Orientadores: Peter Jurgen Tatsch, Jose Alexandre Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T19:29:46Z (GMT). No. of bitstreams: 1 Souza_JairFernandesde_M.pdf: 4396662 bytes, checksum: cf77f050e25403e0bd758bdb52214aa2 (MD5) Previous issue date: 2009 / Resumo: Esta dissertação consiste de duas etapas. Inicialmente são estudados filmes de nitreto de silício depositados por LPCVD, Low Pressure Chemical Vapor Deposition, utilizando-se diferentes relações de concentração de gases reagentes, [SiH2Cl2]/[NH3], e utilizando-se como substrato lâminas de silício tipo p, com e sem camada almofada de oxinitreto de silício; estruturas SiNx/Si e SiNx/SiOxNy/Si, respectivamente. Os filmes foram caracterizados física e eletricamente, bem como do ponto de vista da capacidade de adsorção de monocamadas biologicamente ativas. As características dos filmes foram comparadas, buscando-se identificar um filme cujas propriedades fossem adequadas para utilização como material dielétrico a ser empregado na porta de Transistores de Efeito de Campo química e bioquimicamente sensíveis. Os resultados da elipsometria realizada apontaram filmes com índices de refração variando de 1,875 a 1,990, indicando filmes ricos em nitrogênio, e com espessura diretamente proporcional à relação de concentração dos gases reagentes, ou seja, o aumento na relação de concentração de gases produz aumento na taxa de deposição dos filmes. A espectroscopia de absorção de infra-vermelho permitiu analisar as ligações químicas presentes nos filmes e nas monocamadas automontadas formadas pela imobilização de biomoléculas. Os espectros dos filmes apresentam picos de absorção em 827/837 cm-1 e 451/484 cm-1 que correspondem a ligações Si-N, confirmando a indicação da elipsometria referente à presença de nitrogênio. Após a formação das camadas automontadas, compostas de proteínas do tipo Imunoglobulina, IgG 2,5 e 5%, os espectros mostraram bandas de absorção de IR em torno de 3300 cm-1 e nas faixas de 1700 a 1600 cm-1 e 1600 a 1500 cm-1. Este espectro caracteriza a formação de grupos amida A, I e II, respectivamente, ou seja, a formação das monocamadas biologicamente ativas. Através de espectroscopia micro-Raman foram detectados deslocamentos nos picos principais do substrato de silício. Tais deslocamentos foram relacionados com o stress provocado pelos filmes depositados. Foram fabricados capacitores Metal/Isolante/Semicondutor, MIS, utilizando-se as estruturas dielétrico/semicondutor obtidas. Os capacitores possibilitaram realizar a caracterização elétrica dos filmes através de medidas C-V, capacitância-voltagem, de alta frequência de 1MHz, obtendo-se a densidade de cargas existente na interface dielétrico/semicondutor, em torno de 1011cm-2, e permitiram observar o comportamento da interface com a realização de etapas térmicas e a degradação em suas propriedades de recombinação. Após a fabricação e a caracterização das camadas dielétricas, foi iniciada a segunda etapa do trabalho com a fabricação de matrizes de Transistores de Efeito de Campo, FETs. Foi usado como dielétrico de porta os filmes da etapa anterior que apresentaram melhor desempenho do ponto de vista físico, elétrico, químico e biológico. A caracterização elétrica dos FETs foi realizada utilizando-se dispositivos de controle dispostos isoladamente nas pastilhas. Foram obtidas as características elétricas dos dispositivos e observado seu comportamento nas etapas térmicas. A sensibilidade química foi verificada aplicando-se analitos com diferentes concentrações de íons H+ , correspondente a diferentes valores de pH, na região de porta dos FETs. Foi demonstrada a viabilidade da utilização dos FETs fabricados na detecção química/bioquímica, com possibilidade de emprego em atividades de diagnóstico médico, controle ambiental, controle da produção de fármacos e cosméticos, e aplicações agropecuárias / Abstract: This dissertation consists of two stages. Initially are studied Silicon Nitride films deposited by LPCVD (Low Pressure Chemical Vapor Deposition) using different relationship of reagent gases concentration ([SiH2Cl2] / [NH3]) and using as substratum Silicon wafers p-type with and without pad layer of Silicon Oxinitride - SiNx/Si and SiNx/SiOxNy /Si structures. The films were characterized physically and electrically as well as the point of view of adsorption capacity of biologically active monolayer. The films characteristics were compared, seeking to identify a film whose characteristics are adequate to be used as dielectric material applied at the project and fabrication of chemically and biochemically sensitive Field Effect Transistors - FETs. Ellipsometry results pointed films with refraction indexes ranging from 1,875 to 1,990, it indicating films rich in Nitrogen, and with thickness directly proportional to the relationship of