Dissertations / Theses on the topic 'Angle deposition'
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Robbie, Kevin. "Glancing angle deposition." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0013/NQ39771.pdf.
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Zhou, Wei. "Oblique Angle Deposition Effects on Magnetron-Sputtered Metal Films." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1501067883261477.
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Liu, Xuejing. "GPU Enhanced Simulations of Glancing Angle Deposition of Metal Thin-Films." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1325704817.
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Johansson, Viktor. "Off-normal Film Growth by High Power Impulse Magnetron Sputtering." Thesis, Linköpings universitet, Plasma och beläggningsfysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71315.
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In this study we contribute towards establishing the process-microstructure relationships in thin films grown off-normally by ionized physical vapor deposition. High power impulse magnetron sputtering (HiPIMS) is used at various peak target powers and deposition rates to grow copper (Cu) and chromium (Cr) films from a cathode placed at an angle 90 degrees with respect to the substrate normal. Films are also deposited by direct current magnetron sputtering (DCMS), for reference. Scanning electron microscopy is employed to investigate column tilting and deposition rate while X-ray diffraction techniques are utilized to study crystal structure and grain tilting. It is demonstrated that the columnar structure of Cu tilts less with respect to the substrate normal as the peak target power increases, which has been shown to correspond to a higher ionization degree of the sputtered material [1]. One explanation for this is that the trajectories of the ions are deflected towards the substrate and therefore deposited closer to the normal, as has been suggested in the literature (see e.g. [2]). Energetic bombardment by ions might also increase surface mobility, which further raises the columns. It is also concluded that the change in tilting is not caused by a lower deposition rate obtained when employing HiPIMS. The same is not seen for Cr, where all deposited films exhibit the same tilting angle. When the column tilting of Cu and Cr is compared a large difference is observed, where the columns of Cr are closer to the substrate normal. The reasons for this difference are discussed in light of nucleation and growth characteristics in the two materials. X-ray diffraction analysis reveals that Cu films exhibit an (111) fiber texture. Comparison of films grown by DCMS and HiPIMS shows that in the HiPIMS cases the grains are closer to the surface normal and better oriented with each other. In the case of Cr both DCMS and HiPIMS grown films are (110) biaxially aligned.
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Sawant, Namita Ajay. "Deposition patterns of nasal sprays in children." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6636.
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Nasal sprays used for the treatment of cold and allergy symptoms use same device and formulation in children and adults. Owing to the obvious differences in nasal cavity dimensions between adults and children, the performance of nasal sprays products in children needs to be critically assessed.
In an effort to evaluate the deposition patterns of nasal sprays administered to children, a nasal cast based on MRI images obtained from a 12-year-old child’s nasal cavity was developed using 3D printing technology. Glycerin-water mixtures providing sprays with a range of plume angles (26° - 62°), along with three additional commercial nasal sprays, were investigated by actuating the device into the cast under controlled conditions. Following spray administration, the cast was disassembled and subjected to image analysis followed by quantification of formulation deposition in each section of the cast using both chemical and image analysis. The results showed that nasal sprays impacted entirely in the anterior region of the 12-year-old child’s nasal cavity and limited amount of spray entered the turbinate region – the effect site for most topical drugs.
Additional experiments were conducted to measure the deposition patterns of nasal sprays in the presence of a mucus layer on the surface of the nasal cast. In an effort to make the nasal deposition studies more relevant to human nasal conditions, the mucus coated nasal cast was tilted in order to induce a physical movement of the mucus layer from the anterior region to the nasopharynx. The presence of mucus did not result in a significant increase in the turbinate region deposition but tilting of the mucus coated nasal cast resulted in 20% - 40% deposition in the turbinate region, improving the posterior region deposition of sprays. Even with the enhanced posterior movement nearly 60% of the spray formulations remained in the anterior region, a site with poor absorption characteristics.
The computational fluid dynamic simulations evaluated the impact of multiple parameters including plume angle, droplet diameter and administration conditions on the deposition of nasal sprays in the 12-year-old child’s nasal cavity. The simulations showed significant anterior deposition for all plume angles (10° – 50°) and droplet diameters (30 µm – 400 µm) tested, similar to the observations from the in vitro experiments. An additional parameter, the direction of nasal spray actuation in the nasal cavity, was identified as a critical factor improving the turbinate region deposition of sprays in the 12-year-old child’s nasal cavity in spite of the narrow nasal valve region.
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Shah, Piyush J. "Nanostructured Columnar Thin Films Using Oblique Angle Deposition: Growth, SERS Characterization and Lithographic Processing." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1341852929.
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Attinger, Daniel. "An investigation of microdroplet surface deposition : transient behavior, wetting angle dynamics and substrate melting phenomenon /." Zürich : [s.n.], 2001. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14004.
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Shaoguang, Chen. "Experimental Investigation on Mechanical Properties of Nanospring Thin Films Fabricated by Glancing Angle Deposition Technique." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225556.
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Deng, Junhong. "Numerical and analytical studies of ciricular dichroism of plasmonic nanospirals generated by glancing angle deposition /Deng Junhong." HKBU Institutional Repository, 2017. http://repository.hkbu.edu.hk/etd_oa/345.
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As emerging chiral metamaterials, plasmonic nanospirals (NSs) show strong optical activity that is expected to enhance the enantiodiscrimination of chiral molecules or help in the design of a new generation of integrated optical devices. The study of the optical activity of plasmonic NSs is still in its infancy, and no analytical model exists to describe their chiroptical mechanism. In this study, numerical and analytical simulations are devised to investigate the optical activity of plasmonic NSs that are generated by glancing-angle deposition. The findings will pave the way for the development of novel optical and optoelectronic devices with integrated functions. The CD spectrum of a closely packed random AgNS array has two CD peaks in the UV and visible regions with opposite signs. The pitch-normalized CD in the UV regime tends to be independent of the helical pitch, but that in the visible regime decreases in amplitude as helical pitch increases. The difference can be explained using an analytical LC circuit model and finite-element method simulation. The LC circuit model is used to quantitatively evaluate the chiroptical contribution. It is revealed that radiative loss makes an important chiroptical contribution to the two CD modes and that the visible CD mode receives a greater contribution from radiative loss than does the UV CD mode. Finally, the heterochiral biaxial AgNS arrays alter the sign of the visible CD by switching the incident direction, which shows that the arrays can function as circular polarizers in the visible regime. Furthermore, when AgNSs are deposited on a polymer substrate coated with indium tin oxide, the chiroptical flexible thin film has excellent chiroptical stability when exposed to forward mechanical bending, paving the way for the development of flexible or wearable chiroplasmonic devices.
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Dudipala, Ajay Prasad Reddy Gupta Sanju. "Ex situ variable angle spectroscopic ellipsometry studies on chemical vapor deposited boron-doped diamond films layered structure and modeling aspects /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/6079.
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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 7, 2009) Thesis advisor: Dr. Sanju Gupta. Includes bibliographical references.
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Li, Bo. "EFFECT OF FABRIC ANISOTROPY ON THE DYNAMIC MECHANICAL BEHAVIOR OF GRANULAR MATERIALS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1291071699.
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Blunt, Rory Alexander Fabian. "A Study of the Effects of Turning Angle on Particle Deposition in Gas Turbine Combustor Liner Effusion Cooling Holes." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460735904.
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Marotta, Nicole Ella. "Patterned nanoarray sers substrates for pathogen detection." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37274.
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The objectives of the work presented were to 1) fabricate reproducible nanorod array SERS substrates, 2) detection of bacteria using nanorod substrates, 3) detection of DNA hybridization using nanorod substrates and 4) critically evaluate the sensing method.
Important findings from this work are as follows. A novel method for batch fabrication of substrates for surface enhanced Raman scattering (SERS) has been developed using a modified platen machined to fit in a commercial electron beam evaporator. The use of this holder enables simultaneous deposition of silver nanorod (AgNR) arrays onto six microscope slide substrates utilizing glancing angle deposition. In addition to multiple substrate fabrication, patterning of the AgNR substrates with 36 wells allows for physical isolation of low volume samples. The well-to-well, slide-to-slide, and batch-to-batch variability in both physical characteristics and SERS response of substrates prepared via this method was nominal. A critical issue in the continued development of AgNR substrates is their stability over time, and the potential impact on the SERS response. The thermal stability of the arrays was investigated and changes in surface morphology were evaluated using scanning electron microscopy and x-ray diffraction and correlated with changes in SERS enhancement. The findings suggest that the shelf-life of AgNR arrays is limited by migration of silver on the surface. Continued characterization of the AgNR arrays was carried out using fluorescent polystyrene microspheres of two different sizes. Theory suggests that enhancement between nanorods would be significantly greater than at the tops due to contributing electromagnetic fields from each nanostructure. In contrast to the theory, SERS response of microspheres confined to the tops of the AgNR array was significantly greater than that for beads located within the array. The location of the microspheres was established using optical fluorescence and scanning electron microscopy.
