Materials Science and Engineering Commons^™

Semi-Transparent Zno:Al/Cu2o Thin-Film Heterojunction Fabricated At Low Temperature: Effect Of An Intrinsic Zno Buffer Layer At The Junction, Yu-Nung Huang

Material Science and Engineering Theses - Archive

The Al-doped ZnO (AZO)/Cu2O semi-transparent heterojunction was realized by an RF sputtering at low temperature in this study. Specifically, the usage of a buffer layer in the junction structure has been found as a key factor influencing the carrier transport mechanisms and performance of the junction. First, the chemical bath deposition (CBD) has been utilized in depositing an intrinsic ZnO (i-ZnO) buffer layer in order to entirely avoid potential plasma damage from a subsequent sputter deposition process. Increasing pH of CBD solution was critical in delaying the formation of detrimental ZnOHx particles in the solution and the assistance of ultrasonication …

New Media Icc Profiles Construction And Concerns, Reem El Asaleh

Dissertations

With the advent of the modern digital technology, users can now capture an image and reproduce it between different media, such as display it on LCD monitor or tablet computer, print it on desktop printer or send it to a printing press. The challenge has been then to maintain the accuracy of image colors during this reproduction, which has led to the development of Color Management Systems. Using these systems, the color reproduction across-media will be accomplished using device ICC profiles that describe each device’s color characterization data in a standardized format based on International Color Consortium (ICC) specifications.

ICC …

Development Of Multimodal Imaging System Combined With Laser Microbeam For Nanoscale Manipulation And Characterization., Ninad Ingle

Material Science and Engineering Theses - Archive

Optical microscopy has fascinated biologists for probing and observing cellular structure while performing scientific research. While numerous wide-field and scanning microscopic techniques are being developed for probing cellular structure and function with high spatial and temporal resolution, mapping of complete biochemical, material and structural properties of the cell in three dimensions requires integration of multiple microscopic imaging techniques. In this thesis, conventional phase contrast microscopy and epifluorescence microscopy techniques were combined with other imaging methods such as digital holography microscopy (DHM) also known as quantitative phase microscopy, atomic force microscopy (AFM), near-field scanning optical microscopy (NSOM), total internal reflection fluorescence …

Process-Dependent Microstructure And Severe Plastic Deformation In Sicp?? Reinforced Aluminum Metal Matrix Composites, Catalina Uribe-Restrepo

Electronic Theses and Dissertations

Discontinuously reinforced MMCs with optimized microstructure are sought after for exceptional high strain rate behavior. The microstructure evolution of a stir-cast A359 aluminum composite reinforced with 30 vol.% SiCp after isothermal anneal, successive hot-rolling, and high strain rate deformation has been investigated. Quantitative microstructural analysis was carried out for the as-cast, annealed (470°C, 538°C and 570°C) and successively hot rolled specimens (64, 75, 88, and 96% rolling reductions). Selected composites were also examined after high strain rate deformation. X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy were employed for microstructural characterization. The strength and ductility of the …

Observations On Braided Thin Wire Nucleate Boiling In Microgravity, Justin P. Koeln, Jeffrey C. Boulware, Heng Ban, Jr Dennison

Publications

A microgravity experiment was conducted on the Space Shuttle Endeavor (STS-108) to observe sustained nucleate boiling of water. Subcooled water was boiled with a single strand and a braid of three 0.16. mm diameter and 80. mm long Nichrome resistive wires. A CCD video camera recorded the experiment while six thermistors recorded the temperature of the fluid at various distances from the heating element. This paper reports experimental results in observations, measurements, and data analysis. Bubble explosions were found to take place shortly after the onset of boiling for both the single and braid of wires. The explosion may produce …

Polydimethylsiloxane Mechanical Properties Measured By Macroscopic Compression And Nanoindentation Techniques, Zhixin Wang

USF Tampa Graduate Theses and Dissertations

In this thesis, the relationship between the elastic modulus of PDMS and the base/agent ratio (the amount of crosslinking) is studied. Reliable macroscopic compression test instrument was developed. Preload method was applied for the nanoindentation flat punch test to develop full contact.

In chapter 2, an easy instrument setup for macroscopic compression test is described. A series of PDMS samples with different base/agent ratios were tested using the macroscopic compression method. The relationship between PDMS elastic modulus and its base/agent ratio was established.

