Correlações do tipo processo-estrutura-propriedade de filmes têm sido objeto de extensos estudos já a várias décadas, tanto do ponto de vista científico como tecnológico. Mais recentemente, atenção crescente tem sido dada a filmes cada vez mais finos, principalmente para atender as necessidades de novas tecnologias. Para compreender melhor a correlação processo-estrutura, vários pesquisadores propuseram Modelos de Zonas Estruturais para filmes com espessuras, tipicamente, de algumas unidades a dezenas de micrometros. Neste trabalho, propomos Modelos de Zonas Estruturais para filmes finos de elementos do Grupo IV-B (Ti, Zr e Hf) e estudamos os mecanismos de formação da microestrutura dos filmes. Durante o desenvolvimento de nosso trabalho, curiosos aglomerados de grãos, com tamanhos de vários micrometros e com geometria fractal, foram observados nos filmes de Zr. As características geométricas dos aglomerados e os possíveis mecanismos que os originam e levam à sua evolução também são considerados aqui. / Correlations type processing-structure-property of films have been the subject of extensive studies for the last several decades, both from the point of view of science and technology. More recently, growing attention has been given to ever-thinner films, especially to satisfy the needs of newer technologies. To better understand the correlation processing-structure, many researchers have proposed Structure Zone Models for films typically a few to a few tens of micrometers thick. In this work, we propose Structure Zone Models for Group IV-B (Ti, Zr and Hf) thin films and study the microstructure forming mechanisms of the films. During the development of our work, intriguing grain aggregates several micrometers Jorge and with fractal geometry were observed in the Zr films. The geometrical characteristics of the aggregates, their possible origin and evolution mechanisms are also considered here.

O níquel desempenha um papel importante na catálise como uma alternativa ao uso de metais nobres; no entanto, a preparação de nanopartículas de níquel com o tamanho e composição bem controlados não é uma tarefa fácil. O trabalho descrito nessa dissertação compreende a preparação e caracterização de um novo catalisador heterogêneo cotendo nanopartículas de níquel e o estudo da atividade catalítica em reações de hidrogenação em fase gososa e líquida. O catalisador foi preparado por pulverização catódica (magnetron sputtering deposition), que permitiu a deposição de nanopartículas com diâmetro médio de 2,5 ± 0,3 nm sobre um suporte de sílica, sem a utilização de solventes ou estabilizantes. Diferentes tempos de pulverização catódica permitiram a obtenção de catalisadores com diferentes concentrações de metal sobre o suporte. O catalisador preparado foi caracterizado por microscopia eletrônica de transmissão (MET), difração de raios X (DRX), espectroscopia de fotoéletrons excitados por raios X (XPS) e espectroscopia de absorção de raios X (XAS). As análises por técnicas de raios X mostraram que o catalisador oxida parcialmente sua superfície após ser exposto ao ar ambiente. Utilizando XAS, foi possível mostrar que o catalisador como preparado possui 61% de níquel metálico e 39% de níquel óxido. O catalisador exposto ao ar por um ano ainda apresentava 49% de níquel metálico. O desempenho dos catalisadores foi estudado na reação modelo de hidrogenação de cicloexeno, utilizando hidrogênio molecular como agente redutor. Para a hidrogenação em fase líquida, o catalisador não se mostrou ativo nas condições estudadas e não pode ser ativado mesmo após pré-tratamento com hidrogênio molecular. Já na hidrogenação em fase gasosa, o catalisador apresentou atividade catalítica, sendo mais ativo quando submetido a um processo de ativação com fluxo de hidrogênio e aquecimento até 200 ºC. O catalisador perde atividade ao ser utilizado por um longo período ou utilizado em sucessivos ciclos de aquecimento em condições reacionais, mas a atividade pode ser recuperada quando o catalisador é tratado termicamente sob fluxo de hidrogênio. / Nickel plays an important role in catalysis as an affordable alternative for noble metals; however, it is one of the most difficult metal nanoparticles to prepare with well-controlled size and composition. This master thesis comprises the development and characterization of a new heterogeneous catalyst containing nickel nanoparticles and the catalytic studies for hydrogenation reactions in liquid and gas phase. The catalyst was prepared by magnetron sputtering deposition, allowing the deposition of nanoparticles of 2.5 ± 0.3 nm on silica, without using solvents and stabilizers. Different sputtering times allowed the preparation of catalysts with different loading of metal on silica. The catalyst prepared has been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The analysis by X-ray techniques revealed that the catalyst partially oxidize its surface after being exposed to ambient air. By XAS technique, it was possible to show that the catalyst as prepared has 61% of metallic nickel and 39% of nickel oxide. The as prepared catalyst was exposed to air for a year still contains 49% of metallic nickel. The performance of the catalyst was studied in cyclohexene hydrogenation model reaction, using molecular hydrogen as reducing agent. The catalyst was not active for the liquid phase hydrogenation under the studied conditions, and could not be activated by a pre-treatment with hydrogen. In the gas phase hydrogenation, the catalyst showed catalytic activity being more active when submitted to an activation process with hydrogen flow and heating to 200 ºC. The catalyst loses activity when used for a long time on stream or used in consecutive heating cycles under reaction conditions, but the activity can be regenerated when the catalyst is heat-treated under hydrogen flow.