The application of SERS to characterizing pathogens such as bacteria and viruses is an active area of investigation. AgNR array-based SERS substrates have enabled detection of pathogens present in biofluids. Specifically, several publications have focused on determining the spectral bands characteristic of bacteria from different species and cell lines. Studies were carried out on three strains of bacteria as well as the medium in which the bacteria were grown. The spectra of the bacteria and medium were surprisingly similar, so additional spectra were acquired for commonly used bacterial growth media. In many instances, these spectra were similar to published spectra purportedly characteristic of specific bacterial species.
In addition to bacterial samples, nucleic acid hybridization assays were investigated. Oligonucleotide pairs specifically designed to detect respiratory syncytial virus (RSV) in nasal fluids were prepared and evaluated. SERS spectra acquired on oligos, alone or in combination, contain the known spectral signatures of the nucleosides that comprise the oligo. However, spectra acquired on an oligo with a 5'- or 3' thiol were distinctly different from that acquired on the identical oligo without a thiol pendant group suggesting some control over the orientation of the oligo on the nanorod surface. The signal enhancement in SERS depends markedly upon the location of the probe relative to the substrate surface. By systematic placement of nucleotide markers along the oligo chain, the point at which the nucleotide disappears from the spectrum was identified.
The overall findings for AgNR SERS substrates suggest that the applicability of SERS for detecting nucleic acid hybridization is limited. The strong distance dependence coupled with the lack of substrate stability at temperatures required for annealing oligos during hybridization suggest that AgNRs are not the platform to use for hybridization assays.
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Alrashid, Ebtihaj Jr. "Premelting Study of Nickel Nanorod Arrays." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3037.
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In this study, samples of nanoscale structures of nickel (Ni) nanorods were prepared using the glancing angle deposition (GLAD) technique. Annealing was done using a split- top tube furnace at high vacuum chamber pressure. The pre-melting of the nanorods was maintained at 500 °C for 30 minutes in all the samples. Using the samples with 90 minutes of GLAD time, the annealing behavior of the nanorods was studied at 300 °C, 400 °C, 500 °C and 600 °C. The nanorods were then imaged using scanning electron microscopy. Using X-ray diffraction, the crystalline microstructures of the nanorods were studied. It was found that with increasing annealing temperatures, the intensity of peaks for both Ni (111) and Ni (200) increased, which indicates that better crystals were formed. The results indicate that re-crystallization occurs after annealing, leading to the formation of larger grain sizes compared to as-deposited grain sizes. Annealing substantially changed the structure of the nanorods, leading to different smoother, more connected crystal structures for the annealed nanorods compared to as-deposited ones.
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Yu, Qingcheng. "Influence of Discharge Ratio and Junction Angle on Sediment Transport and Deposition Patterns in Open Channel Confluences: An Experimental Study." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38582.
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Open channel confluences are common geographical structures in surface runoff. Most natural rivers originate from mountains and hills, flow into a main stream at confluences and finally head into the sea. Confluences are major sites for a main stream to obtain sediment and water from a tributary. Complex turbulence structures such as vortices, flow stagnation, secondary flow, flow re-circulation and water exchange both in vertical and lateral directions result in complicated sedimentation, erosion, mixing and contaminant transport at open channel confluences. The detailed study of flow dynamics and morphodynamics in confluences is of great significance to the urban flood control, scour of the river bed, design and maintenance of the channel and sediment and pollutants transport. This thesis describes a novel flume experiment on the sediment transport patterns in channel confluences as a function of different flow and geometry conditions. The initial equilibrium bed geometry was developed in a mobile bed confluence flume under four cases including two junction angles and two discharge ratios. The equilibrium bed was fixed for each case allowing for detailed flow velocimetry. The observed spatial patterns of turbulence statistics are evaluated with respect to the equilibrium bathymetry. Sediment were then fed instantaneously to the tributary channel at three different feeding sites in order to study the sediment deposition patterns. It was observed that although the sediment initiated at different feeding sites move along different paths through the confluence, all sediment tend to deposit at the face of the dune in the flow separation zone. This thesis also investigated how the deposition pattern would change versus time when feeding at the same site from the tributary channel. The time history of deposition pattern was also investigated for one of the cases. The sediment that initially deposit at the face of the dune eventually moved to the back of the dune and deposit around the post-confluence scour hole, demonstrating that over time the deposition pattern evolves to a state which is similar with the original bed morphology.
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Gustafson, Johan. "Fabrication and Characterization of Sculptured Thin Silver Films." Thesis, Linköpings universitet, Tillämpad optik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-89988.
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In this work samples with silver nanocolumnar structures were successfully fabricated by glancingangle deposition. From SEM investigations of the samples it is concluded that distinct andseparated nanocolumns can be grown without pre-patterned substrates using this method (givensuitable deposition conditions). The sample that exhibits the most distinct and well separatedcolumns was modelled using HFSS with optical properties of silver in nanocolumns obtained bymeasurements on the samples grown by glancing angle deposition, thin enough to not havedeveloped columns. From numerical calculations it was shown that the unit cell arrangement of thecolumns has a large influence on the optical characteristics. It was found that a diamond-like unitcell designed as two identical square lattices shifted by half the lattice spacing in one direction and2-1/2 times the lattice spacing of the other direction gives the best and a fair agreement to theexperimental ellipsometry data. Based on this model calculations were made to determine thewavelength dependent average local current exhibited in the columns as well as the currentdensity. This study showed the occurrence of broadbanded plasmon resonances of longitudinalmode at λ=1363 nm and of transverse mode at λ=545 nm. It was also shown that the opticalcharacteristics are strongly polarization dependent as is expected for such anisotropic samples.
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Boukhalfa, Sofiane. "Studies of ion electroadsorption in supercapacitor electrodes." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52976.
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Electrochemical capacitors, now often termed supercapacitors, are high power electrochemical energy storage devices that complement or replace high power batteries in applications ranging from wind turbines to hybrid engines to uninterruptable power supplies to electronic devices. My dissertation explores the applications of relatively uncommon techniques for both supercapacitor material syntheses and gaining better mechanistic understanding of factors impacting electrochemical performance of supercapacitors. From fundamental ion electroadsorption studies made possible by using small angle neutron scattering (SANS), to the systematic investigations of coating thickness and microstructure in metal oxide / carbon nanocomposite electrodes realized through the novel use of the atomic layer deposition (ALD) technique, new avenues of material characterization and fabrication have been studied.
In this dissertation I first present the motivation to expand the knowledge of supercapacitor science and technology, and follow with an in-depth literature review of the state of the art. The literature review covers different types of supercapacitors, the materials used in the construction of commercial and exploratory devices, an exploration of the numerous factors which affect supercapacitor performance, and an overview of relevant materials synthesis and characterization techniques The technical objectives for the work performed in this dissertation are then presented, followed by the contributions that I made in this field in my two primary research thrusts: advances to the understanding of ion electroadsorption theory in both aqueous and organic electrolytes through the development of a SANS-based methodology, and advances to metal-oxide carbon nanocomposites as electrodes through the use of ALD.
The understanding of ion electro-adsorption on the surface of microporous (pores < 2 nm) solids is largely hindered by the lack of experimental techniques capable of identifying the sites of ion adsorption and the concentration of ions at the nanoscale. In the first research thrust of my dissertation, I harness the high penetrating power and sensitivity of neutron scattering to isotope substitution to directly observe changes in the ion concentration as a function of the applied potential and the pore size. I have conducted initial studies in selected aqueous and organic electrolytes and outlined the guidelines for conducting such experiments for the broad range of electrode-ions-solvent combinations. I unambiguously demonstrate that depending on the solvent properties and the solvent-pore wall interactions, either enhanced or reduced ion electro-adsorption may take place in sub-nanometer pores. More importantly, for the first time I demonstrate the route to identify the critical pore size below which either enhanced or reduced electrosorption of ions takes place. My studies experimentally demonstrate that poor electrolyte wetting in the smallest pores may indeed limit device performance. The proposed methodology opens new avenues for systematic in-situ studies of complex structure-property relationships governing adsorption of ions under applied potential, critical for rational optimization of device performance.
In addition to enhancing our understanding of ion sorption, there is a critical need to develop novel supercapacitor electrode materials with improved high-energy and high-power characteristics. The formation of carbon-transition metal oxide nanocomposites may offer unique benefits for such applications. Broadly available transition metal oxides, such as vanadium oxide, offer high ion storage capabilities due to the broad range of their oxidation states, but suffer from high resistivities. Carbon nanomaterials, such as carbon nanotubes (CNT), in contrast are not capable to store high ion content, but offer high and readily accessible surface area and high electrical conductivity. In the second research thrust of my thesis, by exploiting the ability of atomic layer deposition (ALD) to produce uniform coatings of metal oxides on CNT electrodes, I demonstrated an effective way to produce high power supercapacitor electrodes with ultra-high energy capability. The electrodes I developed showed stable performance with excellent capacitance retention at high current densities and sweep rates. Electrochemical performance of the oxide layers were found to strongly depend on the coating thickness. Decreasing the vanadium oxide coating thickness to ~10 nm resulted in some of the highest values of capacitance reported to date (~1550 F·g⁻¹VOx at 1 A·g⁻¹ current density). Similar methodology was utilized for the deposition of thin vanadium oxide coatings on other substrates, such as aluminum (Al) nanowires. In this case the VOₓ coated Al nanowire electrodes with 30-50% of the pore volume available for electrolyte access show volumetric capacitance of 1390-1950 F cc⁻¹, which exceeds the volumetric capacitance of porous carbons and many carbon-metal oxide composites by more than an order of magnitude. These results indicated the importance of electrode uniformity and precise control over conformity and thickness for the optimization of supercapacitor electrodes.