reagent gases concentration. In the other words, the increase of the relationship of gases concentration produces an increase of the films deposition rates. The infra-red absorption spectroscopy allowed us to analyze the chemical bonds present in the dielectric films and in the self assembled monolayers formed by the immobilization of biological molecules. The films spectrum have absorption spike in 827/837 cm-I and 451/484 cm-I that correspond to Si-N bonds, confirming the indication of the ellipsometry regarding as nitrogen presence. After self assembled monolayers formation composed by proteins of the type Immunoglobulin - IgG 2.5 and 5%, the spectra showed absorption bands of IR, around 3300 cm-1 and in the ranges of 1700 to 1600 cm-1 and 1600 to 1500 cm-1, spectrum that characterizes the formation of amida groups A, I and II, respectively, in other words, the formation of biologically active monolayers. Through micro-Raman spectrometry were detected displacements in the main spikes of the Silicon substratum. This displacement has been related with the stress induced by the deposited films. It was manufactured Metal Insulating Semiconductor (MIS) capacitors, using the structures dielectric/semiconductor obtained. The capacitors made possible to accomplish the electric characterization of the films through high frequency (1 MHz) capacitance-voltage (C-V) measurements, obtained the density of charges existent on the interface dielectric/semiconductor - around 1011 cm-2; and to observe the behavior of the interface with the accomplishment of thermal stages and the degradation in its recombination properties. After production and characterization of the dielectric layers, has been accomplished the second stage of the work with the production of FETs, being used as dielectric gate the films that presented better performance of the point of view physical, electric, chemical and biological. The electric characterization of the FETs that compose the arrays, has been accomplished being used the control devices disposed separately in the dies allowing to raise the characteristics of the devices construction, as well as, the behavior of the same ones when submitted to thermal stages. The chemical sensibility was verified being applied analytes with different H+ ions concentrations - different pH values - in the gate area of the FETs that compose the arrays. The viability of use of the modified FETs for chemistry/biochemistry detection was demonstrated, with employment possibility in activities of medical diagnosis, environmental control, control of the production of drugs and cosmetics and agricultural applications. / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Orientador: Peter Jurgen Tatsch / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-04T08:00:36Z (GMT). No. of bitstreams: 1 Goncalves_JoseLino_D.pdf: 3898582 bytes, checksum: f1ca023a0f6e0ef12201dd1baad96059 (MD5) Previous issue date: 2002 / Resumo: O objetivo deste trabalho foi o desenvolvimento de um processo para a obtenção de óxido de gálio (A-Ga2O3). Foi montado um sistema de crescimento para deposição química a partir de vapor (CVD - Chemical Vapor Deposition), constituído de uma câmara de reação, aquecida por um forno resistivo de 3 zonas. A partir da reação do gálio metálico com a mistura de H2 e O2 foram sintetizados cristais de A-Ga2O3, e depósitos de filmes de A-Ga2O3 sobre SiO2, em temperaturas entre 800°C e 1050°C. Na síntese foram obtidas estruturas em forma de whiskers e nos depósitos, filmes policristalinos auto-sustentáveis com propriedades semicondutoras do tipo p. Tanto os whiskers como os filmes depositados foram caracterizados pelas técnicas de difratometria de raios X em amostras policristalinas, espectroscopia Raman e efeito Hall. As superfícies foram analisadas por microscopia óptica e microscopia eletrônica de varredura (MEV). As análises mostraram que o material tem boa cristalinidade e é de alta pureza / Abstract: The main objective of this work was to develop a process to obtain gallium oxide (A-Ga2O3) by Chemical Vapor Deposition (CVD). With this purpose, a CVD system was developed and employed for material growth at temperatures between 800°C and 1050°C. In the initial stage a mixture of hydrogen, oxygen and metallic gallium was used to provide the A-Ga2O3 whiskers growth, which were characterized and studied. Next we were able to produce a self-sustainable p-type polycrystalline film of A-Ga2O3 with semiconducting properties. Both, hiskers and films, were characterized using X-ray power difractometry, Raman spectroscopy and Hall effect. Surface analyses were carried out using optical microscopy and scanning electron microscopy (SEM). The whiskers and films were highly pure and of a very good crystallinity / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