by Fung Chi Keung = 採用脈衝直流電源對靶濺射技術製備銦錫氧化物薄膜的硏究 / 馮志強. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Fung Chi Keung = Cai yong mai chong zhi liu dian yuan dui ba jian she ji shu zhi bei yin xi yang hua wu bo mo de yan jiu / Feng Zhiqiang. / Acknowledgements --- p.i / Abstract --- p.ii / 論文摘要 --- p.iii / Table of contents --- p.iv / List of figures --- p.viii / List of tables --- p.xii / Chapter Chapter 1 --- Introduction --- p.1-1 / Chapter 1.1 --- Genesis --- p.1-1 / Chapter 1.2 --- Aims and Objectives --- p.1-1 / Chapter 1.3 --- Layout of Thesis --- p.1-3 / References --- p.1-4 / Chapter Chapter 2 --- Literature Review --- p.2-1 / Chapter 2.1 --- Introduction to transparent conducting oxides (TCOs) --- p.2-1 / Chapter 2.2 --- Indium tin oxide (ITO) --- p.2-2 / Chapter 2.2.1 --- Use of ITO --- p.2-2 / Chapter 2.2.2 --- Structure and properties of ITO --- p.2-3 / Chapter 2.3 --- Properties of ITO films deposited by different growth techniques --- p.2-8 / Chapter 2.3.1 --- Sputtering --- p.2-9 / Chapter 2.3.2 --- Vacuum evaporation --- p.2-11 / Chapter 2.3.3 --- Spray pyrolysis --- p.2-11 / Chapter 2.3.4 --- Chemical vapor deposition (CVD) --- p.2-12 / Chapter 2.3.5 --- Reactive ion plating --- p.2-12 / Chapter 2.4 --- Contradictions in existing literature --- p.2-13 / References --- p.2-15 / Chapter Chapter 3 --- Thin Film Fabrication and Process --- p.3-1 / Chapter 3.1 --- Facing-target sputtering (FTS) --- p.3-1 / Chapter 3.2 --- Asymmetric bipolar pulsed DC power source --- p.3-3 / Chapter 3.2.1 --- Target poisoning --- p.3-3 / Chapter 3.2.2 --- Preferential sputtering --- p.3-4 / Chapter 3.2.3 --- Discussion --- p.3-4 / Chapter 3.3 --- Substrates --- p.3-6 / Chapter 3.3.1 --- Microscopic glass --- p.3-7 / Chapter 3.3.2 --- Corning 7059 glass --- p.3-8 / Chapter 3.3.3 --- Epitaxial growth --- p.3-8 / Chapter 3.3.3.1 --- Epitaxial lattice matching --- p.3-8 / Chapter 3.3.3.2 --- Yttrium stabilized zirconia (YSZ) --- p.3-9 / Chapter 3.3.3.3 --- Sapphire --- p.3-9 / Chapter 3.3.3.4 --- Silicon wafer --- p.3-11 / Chapter 3.3.4 --- Substrate cleaning --- p.3-11 / Chapter 3.4 --- Targets for the reactive sputtering of ITO films --- p.3-13 / Chapter 3.4.1 --- Indium Tin Oxide target (90wt% ln203 : 10wt% Sn04) --- p.3-14 / Chapter 3.4.2 --- Indium Tin alloy target (90wt% In : 10wt% Sn) --- p.3-14 / Chapter 3.5 --- Deposition conditions --- p.3-16 / Chapter 3.5.1 --- Sputter atmosphere --- p.3-16 / Chapter 3.5.2 --- Deposition pressure --- p.3-16 / Chapter 3.5.3 --- Deposition power --- p.3-17 / Chapter 3.5.4 --- Target to substrate distance --- p.3-17 / Chapter 3.5.5 --- Pulse frequency and pulse width --- p.3-17 / Chapter 3.6 --- Deposition --- p.3-17 / References --- p.3-19 / Chapter Chapter 4 --- Measurement and Analysis Techniques --- p.4-1 / Chapter 4.1 --- Resistivity measurement --- p.4-1 / Chapter 4.2 --- "Transmittance, reflectivity and absorption measurements" --- p.4-3 / Chapter 4.3 --- Thickness measurement --- p.4-4 / Chapter 4.4 --- "Crystal structure, surface morphology and roughness measurements" --- p.4-4 / Chapter 4.5 --- Photolithography --- p.4-7 / Chapter 4.6 --- Hall effect measurements --- p.4-8 / References --- p.4-10 / Chapter Chapter 5 --- Experimental results and discussions --- p.5-1 / Chapter 5.1 --- Effect of O2 partial pressure --- p.5-1 / Chapter 5.1.1 --- Deposition rate --- p.5-2 / Chapter 5.1.2 --- Electrical and optical properties --- p.5-4 / Chapter 5.1.3 --- Structure and orientation --- p.5-16 / Chapter 5.1.4 --- Surface morphology and roughness --- p.5-22 / Chapter 5.1.5 --- Conclusion --- p.5-29 / Chapter 5.2 --- Effect of substrate temperature --- p.5-29 / Chapter 5.2.1 --- Electrical and optical properties --- p.5-29 / Chapter 5.2.2 --- Structure and orientation --- p.5-44 / Chapter 5.2.3 --- Surface morphology and roughness --- p.5-49 / Chapter 5.2.4 --- Conclusion --- p.5-54 / Chapter 5.3 --- Effect of vacuum annealing --- p.5-54 / Chapter 5.3.1 --- Electrical and optical properties --- p.5-54 / Chapter 5.3.2 --- Conclusion --- p.5-59 / Chapter 5.4 --- Effect of different substrates --- p.5-59 / Chapter 5.4.1 --- Comparison of heteroepitaxial and polycrystalline ITO films --- p.5-60 / Chapter 5.4.2 --- Conclusion --- p.5-63 / Chapter 5.5 --- Effect of film thickness --- p.5-64 / Chapter 5.5.1 --- Film thickness calibration --- p.5-64 / Chapter 5.5.2 --- Electrical properties --- p.5-64 / Chapter 5.5.3 --- Conclusion --- p.5-67 / Chapter 5.6 --- Effect of deposition pressure --- p.5-68 / Chapter 5.6.1 --- Deposition rate --- p.5-68 / Chapter 5.6.2 --- Electrical properties --- p.5-70 / Chapter 5.6.3 --- Conclusion --- p.5-70 / Chapter 5.7 --- Effect of target pre-conditioning --- p.5-72 / Chapter 5.8 --- Conclusion --- p.5-72 / References --- p.5-74 / Chapter Chapter 6 --- Further works --- p.6-1 / Appendix I

by Chiah Man Fat. / Thesis submitted in: September 1999. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 94-97). / Abstracts in English and Chinese. / Acknowledgements --- p.2 / Abstract --- p.3 / Table of Contents --- p.5 / List of Figures --- p.7 / List of Tables --- p.13 / Chapter Chapter 1 --- Introduction --- p.14 / Chapter 1.1. --- Overview --- p.14 / Chapter 1.2. --- Giant Magnetoresistance (GMR) --- p.15 / Chapter 1.3. --- Application of GMR Materials --- p.20 / Chapter 1.4. --- Preparation Methods --- p.22 / Chapter 1.5. --- This Thesis --- p.23 / Chapter Chapter 2 --- Sample Preparation and Experimental Methods --- p.24 / Chapter 2.1. --- MEVVA Ion Source Implanter --- p.24 / Chapter 2.2. --- The Pulsed Filtered Cathodic Arc Co-deposition System --- p.26 / Chapter 2.3. --- Sample Preparation --- p.29 / Chapter 2.3.1 --- Implantation Condition --- p.29 / Chapter 2.3.2 --- Co-deposition Conditions --- p.31 / Chapter 2.4. --- Characterization methods --- p.32 / Chapter 2.4.1 --- Magnetoresistance Measurement --- p.32 / Chapter 2.4.2 --- Atomic Force Microscopy and Magnetic Force Microscopy --- p.34 / Chapter 2.4.3 --- Rutherford Backscattering Spectroscopy (RBS) --- p.37 / Chapter 2.4.4 --- SQUID Magnetometer --- p.38 / Chapter Chapter 3 --- Characterization of Implanted Samples --- p.39 / Chapter 3.1. --- Introduction --- p.39 / Chapter 3.2. --- Results and Discussion --- p.39 / Chapter 3.2.1 --- Ag Film Thickness Dependence --- p.39 / Chapter 3.2.2 --- Dose Dependence --- p.44 / Chapter 3.2.3 --- Extraction Voltage Dependence --- p.46 / Chapter 3.2.4 --- Annealing Temperature Dependence --- p.49 / Chapter 3.2.5 --- Thicker Layer Formation --- p.56 / Chapter 3.2.6 --- AFM and MFM Measurements --- p.58 / Chapter 3.3. --- Summary --- p.64 / Chapter Chapter 4 --- Characterization of Co-deposited Samples --- p.65 / Chapter 4.1. --- Introduction --- p.65 / Chapter 4.2. --- Results and discussion --- p.65 / Chapter 4.2.1 --- RBS Measurement --- p.65 / Chapter 4.2.2 --- Magnetoresistance Measurement --- p.66 / Chapter 4.2.3 --- AFM Measurement --- p.69 / Chapter 4.2.4 --- MFM Measurement --- p.76 / Chapter 4.3. --- Summary --- p.84 / Chapter Chapter 5 --- Conclusion --- p.85 / Chapter 5.1. --- Main Results of This Work --- p.85 / Chapter 5.2. --- Suggestions on Future Works --- p.87 / Appendix --- p.89 / Reference --- p.94 / Publications --- p.97