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Kitenge, Denis. "Optical detection of CO and H2 based on surface plasmon resonance with Ag-YSZ, Au and Ag-Cu nanoparticle films." Scholar Commons, 2009. http://scholarcommons.usf.edu/etd/2047.
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Silver, gold, and copper metallic nanoparticle films have been utilized in various MEMS devices due to not only their electrical but also their optical properties. The focus of this research is to study the detection at room temperature of carbon monoxide (CO) and hydrogen (H2) via Surface Plasmon Resonance (SPR) phenomenon of silver-embedded Yttrium Stabilized Zirconium (Ag-YSZ) nanocomposite film, gold (Au) nanoparticle film, and an alloy film of silver-copper (Ag-Cu) , grown by the Pulsed Laser Deposition (PLD). To determine the appropriate film materials for quick and accurate CO and H2 detection at room temperature with the PLD technique, the growth process was done repeatedly. Optical tools such as X-Ray Diffraction, Alpha Step 200 Profilometer, Atomic Force Microscopy, and Scanning Electron Microscopy were used to characterize thin films.
The gas sensing performance was studied by monitoring the SPR band peak behavior via UV/vis spectrophotometer when the films were exposed to CO and H2 and estimating the percent change in wavelength. The metallic nanoparticle films were tested for concentration of CO (100 to 1000 ppm) and H2 (1 to 10%). Silver based sensors were tested for the cross-selectivity of the gases. Overall the sensors have a detection limit of 100 ppm for CO and show a noticeable signal for H2 in the concentration range as low as 1%. The metallic films show stable sensing over a one-hour period at room temperature. The SPR change by UV/vis spectrophotometer shows a significant shift of 623 nm wavelength between 100 ppm CO gas and dry air at room temperature for the alloy films of Ag-Cu with a wider curve as compared to silver and gold films upon their exposure to CO and H2 indicating an improvement in accuracy and quick response.
The results indicate that in research of CO and H2 detection at room temperature, optical gas sensors rather than metal oxide sensors are believed to be effective due to not only the absence of chemical involvement in the process but also the sensitivity improvement and accuracy, much needed characteristics of sensors when dealing with such hazardous gases.
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Hubartt, Bradley C. "Nucleation and Growth, Defect Structure, and Dynamical Behavior of Nanostructured Materials." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1416828345.
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Fan, Ming. "Pore-scale Study of Flow and Transport in Energy Georeservoirs." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/101863.
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Optimizing proppant pack conductivity and proppant-transport and -deposition patterns in a hydraulic fracture is of critical importance to sustain effective and economical production of petroleum hydrocarbons. In this research, a numerical modeling approach, combining the discrete element method (DEM) with the lattice Boltzmann (LB) simulation, was developed to provide fundamental insights into the factors regulating the interactions between reservoir depletion, proppant-particle compaction and movement, single-/multiphase flows and non-Darcy flows in a hydraulic fracture, and fracture conductivity evolution from a partial-monolayer proppant concentration to a multilayer proppant concentration. The potential effects of mixed proppants of different sizes and types on the fracture conductivity were also investigated.
The simulation results demonstrate that a proppant pack with a smaller diameter coefficient of variation (COV), defined as the ratio of standard deviation of diameter to mean diameter, provides better support to the fracture; the relative permeability of oil was more sensitive to changes in geometry and stress; when effective stress increased continuously, oil relative permeability increased nonmonotonically; the combination of high diameter COV and high effective stress leads to a larger pressure drop and consequently a stronger non-Darcy flow effect. The study of proppant mixtures shows that mixing of similar proppant sizes (mesh-size-20/40) has less influence on the overall fracture conductivity than mixing a very fine mesh size (mesh-size-100); selection of proppant type is more important than proppant size selection when a proppant mixture is used. Increasing larger-size proppant composition in the proppant mixture helps maintain fracture conductivity when the mixture contains lower-strength proppants. These findings have important implications to the optimization of proppant placement, completion design, and well production.
In the hydraulic-mechanical rock-proppant system, a fundamental understanding of multiphase flow in the formation rock is critical in achieving sustainable long-term productivity within a reservoir. Specifically, the interactions between the critical dimensionless numbers associated with multiphase flow, including contact angle, viscosity ratio, and capillary number (Ca), were investigated using X-ray micro computed tomography (micro-CT) scanning and LB modeling. The primary novel finding of this study is that the viscosity ratio affects the rate of change of the relative permeability curves for both phases when the contact angle changes continuously. Simulation results also indicate that the change in non-wetting fluid relative permeability was larger when the flow direction was switched from vertical to horizontal, which indicated that there was stronger anisotropy in larger pore networks that were primarily occupied by the non-wetting fluid. This study advances the fundamental understanding of the multiphysics processes associated with multiphase flow in geologic materials and provides insight into upscaling methodologies that account for the influence of pore-scale processes in core- and larger-scale modeling frameworks.
During reservoir depletion processes, reservoir formation damage is an issue that will affect the reservoir productivity and various phases in fluid recovery. Invasion of formation fine particles into the proppant pack can affect the proppant pack permeability, leading to potential conductivity loss. The combined DEM-LB numerical framework was used to evaluate the role of proppant particle size heterogeneity (variation in proppant particle diameter) and effective stress on the migration of detached fine particles in a proppant supported fracture. Simulation results demonstrate that a critical fine particle size exists: when a particle diameter is larger or smaller than this size, the deposition rate increases; the transport of smaller fines is dominated by Brownian motion, whereas the migration of larger fines is dominated by interception and gravitational settling; this study also indicates that proppant packs with a more heterogeneous particle-diameter distribution provide better fines control. The findings of this study shed lights on the relationship between changing pore geometries, fluid flow, and fine particle migration through a propped hydraulic fracture during the reservoir depletion process.Doctor of Philosophy
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Yu, Shuwen. "Performance enhancement of organic photovoltaic cells through nanostructuring and molecular doping." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17150.
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Die vorliegende Arbeit beschäftigt sich mit der Leistungssteigerung organischer Solarzellen durch Änderung der Geometrie an der Donor-Akzeptor Grenzfläche und dem Einstellen der elektronischen Eigenschaften von Grenzflächen durch molekulares p-Dotieren. Kristalline und gleichmäßige Nanosäulen aus dem organischen Halbleiter Pentazen wurden durch glancing angle deposition (GLAD) hergestellt, die einen ineinandergreifenden Heteroübergang zu Methanofulleren [6,6]-Phenyl-C61-Butansäure Methylester (PCBM) als Akzeptor ermöglichten. Die Kurzschlussspannung der nanosäulenbasierten Solarzellen war signifikant erhöht im Vergleich zu planaren Heteroübergängen zwischen denselben Materialien. Die Leistungssteigerung der Solarzellen konnte maßgebend der vergrößerten Grenzfläche zugewiesen werden, wegen des verringerten Einflusses der kurzen Exciton Diffusionslänge. Molekulares p-Dotieren mit Tetrafluorotetracyanoquinodimethan (F4TCNQ) als Dotand in polyfuranbasierten Solarzellen wurde für verschiede Dotierkonzentrationen untersucht. Ultraviolettphotoelektronenspektroskopie wurde verwendet, um die Veränderungen der Energieniveaus mit zunehmender Dotierkonzentration zu analysieren, welche zu einer Vergrößerung der 0,2 V Kurzschlussspannung auf bis zu 0,4 V führte. Nach Kombination dieser Beobachtung mit Ergebnissen an dotierten Polymerfilmen, insbesondere bezüglich deren Morphologie und Absorptionsverhalten, wurde vorgeschlagen, dass ein resultierender Dipol an der Donor-Akzeptorgrenzfläche präsent ist. Zusammenfassend zeigt die vorliegende Arbeit das Potential sowohl der GLAD Technik als auch des molekularen, elektrischen Dotierens für die Leistungsverbesserung organischer Solarzellen.The present work mainly focuses on improving the performance of OPVCs by tailoring the donor-acceptor interface geometry and by tuning the electrical properties of interfaces with p-type molecular doping. Crystalline and uniform nanocolumns of pentacene (PEN) and diindenoperylene (DIP) were fabricated by glancing angle deposition (GLAD), forming an interdigitated donor/acceptor heterojunction with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and/or fullerene as the electron acceptor. The short circuit current of nanocolumn-based OPVCs increased significantly compared to planar heterojunction OPVCs made from the same materials. The performance improvement of OPVCs had been verified to be contributed decisively by the donor-acceptor interface area enlargement because of reduced impact of short exciton diffusion length in organic materials. P-type molecular doping as applied in polyfuran (PF) based OPVCs was investigated by using tetrafluorotetracyanoquinodimethane (F4-TCNQ) as the dopant for various doping ratios. Ultraviolet photoelectron spectroscopy (UPS) was applied to analyze the energy level shift with increasing doping ratio leading to the enlargement of the open circuit voltage in OPVCs, from 0.2 V to close to 0.4 V. Combining this observation with the results of doped polymer films, their morphology and absorption behavior, a net dipole pointing towards the donor material at the donor-acceptor interface of OPVCs is proposed. Overall, this work demonstrates the potential of both the GLAD technique and molecular electrical doping for improving the performance of OPVCs.
