Hypersonic vehicles require material systems that can withstand the extreme environment they experience during flight. Carbon-based materials and ultra-high temperature ceramics are candidates for materials systems that will protect hypersonic vehicles. In order to study the material response, an oxyacetylene torch facility and thermal gravimetric analysis are used to investigate the gas-solid interactions under conditions that simulate aspects of flight. The oxyacetylene torch facility is characterized as a function of position from the tip for heat flux and oxygen content. By understanding the local heat flux and oxygen conditions, experiments are designed so that graphite ablation rates can be measured as a function of heat flux and partial pressure of oxygen. Further investigation shows that composition of the material influences the temperature response where ultra-high temperature ceramics exhibit the lowest surface temperatures. Using thermal gravimetric analysis, the isothermal oxidation behavior of ultra-high temperature ceramics from 1000-1600°C is investigated using a Dynamic Non- Equilibrium method in order to understand the reaction kinetics of ZrB₂-SiC where parabolic rate constants are determined. Isothermal oxidation behavior is compared to non-isothermal mass gain and oxide scale formation where specimens oxidized isothermally gain 3 times more mass and have oxide scales 4 times as thick. Finally, the effect of SiC content in ZrB₂ on temperature during oxyacetylene torch testing is determined. Increasing the amount of SiC results in lower front face temperatures because more heat is absorbed due to the endothermic reactions of evaporation of SiO₂.

Environmental microorganisms are implicated as the causative agents in a significant portion of healthcare associated infections (HAI) and antimicrobial resistant infections (AMR), which result in increased costs and suffering around the world. Furthermore, common environmental microorganisms participate in microbiological degradation of materials and the bio-fouling of various systems. This also results in a tremendous amount of damage in many different materials and many different sectors. The focus of this dissertation was the development of an additive that could be easily added to common materials to make them self-disinfecting and to protect them from microbial damage. The ultimate goal was to develop an additive that could be added using standard techniques and without adversely affecting the final material. Cuprous iodide (CuI) was determined to be an ideal starting material for the development of improved antimicrobial materials because of its neutral appearance and high antimicrobial activity as compared to other silver and copper materials. It was found that the antimicrobial efficacy of CuI could be amplified if prepared as a small particle and especially in the presence of vinylpyrrolidone polymers. A comminution process was then developed to produce these small particles. By using select copolymers, various CuI small particles formulation were developed to be compatible with a variety of different matrices. The efficacy of these CuI containing matrices was dependent on the compatibility of the CuI formulation with the matrix. A variety of applications were demonstrated with good antimicrobial efficacy where the particles were easily added to the finished material with minimal or no change in appearance.

The deposition and characterization of HfO2 films for potential application as a high-k gate dielectric in MOS devices has been investigated. DC magnetron reactive sputtering was utilized to prepare the HfO2 films. Structural, chemical, and electrical analyses were performed to characterize the various physical, chemical and electrical properties of the sputtered HfO2 films. The sputtered HfO2 films were annealed to simulate the dopant activation process used in semiconductor processing, and to study the thermal stability of the high-k films. The changes in the film properties due to the annealing are also discussed in this work.Glancing angle XRD was used to analyse the atomic scale structure of the films. The as deposit films are amorphous, regardless of the film thickness. During postdeposition annealing, the thicker films crystallized at lower temperature 600 C, and ultra-Thin (5.8 nm) film crystallized at higher temperature (600 - 720 C). The crystalline phase which formed depended on the thickness of the films. The low temperature phase (monoclinic) formed in the $10-20$ nm annealed films, and high temperature phase (tetragonal) formed in the ultra--thin annealed HfO2 film. The TEM cross-section studies of as deposited samples show the interfacial layer (< 1nm) exists between HfO2/Si for all film thicknesses. The interfacial layer grows thicker during heat treatment, and grows more rapidly when grain boundaries are present. XPS surface analysis shows the as deposited films are fully oxidized with an excess of oxygen. Interfacial chemistry analysis indicated that the interfacial layer is a silicon-rich silicate layer, which tends to transform to silica-like layer during heat treatment.I-V measurements show the leakage current density of the Al/as deposit-HfO2/Si MOS diode is of the order of 10^{-3} A/cm^2, which is two orders of magnitude lower than that of ZrO2 film with similar physical thickness. Carrier transport is dominated by Schottky emission at lower electric fields, and by Frenkel-Poole emission in the higher electric field region. After annealing, the leakage current density decreases significantly as the structure remains amorphous structure. It is suggested that this decrease is assorted with the densification and defect healing which accures when the porous as-deposited amorphous structure is annealed. The leakage current density increases of the HfO2 layer crystallizes on annealing, which is attributed to the presence of grain boundaries. C-V measurements of the as deposited film shows typical C-V characteristics, with negligible hystersis, a small flat band voltage shift, but great frequency dispersion. The relative permittivity of HfO2/interfacial layer stack obtained from the capacitance at accumulation is 15, which corresponds to EOT (equivalent oxide thickness)= 1.66 nm. After annealing, the frequency dispersion is greatly enhanced, and the C-V curve is shifted toward negative voltage. Reliability tests show that the HfO2* 0films which remain amorphous after annealing possess superior resistance to constant voltage stress and ambient aging.This study concluded that the sputtered HfO2 films are amorphous as deposited. The postdeposition annealing alters the crystallinity, interfacial properties, and electrical characteristics. The HfO2 films which remain amorphous structure after annealing possess the best electrical properties.