Au Yeung Yue Fung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Au Yeung Yue Fung. / Abstract --- p.i / 論文摘要 --- p.ii / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.viii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Genesis --- p.1-1 / Chapter 1.2 --- Aims and Objectives --- p.1-2 / Chapter 1.3 --- Layout of thesis --- p.1-3 / References --- p.1-4 / Chapter Chapter 2 --- Literature review / Chapter 2.1 --- Introduction to superconductor --- p.2-1 / Chapter 2.2 --- MgB2 --- p.2-3 / Chapter 2.2.1 --- Significance of MgB2 --- p.2-3 / Chapter 2.2.2 --- Structure and properties of MgB2 --- p.2-4 / Chapter 2.2.3 --- Superconducting mechanism of MgB2 --- p.2-5 / Chapter 2.2.4 --- Physical properties of boron and boride --- p.2-7 / Chapter 2.2.5 --- Physical properties of magnesium --- p.2-7 / Chapter 2.2.6 --- Formation of MgB2 --- p.2-8 / Chapter 2.2.7 --- MgB2 thin films --- p.2-9 / Chapter 2.2.7.1 --- Substrate --- p.2-11 / Chapter 2.2.7.2 --- Substrate temperature --- p.2-12 / Chapter 2.3 --- Contradictions as revealed by existing literatures --- p.2-13 / References --- p.2-14 / Chapter Chapter 3 --- Preparation and characterization of bulk MgB2 / Chapter 3.1 --- Bulk MgB2 fabrication / Chapter 3.2 --- Measurement and analysis techniques of bulk MgB2 --- p.3-4 / Chapter 3.2.1 --- XRD --- p.3-4 / Chapter 3.2.2 --- Meissner effect measurement --- p.3-5 / Chapter 3.3 --- Sintering time of MgB2 --- p.3-6 / Chapter 3.4 --- Concentration of Mg in sintering MgB2 --- p.3-8 / Chapter 3.5 --- Sintering temperature of MgB2 --- p.3-11 / Chapter 3.6 --- Thermal stability of MgB2 --- p.3-13 / Chapter 3.7 --- MgB2 in water --- p.3-17 / References --- p.3-19 / Chapter Chapter 4 --- Preparation and characterization of MgB2thin films / Chapter 4.1 --- Thin film deposition --- p.4-1 / Chapter 4.1.1 --- Facing-target sputtering (FTS) --- p.4-2 / Chapter 4.1.2 --- Vacuum system --- p.4-4 / Chapter 4.1.3 --- Asymmetric bipolar pulsed DC power source --- p.4-6 / Chapter 4.2 --- Fabrication of MgB2 targets --- p.4-10 / Chapter 4.3 --- Substrates --- p.4-11 / Chapter 4.4 --- Deposition procedure --- p.4-12 / Chapter 4.5 --- Deposition condition --- p.4-13 / Chapter 4.5.1 --- Deposition power --- p.4-15 / Chapter 4.5.2 --- Deposition pressure --- p.4-13 / Chapter 4.5.3 --- Annealing temperature --- p.4-18 / Chapter 4.5.4 --- Substrate temperature --- p.4-21 / Chapter 4.5.5 --- Conclusion --- p.4-26 / References --- p.4-29 / Chapter Chapter 5 --- Failed attempts of MgB2 films fabrication by in situ method / Chapter 5.1 --- In-situ method --- p.5-1 / Chapter 5.2 --- Additional FTS guns with Mg target --- p.5-2 / Chapter 5.3 --- Diode sputtering --- p.5-4 / Chapter 5.4 --- Co-evaporating fabrication --- p.5-6 / Chapter Chapter 6 --- Conclusion --- p.6-1