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Borovikov, Valery V. "Multi-scale Simulations of Thin-Film Metal Epitaxial Growth." University of Toledo / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1216928358.
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McNeilly, Ryan J. "Nanostructured Microcantilever for the Detection of Volatile Compounds." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1511803746331593.
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Adhikari, Dipendra. "Optical and Microstructural Properties of Sputtered Thin Films for Photovoltaic Applications." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1573118517150321.
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Ferris, Anaïs. "Structuration de collecteurs de courant d'or pour la réalisation de micro-supercondensateurs à base d'oxyde de ruthénium." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30022/document.
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Depuis une dizaine d'années, on observe un développement de l'électronique embarquée intégrée à la plupart des objets que nous utilisons au quotidien. Il s'agit maintenant de les interconnecter en créant des réseaux embarqués connectés tels que les réseaux de capteurs autonomes sans fils. La miniaturisation des composants permet d'envisager une autonomie énergétique de ces réseaux composés de capteurs, récupérateurs d'énergie et de micro-batteries. Cependant la faible durée de vie des batteries et leur puissance limitée sont problématiques pour de telles applications. Les micro-supercondensateurs représentent une alternative pertinente pour la gestion de l'énergie dans les systèmes embarqués, notamment grâce à leur durée de vie très élevée. L'objectif de cette thèse concerne l'optimisation des performances de ces dispositifs en termes de densité de puissance et d'énergie. La capacité du supercondensateur étant proportionnelle à la surface électrochimiquement active des électrodes, nous nous sommes donc intéressés à la structuration de collecteurs de courant en or pour optimiser les performances des micro-supercondensateurs à base d'oxyde de ruthénium. Nous avons sélectionné deux principales techniques pour fabriquer une structure tridimensionnelle de l'or. Dans un premier temps, le dépôt physique d'or par évaporation à angle oblique (OAD) nous a permis de réaliser un substrat colonnaire suivi d'un dépôt d'oxyde de ruthénium. Dans un deuxième temps, nous avons mis en place un dépôt électrochimique d'or avec un modèle dynamique à bulles d'hydrogène. Cette technique permet la fabrication d'une structure d'or en trois dimensions par le biais d'un dépôt d'or réalisé simultanément avec une évolution d'hydrogène. L'électrodéposition de l'oxyde de ruthénium sur cette structure poreuse a montré une très bonne compatibilité notamment en terme d'homogénéité du dépôt, une forte capacité à faible vitesse de balayage (> 3 F/cm2) et une bonne cyclabilité. Pour tester les performances de ces électrodes, nous avons réalisé un dispositif complet en configuration empilée présentant de bonnes caractéristiques. Cette technologie de fabrication a pu par ailleurs être transférée à la micro-échelle pour des dispositifs planaires à l'aide de procédés de photolithographie sur électrodes interdigitéesThe increasing importance of portable and wearable electronics as well as embedded wireless sensor networks has made energy autonomy a critical issue. Micro-energy autonomy solutions based on the combination of energy harvesting and storage may play a decisive role. However, the short lifetime of micro-batteries is problematic. Micro-supercapacitors are a promising solution in terms of energy storage for embedded systems on the account of their important lifetime. In this work we have focused on the optimization of the performances of micro-supercapacitors in terms of energy and power density. As the capacitance is directly related to the accessible surface area of the electrodes, we have investigated the structuration of the current collectors in order to improve the performances of ruthenium oxide-based micro-supercapacitors. Two mains technics have been studied to obtain three dimensional structures. In a first phase, the oblique angle physical vapor deposition (OAD) has been investigated to fabricate a columnar gold structure, subsequently covered by an electrochemical ruthenium oxide. In a second phase, a highly porous gold architecture has been studied using electrodeposition via a hydrogen bubbles dynamic template. The ruthenium oxide electrodeposited on the resulting mesoporous gold structure shows good compatibility, in terms of homogeneous deposition, with a significant capacitance at slow rate (> 3F.cm-2) and an important cyclability. As proof of concept, a device has been designed in a stack configuration with good performances. Moreover, the technology finalized for electrodes fabrication has been transferred to the micro-scale on planar interdigitated devices using a suitable photolithography process
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Král, Filip. "Mechanické vlastnosti polymerů vyrobených 3D tiskem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378389.
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The thesis deals with the dependence of mechanical characteristics on the anisotropy of polymers Nylon 12 and Ultem 9085 made by a 3D printing technology Fused Deposition Modeling (FDM). The evaluation of the material characteristics was performed on the basis of tensile and non-instrumental impact tests. It was proven that the material characteristics are strongly dependent on anisotropy, i.e. on layer thickness and raster angle for both types of polymers.
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Piot, Adrien. "Etude de la fabrication et de la transduction d'un microgyromètre piézoélectrique tri-axial en GaAs." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS059/document.
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Un microgyromètre 3 axes permet avec une structure unique de mesurer la vitesse de rotation d’un objet autour des trois axes de l’espace. Les micro-gyromètres 3 axes existants sont peu nombreux et typiquement résonants, fabriqués en technologie silicium par micro-usinage de surface, à transductions électro-statiques, et conçus pour des applications de fort volume ou la taille et le coût sont des critères majeurs. Dans cette thèse nous avons étudié la transduction et le procédé de fabrication d’un gyromètre résonant 3 axes à actionnement et détection piézoélectriques, fabriqué par micro-usinage de volume dans du GaAs semi-isolant, et dont les performances sont potentiellement très supérieures à l’état de l’art tout en conservant une taille et un coût limité. Ce microgyromètre nécessite une transduction piézoélectrique 3D et un routage des connexions électriques qui ont été modélisés et optimisés pour réduire les couplages parasites entre les modes de détection et le mode pilote. Un procédé original de fabrication collective du microgyromètre a été développé, modélisé et caractérisé. Ce procédé utilise notamment une gravure ionique réactive très profonde et traversante du GaAs dans un plasma BCl3-Cl2. Il est démontré pour la première fois qu’une gravure anisotrope traversante de tranchées de 450 μm de profondeur peut être réalisée grâce à une optimisation des paramètres de gravure et à l’utilisation d’un masque en résine. Un procédé original de dépôt et de délimitation d’électrodes Au/Cr sur les flancs verticaux d’une structure gravée par évaporation sous incidence oblique avec rotation du substrat et à travers un masque pochoir en film sec photosensible a aussi été étudié en détail. Une caractérisation fine de la structure cristalline, de la résistivité et des contraintes mécaniques avant, pendant et après recuit des couches Au/Cr poreuses évaporées sous incidence oblique a été menée. Des micro-gyromètres complets avec tout le système de transduction 3D ont été réalisés. Des premières caractérisations par vibrométrie optique hors du plan et dans le plan des gyromètres réalisés démontrent des résultats encourageants. Enfin, différentes voies d’amélioration de la conception et du procédé sont proposéesA 3 axis gyroscope allows, with a single mechanical structure, the measurement of rotation rates of an object around 3 perpendicular spatial axes. Existing 3 axis microgyroscopes are scarce and typically resonating, made in silicon technology by surface micromachining, use electrostatic transductions and are designed for high volume applications where size and cost are major characteristics. In this thesis we investigated the transduction and fabrication process of a resonating 3 axis microgyroscope having piezoelectric actuation and detection, made in semi-insulating GaAs by bulk micromachining, and with performances potentially much higher than state of the art while limiting the size and cost. This microgyroscope requires a 3D piezoelectric transduction and circuitry which were modelled and optimized to reduce cross-talks effects. An original batch fabrication process was developed, modelled and characterized. This process notably makes use of very deep through wafer reactive ion etching of GaAs in a BCl3-Cl2 plasma. It is demonstrated for the first time that a through wafer highly anisotropic etching of 450 μm deep trenches can be realized owing to etching parameters optimization and the use of a resist masking layer. An original deposition and patterning process of Au/Cr electrodes on the vertical walls of an etched structure by oblique evaporation on rotated substrate through a dry film shadow mask has also been investigated in details. A fine characterization of the crystallographic structure, resistivity and mechanical stress before, during and after annealing of Au/Cr films evaporated under oblique incidence has been performed. Full microgyroscopes with the whole 3D tranduction system were realized. Preliminary characterizations of realized gyroscopes by out-of-plane and in-plane optical vibrometry demonstrated promising results. Finally, different ways to improve the design and fabrication process are proposed
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Sovar, Robert D. "Novel analytical techniques for the assessment of degradation of silicone elastomers in high voltage applications." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16072/1/Robert_Sovar_Thesis.pdf.
