Ng, Chi Hai Alvin. / Thesis submitted in: December 2002. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Table of Contents --- p.v / List of Figure Captions --- p.ix / List of Table Captions --- p.xx / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Silicon Crystal Structure --- p.1 / Chapter 1.2 --- Silicon Dioxide Structure --- p.2 / Chapter 1.3 --- Wafer Cleaning of Silicon --- p.3 / Chapter 1.3.1 --- Sources of Contamination --- p.4 / Chapter 1.3.2 --- Traditional Approach of Wafer Cleaning --- p.5 / Chapter 1.3.3 --- Recent Developments in Wafer Cleaning --- p.6 / Chapter 1.3.3.1 --- Particles --- p.6 / Chapter 1.3.3.2 --- Metal Contamination --- p.7 / Chapter 1.3.3.3 --- Organic Contamination --- p.9 / Chapter 1.3.3.4 --- Surface Microroughness --- p.9 / Chapter 1.3.3.5 --- Native Oxide --- p.11 / Chapter 1.4 --- Oxidation of Silicon --- p.13 / Chapter 1.4.1 --- The Initial Oxidation Regime --- p.17 / Chapter 1.5 --- Current Status of MOS Structure --- p.19 / Chapter 1.5.1 --- Wafer Cleaning --- p.19 / Chapter 1.5.2 --- Silicon Oxidation --- p.20 / Chapter 1.5.3 --- Ozone Oxidation --- p.24 / Chapter 1.5.4 --- High-k Dielectrics --- p.26 / Chapter 1.5.4.1 --- Silicon Oxynitride --- p.27 / Chapter 1.5.4.2 --- Hafnium Oxide and Zirconium Oxide --- p.28 / Chapter 1.5.5 --- Single Monolayer Oxide of Silicon --- p.32 / Chapter 1.6 --- Oxidation by Conventional Furnace --- p.36 / Chapter 1.7 --- Oxidation by RTO --- p.37 / Chapter 1.7.1 --- Equipment Issues --- p.38 / Chapter 1.8 --- Radiation Effects --- p.38 / Chapter 1.8.1 --- Radiation Effects on Ultrathin Gate Oxides --- p.45 / Reference --- p.45 / Chapter Chapter 2 --- Preparation and Characterization Techniques --- p.48 / Chapter 2.1 --- Conventional Furnace --- p.48 / Chapter 2.2 --- Rapid Thermal Oxidation (RTO) --- p.48 / Chapter 2.3 --- Irradiation Source --- p.49 / Chapter 2.4 --- Capacitance-Voltage (C-V) and Current-Voltage (I-V) Curves --- p.51 / Chapter 2.4.1 --- Definition of Potential and Sign Conventions --- p.51 / Chapter 2.4.2 --- The Poisson Equation --- p.55 / Chapter 2.4.3 --- Low Frequency Capacitance --- p.58 / Chapter 2.4.3.1 --- Sum of Series Capacitors --- p.58 / Chapter 2.4.3.2 --- Discussion of Various Terms Contributing to the Field --- p.60 / Chapter 2.4.3.3 --- Calculation of the Low Frequency Capacitance --- p.62 / Chapter 2.4.3.4 --- "Simpler Forms of Capacitancein Accumulation, at Flatband, in Depletion and Inversion" --- p.63 / Chapter 2.4.4 --- High Frequency C-V Curves --- p.65 / Chapter 2.4.5 --- Experimental Setups --- p.66 / Chapter 2.5 --- Conductance-Voltage (G-V) Characterization --- p.67 / Chapter 2.5.1 --- Experimental Details --- p.68 / Chapter 2.6 --- Ellipsometry --- p.69 / Chapter 2.7 --- Rutherford Backscattering Spectrometry --- p.71 / Chapter 2.7.1 --- Experimental Setup --- p.72 / Reference --- p.72 / Chapter Chapter 3 --- Annealing Effects of Conventional Furnace Grown Oxide --- p.74 / Chapter 3.1 --- Experiment --- p.74 / Chapter 3.2 --- Results --- p.74 / Chapter 3.3 --- Conclusions --- p.85 / Reference --- p.86 / Chapter Chapter 4 --- Rapid Thermal Oxidation of MOS Capacitors --- p.87 / Chapter 4.1 --- Experiment --- p.87 / Chapter 4.2 --- Results and Discussions --- p.90 / Chapter 4.3 --- Conclusions --- p.114 / Reference --- p.115 / Chapter Chapter 5 --- Ionizing Radiation on MOS Capacitors --- p.117 / Chapter 5.1 --- Experimental Setup --- p.117 / Chapter 5.2 --- Results and Discussions --- p.120 / Chapter 5.3 --- Conclusions --- p.149 / Reference --- p.151 / Chapter Chapter 6 --- Conclusions --- p.153 / Chapter 6.1 --- Summary --- p.153 / Chapter 6.2 --- Future Work --- p.155 / Reference --- p.157

The performance of multilayer thin film optical filters depends largely on the microstructure of the component layers. This microstructure varies with the deposition parameters inside the coating chamber. By controlling these parameters, optical filters can be produced to exacting specifications. In 1947, R. M. Rice established the technique of bombarding the substrate with electrons of several kilovolts as the fils were being deposited. This process improved the durability of zinc sulfide films dramatically. This study was performed to quantitatively analyze the effects of bombardment on film microstructure and subsequent effects on optical and mechanical properties. I installed an electron source filament inside the coating chamber and electrically isolated the substrate holder, which was connected to a positive high voltage supply. An accelerating loop placed just above