O níquel desempenha um papel importante na catálise como uma alternativa ao uso de metais nobres; no entanto, a preparação de nanopartículas de níquel com o tamanho e composição bem controlados não é uma tarefa fácil. O trabalho descrito nessa dissertação compreende a preparação e caracterização de um novo catalisador heterogêneo cotendo nanopartículas de níquel e o estudo da atividade catalítica em reações de hidrogenação em fase gososa e líquida. O catalisador foi preparado por pulverização catódica (magnetron sputtering deposition), que permitiu a deposição de nanopartículas com diâmetro médio de 2,5 ± 0,3 nm sobre um suporte de sílica, sem a utilização de solventes ou estabilizantes. Diferentes tempos de pulverização catódica permitiram a obtenção de catalisadores com diferentes concentrações de metal sobre o suporte. O catalisador preparado foi caracterizado por microscopia eletrônica de transmissão (MET), difração de raios X (DRX), espectroscopia de fotoéletrons excitados por raios X (XPS) e espectroscopia de absorção de raios X (XAS). As análises por técnicas de raios X mostraram que o catalisador oxida parcialmente sua superfície após ser exposto ao ar ambiente. Utilizando XAS, foi possível mostrar que o catalisador como preparado possui 61% de níquel metálico e 39% de níquel óxido. O catalisador exposto ao ar por um ano ainda apresentava 49% de níquel metálico. O desempenho dos catalisadores foi estudado na reação modelo de hidrogenação de cicloexeno, utilizando hidrogênio molecular como agente redutor. Para a hidrogenação em fase líquida, o catalisador não se mostrou ativo nas condições estudadas e não pode ser ativado mesmo após pré-tratamento com hidrogênio molecular. Já na hidrogenação em fase gasosa, o catalisador apresentou atividade catalítica, sendo mais ativo quando submetido a um processo de ativação com fluxo de hidrogênio e aquecimento até 200 ºC. O catalisador perde atividade ao ser utilizado por um longo período ou utilizado em sucessivos ciclos de aquecimento em condições reacionais, mas a atividade pode ser recuperada quando o catalisador é tratado termicamente sob fluxo de hidrogênio. / Nickel plays an important role in catalysis as an affordable alternative for noble metals; however, it is one of the most difficult metal nanoparticles to prepare with well-controlled size and composition. This master thesis comprises the development and characterization of a new heterogeneous catalyst containing nickel nanoparticles and the catalytic studies for hydrogenation reactions in liquid and gas phase. The catalyst was prepared by magnetron sputtering deposition, allowing the deposition of nanoparticles of 2.5 ± 0.3 nm on silica, without using solvents and stabilizers. Different sputtering times allowed the preparation of catalysts with different loading of metal on silica. The catalyst prepared has been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The analysis by X-ray techniques revealed that the catalyst partially oxidize its surface after being exposed to ambient air. By XAS technique, it was possible to show that the catalyst as prepared has 61% of metallic nickel and 39% of nickel oxide. The as prepared catalyst was exposed to air for a year still contains 49% of metallic nickel. The performance of the catalyst was studied in cyclohexene hydrogenation model reaction, using molecular hydrogen as reducing agent. The catalyst was not active for the liquid phase hydrogenation under the studied conditions, and could not be activated by a pre-treatment with hydrogen. In the gas phase hydrogenation, the catalyst showed catalytic activity being more active when submitted to an activation process with hydrogen flow and heating to 200 ºC. The catalyst loses activity when used for a long time on stream or used in consecutive heating cycles under reaction conditions, but the activity can be regenerated when the catalyst is heat-treated under hydrogen flow.