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Over the last 20 years "composite" insulators have been increasingly used in high voltage applications as an alternative traditional materials. More recently, polydimethylsiloxane (PDMS) have been used as weather sheds on these composite insulators. The main attraction with PDMS is that the surface hydrophobicity can be recovered following pollution or surface discharges. Among the possible mechanisms for recovery the most likely is the migration of low molecular weight silicone oil (LMWS) from the bulk to the surface encapsulating pollutant particles. Although it is widely recognised that the migration of LMWS is the cause of this recovery of hydrophobicity, the mechanism of what actually occurs is not well understood. It is also not known for how long this process will continue.
The main objective of this study program was to gain improved understanding of the surface hydrophobic recovery process that is unique to polydimethlysiloxane high-voltage insulators. Fundamental knowledge of this mechanism has been increased through the development of the Contact Angle DRIFT Electrostatic Deposition (CADED) novel analytical technique. This technique enabled study of the degradation of silicone elastomers subjected to high voltage environments by closely following LMWS migration from the bulk material to the surface and linking it to the contact angle measurements. The migration rate data showed that the aged material recovered faster that the virgin material. Differences in the rate and maximum surface levels of silicone were seen between materials from different manufacturers. This has significant implications for the life-time of these materials
A model system has been developed to examine LMWS diffusion through the bulk material and into the interface of surface and pollutant. This was achieved by examining theoretical and empirically derived equations and using existing experimental data to better understand the mechanism of recovery. This diffusion was Fickian in the initial stages of recovery.
X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used to substantiate the degree of degradation in in-field silicone insulators by quantifying the levels of the major degradation products: silica and silica-like material and alumina.
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Sovar, Robert D. "Novel Analytical Techniques For the Assessment of Degradation of Silicone Elastomers in High Voltage Applications." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16072/.
Full textAbstract:
Over the last 20 years "composite" insulators have been increasingly used in high voltage applications as an alternative traditional materials. More recently, polydimethylsiloxane (PDMS) have been used as weather sheds on these composite insulators. The main attraction with PDMS is that the surface hydrophobicity can be recovered following pollution or surface discharges. Among the possible mechanisms for recovery the most likely is the migration of low molecular weight silicone oil (LMWS) from the bulk to the surface encapsulating pollutant particles. Although it is widely recognised that the migration of LMWS is the cause of this recovery of hydrophobicity, the mechanism of what actually occurs is not well understood. It is also not known for how long this process will continue. The main objective of this study program was to gain improved understanding of the surface hydrophobic recovery process that is unique to polydimethlysiloxane high-voltage insulators. Fundamental knowledge of this mechanism has been increased through the development of the Contact Angle DRIFT Electrostatic Deposition (CADED) novel analytical technique. This technique enabled study of the degradation of silicone elastomers subjected to high voltage environments by closely following LMWS migration from the bulk material to the surface and linking it to the contact angle measurements. The migration rate data showed that the aged material recovered faster that the virgin material. Differences in the rate and maximum surface levels of silicone were seen between materials from different manufacturers. This has significant implications for the life-time of these materials A model system has been developed to examine LMWS diffusion through the bulk material and into the interface of surface and pollutant. This was achieved by examining theoretical and empirically derived equations and using existing experimental data to better understand the mechanism of recovery. This diffusion was Fickian in the initial stages of recovery. X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used to substantiate the degree of degradation in in-field silicone insulators by quantifying the levels of the major degradation products: silica and silica-like material and alumina.
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Booso, Benjamin David. "The Growth of Columnar Thin Films and Their Characterization Within the Visible and Near Infrared Spectral Bands." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1272587327.
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Thibodeau, Alexis. "3D-Printed Surrogate Lower Limb for Testing Ankle-Foot Orthoses." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42755.
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Traditionally, the mechanical testing of ankle-foot orthoses (AFOs) has been performed with simple limb surrogates, typically with a single axis ankle joint and rigid foot and shank components. Since many current AFO designs allow 3D motion, a surrogate lower limb (SLL) that provides anatomically similar motion in all planes is needed to enable realistic load testing and cyclic testing in a controlled manner. The aim of this thesis was to design, fabricate and test a novel SLL that provides anatomically realistic 3D foot motion, based on a consensus of the passive lower limb range of motion (RoM) found in the literature.
The SLL design was inspired by the Rizzoli model, sectioning the lower limb into five segments (shank, hindfoot, midfoot, forefoot, toes). Ball and socket joints were used for the shank-hindfoot, hindfoot-midfoot, and midfoot-forefoot. Forefoot-toes used a hinge-type joint. 3D printed flexible thermoplastic polyurethane (TPU) snap-fit connectors connected the 3D printed nylon foot blocks. A threaded ball stud connected the shank shaft and hindfoot. This shank shaft was surrounded by a 3D printed polylactic acid (PLA) shank cover. The foot was cast in silicone rubber to emulate soft tissue, with a PLA custom mould based on a Össur prosthetic foot cover model.
The SLL was successfully designed for easy fabrication using readily available techniques, materials, and components. Only the metal shaft required additional machining. 3D printed components used an affordable 3D printer (Artillery Sidewinder X1), and readily available nylon, PLA, and TPU.
Using motion capture testing, SLL foot rotation angles were found to be within standard deviation of mean foot passive rotation angle ranges found in the literature, showing that most joints were within 5° of target maximum rotation angles. With load testing, the SLL was shown to survive static loads representing 1.5 times body weight for a 100 kg individuals and cyclic loads representing normal gait loading for 500,000 cycles.
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Garrow, Duncan. "Pits, settlement and deposition during the Neolithic and early Bronze age in East Anglia /." Oxford : J. and E. Hedges, 2006. http://catalogue.bnf.fr/ark:/12148/cb402149296.
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Jenkins, Gareth. "An investigation of marine influence during deposition of the Lower Old Red Sandstone, Anglo-Welsh Basin, UK." Thesis, Cardiff University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287490.
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Maudet, Florian. "Couches nanostructurées par dépôt en incidence oblique : corrélations microstructure et propriétés optiques pour application aux traitements antireflets hautes performances dans le visible étendu et l'infrarouge." Thesis, Poitiers, 2018. http://www.theses.fr/2018POIT2295/document.
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Les traitements antireflets (AR) sont très largement utilisés pour améliorer la transmission de systèmes optiques composés de hublots, lentilles, de lames séparatrices,… Dans cette thèse les gammes spectrales visées sont le visible étendu [400-1800nm] et le moyen infrarouge [3,7-4,8µm]. La méthode de nanostructuration par dépôts de films minces utilisant des techniques PVD en incidence oblique (Oblique Angle Deposition) a été choisie car elle permet d’envisager des AR hautes performances sur une large gamme de longueur d’onde, via un procédé industrialisable. L’introduction de porosité via le contrôle des angles de dépôt est utilisée pour nanostructurer l’architecture de chaque couche et de l’empilement ; méthode permettant de modifier et d’optimiser les propriétés optiques des couches constituantes en vue d’un design complet optimal. Une cartographie des indices effectifs accessibles par OAD a été dégagée concernant les trois matériaux déposés (TiO2, SiO2 et Ge). Mais les propriétés optiques de ces couches nanostructurées diffèrent largement de celles des couches denses du fait de la présence d’anisotropie, de gradient d’indice, de diffusion et d’absorption. A partir de caractérisations microstructurales, chimiques et optiques poussées (AFM, MEB, MET, tomographie FIB, tomographie MET, EDX, EELS, spectrophotométrie et ellipsométrie généralisée) un modèle optique analytique plus complexe et couplé à des analyses par éléments finis (FDTD) est présenté. L’ensemble du travail a permis d’élaborer par OAD de simples antireflet bicouches démontrant déjà de hauts niveaux de transmission, supérieurs aux traitements AR existants (interférentiel) ou en développement (Moth-eyes)Anti-reflective (AR) coatings are widely used to improve the transmission of optical systems composed of window, lenses, separating filters,... In this thesis, the spectral ranges targeted are the extended visible [400-1800nm] and the mid infrared [3.7-4.8µm]. Thin film deposition nanostructuring method using oblique angle deposition (oblique angle deposition) PVD technique was chosen because it allows high performance AR to be considered over a wide wavelength range, by an industrial process. The introduction of porosity with the control of deposition angle is used to nanostructure the architecture of each layer and stack; a method for modifying and optimizing the optical properties of the constituent layers for optimal complete design. A mapping of the effective indices accessible by OAD has been identified for the three materials deposited (TiO2, SiO2 and Ge). However optical properties of these nanostructured layers differ greatly from those of dense layers due to the presence of anisotropy, index gradient, diffusion and absorption. Based on advanced microstructural, chemical and optical characterizations (AFM, SEM, TEM, FIB tomography, TEM tomography, EDX, EELS, spectrophotometry and generalized ellipsometry) a more complex analytical optical model coupled with finite element analyses (FDTD) is presented. All the work has enabled OAD to develop simple two-layer anti-reflective coatings that already demonstrate high levels of transmission, superior to existing (interferential) or work in progress (Moth-eyes) AR treatments
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Madaan, Nitesh. "Synthesis and Characterization of Complex Molecular Assemblies on Surfaces." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5748.