Ammonia-peroxide mixture (APM) is a widely used wet chemical system for particle removal from silicon surfaces. The conventional APM solution in a volume ratio of 1:1:5 (NH4OH:H2O2:H2O) is employed at elevated temperatures of 70-80 °C. At these temperatures, APM solution etches silicon at a rate of ~3 Å/min, which is unacceptable for current technology node. Additionally, APM solutions are unstable due to the decomposition of hydrogen peroxide and evaporative loss of ammonium hydroxide resulting in the change in APM solution composition. This has generated interest in the use of dilute APM solutions. However, dilution ratios are chosen without any established fundamental relationship between particle-wafer interactions and APM solutions.Atomic force microscopy has been used to measure interaction forces between H-terminated Si surface and Si tip in APM solutions of different compositions. The approach force curves results show attractive forces in DI-water, NH4OH:H2O (1:100) and H2O2:H2O (1:100) solutions at separation distances of less than 10 nm for all immersion times (2, 10 and 60 min) investigated. In the case of dilute APM solutions, the forces are purely repulsive within 2 min of immersion time. During retraction, the adhesion force between Si surface and Si tip was in the range of 0.8 nN to 10.0 nN. In dilute APM solutions, no adhesion force is measured between Si surfaces and repulsive forces dominated at all distances. These results show that even in very dilute APM solutions, repulsive forces exist between Si surface and particle re-deposition can be prevented.The stability of APM solutions has been investigated as a function of temperature (24 - 65 °C), dilution ratio (1:1:5 - 1:2:100), solution pH (8.0 - 9.7) and Fe2+ concentration (0 - 10 ppb) using an optical concentration monitor. The results show that the rate of H2O2 decomposition increased with an increase in temperature, solution pH and Fe2+ concentration. The kinetic analysis showed that the H2O2 decomposition follows a first order kinetics with respect to both H2O2 and OH- concentrations. In the presence of Fe2+, hydrogen peroxide decomposition follows a first order reaction kinetics with respect to H2O2 concentration.

Fabrication and synthesis of nanostructured materials are essential aspects of nanoscience and nanotechnology. Although researchers are now able to create and tailor different nanostructured materials, the ability to precisely control the materials' sizes, shapes, and properties at the nanoscale level remains challenging. The aim of this dissertation was to develop new methods to aid researchers in overcoming these challenges. The study investigated two different methods used to create one-dimensional carbon nanostructures, i.e. carbon nanotubes and carbon nanopillars.In the first section, chemical vapor deposition method was used to grow carbon nanotubes (CNTs). Studies examining the effects of methane and hydrogen flow rates on the growth of CNTs were conducted. Results indicated that multi-walled CNTs with metallic properties could be obtained at a methane flow rates as low as 300 cc/min. At higher methane flow rates, i.e. 600-700 cc/min, semiconducting single-walled CNTs and double-walled CNTs were produced. Another phase of this section developed a new and simple CNT growth method using a solid carbon source and indicated polyacrylonitrile and nanosized SiO₂ were effective in producing MWCNTs. In the second part, a new nanoimprint technique was developed to enable printing of nanostructures at sub-100nm level using various polymers. This technique inherited its high-resolution feature from traditional nanoimprint lithography, but without the use of pressure. To demonstrate, PAN nanopillar structures were printed and converted to carbon. In another phase of the part, the use of our imprint technique resulted in the creation and conversion of polysilazane nanostructures to ceramic for the first time.The final section of this dissertation is devoted to study the impact of porosity in gas diffusion layers (GDLs) on the performance of fuel cells. In one study, a new technique using SEM images to determine GDL porosity was developed. The difference between SEM calculated porosities and mercury intrusion porosimetry measurements were less than 2%. The second study characterized fuel cell performances using GDLs constructed with additional micro porous layers (MPLs) and treated with different wet proofing treatments (WPT). Results showed that when MPL is added, cell performance decreases. However, the increase in WPT in the MPL improved cell performance.