In chapter 3, PDMS nanoindentation DMA tests provide stable data with different test control models. The storage …

Stress-Strain Management Of Heteroepitaxial Polycrystalline Silicon Carbide Films, Christopher William Locke

USF Tampa Graduate Theses and Dissertations

Silicon carbide (SiC) is one of the hardest known materials and is also, by good fortune, a wide bandgap semiconductor. While the application of SiC for high-temperature and high-power electronics is fairly well known, its utility as a highly robust, chemically-inert material for microelectrical mechanical systems (MEMS) is only beginning to be well recognized. SiC can be grown on both native SiC substrates or on Si using heteroepitaxial growth methods which affords the possibility to use Si micromachining methods to fabricate advanced SiC MEMS devices.

The control of film stress in heteroepitaxial silicon carbide films grown on polysilicon-on-oxide substrates has …

Fatigue Lifetime Approximation Based On Quantitative Microstructural Analysis For Air Plasma Sprayed Thermal Barrier Coatings, Carmen Bargraser

Electronic Theses and Dissertations

The durability of thermal barrier coatings (TBCs) affects the life of the hot section engine components on which they are applied. Fatigue is the general failure mechanism for such components and is responsible for most unexpected failures; therefore it is desirable to develop lifetime approximation models to ensure reliability and durability. In this study, we first examined the microstructural degradation of air plasma sprayed ZrO2-8wt.%Y2O3 TBCs with a low-pressure plasma sprayed CoNiCrAlY bond coat on an IN 738LC superalloy substrate. The durability of TBCs were assessed through furnace thermal cyclic tests carried out in air at 1100°C with a 1-, …

Fiber-Reinforced Calcium Sulfate Bone Cement Composites With Enhanced Bioactivity, Mechanical Properties And Controlled Biodegradability, Nuha Fathi Hussien

Theses

Hard tissues are natural composites of inorganic and organic components. The inorganic component is a basic Calcium phosphate; known as hydroxyapatite (HAp) while the organic is a natural polymer; known as collagen. The interlocking between the collagen nanofibers and the Hap nanocrystals growing on them offers the known unique mechanical stability of hard tissues. In case of partial fractures; bone or dental cements are often used. Cements such as polymethylmethacrylate (PMMA) has been long used in this regard. However, this polymer is classified as a bio inert material that can be accepted by the human body without having a positive …

Friction Stir Lap Welded Advanced High Strength Steels: Microstructure And Mechanical Properties, M. Ghosh, K. Kumar, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Friction stir welding was carried out under different heat input and cooling rates to produce lap joints between high strength martensitic steel sheets. the microstructure of the welds was characterized, and microhardness was evaluated. Joint efficiency was determined by lap shear test. Variation in processing conditions governed total heat input, peak temperature and cooling rate during friction stir welding. Weld nugget microstructure depended principally on cooling rate. the slowest cooling rate promoted ferrite-pearlite and the fastest cooling rate resulted in martensite formation in the weld nugget. the weakest region of all the joints was the heat affected zone, which consists …

Beneficial And Technological Analysis For The Recycling Of Solar Grade Silicon Wastes, Anping Dong, Lifeng Zhang, Lucas N.W. Damoah

Materials Science and Engineering Faculty Research & Creative Works

In the current paper, different kinds of silicon wastes during the production of SoG-Si were summarized and the beneficial analyses, such as financial value, energy value, CO₂ emissions, and efficiency and energy payback time, were briefly discussed for the recycling of SoG-Si wastes. Possible technologies to recycle and purify SoG-Si wastes were reviewed: such as filtration, sedimentation, solidification control, electromagnetic separation, plasma oxidation, centrifugation, and high temperature remelting process, et al. © 2011 TMS.

A Stress-Strain Model For A Two-Phase Ultrafine-Grained Aluminum Alloy, P. S. De, J. Q. Su, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Two-phase ultrafine-grained (UFG) aluminum alloys with different precipitate and low-angle boundary distributions were examined for their monotonic stress-strain behavior. Precipitates in combination with low-angle grain boundaries were found to determine the deformation micro mechanism. It is proposed that thermally activated vacancy movement plays a central role in this regard. the experimental stress-strain curves matched well with the trend predicted by a modified Blum-Zheng model based on vacancy-assisted dislocation annihilation mechanism. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Femtosecond Laser Writing Of Waveguides In Zinc Phosphate Glasses [Invited], Luke B. Fletcher, Jon J. Witcher, Neil Troy, Signo Tadeu Dos Reis, Richard K. Brow, R. M. Vazquez, R. Osellame, Denise M. Krol