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The research presented in this dissertation is focused on the construction of complex molecular structures on planar gold and silicon dioxide surfaces using a variety of surface modification techniques, along with thorough surface characterization at each modification step. The dissertation is structured into six separate chapters. In Chapter 1, an introduction to the importance and implications of molecular level surface modification, commonly employed surface modification methods, and available surface characterization techniques is presented. Chapter 2 shows applications of novel methodologies for the functionalization of gold surfaces using alkane dithiol self-assembled monolayers and thiol-ene click chemistry. The resulting functionalized gold substrates demonstrate higher chemical stability than alkanethiol self-assembled monolayers alone and allow spatially controlled functionalization of gold surfaces with light. In Chapter 3, work on tunable hydrophobic surfaces is presented. These surfaces are prepared using a combination of organosilane chemistry, layer-by-layer polyelectrolyte deposition, and thiol-ene chemistry. These hydrophobic surfaces demonstrate high mechanical and chemical stability, even at low pH (1.68). The pinning of water droplets could be tuned on them by the extent of their thermal treatment. Comprehensive surface characterization using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), spectroscopic ellipsometry, atomic force microscopy, and water contact angles was carried out on the molecular assemblies prepared on gold and silicon dioxide surfaces. Chapters 4 and 5 are focused on the application, data interpretation, and enhancement in sensitivity of different surface characterization methods. In Chapter 4, XPS, ToF-SIMS, and principal components analysis are used to probe a real world corrosion-type problem. This systemic study showed the destruction of a protective coating composed of a nitrilotris(methylene)triphosphonic acid by a low-intensity fluorine plasma. In Chapter 5, enhancement in ToF-SIMS signals is shown via bismuth metal deposition. These surfaces are also probed by spectroscopic ellipsometry using the interference enhancement method. Finally, Chapter 6 concludes this dissertation by describing possible future work.
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Charles, Cédric. "Etude théorique et expérimentale des relations architecture - propriétés optiques de films minces d'oxyde de tungstène pulvérisés par GAD." Phd thesis, Université de Franche-Comté, 2013. http://tel.archives-ouvertes.fr/tel-01063023.
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Cette thèse participe à l'étude générale et à la compréhension des relations structure- propriétés optiques de couches minces d'oxyde de tungstène, nanostructurées lors de leur dépôt par la technique Glancing Angle Déposition. Cette technique repose sur le contrôle de l'orientation relative du substrat vis à vis de la source de vapeur.[...]
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Turner, Jeffrey W. "High resolution nuclear magnetic resonance investigations of polymethylenic plant biopolymers structural determinations and post-depositional ammonia nitrogen incorporation /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1189438308.
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Fecko, Peter. "Mikrostruktury mimikující povrch tlapky gekona." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400722.
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Adhezní schopnosti gekona byly předmětem mnoha studií a inspirací pro vytvoření mnoha napodobenin. Tato práce navrhuje vlastní verzi umělých gekoních struktur ve tvaru mikroskopických pilířů, které by vykazovaly adhezní vlastnosti srovnatelné s tlapkou gekona. Vyrobeny byli struktury z polymeru Parylen C pomocí fotolitografie a technik na leptání křemíku. Dalším cílem bylo různými metodami pro modifikaci povrchu a charakterizaci vytvořených struktur, které určí adhezní síly těchto povrchů, před a po modifikacích.
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Cross, Pamela J. "By the Head of a Spirited Horse: A Biocultural Analysis of Horse-Depositions as Reflections of Horseman Identities in Early Britain (Iron Age to Early Medieval Period)." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/18396.
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Arts & Humanities Research Council (AHRC).
Financial support also came from the project partners, particularly author Bernard Cornwell, the Sutton Hoo Society. Additional financial support for equine osteological research was supplied by SYNTHESYS.The full text of the thesis will be available at the end of the embargo: 30th June 2021.
The appendices which accompany the thesis are not available online.
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GALIZIA, PIETRO. "Production and morphological and microstructural characterization of bulk composites or thick films for the study of multiphysics interactions." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2674672.
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The surge of interest in multifunctional materials over the past 15 years has been driven by their fascinating physical properties and huge potential for technological applications such as sensors, microwave devices, energy harvesting, photovoltaic technologies, solid-state refrigeration, and data storage recording technologies. Among the others, magnetoelectric multiferroic composites are a special class of advanced solid-state compounds with coupled ferromagnetic and ferroelectric ferroic orders which allow to perform more than one task by combining electronic, magnetic and mechanical properties into a single device component. The production and characterization of lead zirconate titanate (PZT)- cobalt ferrite composites was the main topic of the thesis.
During the PhD activity different ceramic processing and characterization technologies were studied and involved in order to optimize the produced materials as a function of the final microstructural and functional properties.
The synthesis of cobalt ferrite (CF) and niobium-doped lead zirconate titanate (PZTN) powders by solid state reaction method and sol-gel technique, to control the particle size distributions and their microstructural and functional properties through calcination and milling treatments has been addressed first, followed by the mixing of the PZT and CF powders to produce particulate composites. The dispersion of PZT and CF in a liquid media, to produce layered composites by depositing the particles by electrophoretic deposition was an objective of the work as well.
Key issues such as the lead loss during the sintering of PZTN-CF composites and the reaction between CF and titania have been addressed and have resulted in improvements in the sintering and characterization techniques leading to the production of fully dense PZTN-CF dual-particulate composites. In particular, the optimized sintering parameters have configured a new paradigm of ceramic sintering, which has been called quite-fast sintering, in respect to the traditional one, and the study of the PbO loss has led to propose an equation to calculate the PbO loss through XRD analysis. Further important achieved results were: the production of nanocobalt ferrite particles by multi-step milling, the correlation between the spin-canting angle with the microstrain and the average crystallite size of nanocobalt ferrite particles, the understanding of the CF growth mechanisms, the extension of the Globus model from small ferromagnetic grains “having no defect inside” to multiparallel-twinned overgrown ones, the understanding of heating rate effect on the interface nucleation onset of the anatase-to-rutile transformation and the anatase particle size, and the reaction products between CF and rutile at 1200 °C at the variation of CF/rutile ratio.
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Hawkeye, Matthew Martin. "Engineering optical nanomaterials using glancing angle deposition." Phd thesis, 2010. http://hdl.handle.net/10048/1658.
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Advanced optical technologies profoundly impact countless aspects of modern life. At the heart of these technologies is the manipulation of light using optical materials. Currently, optical technologies are created using naturally occurring materials. However, a new and exciting approach is to use nanomaterials for technology development. Nanomaterials are artificially constructed material systems with precisely engineered nanostructures. Many technological revolutions await the development of new nanoscale fabrication methods that must provide the ability to control, enhance, and engineer the optical properties of these artificial constructs.
This thesis responds to the challenges of nanofabrication by examining glancing angle deposition (GLAD) and improving its optical-nanomaterial fabrication capabilities. GLAD is a bottom-up nanotechnology fabrication method, recognized for its flexibility and precision. The GLAD technique provides the ability to controllably fabricate high-surface-area porous materials, to create structurally induced optical-anisotropy in isotropic materials, and to tailor the refractive index of a single material. These three advantages allow GLAD to assemble optical nanomaterials into a range of complex one-dimensional photonic crystals (PCs).
This thesis improves upon previous GLAD optical results in a number of important areas. Multiple optical measurement and modeling techniques were developed for GLAD-fabricated TiO2 nanomaterials. The successful characterization of these nanomaterials was extended to engineer PC structures with great precision and a superior degree of control. The high surface area of basic PC structures was exploited to fabricate an optimized colourimetric sensor with excellent performance. This colourimetric sensor required no power source and no read-out system other than the human eye, making it a highly attractive sensing approach. Incorporating engineered defects into GLAD-fabricated PCs established a new level of design sophistication. Several PC defect structures were examined in detail, including spacing layers and index profile phase-shifts. Remarkable control over defect properties was achieved and intriguing polarization-sensitive optical effects were investigated in anisotropic defect layers. The success of these results demonstrates the precision and flexibilty of the GLAD technique in fabricating optical nanomaterials and advanced photonic devices.Micro-Electro-Mechanical Systems (MEMS) and Nanosystems
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Lai, Chung-Ho, and 賴忠和. "Porous conductive substrates prepared by glancing angle deposition." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/30944540366502627938.