the filament enhanced its efficiency. The source was calibrated by measuring the current through the substrate holder. Single layer films of five different materials were deposited, each at its own set of electron bombardment parameters. The microstructure was analyzed with an X-ray diffractometer and a transmission electron microscope. Optical properties were measured with guided waves, induced absorption, and spectrophotometric analysis. Film durability was analyzed with scotch tape, eraser, and controlled humidity tests. Antimony trioxide films showed a shift in lattice orientation, but this did not affect columnar structure or macroscopic quantities. Potassium hexafluorozirconate films showed elimination of both crystal structure and columnar growth, resulting in slightly reduced durability and some absorption. Silicon monoxide films suffered no change in structure or properties. Zinc sulfide films demonstrated the change in crystal structure, which was quantified and shown to improve moisture resistance. Optical properties were unaffected. Magnesium fluoride films showed a slight increase in crystallinity with only subtle changes in durability and optical properties. Generally, electron bombardment reduced or rearranged crystal structure. The effects on macroscopic properties varied with each material, with no clear trend evident.

Thesis (M.Sc.) -- University of Adelaide, Dept. of Physics, 1974.

Emission of electromagnetic radiation due to the temperature of a body is an inherent property in nature. Electromagnetic radiation sources relying on thermal emission are critical in application of energy harvesting, lighting, spectroscopy and sensing. However, many of these sources, typically made of several hundreds of microns thick bulk objects, are inefficient and radiate much less power than an ideal blackbody. In the first part of this work, we demonstrate an efficient thermal emitter based on material films that are nanometers thin. Nano-film based thermal sources are generally poor emitters, but have received much interest lately since they require significantly lower heating power compared to their bulk counterparts. We show a novel approach for realizing thin-film based blackbody emitters by placing them inside an external optical cavity, engineered to provide enhancement of thermal emission while maintaining a constant temperature. Our approach is independent of the emitter material and can be tuned to operate at any temperature since the optical elements and the emitter are physically disconnected. The work opens new avenues for realizing blackbody-type thermal sources consuming significantly lower heating power than the current state-of-art, thus suggesting direct applications in lighting, spectroscopy and energy harvesting. Furthermore, we utilize the nano-film broadband emitters for demonstrating heat transfer that beats conventional blackbody limit at deep-subwavelength distances. We demonstrate the first of its kind, fully integrated and re-configurable thermo-photovoltaic on silicon platform. We report over an order of magnitude increase in generated electrical power by electro-statically tuning the distance between a suspended hot emitter TE ~ 880 K) and an underlying detector (maintained at TD ~ 300 K) from ~500 nm to ~100 nm. We believe this demonstration will be influential for the fields of active energy harvesting as well as in realizing integrated thermal control systems. In the third part of this work, we shift our focus away from broadband emitters, towards spectrally narrow band thermal emitters and propose a novel technique for long-distance transport of thermal radiation. In order to do so, we rely on enhanced near-field heat transfer over blackbody limits aided by surface plasmon polaritions (SPP). We then show that a dispersion engineered sub-wavelength waveguide can allow required states for SPP aided electromagnetic emission to propagate. We show computational analysis of the a composite structure using the open-source electromagnetic solvers SCUFF-EM that captures the effects of surface current distribution induced electromagnetic field effects inside and outside the emitter. We furthermore show a prototype structure of the proposed thermal-waveguide with doped silicon emitters that support SPP. We discuss the measurement technique and present preliminary results of thermal transport over a waveguide that is ~34 μm long. We believe that our proposed approach shown here could advance the field towards development of novel devices for thermal control.