Materials Science and Engineering Faculty Research & Creative Works

We have studied the relationship between the initial glass composition and the structural changes associated with laser-induced refractive index modification in a series of Er-Yb doped and undoped zinc phosphate glasses. White light microscopy and waveguide experiments are used together with Raman and fluorescence spectroscopy to characterize the structural changes. The correlation between Raman peak shifts and fluorescence from phosphorus-oxygen hole center (POHC) defects indicates that fs-laser writing results in a depolymerization of the phosphate glass network. The results also show that the exact glass composition should be taken into account when fabricating waveguide devices in phosphate glasses, in order …

Direct Femtosecond Laser Waveguide Writing Inside Zinc Phosphate Glass, Luke B. Fletcher, Jon J. Witcher, Neil Troy, Signo Tadeu Dos Reis, Richard K. Brow, Denise M. Krol

Materials Science and Engineering Faculty Research & Creative Works

We report the relationship between the initial glass composition and the resulting microstructural changes after direct femtosecond laser waveguide writing with a 1 kHz repetition rate Ti:sapphire laser system. A zinc polyphosphate glass composition with an oxygen to phosphorus ratio of 3.25 has demonstrated positive refractive index changes induced inside the focal volume of a focusing microscope objective for laser pulse energies that can achieve intensities above the modification threshold. The permanent photo-induced changes can be used for direct fabrication of optical waveguides using single scan writing techniques. Changes to the localized glass network structure that produce positive changes in …

Hollow Hydroxyapatite Microspheres For Controlled Delivery Of Proteins, H. Fu, M. N. Rahaman, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

Hollow hydroxyapatite (HA) microspheres were prepared by reacting solid microspheres of a lithium-calcium-borate glass (106-150 microns) for 2 days in K₂HPO₄ solution (0.02 M; 37°C) and evaluated as a controlled delivery device for a model protein, bovine serum albumin (BSA). the as-prepared HA microspheres had a hollow core with a diameter equal to 0.6 the external diameter, a surface area of V100 m²/g, and a mesoporous shell wall (pore size of ≈13 nm). after loading the hollow HA microspheres with a solution of BSA, release of the BSA into a medium of phosphate-buffered saline (PBS) …

A Study On The Combined Effect Of Forging And Aging In Mg-Y-Re Alloy, S. K. Panigrahi, W. Yuan, R. S. Mishra, R. Delorme, B. Davis, R. A. Howell, K. Cho

Materials Science and Engineering Faculty Research & Creative Works

The combined effect of forging and aging on microstructural evolution and mechanical properties of a Mg-Y-RE alloy was studied in the present work by employing hardness measurements, tensile tests, optical microscopy (OM), scanning electron microscopy (SEM) and electron back scattered diffraction (EBSD) analysis. the -F temper treated bulk Mg-Y-RE alloy samples were subjected to forging for microstructural refinement and subsequent aging to maximize the strength-ductility combination. the forged samples combined with peak aging treatment (60 h at 180 °C) exhibited an excellent combination of high strength (388 MPa) and high ductility (23%). the combined effect of grain refinement, work hardening, …

Supercritical Carbon Dioxide-Processed Resorbable Polymer Nanocomposites For Bone Graft Substitute Applications, Kevin Baker

Wayne State University Dissertations

Numerous clinical situations necessitate the use of bone graft materials to enhance bone formation. While autologous and allogenic materials are considered the gold standards in the setting of fracture healing and spine fusion, their disadvantages, which include donor site morbidity and finite supply have stimulated research and development of novel bone graft substitute materials. Among the most promising candidate materials are resorbable polymers, composed of lactic and/or glycolic acid. While the characteristics of these materials, such as predictable degradation kinetics and biocompatibility, make them an excellent choice for bone graft substitute applications, they lack mechanical strength when synthesized with the …

Preparation And Characterization Of Iron Oxide And Hydroxide Based Nanomaterials, Guillermo Carbajal Franco

