincing correlation between photoemission peaks and areas of early breakdown. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Thesis (MAppSc)--University of South Australia, 1995

No description available.

No description available.

Materials chemistry represents a very broad, but extremely applicable field of study to everyday life. Since many of the useful applications of these ‘sponge-like’ porous materials are dependent on the amount of surface area, the development and use of highly-porous materials with tremendous surface areas significantly enhances the effectiveness of these materials. Examples of such traditional applications include adsorption, separation, and catalytic applications. The study of porous materials has brought the ability to accurately synthesize and modify these materials to meet specific application requirements. The field of porous materials has been traditionally dominated by many “natural” or traditionally inspired materials such as zeolites and porous carbon materials. Although very effective, these materials have very small pore-windows that prevent their application in all but very small molecule applications. This limitation drove the development of large pore-window materials in the 1990s, known as mesoporous materials. Mesoporous materials are defined by IUPAC as possessing pore-openings between 20 and 500 Å. This much broader size-range spurred the use of mesoporous materials into other applications, including large-molecule heterogeneous catalysis and biomedical applications. Chapter one of this dissertation presents an introduction to the field of mesoporous materials, with both silica based and carbon based materials covered. Chapter two and three cover the development of a new mesoporous/microporous silica material. The purpose of this material was to combines the advantages of both types of materials, namely the large pore-opening of mesoporous materials with the stability of a traditional microporous material. The combined material, named MMM-2, is doped with titanium heteroatoms for use in catalytic reactions. The chapter presents a thorough study of the synthesis and characterization of MMM-2 along with its application as a more effective catalysis in the oxidation of cyclohexene. Chapters four and five further extend the work on the MMM-2 materials by incorporating aluminum into the silica framework to form a solid acid-catalyst. Again, thorough treatment is given to the synthesis and characterization of this material. Al- MMM-2 is shown to possess unique structural properties relative to the pure mesoporous and microporous materials that it is related to. Moreover, Al-MMM-2 is shown to be more effective in acid-catalysis reactions as well as possessing improved structural stability upon the reuse of the material in successive reaction cycles. Chapters six and seven cover the use of the mesoporous material, APMS in the adsorption and delivery of DNA. APMS, which is spherically shaped, is shown to be an effective adsorbant of DNA into its internal pores with adsorption determined to be dependent on several factors such as the ionic environment, pore size, and surface characteristics. Finally, chapter eight covers the templated synthesis and characterization of a new, spherically shaped, porous carbon material. This material, based upon APMS, provides tremendous increase in surface area and pore volume relative to its silica parent. The large increase in the physical properties provides enhanced adsorption of DNA.

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No description available.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1928. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed October 26, 2009) Includes bibliographical references (p. 17).