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The goal of this research is to investigate how to deposit SiC material from methyltrichlorosilane (MTS) and H2 using the LCVD technique. Two geometries were targeted, fiber and line. In order to eliminate the volcano effect for LCVD-SiC deposition, a thermodynamics model was developed to check the feasibility and determine the deposition temperature ranges that will not cause the volcano effect, theoretically. With the aid of the thermodynamic calculations and further experimental explorations, the processing conditions for SiC fibers and lines without volcano effect were determined. The experimental relationships between the volcano effect and the deposition temperatures were achieved. As for the SiC lines, the deposition conditions for eliminating volcano effect were determined with the help of surface response experiment and the experience of SiC fiber depositions. The LCVD process of SiC deposition was characterized by performing a kinetic study of SiC deposition. The deposits were characterized by the means of polishing, chemical etching, and SEM technique. A coupled thermal and structural model was created to calculate the thermal residual stress present in the deposits during the deposition process and during the cooling process. Laser heating of LCVD system was studied by developing another model. The transient temperature distribution within the fiber and substrate was obtained. The theoretical relationships between the laser power and the fiber heights for maintaining constant deposition temperatures were achieved.

Factors governing the efficiency of convective moistening in the tropical upper troposphere between 15

The International Technology Roadmap for Semiconductors (ITRS) predicts that microprocessor power consumption will continue to increase in the foreseeable future. It is also well known that microprocessor performance can be improved by lowering the junction temperature: recent analytical studies show that for a power limited chip, there is a non-linear scaling effect that offers a 4.3x performance enhancement at -100 °C, compared to 85 °C operation. Vapor Compression Refrigeration (VCR) is a sufficiently compact, low cost, and power efficient technology for reducing the junction temperature of microprocessors below ambient, while removing very high heat fluxes via phase change. The current study includes a scaling analysis of single- and multiple-stage VCR systems for electronics cooling and an experimental investigation of small-scale, two-stage cascaded VCR systems. In the scaling analysis, a method for estimating the size of single- and multiple-stage VCR systems is described, and the resulting trends are presented. The compressor and air-cooled condenser are shown to be by far the largest components of the system, dwarfing the evaporator, expansion device, and inter-stage heat exchanger. For systems utilizing off-the-shelf components and removing up to 200 W at evaporator temperatures as low as 173 K, compressor size dominates the system and scales with the compressor s motor. The air-cooled condenser is the second largest component, and its size is constrained by the air-side heat transfer coefficient. In the experimental work, a two-stage cascaded VCR system with a total volume of 60000 cm3 is demonstrated that can remove 40 W at -61 °C.

This thesis is devoted to the fabrication of carbon nanotube structures for microelectronics packaging applications with an emphasis on fundamental studies of nanotube growth and assembly, wetting of nanotube structures, and nanotube-based composites. A CVD process is developed that allows controlled growth of a variety of CNT structures, such as CNT films, bundles, and stacks. Use of an Al2O3 support enhances the Fe catalyst activity by increasing the CNT growth rate by nearly two orders of magnitude under the same growth conditions. By introducing a trace amount of weak oxidants into the CVD chamber during CNT growth, aligned CNT ends can be opened and/or functionalized, depending on the selection of oxidants. By varying the growth temperature, CNT growth can be performed in a gas diffusion- or kinetics-controlled regime. To overcome the challenges that impede implementation of CNTs in circuitry, a CNT transfer process was proposed to assemble aligned CNT structures (films, stacks &bundles) at low temperature which ensures compatibility with current microelectronics fabrication sequences and technology. Field emission and electrical testing of the as-assembled CNT devices indicate good electrical contact between CNTs and solder and a very low contact resistance across CNT/solder interfaces. For attachment of CNTs and other applications (e.g. composites), wetting of nanotube structures was studied. Two model surfaces with two-tier scale roughness were fabricated by controlled growth of CNT arrays followed by coating with fluorocarbon layers formed by plasma polymerization to study roughness geometric effects on superhydrophobicity. Due to the hydrophobicity of nanotube structures, electrowetting was investigated to reduce the hydrophobicity of aligned CNTs by controllably reducing the interfacial tension between carbon nanotubes (CNTs) and liquids. Electrowetting can greatly reduce the contact angle of liquids on the surfaces of aligned CNT films. However, contact angle saturation still occurs. Variable frequency microwave (VFM) radiation can greatly improve the CNT/epoxy interfacial bonding strength. Compared to composites cured by thermal heating, VFM-cured composites demonstrate higher CNT/matrix interfacial bonding strength, which is reflected in composite negative thermal expansion. The improved CNT/epoxy interface enhances the thermal conductivity of the composites by 26-30%.

In this paper, polar free-standing (0002)GaN wafer were fabricated by using the hydride vapor phase epitaxy(HVPE) technique on (002) LiGaO2 substrates. Polar of The (0002) GaN affects its luminous efficiency, but compared to other surface between the substrate, it has the smallest lattice mismatch. With the high growth rate of HVPE, hoping to grow high quality GaN thick layer. In the self-designed reactor, Metallic gallium and NH3 were the source of Ga and N. Nitrogen and hydrogen were used as the carrier gases HCl and nitrogen was designed to pass through liquid Ga to form GaCl fully. GaN deposition was realized Efficaciously by conducted steady NH3 and GaCl flows to the substrate suface, accommodated with additional hydrogen and nitrogen atmosphere flows.The parameters set of research mainly focus on reaction pressure, temperature, and growth time. In order to obtain better crystal quality, more attempts were made to grow buffer layer by chemical vapor deposition first, then a thick GaN layer by HVPE. The next step is to do the experiment and analyze with various instruments. Scanning Electron Microscope and atomic force microscopy Atomic Force Microscpoic are used to observe the surface morphology. X-ray Diffracion and transmission electron microscopy are used to know the lattice structure, and to understand the interface between the substrate and the GaN film crystal structure and epitaxial relationship. Finally, Photoluminescence spectroscopy is used to measure its optical properties and compare its defects and epitaxial quality.