Open Access Theses & Dissertations

Iron (Fe) oxides and hydroxides are common and abundant materials. They exhibit diverse crystal structures, properties and phenomena by virtue of which they find a wide range of scientific and technological applications. Controlled growth and manipulation of the specific structure and electronic behavior to meet the requirements of a given application is a challenging problem in view of many possible phases and composition of the resulting materials. The preparation method and experimental conditions will, therefore, significantly affect the properties and performance of Fe oxides and hydroxides. The goal of the project is to obtain Fe-based oxide/hydroxide catalytic materials and to …

High Conductivity Solid Oxide Electrolyte Composite-Laminates Utilizing Scandia/Ceria Co-Doped Zirconia Core With Yttria Stabilized Zirconia Outer Skins, Jay Neutzler, Xinyu Huang, Joshua Sightler, Yan Chen, Nina Orlovskaya

Faculty Publications

Increasing the conductivity of electrolytes in lower temperature Solid Oxide Fuel Cells (SOFC) is of great importance. However, there are several challenges that are to be addressed, which include phase stability of electrolyte’s crystal structure, chemical stability in both oxidizing and reducing environments, and maintaining mechanical integrity and high ionic conductivity over time.

Effects Of Radiation-Induced Carbon Contamination On The Printing Performance Of Extreme Ultraviolet Masks, Yu-Jen Fan

Legacy Theses & Dissertations (2009 - 2024)

This dissertation investigates one of the remaining issues for extreme ultraviolet (EUV) lithography, the effects of radiation induced carbon contamination on the printing performance of patterned EUV masks. The impact of carbon contamination on EUV masks is significant due to the throughput loss and potential effects on imaging performance, and occurs when multilayer surfaces are exposed to EUV radiation with residual carbonaceous species present. Current carbon contamination research is primarily focused on the lifetime of the multilayer surfaces, determined by reflectivity loss and reduced throughput in EUV exposure tools. However, contamination on patterned EUV masks can cause additional effects on …

Effects Of Low Energy E-Beam Irradiation On Graphene And Graphene Field Effect Transistors And Raman Metrology Of Graphene On Split Gate Test Structures, Gayathri Rao

Legacy Theses & Dissertations (2009 - 2024)

Apart from its compelling performance in conventional nanoelectronic device geometries, graphene is an appropriate candidate to study certain interesting phenomenon (e.g. the Veselago lens effect) predicted on the basis of its linear electron dispersion relation. A key requirement for the observation of such phenomenon in graphene and for its use in conventional field-effect transistor (FET) devices is the need to minimize defects such as consisting of - or resulting from - adsorbates and lattice non-uniformities, and reduce deleterious substrate effects. Consequently the investigation of the origin and interaction of defects in the graphene lattice is essential to improve and tailor …

Synthesis, Processing And Characterization Of Silicon-Based Templated Nanowires, Jae Ho Lee

Legacy Theses & Dissertations (2009 - 2024)

Semiconductor and metallic nanowires have attracted substantial attention due to their wide variety of applications, ranging from nanoelectronics to energy storage devices. In particular, self-assembled silicon nanowires (SiNWs) may be an attractive alternative to conventionally processed planar silicon since SiNWs can potentially function as both the switch (i.e. transistor) and local interconnect (e.g. metal silicide nanowire) to form an inherently integrated nanoelectronic system. Also, hierarchical (branched) nanowire systems hold potential for catalysts or porous electrode applications for energy applications

Applying X-Ray Microscopy And Finite Element Modeling (Fem) To Identify The Mechanism Of Stress-Assisted Void Growth In Through Silicon Via (Tsv), Lay Wai Kong

Legacy Theses & Dissertations (2009 - 2024)

Fabricating through-silicon vias (TSVs) is challenging, especially for conformally filled TSVs, often hampered by the seam line and void inside the TSVs. Stress-assisted void growth in TSVs has been studied by finite element stress modeling and X-ray computed tomography (XCT). Because X-ray imaging does not require TSVs to be physically cross-sectioned, the same TSV can be imaged before and after annealing. Using 8 keV laboratory-based XCT, voids formed during copper electroplating are observed in as-deposited samples and void growth is observed at the void location after annealing. We hypothesize that the mechanism generating voids is hydrostatic stress-assisted void growth. Stresses …

Electron-Phonon Interactions And Quantum Confinement Effects On Optical Transitions In Nanoscale Silicon Films, Vimal Kumar Kamineni

Legacy Theses & Dissertations (2009 - 2024)