L’une des solutions proposées pour la diminution du coût par watt d'électricité produite par le photovoltaïque est de réduire la quantité des matériaux semiconducteurs entrants dans la fabrication de la cellule solaire. La 3ème génération des cellules solaires en couches minces nanostructurées vient pour répondre à cette exigence. Les matériaux CIGS sous leurs structures chalcopyrites, sont de nouveaux matériaux semiconducteurs fortement recommandés pour la fabrication des cellules solaires à base de couches minces. La synthèse par la méthode de pulvérisation cathodique et la caractérisation de ces derniers matériaux ont été l’objectif général de cette thèse. Toutes les couches ont été déposées grâce à une seule cible constituée par des grains nanométriques de CIGS, ces derniers ont été obtenus par la voie solvothermale. Dans la première partie de ce travail, nous avons étudié l’effet des différents paramètres de synthèse (température, durée de synthèse, le traitement thermique et l’effet du taux molaire de gallium et d’indium) sur les propriétés des nanoparticules CIGS, les mécanismes réactionnels mis en jeu ont été aussi étudié. Les conditions de synthèse optimales sont une température et une durée de synthèse égale à 220 °C et 24 heures. Après un traitement thermique, les nanoparticules de CIGS sont cristallisées suivant la structure chalcopyrite, avec l’absence des pics correspond aux phases secondaires, les diamètres des grains varie entre 15 et 30 nm. Dans la deuxième partie, Nous sommes intéressés à l’élaboration et la caractérisation des couches absorbantes ternaire et quaternaire de type CIS et CIGS (x = 0 et x = 0.3) obtenues par pulvérisation cathodique en variant la puissance de dépôt de 60 à 100 W. Toutes les couches élaborées présentent la phase chalcopyrite avec (112) comme axe d’orientation préférentiel de croissance. La taille moyenne des grains a le même ordre de grandeur que les poudres initiales. Les couches de CIGS sont généralement de type de conduction p avec des faibles valeurs de résistivités. Les caractérisations optiques des couches présentent une bonne absorption de l’ordre de 95 % dans la gamme de visible et le proche infra-rouge. La variation du coefficient d’absorption en fonction de l’énergie du photon, nous a permis de déterminer l’énergie du gap optique. Les valeurs obtenues pour les différentes couches sont cohérentes avec l’optimum pour la conversion photovoltaïque. / One of the proposed solutions for reducing the cost of electricity produced by the photovoltaic is to reduce the amount of incoming semiconductor materials in the manufacture of the solar cell. The 3rd generation solar cells based on nanostructured thin film come in response to this requirement. CIGS under their structures chalcopyrite are highly recommended for the manufacture of this solar cells type. The synthesis of these materials using sputtering method and their characterization were the overall goal of this thesis. All films were deposited onto glass substrates from single target composed trough nanoparticles of CIGS, which are obtained by the solvothermal route. In the first part of this work, we studied the effect of different synthesis parameters (temperature, synthesis time, the heat treatment and the effect of the molar ratio of gallium and indium) on the properties of CIGS nanoparticles. The reaction mechanisms were also studied. The optimum synthesis conditions are a temperature and a synthesis time equal to 220 ° C and 24 hours. After heat treatment, the nanoparticles are crystallized according CIGS chalcopyrite structure, with the absence of the peaks corresponding to the secondary phases, grain size between 15 and 30 nm. In the second part, we are interested in the deposition and characterization of ternary and quaternary absorbent thin film CIS and CIGS (x = 0 and x = 0.3) obtained by sputtering deposition by varying the power of pulverization from 60 to 100 W. All layers have crystallized in the chalcopyrite structure with the preferential orientation in the (112) plane were obtained. The average grain size has the same order of magnitude as the initial powders. All films are generally p-type conduction with low resistivity values. Optical characterizations of the layers exhibit a good absorption in the visible range and the near infrared. The variation of the absorption coefficient as a function of photon energy enabled us to determine the energy of the optical gap. The values obtained for the different layers are consistent with the optimum for the photovoltaic conversion.