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碩士南台科技大學
奈米科技研究所
96
In this study, porous conductive films were grown on glass substrates, metal substrates and nickel bowl-like array substrates by using glancing angle deposition (GLAD) of aluminum (Al), copper (Cu) and titanium (Ti). Surface morphology and structure of porous thin films were analyzed by FE-SEM and XRD, and the porosity was characterized by both reflectance and photocurrent of atomic-layer-deposited TiO2 films. The results show that the porous Al, Cu and Ti films can be prepared by GLAD, and the porosity of Al was the best of all. The porosity was found to be independent of deposition rate for films grown on substrates without rotating. As rotating the substrate, the porosity increases with increasing the deposition rate for Al films, but almost unchanged for Ti and Cu films. The porosity is independent of the rotation speed for all samples. The Ti and Cu films with low porosity can be further improved by using the nickel bowl-like arrays as the substrates. It was found that increasing the porosity improves the light trapping ability and enhance the photocurrent of coated TiO2 films. Keyword：glancing angle deposition、porous conductive substrates、photocurrent
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Chew, Han Guan, Wee Kiong Choi, Wai Kin Chim, and Eugene A. Fitzgerald. "Oblique Angle Deposition of Germanium Film on Silicon Substrate." 2004. http://hdl.handle.net/1721.1/7370.
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The effect of flux angle, substrate temperature and deposition rate on obliquely deposited germanium (Ge) films has been investigated. By carrying out deposition with the vapor flux inclined at 87° to the substrate normal at substrate temperatures of 250°C or 300°C, it may be possible to obtain isolated Ge nanowires. The Ge nanowires are crystalline as shown by Raman Spectroscopy.Singapore-MIT Alliance (SMA)
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Yang, Jian. "Optically Active Chiral Mediums Fabricated with Glancing Angle Deposition." Thesis, 2012. http://hdl.handle.net/1974/7315.
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Optically active helical microparticles are studied in the forms of thin films, suspensions and powders. From fabricated helical porous thin films, microparticle suspensions are obtained by removing the microparticles (film columns) from their substrates and dispersing them into water. For removing microparticles, four methods are explored and compared: sacrificial NaCl layer, gold (Au) layer, buffered oxide etching, and direct ultrasonic agitation. The primary film material studied in this work is amorphous silicon (Si). Physical morphology of the microparticles is examined with scanning electron microscopy (SEM). Methods employed to characterize optical activity of the microparticles include: polarimetry, spectrophotometry, and spectroscopic ellipsometry (SE). The produced chiral microparticles exhibit optical activity: optical rotation (OR) and circular dichroism (CD - in the form of differential circular transmission (DCT)). Significant findings include: (a) we observe the largest optical rotatory power ever reported in scientific literature, 11◦/μm at 610 nm wavelength for a Si film; (b) for the helical thin films, there is one dominant DCT band in the measured wavelength range; however for microparticle suspensions and powders, there exist two DCT bands: one broad band at long wavelengths, and one narrow band in the short wavelength range; compared to their thin film forms, microparticle suspensions and powders have inverted sign for the broad DCT band. A discrete dipole approximation (DDA) model is employed to calculate optical response (e.g. extinction, scattering, and absorption cross-sections) of the microparticles, so as to enable us to understand the effects of different structural parameters of the microparticles on their optical response. Calculation confirms that optical activity of chiral microparticles is due to coherent light scatterings with the chiral structures of the particles. The inversion in sign of the broad DCT bands of microparticle suspensions and powders is likely due to the averaging effect from random orientation of the helical microparticles, as is indicated both from experimental results and from calculation.Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-07-06 09:59:20.751
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Grüner, Christoph. "Oblique Angle Deposition of Thin Films – Theory, Modelling, and Application." 2019. https://ul.qucosa.de/id/qucosa%3A34667.
Full textAbstract:
With the aim to gain a deeper understanding of the role of the angle of incidence in physical vapor deposition, experimental, and computer-based studies were conducted. Electron beam evaporation and ion beam sputtering were used as deposition methods. The materials germanium, silicon, and molybdenum were deposited at different incidence angle, different temperatures and varied residual gas atmospheres. Established models could not be used to adequately explain the obtained relations between morphological parameters, as the tilt angle, with the incidence angle. To investigate the interplay of self-shadowing and competitive growth, an on-lattice simulation was developed. Care was taken to avoid any artificial anisotropy. Comparison with an, additionally developed, off-lattice simulation was used to verify this. Based on the made observations, an analytical model was deduced that combines the material properties and the deposition conditions into a single parameter. The predictions of this model were verified for the experimental observations, the results of the computer simulations, and on literature data. In the last part of the thesis, methods are shown that facilitate to modify the properties of the obliquely deposited thin films to fit requirements of various applications. This includes in situ doping of silicon nanostructures, creation of core-shell structures, as well as biochemical surface functionalization of silver nanostructures. On the example of the latter, various bio-sensing applications are presented.:1 MOTIVATION 7
2 BASIC CONCEPTS 9
2.1 Physical vapor deposition (PVD) 9
2.2 Deposition at oblique angles 14
2.3 Controlling the thin film morphology 16
3 EXPERIMENTAL METHODS 19
3.1 Sample preparation 19
3.2 Characterization techniques 32
4 EXPERIMENTAL RESULTS 37
4.1 Columnar structure and evolutionary selection 37
4.2 Tilt angles and density 42
4.3 Fan angles 45
4.4 Relevance of beam divergence 47
4.5 Summary 50
5 SIMULATION 53
5.1 Introduction 53
5.2 Off-lattice approach 54
5.3 On-lattice approach 59
5.4 Further applications of the on-lattice simulation 64
5.5 Other aspects 72
5.6 Summary 76
6 OBLIQUE ANGLE DEPOSITION MODEL 77
6.1 Semi-Empirical models 77
6.2 Tanto’s fan model 78
6.3 Development of the Competition Model 80
6.4 Verification of the model 84
6.5 Summary 89
7 FILM OPTIMIZATION FOR APPLICATIONS 91
7.1 Boron doped Si nanostructures 91
7.2 Surface functionalization for biosensors 95
7.3 Core-shell structures by pulsed electrodeposition 101
7.4 Summary 105
8 SUMMARY 107
9 BIBLIOGRAPHY 109
10 LIST OF ABBREVIATIONS 121
11 ACKNOWLEDGEMENTS 123
APPENDIX 125
PUBLICATION LIST 131
SELBSTSTÄNDIGKEITSERKLÄRUNG 133Mit dem Ziel ein besseres Verständnis des Einflusses des Einfallswinkels in der physikalischen Gasphasenabscheidung zu erreichen, wurden experimentell realisierte und am Computer simulierte Dünnschichten untersucht. Als Abscheidetechniken kamen sowohl Elektronenstrahl-Verdampfen als auch Ionenstrahl-Zerstäubung zum Einsatz. Es wurden die Materialien Germanium, Silicium und Molybdän verwendet, die bei verschiedenen Einfallswinkeln, verschiedenen Substrattemperaturen und variiertem Restgas abgeschieden wurden. Die beobachteten Zusammenhänge, von bspw. kolumnarer Verkippung und Einfallswinkel, konnten nicht mit den etablierten Modellen in Einklang gebracht werden. Um das genaue Zusammenspiel von Abschattung und Konkurrenz-Wachstum zu verstehen, wurde eine „on-lattice“ Computersimulation entwickelt, mit dem besonderen Augenmerk auf die Vermeidung von gitterbasierten Anisotropien. Dies wurde durch Vergleich mit einer, ebenfalls entwickelten, „off-lattice“ Simulation sichergestellt. Ausgehend von den beobachteten Effekten konnte ein analytisches Modell entwickelt werden, welches die Materialeigenschaften und Abscheidebedingungen in einen einzigen Parameter vereint. Die Vorhersagen des Modells wurden an den hergestellten Schichten, den Computersimulationen und an Literaturdaten verifiziert. Abschließend werden Methoden aufgezeigt, die schräg abgeschiedenen nanostrukturierten Schichten verschiedenen Anwendungen anzupassen. Dies umfasst die in situ Dotierung von Siliciumnanostrukturen, die Erzeugung von Kern-Schale-Strukturen, sowie die biochemische Oberflächenfunktionalisierung von Silbernanostrukturen. Am Beispiel der letztgenannten werden verschiedene Anwendungen in der Biosensorik detaillierter vorgestellt.:1 MOTIVATION 7 2 BASIC CONCEPTS 9 2.1 Physical vapor deposition (PVD) 9 2.2 Deposition at oblique angles 14 2.3 Controlling the thin film morphology 16 3 EXPERIMENTAL METHODS 19 3.1 Sample preparation 19 3.2 Characterization techniques 32 4 EXPERIMENTAL RESULTS 37 4.1 Columnar structure and evolutionary selection 37 4.2 Tilt angles and density 42 4.3 Fan angles 45 4.4 Relevance of beam divergence 47 4.5 Summary 50 5 SIMULATION 53 5.1 Introduction 53 5.2 Off-lattice approach 54 5.3 On-lattice approach 59 5.4 Further applications of the on-lattice simulation 64 5.5 Other aspects 72 5.6 Summary 76 6 OBLIQUE ANGLE DEPOSITION MODEL 77 6.1 Semi-Empirical models 77 6.2 Tanto’s fan model 78 6.3 Development of the Competition Model 80 6.4 Verification of the model 84 6.5 Summary 89 7 FILM OPTIMIZATION FOR APPLICATIONS 91 7.1 Boron doped Si nanostructures 91 7.2 Surface functionalization for biosensors 95 7.3 Core-shell structures by pulsed electrodeposition 101 7.4 Summary 105 8 SUMMARY 107 9 BIBLIOGRAPHY 109 10 LIST OF ABBREVIATIONS 121 11 ACKNOWLEDGEMENTS 123 APPENDIX 125 PUBLICATION LIST 131 SELBSTSTÄNDIGKEITSERKLÄRUNG 133
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BROWN, Timothy James. "Morphogenesis of nanostructures in glancing angle deposition of metal thin film coatings." Thesis, 2010. http://hdl.handle.net/1974/6276.