The first part of this dissertation focuses on self-assembled composites. Self-assembled composites composed of vertically aligned multiwalled carbon nanofibers (VA-MWCNF) combined with a graphitic layer (GL) arranged perpendicular to MWCNF axes‘ have been produced at low temperature (445 °C) using low pressure thermal chemical vapor deposition (LPCVD). Electron microscopy and Raman spectroscopy were used to analyze composite morphology, structure and quality. It is found that different composite morphologies and modification of the GL structure can be obtained by varying the nickel (Ni) catalyst underlayer materials, the catalyst pre-treatment method, the gas recipe, the gas flow rates and the pressure conditions of the LPCVD process. Pre-treatment of the catalyst with H2 plasma or NH₃ gas was also investigated. It is found that even a short, one minute H2 plasma pre-treatment of the catalyst results in a significant break-down of the VA-MWCNF/GL composite structure. On the other hand, a one or ten minute catalyst pre-treatment with NH₃ gas results in a structural modification of the GL but retains the VA-MWCNF/GL composite structure. An increase in time of NH₃ gas pre-treatment leads to reduced VA-MWCNF/GL composite height. A growth mechanism for VA-MWCNF/GL composites was proposed. The focus, of the second part of this dissertation, is on the analysis of natural chalks used in traditional old master drawings. Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) analysis were performed on bulk samples of natural black chalk, steatite and calcite natural white chalks and on samples of these chalks applied to paper using various techniques. Critical information was obtained about the morphology and sub-micron features of the chalk particles, the chalk/paper interaction of each application technique and elemental composition of the bulk chalk samples. It was found that the particle size and morphology of the natural white chalks reduced their ability to hold to the paper. This information provides insight as to why black chalk is more resistant to abrasion than the natural white chalks which is important for the conservation of extant chalk drawings.

In semiconductor manufacturing, a large amount (50 billion gallons for US semiconductor fabrication plants in 2006) of ultrapure water (UPW) is used to rinse wafers after wet chemical processing to remove ionic contaminants on surfaces. Of great concern are the contaminants left in narrow (tens of nm), high-aspect-ratio (5:1 to 20:1) features (trenches, vias, and contact holes). The International Technology Roadmap for Semiconductors (ITRS) stipulates that ionic contaminant levels be reduced to below ~ 10¹⁰ atoms/cm². Understanding the bottlenecks in the rinsing process would enable conservation of rinse water usage. A comprehensive process model has been developed on the COMSOL platform to predict the dynamics of rinsing of narrow structures on patterned SiO₂ substrates initially cleaned with NH₄OH. The model considers the effect of various mass-transport mechanisms, including convection and diffusion/dispersion, which occur simultaneously with various surface phenomena, such as adsorption and desorption of impurities. The influences of charged species in the bulk and on the surface, and their induced electric field that affect both transport and surface interactions, have been addressed. Modeling results show that the efficacy of rinsing is strongly influenced by the rate of desorption of adsorbed contaminants, mass transfer of contaminants from the mouth of the feature to the bulk liquid, and the trench aspect ratio. Detection of the end point of rinsing is another way to conserve water used for rinsing after wet processing. The applicability of electrochemical impedance spectroscopy (EIS) to monitor rinsing of Si processed in HF with and without copper contaminant was explored. In the first study, the effect of the nature of surface state (flat band, depletion, or accumulation) of silicon on rinsing rate was investigated. The experimental results show that the state of silicon could affect rinsing kinetics through modulation of ion adsorption. In the second study, silicon was intentionally contaminated by spiking HF with copper ions, cleaned in dilute HCl and then rinsed, and the entire process was followed by continuous impedance measurements. The measured impedance values at different stages have been correlated to the nature of the silicon surface, as characterized by scanning electron microscope (SEM) and inductively coupled plasma mass spectrometry (ICP-MS) methods.