The effects of water vapor and carbon dioxide on temperature and heat transfer in the troposphere layer, which is less than the altitude of 10 km, in the atmosphere are presented in this work. Accounting for realistic temperature- and pressure- or concentration-dependent radiative properties, this work systematically evaluates heat transfer encountered in atmosphere. For simplicity, the heat transfer is assumed to be one-dimensional and pure conduction and radiation modes. The solar irradiation penetrates through the atmosphere within its short wavelength range near around visible range between 0.4-0.7 £gm, and absorbed and reflected by the earth ground with a gray body property. The ground emits radiation in longwave range. Water vapor is transparent to longwave range 8-12 £gm and absorbed in five long wavelength bands centered at 71, 6.3, 2.7, 1.87, 1.38 £gm, whereas carbon dioxide is absorbed in four long wavelength bands centered at 15, 4.3, 2.7 and 2.0 £gm. The computed results quantitatively show that water vapor and carbon dioxide are the most important factors affecting temperature difference around 2 Celsius degrees.

In this thesis, the growth of nonpolar m-plane zinc oxide (ZnO) nano-materials on (100) £^¡VLiAlO2 (LAO) substrates by a chemical vapor deposition (CVD) process had been studied. The mixture powders of ZnO and graphite are used as the precursor of reaction sources. Ar/O2 are used as the carrier gas and reaction gas source respectively, and the Au thin-film coated on the LAO substrate is the catalyst for the vapor-liquid-solid (VLS) growth mode. The X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to study the influence of the varied growth conditions, such as deposition time, reaction pressure, growth temperature, and the distance between substrates and reaction powder ¡K etc., on the crystal structure, surface morphology, orientation and microstructure characterizations of the ZnO nanostructure. The pure (10-10) m-plane ZnO nano-materials can be obtained at the growth parameters of 830¢XC, 10 torr, 5 minutes, and 50 sccm of Ar/O2. Furthermore, photoluminescence (PL), cathodoluminescence (CL) and Raman spectroscope (Raman) were used to study optical properties and the inner stress of the materials.

Liquefied Natural Gas (LNG) hazards include LNG flammable vapor dispersion and LNG pool fire thermal radiation. A large LNG pool fire emits high thermal radiation thus preventing fire fighters from approaching and extinguishing the fire. One of the strategies used in the LNG industry and recommended by federal regulation National Fire Protection Association (NFPA) 59A is to use expansion foam to suppress LNG vapors and to control LNG fire by reducing the fire size. In its application, expansion foam effectiveness heavily depends on application rate, generator location, and LNG containment pit design. Complicated phenomena involved and previous studies have not completely filled the gaps increases the needs for LNG field experiments involving expansion foam. In addition, alternative LNG vapor dispersion and pool fire suppression methodology, Foamglas® pool fire suppression (PFS), is investigated as well. This dissertation details the research and experiment development. Results regarding important phenomena are presented and discussed. Foamglas® PFS effectiveness is described. Recommendations for advancing current guidelines in LNG vapor dispersion and pool fire suppression methods are developed. The gaps are presented as the future work and recommendation on how to do the experiment better in the future. This will benefit LNG industries to enhance its safety system and to make LNG facilities safer.

Disulfide bonds play important roles in establishing and stabilizing three-dimensional protein structure, and mass spectrometry (MS) has become the primary detection method to decipher their biological and pathological roles. Several experimental methods before or after MS detection have been developed to aid in disulfide bond assignment, such as tandem MS followed by database searching or modification of the disulfide bond via chemical reduction or oxidation. Despite these technological advancements, the detection and proper assignment of disulfide bonds have remained experimentally difficult. Therefore, we have developed an alternative method for disulfide bond elucidation using capillary electrophoresis-mass spectrometry (CE-MS) combined with an on-target performic acid oxidation method for matrix assisted laser desorption/ionization (MALDI) deposited samples. An information rich CE-MS method that results in distinct charge-state trends observed in two-dimensional plots of log(mu eff) versus log (MW) was developed to enhance the confidence of peptide and protein identifications. The charge-state trends provide information about the number of basic amino acid residues present within each peptide. This information can be used to develop methods to screen for posttranslationally modified peptides (e.g., phosphorylation, disulfide bonds, etc.). In the case of disulfide bonds, the highly charged peptides (i.e., 3, 4 or greater charge states) have a high probability of being disulfide-linked peptides, owing to charge contribution of both peptides forming the disulfide bridged peptide. However, intra-linked disulfide bridged peptides can also be present at lower charge states. Therefore, a chemically selective method to rapidly locate disulfide-linked peptides that have been separated by CE-MS must be developed. An on-target performic acid oxidation method was developed to provide the chemical selectivity towards disulfide bonds, i.e., converting the cystine bond to form two peptides modified with a cysteic acid (SO3H) side chain. The on-target oxidation method offers (i) no post-oxidation sample cleanup, (ii) improved throughput over solution-phase oxidation methods, and (iii) easily adapted to CE separations coupled offline with MALDI-MS. The evaluation of the on-target oxidation experimental parameters, the fragmentation behavior of cysteic acid-containing peptides and an alternative method for disulfide bond elucidation, using CE-MS combined with the ontarget oxidation method, are discussed within.