Magister Scientiae - MSc / The overall aim of this project is to study the heat transfer inside the reaction chamber of the Hot-Wire Chemical Vapor Deposition (HWCVD) system with a commercial software package FLUENT6.3; it is one of the most popular Computational Fluid Dynamics solvers for complex flows ranging from incompressible to mildly compressible to even highly compressible flows. The wealth of physical models in FLUENT allows us to accurately predict laminar and turbulent flows, various modes of heat transfer, chemical reactions, multiphase flows and other phenomena with complete mesh flexibility and solution-based mesh adaptation. In this study the 3-D HWCVD geometry was measured and created in GAMBIT which then generates a mesh model of the reaction chamber for the calculation in FLUENT. The gas flow in this study was characterized as the steady and incompressible fluid flow due to the small Mach number and assumptions made to simplify the complexity of the physical geometry. This thesis illustrates the setups and solutions of the 3-D geometry and the chemically reacting laminar and turbulent gas flow, wall surface reaction and heat transfer in the HWCVD deposition chamber. / South Africa

No description available.

Filmes de carbeto de silício, SiC, cristalinos foram depositados sobre peças de mulita por meio da técnica de deposição química por vapor (CVD) a pressão atmosférica. As características da superfície do substrato determinam se o filme será denso ou poroso, enquanto a temperatura define a cristalinidade e a taxa de nucleação para formação do filme. Durante os procedimentos de preparação do substrato de mulita para a deposição do filme, observou-se o fenômeno da formação de whiskers de mulita quando adicionados 3%mol de terras raras a peça. O fenômeno de crescimento destes whiskers foi sistematicamente estudado para sua caracterização e compreensão do mecanismo de formação. A adição de terras raras promoveu um abaixamento na temperatura de mulitização e a formação de whiskers com uma composição cuja razão alumina / sílica é de 1,3, uma das mais baixas observadas. / Crystalline silicon carbide, SiC, films were deposited on mullite by atmospheric pressure chemical vapor deposition (CVD) method. The characteristic of substrate surface determinate if the film will be dense or porous, while the deposition temperature defines its crystalinity and nucleation rate in film formation. During the mullite substrate preparation process for film deposition, it was observed a whisker formation phenomenon when the piece was doped with 3%mol of rare earth. The growth phenomenon of these whiskers was studied systematically to its characterization and comprehension of its formation mechanism. The addiction of rare earth promote a reduction in mullitization temperature and the formation of whiskers with a composition that alumina / silica ration was 1.3, one of the lowest one ever observed.

In Topologischen Isolatoren (TI) werden metallische Zustände an der Oberfläche beobachtet, während die entsprechenden Volumenzustände eine Bandlücke aufweisen. Der Volumenbeitrag zur Leitfähigkeit von TI-Materialien macht eine Synthese von Nanokristallen bzw. eine Dotierung nötig. Der Fokus der Untersuchungen dieser Arbeit liegt dabei auf der Erzeugung von Nanokristallen der TI-Materialien Bi2Te3- und Bi2Te2Se sowie dotierter Bi2Se3-Nanokristallen. Die Synthese der Nanokristalle erfolgte durch den Gasphasentransport im geschlossenen System über den Mechanismus einer Zersetzungssublimation bzw. unter dem Einsatz eines Transportmittels. Für eine erfolgreiche Erzeugung der Nanokristalle sind im Vorfeld thermodynamische Modellierungen des Gasphasentransports sowie Versuche zum chemischen Transport für die quasibinären Systeme Bi2Se3-Bi2Te3, Bi2Se3-Sb2Se3 und Bi2Se3-FeSe sowie für das ternäre System Mn-Bi-Se durchgeführt worden. Durch Versuche zum chemischen Transport konnten die Aussagen der Modellierung bestätigt und im Weiteren der Dotandengehalt in den abgeschiedenen Kristallen sowie der Einlagerungsmechanismus durch Ergebnisse aus XRD- und ICP-OES-Untersuchungen beschrieben werden. Die Synthese bzw. Dotierung der Nanokristalle wurde hauptsächlich durch die Transportrate und den Dampfdruck des Dotanden bestimmt. In den Systemen Bi2Se3-Bi2Te3 und Bi2Se3-Sb2Se3 ist ein Gasphasentransport über eine Zersetzungssublimation durchführbar und resultierte in einer erfolgreichen Darstellung von Bi2Te3- und Bi2Te2Se-Nanokristallen sowie von dotierten (SbxBi1-x)2Se3-Nanokristallen. Entgegen dessen erfolgte der Gasphasentransport in den Systemen Bi2Se3-FeSe und Mn-Bi-Se unter Verwendung eines Transportmittels. Hierbei verringerten die gesteigerten Transportraten das Wachtum von Nanokristallen. Im Weiteren gelang es dotierte (Fe,Mn)xBi2-xSe3-Volumenkristalle sowie MnBi2Se4-Einkristalle darzustellen und mittels XRD, ICP-OES, magnetischer Messungen sowie elektrischem Transport zu charakterisieren.