This thesis examines melting in superheated silicon films in contact with SiO₂ under pulsed laser irradiation. An excimer-laser pulse was employed to induce heating of the film by irradiating the film through the transparent fused-quartz substrate such that most of the beam energy was deposited near the bottom Si-SiO₂ interface. Melting dynamics were probed via in situ transient reflectance measurements. The temperature profile was estimated computationally by incorporating temperature- and phase-dependent physical parameters and the time-dependent intensity profile of the incident excimer-laser beam obtained from the experiments. The results indicate that a significant degree of superheating occurred in the subsurface region of the film. Surface-initiated melting was observed in spite of the internal heating scheme, which resulted in the film being substantially hotter at and near the bottom Si-SiO₂ interface. By considering that the surface melts at the equilibrium melting point, the solid-phase-only heat-flow analysis estimates that the bottom Si-SiO₂ interface can be superheated by at least 220K during excimer-laser irradiation. It was found that at higher laser fluences (i.e., at higher temperatures), melting can be triggered internally. At heating rates of 10¹⁰ K/s, melting was observed to initiate at or near the (100)-oriented Si-SiO₂ interface at temperatures estimated to be over 300K above the equilibrium melting point. Based on theoretical considerations, it was deduced that melting in the superheated solid initiated via a nucleation and growth process. Nucleation rates were estimated from the experimental data using Johnson-Mehl-Avrami-Kolmogorov (JMAK) analysis. Interpretation of the results using classical nucleation theory suggests that nucleation of the liquid phase occurred via the heterogeneous mechanism along the Si-SiO₂ interface.

Orientador: Leila Peres / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T10:58:00Z (GMT). No. of bitstreams: 1 Oliveira_Jenerde_M.pdf: 3164863 bytes, checksum: 8449d73e4bcbb869e01f38cb81b7f962 (MD5) Previous issue date: 2012 / Resumo: Filmes poliméricos são amplamente utilizados no setor alimentício e médico hospitalar e as principais aplicações são como embalagens, substratos para fitas e curativos. A escolha do melhor material está intrinsecamente ligada às suas propriedades e também ao custo de cada polímero. Por isso é extremamente relevante a preocupação com o processo de degradação, que influencia diretamente as propriedades dos polímeros e é o resultado do ataque físico e/ou químico proporcionado pelo ambiente (temperatura, umidade, radiações ionizantes), tempo de exposição e condições de processamento e de serviço. Neste trabalho buscou-se analisar a prevenção destes processos degradativos em filmes de polipropileno bi-orientado - BOPP, polímero comercialmente atraente pela sua versatilidade, por meio do uso de aditivos antioxidantes e de absorvedores de radiação UV comerciais, estes últimos na forma de compostos orgânicos e de nanopartículas inorgânicas, aplicados no filme em massa ou em recobrimentos especialmente formulados para este fim. O uso do recobrimento teria ainda como vantagem adicional, a possibilidade de aplicação durante o processo de impressão, protegendo não só o filme como também as cores da impressão, permitindo, além disso, a partir de um filme commodity e formulações de recobrimento feitas sob medida para cada cliente, inclusive de pequeno porte, a obtenção de filmes especiais a um menor custo. Amostras de filmes preparados foram envelhecidas artificialmente e naturalmente e suas propriedades foram monitoradas em ensaios de resistência à tração (tensão na ruptura e alongamento), medida do índice de carbonila por espectroscopia de infravermelho, medida da absorção de radiação ultravioleta por meio de espectrofotometria de UV/visível e análise térmica (temperatura de transição vítrea e de fusão). O trabalho gerou resultados promissores, conclusão obtida pela análise dos ensaios mecânicos, sendo que a tensão de ruptura de um dos filmes aditivados no recobrimento, submetido ao intemperismo por 24 semanas, foi de 1,5 kg/cm versus 1 kg/cm no filme virgem (sem aditivos) submetido a 11 semanas. Houve redução na taxa de degradação medida nos ensaios de absorção de infravermelho, sendo o índice de carbonila mantido a patamares de 0,01 para filmes aditivados versus 0,7 para filmes não aditivados, quando sujeitos a degradação acelerada em equipamento QUV. Houve aumento da absorção de radiação ultravioleta em até 75% comparativamente ao filme virgem, resultado obtido pela adição de absorvedores orgânicos ou também de nanopartículas de óxido metálico / Abstract: Polymeric films are very used on products for food and hospital markets, mainly for packaging, adhesive tapes backing and dressings. The material's choose for both markets are done based on polymer properties and cost. Due this reason, it is too relevant to worry with degradation of material that influences the polymer properties. The degradation process comes from chemical and physical attack. An example is the environmental conditions, like temperature, humidity, radiation, exposure time and process/service conditions. This work looked for to evaluate and to prevent this degradation process that occur on bi-oriented polypropylene films (BOPP) through the use of different additives, like antioxidants and UV absorbers, organic compounds/inorganic nanopartículas, that can be applied on the film by different process, like inside its matrix or through