O uso de implantes osseointegrados vem crescendo nas últimas décadas e, juntamente com eles, suas complicações. A periimplantite se apresenta como uma infecção bacteriana que afeta os tecidos moles e duros ao redor do implante, promovendo perda da osseointegração. Assim, o objetivo primário deste estudo foi analisar a efetividade da remoção de bactérias, através do software ImageJ, aderidas às superfícies de titânio por diferentes agentes químicos condicionantes, por meio de análise em microscopia eletrônica de varredura (MEV). Juntamente foi analisado a alteração da rugosidade de superfície após a utilização dos agentes. Foi realizado estudo in vitro, no qual 70 covers (protótipos de implantes) passaram por preparo das superfícies para adequação do meio à cultura bacteriana, fixação das bactérias; e em seguida, foram divididos em 7 grupos (n=10), de acordo com o tratamento: AF180 aplicação de ácido fosfórico (AF) por 180 segundos; AF90- AF por 90 segundos; EDTA180 EDTA por 180 segundos; EDTA90 EDTA por 90 segundos; AC180 ácido cítrico por 180 segundos; AC90 AC por 90 segundos; Controle RAR. A análise comparativa do grau de contaminação bacteriana observado antes e depois do tratamento entre os diferentes grupos foi realizada por meio do teste não paramétrico de Kruskal-Wallis; e as alterações da rugosidade superficial foram analisadas por meio do teste ANOVA a dois critérios, pós-teste de Dunnett. Através desta metodologia, este trabalho sugere que o tratamento de superfícies de titânio contaminadas por meio do emprego de solução em gel de EDTA a 24% por 90 e 180 segundos e ácido cítrico a 50% por 180 segundos é efetiva para remoção de A. atinomycetencomitans. Além disso, o tratamento por meio de EDTA por 90 e 180 segundos promove alteração significativa dos parâmetros de rugosidade superficial, especialmente quando comparado aos grupos controle e AF180, indicando que este tratamento pode resultar em subtração ácida adicional. / The use of dental implants has grown in recent decades and, with them, their complications. The periimplantitis is presented as a bacterial infection that affects the soft and hard tissue around the implant, promoting loss of osseointegration. Thus, the primary objective of this study was to analyze the effectiveness of removal of bacteria tby means of the ImageJ software, adhered to the titanium surfaces by different chemical conditions, through analysis in scanning electron microscopy (SEM). The change of surface roughness was also analyzed after using the chemical agents. An in vitro study in which 70 covers (implant prototypes) was prepared for the bacteria culture, fixation of the bacterias; and then they were divided into 7 groups (n = 10), according to the surface treatment: AF180- application of phosphoric acid (FA) for 180 seconds; AF90- AF for 90 seconds; EDTA180 - EDTA for 180 seconds; EDTA90 - EDTA for 90 seconds; AC180 - citric acid for 180 seconds; AC90 -AC for 90 seconds; Control - RAR. The comparative analysis of the degree of bacterial contamination was performed using Kruskal-Wallis non parametric test; and changes of surface roughness were analyzed by ANOVA two criteria, post-test Dunnett. Through this method, this work suggests that treatment of titanium contaminated surfaces by means of EDTA gel solution employing 24% for 90 and 180 seconds and citric acid 50% for 180 seconds is effective for removing A. atinomycetencomitans. Moreover, treatment using EDTA for 90 to 180 seconds promotes significant change of surface roughness parameters, especially when compared to control groups and AF180, indicating that this treatment can result in additional acidic subtraction.

When porous silicon is plated with a catalytic metal, the two materials can act together as a single entity whose electrical properties are sensitive to its environment – the sensing component of an electrochemical gas sensor. Etching pores into silicon is an electrochemical process; and which type of doped silicon used is one of its key parameters. For nearly all reported porous silicon gas sensors, the silicon has been of the p-doped variety – because p-doped porous etching is better understood and the layers that result from it are more predictable – despite n-doped silicon having potentially significant benefits in ease of fabrication and being more conducive to plating by a catalyst. This experiment is an attempt at creating a palladium plated n-doped porous silicon layer, and an examination into what differentiates this fabrication process and the layers that result from the traditional p-doped type. The porous layers to be plated are to be the same and would ideally have properties that are a close approximation to what a functional gas sensor would require. This experiment defined a process that fabricated this “ideal” layer out of N-type, , double polished silicon wafers with a resistance of 20 Ω cm. The wafers were subjected to the anodic etching method with an HF/ethanol mixture as the electrolyte; and only two (of among many) fabrication parameters were varied: HF concentration of the electrolyte and total etching time. We find that a concentration of 12% HF (by volume) and an etching time of 6 hours result in layers most appropriate to carry into plating. The anodization current density is 15 mA cm-2. Deposition of the catalyst, palladium, is done using the electroless method by immersing the porous layer in a .001M PdCl2 aqueous bath. Characterization of this Pd/Porous Silicon layer was done by measuring resistivity by four point probe and imaging through Scanning Electron Microscopy. It was found that layers of a maximum average of 63 ± 6% porosity were created using our fabrication method. There is evidence of palladium deposition, but it is spotty and irregular and is of no improvement despite the n-doping wafer makeup. Resistivity in well-plated regions was measured to be 7-10 Ωcm, while resistivity in regions not well-plated was measured to be 70-140 Ω cm. This is comparable to previous literature values, indicating n-silicon porous silicon can be fabricated and still have potential as a catalytic layer, should metal deposition methods improve.