Theoretical studies have attributed the temperature dependence of the linear optical response (dielectric function) of bulk semiconductors to electron-phonon interactions and thermal expansion of the lattice. However, the role of phonons in the optical properties of nanoscale structures is often overlooked. This thesis systematically investigates the impact of both carrier confinement and electron-phonon interactions using nanoscale films of silicon in crystalline silicon quantum wells (c-Si QW). Spectroscopic ellipsometry (SE) is a linear optical technique used to of extract the dielectric function and thickness of very thin films. X-ray reflectivity (XRR) was used as the complementary thickness metrology method. The dielectric …

Investigation Of Novel Alumina Nanoabrasive And The Interactions With Basic Chemical Components In Copper Chemical Mechanical Planarization (Cmp) Slurries, Shravanthi Lakshmi Manikonda

Legacy Theses & Dissertations (2009 - 2024)

Chemical mechanical planarization (CMP) is an enabling process technology for IC fabrication to maintain global planarity across the wafer to satisfy lithographic depth of focus constraints. It also enables integration of materials that cannot be anisotropically etched, such as Cu. CMP utilizes nanoparticle abrasives in aqueous slurry to aid in planarization.

Energy Band Engineering Using Polarization Induced Interface Charges In Mocvd Grown Iii-Nitride Heterojunction Devices, Neeraj Tripathi

Legacy Theses & Dissertations (2009 - 2024)

Characteristics of III-nitride based heterojunction devices are greatly influenced by the presence of high density of polarization induced interface charges. Research undertaken in the current doctoral thesis demonstrates the effect of presence of one, three and six sheets of polarization induced charges in three different III-nitride based devices, namely in a photocathode, a high electron mobility transistor (HEMT) and a hyperspectral detector structure. Through a systematic set of experiments and theoretical modeling an in-depth study of the interaction between multiple sheets of polarization induced charges and their impact on energy band profile was undertaken. Various device designs were studied and …

Development Of High Band Gap Absorber And Buffer Materials For Thin Film Solar Cell Applications, Daniel Dwyer

Legacy Theses & Dissertations (2009 - 2024)

CuInGaSe₂ (CIGS) device efficiencies are the highest of the thin film absorber materials (vs. CdTe, α-Si, CuInSe₂). However, the band gap of the highest efficiency CIGS cells deviates from the expected ideal value predicted by models. Widening the band gap to the theoretically ideal value is one way to increase cell efficiencies. Widening the band gap can be accomplished in two ways; by finding a solution to the Ga-related defects which limit the open circuit voltage at high Ga ratios, or by utilizing different elemental combinations to form an alternative high band gap photoactive Cu-chalcopyrite (which includes …

Nucleation, Wetting And Agglomeration Of Copper And Copper-Alloy Thin Films On Metal Liner Surfaces, Stephanie Florence Labarbera

Legacy Theses & Dissertations (2009 - 2024)

One of the key challenges in fabricating narrower and higher aspect ratio interconnects using damascene technology has been achieving an ultra-thin (~2 nm) and continuous Cu seed coverage on trench sidewalls. The thin seed is prone to agglomeration because of poor Cu wetting on the Ta liner. Using in-situ conductance measurements, the effect of lowering the substrate temperature during Cu seed deposition has been studied on tantalum (Ta) and ruthenium (Ru) liner surfaces. On a Ta surface, it was found that lowering the deposition temperature to -65°C increases the nucleation rate of the Cu thin film, and reduces the minimum …

Understanding And Improving Lithium Ion Batteries Through Mathematical Modeling And Experiments, Rutooj D. Deshpande

Theses and Dissertations--Chemical and Materials Engineering

There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary.

One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result …

Synthesis And Characterization Of Carbon Magnetic Nanoparticles, Sunilsingh Gusain

Material Science and Engineering Theses - Archive

Carbon incorporated iron nanoparticles (Fe-CNPs) were successfully synthesized using ultrasonic cavitation in Benzene. This novel method of carbon nanoparticle (CNP) synthesis is a very cost-effective and versatile as one can easily tune the microstructure and magnetic properties by varying few parameters, for e.g. voltage. The Fe-CNP complexes are produced due to the electric plasma discharge generated between the electrodes in an ultrasonic cavitation field of liquid benzene. The constituent of the CNPs can be easily modified by different choice of electrode materials- iron and graphite. The resultant Fe-CNPs were characterized by high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy to …