varnish coatings. Samples of said films was aged on different conditions, natural or accelerated aged, and its properties was evaluated through different techniques, like tension/elongation, carbonyl index, FTIR, UV-Vis absorbance and thermo analysis (TGA, DSC). Through these techniques, it was evaluated the achieved protection grade of the film when treated by: UV absorber and Antioxidant applied by coating varnish UV absorber and antioxidant applied inside its matrix Nanoparticle of ZnO applied inside its matrix. The coating with varnishes can be easily made by a printing process. This process to protect the film was chosen in the work in order to study its influence to protect not only the film, but also the inks printed over it, allowing the use of a commodity film. This way, it is possible to get a tailor-made film, in order to achieve desired properties with a low cost process. It was possible to achieve promising results. This conclusion was made based on the tests results, like: the tensile strength analysis of films subjected to weather aging for 24 weeks shown results of 1.5 kg/cm against 1 kg/cm of virgin film aged during 11weeks; FTIR shown a reduction on the polymer degradation rate measured by infrared absorption; the carbonyl index of films with additives, when submitted to QUV or weather aging, maintained at levels of 0.01 versus 0.7 of virgin polymers; it was possible to achieve 75% of UV absorption if compared to virgin film. All the different additives and process conditions presented some advantage if compared with virgin polymer, as presented by this work / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Microstructure changes in uranium and uranium/metal alloys due to radiation damage are of great interest in nuclear science and engineering. Titanium has attracted attention because of its similarity to Zr. It has been proposed for use in the second generation of fusion reactors due to its resistance to radiation-induced swelling. Aluminum can be regarded as a standard absorbing material or backing material for irradiation targets. Initial study of thin aluminum films irradiation by �������Cf fission fragments and alpha particles from source has been conducted in the Radiation Center, Oregon State University. Initial study of thin aluminum films irradiation by �������Cf fission fragments and alpha particles from source has been conducted in the Radiation Center, Oregon State University. Aluminum can be regarded as a standard absorbing material or backing material for irradiation targets. The AFM investigation of microstructure damages of thin aluminum surfaces revealed that the voids, dislocation loops and dislocation lines, formed in the thin aluminum films after bombardment by �������Cf fission fragments and alpha particles, depends on the irradiation dose. The void swelling and diameter and depth of voids increase linearly with the fluence of particles and dose; however, the areal density of voids decreased when formation of dislocation loops began. Study of deposition of uranium on titanium backing material by molecular plating and characterization of produced U/Ti film has been performed. The U/Ti film has smooth and uniform surfaces but the composition of the deposits is complex and does not include water molecules which probably involve the presence of U (VI). A possible structure for the deposits has been suggested. X-ray diffraction pattern of U/Ti films showed that The U/Ti film has an amorphous structure. Uranium films (0.500 mg/cm��) and stack of titanium foils (thickness 0.904 mg/cm��) were used to study the microstructural damage of the uranium film and its backing material. Irradiation of U/Ti film and Ti foils with 1 MeV/u (136 MeV) �������Xe�������� ions in was performed in the Positive Ion Injector (PII) unit at the Argonne Tandem Linear Accelerator System (ATLAS) Facility at Argonne National Laboratory, IL. Pre- and post- irradiation of samples was analyzed by X-ray diffraction, Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) and Atomic Force Microscopy (AFM). The irradiation of U/Ti films results in the formation of a crystalline U���O��� phase and polycrystalline Ti phase. Annealing of the thin uranium deposit on a titanium backing at 800��C in the air atmosphere condition for an hour produced a mixture of UO���, U���O���, Ti, TiO and TiO��� (rutile) phases; meanwhile, annealing at 800oC for an hour in the argon environment produced a mixture of ��-U���O���, Ti and TiO��� (rutile) phases. These phenomena indicate that the damage during irradiation was not due to foil heating. Microstructural damage of irradiated uranium film was dominated by void and bubble formation. The microstructure of irradiated titanium foils is characterized by hillocks, voids, polygonal ridge networks, dislocation lines and dislocation networks. Theory predicts that titanium undergoes an allotropic phase transformation at 882.5 ��C, changing from a closed-packed hexagonal crystal structure (��-phase) into a body-centered cubic crystal structure (��- phase). When the titanium foils were irradiated with 136MeV �������Xe�������� at beam intensity of 3 pnA corresponding to 966��C, it was expected that its structure can change from hexagonal-close packed (hcp) to body-centered cubic (bcc). However, in contrast to the theory, transformation from ��-Ti (hcp) phase to fcc-Ti phase was observed. This phenomenon indicates that during irradiation with high energy and elevated temperature, the fcc-Ti phase more stable than the hcp-Ti Phase. / Graduation date: 2012