"October, 2005" / Coursework / Bibliography: leaves 97-105. / xvi, 136 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D.Clin.Dent.)--University of Adelaide, Dental School (Endodontics), 2005

<p>Patterning of multi crystalline silicon Solar cell is prepared with photolithography etching. Electroless plating is used to get metallization of Nickel contacts. SEM analysis of Nickel deposition and measurement of contact resistance for series and shunt resistance is done. To increase the fill factor, the screen printed electrodes are subjected to different firing temperatures there by increasing the efficiency of solar cell. Nickel-silicide formation at the interface between the Silicon and Nickel enhances stability and reduces the contact resistance, resulting in higher energy conversion efficiency.</p><p> </p>

A gas phase kinetic model for the CF���/O��� microwave discharge plasma and afterglow of our laboratory has been developed. A reaction pathway identifying the major chemical reactions is proposed. The rate coefficients of the electron impact dissociation reactions are determined at three different plasma powers using both published electron molecule collision cross section data and plug flow analysis of data collected in our system. Agreement between calculated and experimental rate coefficients is better than 20%. Fluid simulations of a two-dimensional mathematical model were performed using computational fluid dynamics. It is found that the model reproduced qualitatively the general trends of the experimental data. The effects of plasma power, feed gas composition, residence time and pressure on the product distribution of the system are studied. CF��� conversion increases with power and residence time. The variation of CF��� conversion and carbon containing species distribution falls into two regimes. In the oxygen rich regime (below 25 mole % CF��� in the feed), CO��� is found to be the major product of CF��� decomposition; homogeneous recombination reactions between atomic oxygen and the free radicals are found to be the dominant mechanism in the afterglow region resulting in high CF��� conversions. Homogeneous reactions convert CO to CO���. In the CF��� rich regime (above 50 mole % CF���), COF��� is found to be the major product of CF��� decomposition. Recombination reactions of CF��� with atomic fluorine dominate in the afterglow region and limit conversion. Lowering pressures result in increased conversion of CF��� and increased concentration of the carbon containing species. / Graduation date: 1998

Current research in materials science and engineering continues to drive it's attention to systems on the nanoscale. Thin films, nano-particles, quantum dots, nano-wires, etc are just a few of the areas that are becoming important in projects ranging from biomedical transport to nano-gears. Thus, understanding, producing, and creating these system is also becoming an important challenge for scientists and engineers to overcome. Physically manipulating objects on the atomic scale requires more than just "micro tweezers" to arrange them in a particular system. Another concern is that forces and interactions that could be ignored or approximated at larger scales no longer hold in this regime. It is the goal of this project to use computational models to simulate nano-particles interacting with customized, highly tailored surfaces in order to confine and pattern them to desired specifications. The interactions to be considered include electrostatic attraction and repulsion, hamaker forces, steric effects, dielectric effects of the medium, statistical variability, mechanical induced surface vibrations, etc. The goal is to be able to manufacture such systems for experimentation in order to compare results to the models. If the models do not hold, we hope to understand the origin of these discrepancies in order to create more robust models for this length scale. Lithography, CVD, and chemical etching will be the primary methods used to create these surfaces on glass substrates. TEM analysis will be compared to modeling through various MD program packages. / Singapore-MIT Alliance (SMA)

The fabrication characteristic of etching and deposition of focused ion beam (FIB) on the submicron structure of silica and quartz glass was investigated. FIB has several advantages such as high sensitivity, high material removal rate, and direct fabrication in some selected areas without the use of etching mask, etc. In this study, silicon and quartz glass materials etched by FIB were used for fast fabrication of 3-D submicron structures to investigate the differences between the samples before and after fabrication. The expansion effect of silicon with sputtered platinum on surface is compared with Pyrex glass with sputtered chromium on surface. The result shows the side wall of structure in the center wouldn¡¦t be vertical after etching and trimming on the quartz glass and the silicon substrate. Trenches with different depth and width on the surface of silicon were etched by FIB and measured by Atomic Force Microscope. Lines with different interval were deposited by FIB on the surface of quartz glass and were measured by Atomic Force Microscope.

