Design and Fabrication of Electrostatically Actuated Serpentine-Hinged Nickel-Phosphorous Micromirror Devices

A process for micromachining of micro-mirror devices from silicon-on-insulator wafers was proposed and implemented. Test methods and force applicators for these devices were developed. Following successful fabrication of these devices, a novel process for fabrication of devices out of the plane of the silicon wafer was proposed, so that the devices could be actuated electrostatically. In particular, the process makes use of thick photoresist layers as a sacrificial mold into which an amorphous nickel-phosphorous alloy may be deposited. Ideal design of the electrostatically actuated micro-mirrors was investigated, and a final design was selected and modeled using FEA software, which found that serpentine-hinged devices require approximately 33% of the actuation force of their straight-beamed counterparts. An aqueous electroless plating solution composed of nickel acetate, sodium hypophosphite, citric acid, ammonium acetate, and Triton X-100 in was developed for use with the process, and bath operating parameters of 85°C and 4.5 pH were determined. However, this electroless solution failed to deposit in the presence of the photoresist. Several mechanisms proposed for deposition failure included leaching of organic solvents from the photoresist, oxidation of the nickel-titanium seed layer on which the deposition was intended to occur, and nonlinear diffusion of dissolved oxygen in the solution

Investigations of Structure / Property Interrelationships of Organic Thin Films Using Scanning Probe Microscopy and Nanolithography

Studies of the surface assembly and molecular organization of organic thin films were studied using scanning probe microscopy (SPM) and scanning probe lithography (SPL). Systems of organic thin films such as n-alkanethiols and pyridyl functionalized porphyrins were characterized at the molecular level, and measurements of the conductive properties of polythiophenes containing in-chain cobaltabisdicarbollides were accomplished. Understanding the self-organization and mechanisms of self-assembly of organic molecules provides fundamental insight for structure/property interrelationships. Investigations of the surface assembly of 5,10-diphenyl-15,20-di-pyridin-4-yl-porphyrin (DPP) on Au(111) were done using SPL methods of nanoshaving and nanografting. Automated computer designs were developed for nanofabrication to provide local characterizations of the thickness of DPP films and nanostructures. Nanolithography was accomplished using DPP films as either matrix self-assembled monolayers (SAMs) or as molecules for nanofabrication. Results presented in this dissertation demonstrate that DPP forms compact layers on Au(111), which can be used for inscribing nanopatterns of n-alkanethiols. Arrays of DPP nanopatterns with precise geometries and alignment were fabricated within n-alkanethiols by nanografting, demonstrating nanoscale lithography with pyridyl porphyrins can be accomplished to produce an upright surface orientation on Au(111) mediated by nitrogen-gold chemisorption. Beyond research investigations, the applicability of atomic force microscopy (AFM) and advancements with automated SPL were applied for teaching undergraduate chemistry laboratories to introduce the fundamentals of surface chemistry and molecular manipulation. New classroom activities were developed for the Chemistry 3493 Physical Chemistry laboratory to give students “hands-on” training with AFM. Undergraduates were trained to prepare nanopatterns of n-alkanethiols using software to control the position, force and speed of the AFM tip for nanolithography experiments. The sensitivity and nanoscale resolution of current sensing AFM was applied for studies of the conductive properties of electropolymerized thin films of polythiophenes with cobaltabisdicarbollide moieties. Images acquired with AFM furnished views of the morphology of different polymers prepared on gold surfaces. Surface maps of the conductivity of electropolymerized films were acquired with AFM current images. These studies provide new insight of the effects of the bound cobaltabisdicarbollide moiety and coordinated metal centers for the electronic properties of the resulting conducting materials

Préparation et études des propriétés des films magnétiques nanostructures pour des applications en dispositifs magnéto-acoustiques et spintroniques