The production of lead glaze paints has intrigued Southwestern archaeologists since the 1930s, and significant efforts have been dedicated to the study of this technology by researchers interested in the Pueblo IV (ca. 1275-1400 CE) glazes. In this dissertation I explore the technology of production of the earliest glaze paints produced in the Southwest: the Pueblo I (ca. 700-850 CE) glaze paints from the Upper San Juan. These glaze paints were produced nearly 500 years before the later and well studied Pueblo IV glaze paints, and these technologies represent two separate, independent instances of invention of glaze technology in the prehistoric Southwest. The unique aspect of prehistoric Southwestern glazes is that they were developed as paints, thus serving as decorations. Glaze paints are culturally and technologically significant because it is in the production of the paint that potters are innovating and experimenting with materials. This dissertation presents evidence for a patterned technological behavior in the production of Pueblo I glaze paints - while there is no evidence of specialization, there is evidence for shared technological knowledge regarding other aspects of production. The lack of control over the variability in visual appearance as related to the variability in compositions indicates that it is unlikely that any differences in composition represent intentional technological choices; therefore, Pueblo I potters were not using standardized recipes in the production of glaze paints. I argue that potters were aware of the effect of applying a lead-based paint to the ceramic, thus indicating intentionality, but could not control all of the variables that are involved in the production of a ceramic ware. To understand the mechanisms of invention, and later abandonment, of this technology, I looked for clues in the history of ceramic production in the area, and coupled it with a study of the social and environmental constraints placed on the production. My research suggests that the production of the Pueblo I glaze paints, while not as specialized and widespread as that of the later glaze paints, is a significant technological component of the sequence of ceramic production in the Southwest.

The effects of implantation conditions and annealing conditions on the formation of buried oxide layers in the low-dose low-energy SIMOX materials were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), electron paramagnetic resonance spectroscopy (EPR). The electrical properties of the buried oxide layers were investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements.The distribution of oxygen and defects in the as-implanted materials due to the implantation conditions (oxygen dose and energy) had significant effects on the formation of the buried oxide layer in low-dose low-energy SIMOX substrates. Multiply faulted defects (MFDs) and small oxide precipitates were observed in the projection range (Rp) in as-implanted samples. As increasing the dose, the mixture of silicon and oxide (silicon striations) also formed around Rp. The locations and shapes of the silicon striations control the density and size of silicon islands in the fully-annealed SIMOX at 1350oC.Upon annealing, the buried oxide layers become stoichiometric. Also, different domains including round, square, and pyramid shapes with the step-terrace structure were observed at the top silicon and buried oxide interface. Round domains are observed in the early stage of the annealing process, while the square and pyramid domains are observed after the high temperature annealing. The mean RMS roughness decreases with increasing time and annealing temperature and decreases with either increasing the implantation dose or decreasing implantation energy. Qualitative mechanisms of Si-SiO2 surface flattening are presented in terms of the variations of morphological features with the processing conditions.In the fully-annealed SIMOX wafers, the silicon pipes and silicon islands were observed in the sample implanted with the dose below 3.0×1017 O+/cm2 and above 3.5×1017 O+/cm2, respectively for the samples implanted at 100 keV. The presence of silicon pipes and islands degrades the quality of the buried oxide layer by reducing the breakdown field strength. It was found that proper annealing ambient and ramping rates would allow the formation of the buried oxide layer containing no silicon island. By controlling the oxygen content in the ambient, the growth of the buried oxide can be enhanced.

The present work deals with the study of infrared transparent glasses and their applications for sensor use. Their behavior under LASER irradiation, as well as the possibility to modify the surface, and the exploration of new glass compositions has been studied. Four tasks were completed with the main goal of designing infrared optical sensors. In a first task, the deposition of various thin films at the surface of a chalcogenide glass has been investigated in order to produce nano porous surfaces. Films were produced by vapor deposition and cathodic sputtering. Vapor deposition did not produce homogeneous films while cathodic sputtering lead to layers of controlled thickness which could produce a porous surface by selective etching. In a second task, the possibility of writing waveguide with femtosecond laser was investigated in Ge-Ga-S/Se-CsCl glasses. It was shown that high power leads to negative index changes unfit for light guiding, while low power lead to small positive index change. It was also shown that the filamentation method lead to homogeneous waveguide with large positive index changes. In a third task, photo-induced phenomena were investigated, especially photo-induced fluidity, on the binary system Ge-Se. The study initiated with the work on relaxation of fiber optics of composition Ge-Se₃ Ge-Se₄ and Ge-Se₉ and their response to shear stress under LASER irradiation in the Urbach region. This leads to the determination of their viscosity under irradiation as a function of the power and wavelength used. This preliminary study enabled using this technique for optical tapering of chalcogenide fibers. A tapered fiber was obtained with good control over the diameter, and length of the sensor and improved sensing sensitivity was demonstrated. Finally, exploration of new glassy systems containing no chalcogenide elements but only heavy halide compounds (PbI₂, PbBr₂, CsI…) were investigated. These amorphous ionic compounds lead to infrared window transmitting from 500 nm up to 26 μm, unfortunately their moisture sensitivity as well as poor mechanical and thermal properties did not make them good candidate for sensor applications.