Neste trabalho serão apresentados os resultados referentes à síntese e caracterização de materiais híbridos constituídos de nanotubos de TiO2 e clusters de CdSe (Nt-TiO2/CdSe), além de sua aplicação em células fotoeletroquímicas utilizadas na produção de hidrogênio (H2). A primeira etapa do trabalho envolveu a síntese e caracterização dos nanotubos de TiO2. Inicialmente foram encontradas as condições ótimas para síntese e tratamento térmico dos nanotubos. Foi observado que nanotubos de TiO2 apresentam melhor resposta fotoeletroquímica quando obtidos com cerca de 1 μm de comprimento, no entando a temperaturas de tratamento termico estudas neste trabalho não afetaram sifnificativamente seu comportamento fotoeletroquímica. A segunda etapa envolveu a utilização da técnica de RF Magnetron Sputtering para deposição de nanoparticulas e clusters de CdSe sobre os nanotubos. Primeiramente foi realizado um estudo sobre a dependência das propriedades fotoeletroquímicas com a concentração de CdSe sendo a concentração ótima para este sistema de 3,18x1017 at.cm-2 de Cd e Se. Para avaliar o efeito da cristalinidade do TiO2 sobre a resposta fotoeletroquímica do sistema híbrido (Nt-TiO2/CdSe) antes da deposição de CdSe os nanotubos de TiO2 foram submetidos a tratamentos térmicos em diferentes temperaturas. Nesta etapa foi verificado um efeito significativo da temperatura de tratamento térmico dos nanotubos de TiO2 na formação do hibrido, o qual influenciou suas propriedades morfológicas, ópticas e fotoeletroquímicas. Adicionalmente, as amostras de nanotubos recobertos com CdSe foram submetidas a tratamentos térmicos em vácuo resultando em uma melhora significativa das suas propriedades fotoeletroquímicas. A maior fotocorrente foi obtida de uma amostra de nanotubos de TiO2 tratada termicamente a 400°C por 3h seguido da deposição de CdSe e tratamento térmico a 400°C por 30 min em vácuo, gerando uma densidade de corrente de 1,9 mA.cm-2 sob irradiação do espectro solar terrestre ou somente do espectro visível. Os resultados obtidos neste trabalho sugerem que o comportamento sinérgico do material híbrido produzido está relacionado a diminuição da resistência eletrica na interface CdSe/TiO2 e o consequente aumento da transferência de cargas do CdSe para TiO2 após o tratamento de térmico em uma condição específica. De acordo com os resultados indiretos de produção de hidrogênio através de medidas de fotocorrente, podemos concluir que o material hibrido desenvolvido neste trabalho apresenta um grande potencial para geração de hidrogênio. / In this work we present the results obtained from the synthesis and characterization of a hybrid materials consisting of TiO2 nanotubes and CdSe clusters (CdSe/Nt-TiO2) as well as its application in photoelectrochemical cells used to produce hydrogen (H2). The primary step of this work was the synthesis and characterization of the TiO2 nanotubes. At first, the ideal parameters for the synthesis and thermal treatment of the nanotubes were found. The best photoelectrochemical results were obtained from 1 micrometer long nanotubes, however the temperatures studied in this work are not found to have an effect on the photoelectrochemical behavior. The second part of this work concerned the use of RF Magnetron Sputtering to deposit CdSe nanoparticles and agglomerates on the TiO2 nanotubes. From the study of the photoelectrochemical dependence on the CdSe concentration we have found the best concentration to be 3.18x1017 at.cm-2 of Cd and Se. In order to evaluate the effect of TiO2 crystallinity on the photoelectrochemical response of Nt-TiO2/CdSe, CdSe was deposited on TiO2 nanotubes previously treated at different temperatures. The effect of the thermal treatment on the TiO2 nanotubes before CdSe deposition resulted in improved optical, morphological and photoelectrochemical behavior. In addition the CdSe covered TiO2 nanotubes were thermally treated under vacuum resulting in significant improvement of the photoelectrochemical properties. The highest photocurrent density was obtained from the samples thermally treated at 400°C before and after CdSe deposition, generating a photocurrent density of 1.9 mA/cm-2 under simulated sun or visible light irradiation. The results obtained in this work strongly suggest a synergistic behavior in the hybrid material related to a decrease of the electrical resistance at the CdSe/TiO2 interface, hence to an improvement of charge transfer from the CdSe to the TiO2 after thermal annealing at specific conditions. According to the results obtained from indirect measurements of hydrogen production by measuring photocurrent, we conclude that the hybrid material developed in this work presents potential for hydrogen generation.