This thesis investigates different material systems and processing technology for high temperature compatible laser diodes used in volume applications within the 1.3-μm telecom wavelength window. Laser diodes built from such materials are much desired in order to eleminate the need for active temperature control needed in current systems, which significantly increases both complexity, size and cost. The structures were grown by Metal-Organic Chemical Vapor Deposition (MOCVD) and the evaluation of materials was performed using different characterization methods such as High-Resolution X-Ray Diffraction (HR-XRD), Photoluminescence (PL), Time-Resolved Photoluminescence (TR-PL). Fabrication and evaluation of Fabry-Perot lasers with different geometries was used to check the material quality and temperature performance. A novel in-situ etching technique was developed for the use i future more advanced, buried hetrostructure lasers. The first studied materials system was AlGaInAsP/InGaAsP/InP. To handle a 5-element material with the precision required, modelling of the materials and heterostructure properties was performed. The addition of Al to the InGaAsP barrier allows better electron confinement with little change in valence band properties. The optimum aluminium content was found to be about 12%. Although the effect of Al could be identified, it was not sufficient with T0 of only 90 K only up to 60 °C. A second materials system InGaP/InAsP/ InP initially looked quite promising from a materials and quantum well design point of view but encountered severe problems with the device integration and further work was discontinued. The main effort was therefore was devoted to a third materials system: AlGaInAs/AlGaInAs/InP. This material system is not unknown but has hitherto not found a widespread application for fibre optic applications. In this work, the MOCVD growth of 1.3 μ;m quantum well laser structures was optimized and ridge waveguide laser devices with excellent temperature performance was fabricated (T0 = 97 K at 85 °C). A ridge waveguide laser was identified as suitable structure since it requires only a single epitaxial growth, thus avoiding the main problem of oxidation of Al based buried structures. The dynamic performance was excellent up to 110 °C and the device fabrication is highly reliable (lifetime &gt;7000 h). This high yield uncooled ridge Fabry-Perot laser process has now been transferred to production and is applied in short length 10 Gb/s multimode links. In order to further improve the usefulness of the Al-containing materials in even higher performance devices needed in future applications developments towards fully buried heterostructure device geometry were also pursued. To overcome difficulty of oxidation of Al containing layers at the mesa walls an in-situ etching technique was implemented. Different chemistry approaches were investigated and the first results of lasers devices were reported. / QC 20100930

Patterning of multi crystalline silicon Solar cell is prepared with photolithography etching. Electroless plating is used to get metallization of Nickel contacts. SEM analysis of Nickel deposition and measurement of contact resistance for series and shunt resistance is done. To increase the fill factor, the screen printed electrodes are subjected to different firing temperatures there by increasing the efficiency of solar cell. Nickel-silicide formation at the interface between the Silicon and Nickel enhances stability and reduces the contact resistance, resulting in higher energy conversion efficiency.

In this master thesis, the goal was to devise design patterns and a fabrication processfor manufacturing a 3-D rotationally symmetric converging-diverging cold gasmicronozzle in silicon.The report explains the theory of etching and the methods involved. The work beginswith calculations and simulations of the etching processes. The chosen etch techniqueutilizes so called microloading and reactive ion etching lag effects, which essentially arephenomena where the etch rate can be adjusted by breaking up mask features intosubpatterns, and the etch depth for a given recipe and time can be made to differlocally. The subpatterns consisted of very small rectangles and triangles withalternating concentration. Five different recipes for the reactive ion etching weretried, where the coil power, platen power, pressure, temperature and time wasvaried.Etch rates could be made to differ locally depending on the concentration ofsubpatterns within the mask feature. The etch rates were also affected by the recipeparameters such as coil power, platen power, and pressure. High coil and platenpower increased the etch rate, while high pressure reduced the etch rate. The platenpower also affected the surface roughness.A solution for reducing misalignment problems in the future for the fusion bondingprocess resulted in the proposed moiré patterns that were made to showmisalignments down to 0.2 μm.Through scanning electron microscopy, the Nozzle 5_4_2 was concluded to have themost rotationally symmetric cross section at both the throat and the outlet. It hasthroat diameter of 31.1 μm with a depth of 34.2 μm and an outlet diameter of146.4 μm with a depth of 113.2 μm