Nowadays, structures based on ferromagnetic materials are largely used for different applications: random access magneto-resistive memories, magnetic sensors, and also new electronic components and spintronic devices. The general trend of modern electronic is the reduction of dimensions down to submicronic scales. Therefore, the magnetic nanostructures are of great interest and their methods of fabrication and properties largely studied.The main goal of this work is the preparation and experimental and theoretical research on properties of magnetic nanostructures for applications in magnetoresistive and photonic devices. The Scanning Probe Lithography (SPL) and Electron Beam Lithography (EBL) were used for the nanostructures fabrications. First steps were also achieved in fabrication of phononic cristals sensitive the magnetic field.Aujourd'hui, les structures basées sur les matériaux ferromagnétiques sont largement utilisées pour différentes applications: mémoires magnéto-résistives à accès non séquentiel, capteurs magnétiques et également nouveaux composants électroniques et dipositifs spintroniques. La tendance générale de l'électronique moderne est une réduction de la dimension des éléments à l'échelle submicronique. Ainsi, les nanostructures magnétiques sont d'un grand intérêt et leurs méthodes de fabrication et propriétés sont étudiées activement.Le but principal de ce travail est la préparation et la recherche expérimentale et théorique des propriétés de nanostructures magnétiques pour applications aux composants magneto-résistifs et phononiques. La lithographie à sonde locale (SPL) et la lithographie par faisceau d’électrons (EBL) ont été utilisées pour la fabrication des nanostructures. De premiers pas ont également été réalisés en fabrication des cristaux phononiques sensibles au champ magnétique

Novel Technologies for Mitigation of Flow Accelerated Corrosion of the Secondary Side of Pressurized Water Reactors

Department of Nuclear EngineeringSecondary side of pressurized water reactors undergo severe erosion-corrosion (E-C) under high-temperature flowing water, and one of the most damaging phenomenon is flow accelerated corrosion (FAC). Due to FAC, many failures of the secondary system occurred which threatened the safety and the integrity of nuclear power plants. In this study, novel technologies, which include development of FAC resistive coatings and alloys, are proposed and their performance was evaluated in various FAC conditions. As the resistive coatings, Ni-P/TiO2 nanocomposite and Fe-based amorphous metallic coatings (AMCs) were deposited on carbon steel substrate. Since they are known to possess outstanding corrosion and erosion resistance. In case of FAC resistive alloys, low alloy steels with different Cr and Mo contents were developed since Mo could be substituted by higher Cr contents according to Ducreux???s equation. Also, Nakamura???s crack susceptibility model and manufacturing costs of the alloys were considered. As a product, FAC resistive alloys (FRAs) are manufactured via vacuum arc melting method. And, the performance of the FAC resistive coatings and the alloys have been experimentally demonstrated by employing various FAC instruments. At first, their electrochemical properties under seawater have been evaluated using linear sweep voltammetry and electrochemical impedance spectroscopy. Ni-P/TiO2 coating shows excellence corrosion resistance due to the anodic protection for Ni-P matrix by spatially dispersed TiO2 nanoparticles and the stability of NiO. However, Fe-based AMC shows susceptibility in seawater corrosion due to intrinsic surface morphology, defects, and surface area. In case of FRAs, the corrosion behavior in seawater condition has similar trend indicating that Mo could be substituted by high Cr. Electrochemical behavior of Ni-P and Ni-P/TiO2 coatings under simulated secondary water chemistry is also evaluated. Compared to Ni-P coating, Ni-P/TiO2 coating is less activated where FAC is favored i.e., 150 oC. However, the effect of spatially dispersed TiO2 nanoparticle is vanished at 125, 175 and 200 oC but still the coating can suppress the corrosion. To evaluate FAC resistive performance, secondary water chemistry control system and an autoclave system is prepared. At temperature range 125 to 200 oC, FAC simulation performance of the coatings and the alloys have been tested under deaerated water with pH 9.3, which is controlled by ethanolamine. In case of the coatings, Ni-P/TiO2 coating effectively suppress the corrosion by the galvanic coupling compared to Ni-P. Fe-based AMC also shows remarkable corrosion resistance since FAC is a complex phenomenon of corrosion and erosion. Instead of weight loss, slight weight gain is observable for Fe-based AMC. In case of FRAs, the oxide morphology is two-layer structure. The outer oxide layer is composed of Cr-rich amorphous oxide and the inner oxide is Cr-substituted magnetite according to their crystal structure. The corrosion rates of the alloys are in good agreement with Ducreux???s model. Finally, FAC tests at 5.7 m/s of flow were carried in the test facilities. To test FAC performance of the coatings, coated 90o elbows were prepared and their thickness is measured by ultrasonic thickness technique. In case of A106 Gr.B carbon steel, significant thickness reduction is observable at intrados due to localized acceleration of flow velocity while A335 P22 keeps its thickness for 21 days of immersion. Ni-P/TiO2 coating also shows significant thickness reduction at intrados and surface and cross section morphologies confirms that the coating is detached. However, Fe-based AMC does not show thickness reduction but slight increased thickness is observable due to the formation of thick oxide. Thus, it can be concluded that: Ni-P/TiO2 coating is good corrosion resistive coating under corrosive condition but not effective under erosion conditionFe-based AMC is susceptible to seawater corrosion but highly effective under erosion-corrosion conditionMo-free FRA is available option for the substitution of commercial low alloy steel.ope