Neste trabalho são apresentados resultados que concernem ao estudo da magnetorresistência gigante (GMR) em amostras de multicamadas de Co/Cu com larguras de ordem micrométricas. Para isto, filmes com largura macroscópica foram depositados por sputtering e empregou-se técnica de litografia ótica, associada à corrosão úmida, para se proceder com o processo de conformação da estrutura. Foram mantidos constantes o comprimento e a espessura da amostra enquanto que a largura foi variada dentro de uma faixa de 2 a 30 m. Com o objetivo de identificar a ocorrência de possíveis modificações estruturais devidas ao aquecimento da amostra durante o processo de litografia, uma análise prévia da estabilidade térmica da estrutura se fez necessária. Para isso um sistema de tratamento térmico com monitoramento in situ de sua resistência elétrica foi operacionalizado. Foi constatado que é improvável que as temperaturas empregadas durante a conformação da amostra promovam alguma modificação perceptível na amostra. Pudemos observar efeitos sobre a curva de magnetorresistência (MR) decorrente do valor da largura da amostra e isso foi associado a possíveis mudanças no processo de magnetização. Para tanto, relacionamos as medidas MR e de efeito Hall planar (PHE), estabelecendo que, com a diminuição da largura (w), houve uma maior tendência de que as magnetizações das camadas vizinhas realizassem um tipo de “movimento de tesoura” durante suas rotações, o que progressivamente leva a um perfil mais simétrico (em torno do campo coercivo) da curva de magnetorresistência. Interpretamos que isso se deve a uma melhor correlação entre as camadas (ou mesmo domínios) vizinhas, impelidos pela aproximação de um estado de monodomínio induzido pela diminuição de w. Além disso, uma contribuição adicional ao acoplamento antiferromagnético pré-existente pode ter se originado a partir da interação magnetostática entre as bordas de camadas adjacentes. / This thesis presents results that concern the study of giant magnetoresistance (GMR) in Co / Cu multilayers bearing widths (w) of micrometer dimensions. For this, macroscopic width films were deposited by sputtering, and optical lithography associated with wet etching were employed to proceed with the changes to the structures. We kept constant both length and thickness of the sample, while the width was varied in the range 2 to 30 micrometers. In order to identify possible spurious effects from sample heating during the lithography process, a preliminary analysis of the thermal stability of the structure was performed. For this purpose, a heat treatment system with in situ monitoring of the sample’s electrical resistance was used. We found that it is unlikely that the temperatures employed during the lithographic process produce any noticeable change in the samples. We have observed effects on the magnetoresistance curve (MR) due to the sample width value, and this was associated with possible changes in the magnetization process. To do so, we used both the MR and Planar Hall effect (PHE) measurements, establishing that, with decreasing w, there was a greater tendency that the magnetization of neighboring layers perform a kind of “scissors movement” during their rotations, which gradually leads to a symmetric plot (around the coercive field) of the magnetoresistance. We interpret that this is due to a better correlation between the adjacent layers (or even domains), prompted by the approach of a monodomain state induced by the decrease in w. Furthermore, an additional contribution to the pre-existing antiferromagnetic coupling may have originated from the magnetostatic interaction between the edges of adjacent layers.

Thin films are used for a variety of applications, which can include electronic devices, optical coatings and decorative parts. They are used for their physical, electrical, magnetic, optical and mechanical properties, and many times these properties are required simultaneously. Obtaining these desired properties starts with the deposition process and they are verified by a number of analysis techniques after deposition. A DC magnetron sputter system was used here to deposit tungsten films, with film thickness and residual stress uniformity being of primary interest. The film thickness was measured to vary by up to 45 % from the center to outer edge of a 4" wafer. Ar pressure was found to influence the thin film residual stress with lower Ar pressures leading to compressive residual stress (-1.5 GPa) and higher Ar pressures leading to tensile residual stress (1 GPa). Residual stress measurements of the tungsten films were made using a wafer curvature technique and X-ray diffraction. The results of the two techniques were compared and found to be within 20 %. Nanoindentation was used to analyze the mechanical properties of several types of thin films that are commonly used in microelectronic devices. Thin film reduced modulus, hardness, interfacial toughness and fracture toughness were some of the mechanical properties measured. Difficulties with performing shallow indents (less than 100 nm) were addressed, with proper calibration procedures for the indentation equipment and tip area function detailed. Pile-up during the indentation of soft films will lead to errors in the indentation contact depth and area, leading to an overestimation of the films' reduced modulus and hardness. A method was developed to account for pile-up in determining the indentation contact depth and calculating a new contact area for improving the analysis of reduced modulus and hardness. Residual stresses in thin films are normally undesired because in extreme cases they may result in thru-film cracking or interfacial film delamination. With the use of lithography techniques to pattern wafers with areas of an adhesion reducing layer, thin film delamination was controlled. The patterned delamination microchannels may be used as an alternative method of creating microchannels for fluid transport in MEMS devices. Delamination morphology was influenced by the amount of residual stress in the film and the critical buckling stress, which was primarily controlled by the width of the adhesion reducing layers.