Full textAbstract:
Atomic vapors condensed onto solid surfaces form a remarkable category of condensed matter materials, the so-called thin films, with a myriad of compositions, morphological structures, and properties.
The dynamic process of atomic condensation exhibits self-assembled pattern formation, producing morphologies with atomic-scale three-dimensional structures of seemingly limitless variety.
This study attempts to shed new light on the dynamical growth processes of thin film deposition by analyzing in detail a previously unreported specific distinct emergent structure, a crystalline triangular-shaped spike that grows within copper and silver thin films.
I explored the deposition parameters that lead to the growth of these unique structures, referred to as ``nanospikes'', fabricating approximately 55 thin films and used scanning electron microscopy and x-ray diffraction analysis.
The variation of parameters include: vapor incidence angle, film thickness, substrate temperature, deposition rate, deposition material, substrate, and source-to-substrate distance.
Microscopy analysis reveals that the silver and copper films deposited at glancing vapor incidence angles, 80 degrees and greater, have a high degree of branching interconnectivity between adjacent inclined nanorods.
Diffraction analysis reveals that the vapor incidence angle influences the sub-populations of crystallites in the films, producing two different [110] crystal texture orientations.
I hypothesize that the growth of nanospikes from nanorods is initiated by the stochastic arrival of vapor atoms and photons emitted from the deposition source at small diameter nanorods, and then driven by localized heating from vapor condensation and photon absorption.
Restricted heat flow due to nanoscale thermal conduction maintains an elevated local temperature at the nanorod, enhancing adatom diffusion and enabling fast epitaxial crystal growth, leading to the formation and growth of nanospikes.
Electron microscopy and x-ray diffraction analysis, and comparisons to related scientific literature, support this hypothesis.
I also designed a highly modular ultrahigh vacuum deposition chamber, capable of concurrently mounting several different pieces of deposition equipment, that allows for a high degree of control of the growth dynamics of deposited thin films.
I used the newly designed chamber to fabricate tailor-made nanostructured tantalum films for use in ultracapacitors, for the Cabot Corporation.Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2011-01-17 15:22:47.533
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Cheng, Chao-Hsien, and 鄭照賢. "Dual SPR-SERS Plasmonic Sensors Using Gold Nanoslit and Oblique Angle Deposition Technique." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/87073814093117109157.
Full textAbstract:
碩士國立陽明大學
生醫光電研究所
101
Surface plasmon resonance (SPR) sensing is a real-time and label-free detection technique which has the potential to benefit numerous important fields, including medical diagnostics, environmental monitoring, and food safety. However, such a sensing technique is not suited for molecular identification. On the other hand, the surface-enhanced Raman scattering (SERS) spectroscopy is a highly specific technique to identify molecules. In this study, we proposed the fabrication of multifunctional plasmonic biochips and established an optical platform to integrate plasmonic sensing and surface-enhanced Raman scattering techniques. Periodic metallic nanostructures with rough metal surfaces were made on a plastic substrate using nanoimprinting and oblique angle deposition techniques. First, the grating nanostructures with a period of 750 nm were made on a polymer film using a silicon template. An 80-nm-thick gold film was then deposited on the plastic film using the oblique angle deposition technique. The transmission spectra of the biochips with different deposition angles were measured. Transverse-magnetic polarized wave in the gold nanostructure with a deposition angle of 0° generated a sharp and asymmetric Fano resonance in transmission spectrum. It was due to the interference of broad-band cavity resonance in the grooves and narrowband surface plasmon resonance on the periodic gratings. With the increase of the deposition angle, a symmetric surface plasmon resonance instead of the Fano resonance was observed in the transmission spectrum. The observed phenomenon was attributed to the asymmetric nanostructures formed by the oblique angle deposition which destroyed the cavity resonance. We also measured the SERS spectra of para-mercaptobenzoic (pMBA) acid molecules on different plasmonic biochips. It was found that the SERS signal for the periodic nanostructure was 10 times the background SERS signal. The SERS signal increased by 6 times when the deposition angle was increased from 0° to 75°. In addition, the optical systems for measuring transmission and SERS spectra were integrated. The 785-nm laser light was normally incident on the plasmonic biochip. The reflected light and transmitted light were collected and measured by a charge-coupled device array spectrometer and Raman spectrometer, respectively. The quantification and qualification analysis of the sample can be accomplished at the same time by measuring the changes in transmitted intensity and SERS spectra. Therefore, the combination of plasmonic sensing and SERS spectroscopy provides a promising way for multifunctional chemical analysis to increase the reliability of biological detection and can benefit sensing applications.
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Cheang, Hou-Lon, and 鄭浩倫. "Surface-enhanced Raman scattering from titanium nitride nanostructures fabricated using glancing angle deposition." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9ptb3t.
Full textAbstract:
碩士國立臺北科技大學
光電工程系
107
Titanium nitride (TiN) nanostructures were fabricated by glancing angle deposition(GLAD) in direct current (DC) magnetron reactive sputtering. Slanted nanorods arrays (NRAs)was grown by controlling the substrate orientation during deposition. The impact of nitrogen flow rate relative to that of argon during deposition, and the deposition substrate temperatures of TiN were discussed. The TiN NRAs were analyzed by X-ray diffraction (XRD). The surface enhance Raman scattering (SERS) signals from Rhodamine 6G (R6G) of dropped on the substrates were detected by excited wavelength at 532nm. The influence of the length of TiN nanorods and corresponding resistivity on SERS peak intensities was investigated. In order to study the durability, the difference of variation of SERS intensity between TiN and Ag deposited NRAs with time was proposed here.
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Song, Yeng-Teng, and 宋晏瑭. "Anistropic ITO nanocolumnar conductivity layerprepared by Oblique-angle of deposition andGaN-based LED Application." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/49rgkr.
Full textAbstract:
碩士國立臺北科技大學
光電工程系研究所
97
This work presents a nanocolumnar structure anisotropic indium tin oxide (ITO) film deposited with different oblique-angle by a radio-frequency magnetron sputtering system for glass substrate. Sputtering the different angle of ITO films by oblique-angle to tilt the angle of substrate, and the morphology and cross-sectional structure was observed. The refractive index of ITO nanocolumnar films decreases with incidence angle increases. This may attribute by the oxygen increases into ITO nanocolumnar films but Indium and Tin decreases. After The method use to the GaN-based LED with an anisotropic ITO nanocolumnar .
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Wu, Kai-Lun, and 吳凱倫. "Glancing Angle Deposition of Titanium Nitride Nanorod Array: Surface Morphology and Optical Properties Analysis." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7vc3zt.
Full textAbstract:
碩士國立臺北科技大學
光電工程系
106
In this work, we used DC magnetron sputtering and glancing angle deposition (GLAD) to deposit titanium nitride (TiN) nanorod array on silicon wafer, glass substrate (BK7) and sapphire substrate. The surface morphology of the nanostructures was explored by changing the process parameters such as the deposition angle, post-deposition annealing, and ratio of argon-nitrogen. The morphology and the lattice orientation (111) and (200) were analyzed by SEM and X-ray diffraction (XRD), respectively. In addition, X-ray photoelectron spectroscopy (XPS) confirms its chemical analysis. The equivalent optical constants were measured by using ellipsometer. The relationship between optical constants and lattice composition was discussed and analyzed. In the experimental results, the columnar angle of the nanorods becomes larger and the column diameter becomes smaller because the proportion of nitrogen increases in the nanostructure. However, the crystallite size and the amount of nitrogen are proportional and the proportion of nitrogen increases the lattice orientation which will grow along the (200) orientation. The larger crystallite increases the porosity of the film that cause the high resistance. Thus, the porosity of the film resulting in the increase of transmission and decrease of reflection.