High temperature gas cooled nuclear reactors often make use of Tristructural Isotropic (TRISO) coated fuel particles. In these particles, a layer of silicon carbide plays the key role of providing mechanical strength and acting as a diffusion barrier so preventing the release of fission products. TRISO particles are produced by a chemical vapor deposition (CVD) process in a spouted bed coater. Operating conditions of chemical vapor deposition processes are known to influence the properties of the deposited material. In the case of silicon carbide deposited by pyrolysis of methyltrichlorosilane (MTS) in a hydrogen atmosphere, process parameters that may influence the properties of the silicon carbide deposited include deposition temperature, MTS concentration and hydrogen flow rates. In this study the coating process was investigated using a laboratory scale spouted bed CVD coater. In all the test work conducted, carbon coated zirconia particles were used as a starting material. Only silicon carbide was deposited during these trials. Process parameters investigated were temperature, MTS concentration and hydrogen flow rate. The range investigated was 1250 °C to 1550 °C for temperature, 0.5 % to 2.5 % for MTS concentration and 10.0 l.minute-1 to 15.0 l.minute-1 for hydrogen flow. This covered the range that is typically used for small-scale production coaters. Two different gas inlet configurations, a conventional water cooled inlet and an inlet without any cooling, were used in the investigation. Properties of the coating process, such as the deposition rate and coating efficiency, as well as material properties were measured. Material properties investigated included: density, crush strength, micro-hardness, fracture toughness, nano-hardness, Young’s modulus, elemental composition, phase composition and microstructure. It was found that, of the variables investigated, temperature had the strongest effect while hydrogen flow rate had the least effect on material properties. There was considerable variability in all measured parameters; this introduced considerable uncertainty into the predicted effects of process conditions on material properties. / Thesis (PhD)--University of Pretoria, 2012. / Materials Science and Metallurgical Engineering / unrestricted

No description available.

The doctoral thesis deals with the structure and properties of the polycrystalline silicon layers deposited on the silicon wafers backside. The wafers are further used for production of semiconductor devices. This work is focused on detailed description of the layers structure and study of the gettering properties and residual stress of the layers. The main goal of this work is to develop two novel technologies. The first one leads to improvement of the temperature stability of the gettering properties of the layers, and the second one solves the deposition of the layers with pre-determined residual stress. This doctoral thesis was created with the support of the company ON Semiconductor Czech Republic, Rožnov pod Radhoštěm.

We report approaches to grow ultrathin Ru films for application as a seed layer and Cu diffusion barrier. For chemical vapor deposition (CVD) with Ru3(CO)12 we show the role surface hydroxyl groups have in nucleating the Ru islands that grow into a continuous film in a Volmer-Weber process, and how the nucleation density can be increased by applying a CO or NH3 overpressure. Thinner continuous films evolve in the presence of a CO overpressure. We report an optimun ammonia overpressure for Ru nucleation and that leads to deposition of smoother Ru thin films. Finally, we report a comparison of amorphous Ru films that are alloyed with P or B and demonstrate 3-nm thick amorphous Ru(B) films function as a Cu diffusion barrier.