Scanning Probe Investigations of Magnetic Nanoparticles, Protein Binding and the Synthesis of Rare Earth Oxide Nanoparticles Using Nanoscale Lithography

Approaches to prepare spatially selective surfaces were developed in this dissertation for constructing assemblies of biomolecules and inorganic materials. Nanoscale surface patterns of organic thin films were prepared using particle lithography combined with organosilane chemistry. Biological and inorganic nanomaterials can be patterned with tailorable periodicities, which can be controlled by selecting the diameter of mesospheres used as surface masks. The surface platforms of well-defined nanopatterns are ideal for high resolution investigations using scanning probe microscopy (SPM). Local measurements of surface properties combined with visualization of the steps of chemical reactions at the molecular level were accomplished. Fundamental studies of the chemical steps for patterning proteins are critical for the integration of biomolecules into miniature biological-electronic devices for protein sensing. Rare earth oxide (REO) nanomaterials have useful properties such as upconversion, catalysis, and magnetism. For commercial applications REO nanomaterials should have well defined sizes and be arranged as surface arrays. Sample characterizations were accomplished with selected modes of SPM. Scanning probe studies can be used to probe the morphological and physical properties of samples, when discrete arrangements of nanomaterials are prepared. Atomic force microscopy (AFM) can be used to analyze many types of samples in ambient and liquid environments. Arrays of protein nanopatterns were fabricated using the spatial selectivity of chemical patterns prepared with particle lithography. The steps for patterning protein and protein binding were visualized with AFM. The protein arrays were tested for the selectivity of binding IgG to evaluate if protein function was retained

Nanoporous hosts for the encapsulation of conductive nanostructured materials

The aim of the Thesis is to understand nanoporous systems, learn to control their design, and to explore potential functionality. It is aimed to show that such systems can serve as host matrixes for incorporation of conducting materials at the nanometer scale. By designing nanoporous host structures we are trying to manipulate the growth process and the properties of the embedded conductive nanostructures. The focus is on liquid-crystal templated silica-based mesoporous materials prepared under different sol-gel synthetic conditions and characterized by a variety of physico-chemical methods. Morphologies include bulk materials and thin mesoporous films on different substrates; the latter may offer potential as components for the construction of molecular electronic devices. It was aimed to gain knowledge of the physico-chemical characteristics of the mesoporous solids and to access differences in their bulk and surface properties that can be essential for further functionalization and modification. The encapsulation of conductive nanostructures in ordered mesoporous hosts is exemplified with several distinct cases by developing new synthetic methods for selective confinement of the guest structures. Namely, carbon filaments and nanotubes, metal nanowires and nanoarrays, and semiconducting nanoparticles and wires are prepared in the mesoporous systems by selective functionalization of the host matrix followed by restricted growth in the nanosized porous system. The analytic techniques that were used during the PhD work include transmission electron microscopy, scanning electron microscopy, IR and Raman spectroscopy, 29Si and 13C NMR spectroscopy, N2 sorption and X-ray diffraction as well as techniques typical for the characterization of thin layers such as grazing-incident diffraction, atomic force microscopy and quartz crystal microbalance devices

The effect of crystal growth conditions and surface treatment on CdZnTe bulk single crystal

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de Materiales. Fecha de lectura: 17-06-201

High speed selective jet electrodeposition of gold and gold alloys using single circular jets

High speed selective jet electrodeposition of gold and gold alloys using single circular jet

Binary metal oxide and polymer based liquid repellent self-cleaning surfaces

Ph.DDOCTOR OF PHILOSOPH

Gold nanoparticles based DNA detection in microfluidics

This study shows gold nanoparticle based DNA detection in microfluidics has the potential to revolutionize the early detection of infectious diseases. Taking advantage of gold nanoparticles, the signal of binding event was enhanced and an insight into the interactions of the interface was provided.<br /