>Magister Scientiae - MSc / Without reverting to encapsulation, organic bulk - heterojunction solar cells can be protected from the oxidation of the highly reactive low work function cathode metal electrode, by the deposition of metal oxide buffer layers onto an indium-tin oxide (ITO) substrate. The zinc-oxide (ZnO) or titanium dioxide (TiO2) layer can serve as an electron collecting contact. In such a case the ordering of layer deposition is inverted from the traditional layer sequencing, using an additional effect of the metal oxide layer acting as a hole blocking contact

This master’s thesis deals with ways of lamination of ceramic tapes prepared by gel–tape casting method. The thesis is divided into two parts. The first part, a literary recherche, describes methods of production of thin ceramic layers. The main focus is on the tape casting method. The second, experimental, part of the thesis describes the preparation of ceramic suspensions, the fabrication of thin ceramic layers by gel–tape casting method, the preparation of laminated bodies from thick-walled discs and laminated tapes and it also shows a possibility of creating of ceramic layers by the spin coating method used on polycrystalline ceramic substrate.

Metal oxide thin films serve as critical components in many modern technologies, including microelectronic devices. Industrial state-of-the-art production utilizes vapor-phase techniques to make high-quality (dense, smooth, uniform) thin film materials. However, vapor-phase techniques require large energy inputs and expensive equipment and precursors. Solution-phase routes to metal oxides have attracted great interest as cost-effective alternatives to vapor-phase methods and also offer the potential of large-area coverage, facile control of metal composition, and low-temperature processing. Solution deposition has previously been dominated by sol-gel routes, which utilize organic ligands, additives, and/or solvents. However, sol-gel films are often porous and contain residual carbon impurities, which can negatively impact device properties. All-inorganic aqueous routes produce dense, ultrasmooth films without carbon impurities, but the mechanisms involved in converting aqueous precursors to metal oxides are virtually unexplored. Understanding these mechanisms and the parameters that influence them is critical for widespread use of aqueous approaches to prepare microelectronic components. Additionally, understanding (and controlling) density and composition inhomogeneities is important for optimizing electronic properties. An overview of deposition approaches and the challenges facing aqueous routes are presented in Chapter I. A summary of thin film characterization techniques central to this work is given in Chapter II. This dissertation contributes to the field of solution-phase deposition by focusing on three areas. First, an all-inorganic aqueous route to high-κ metal oxide dielectrics is developed for two ternary systems. Chapters III and IV detail the film formation chemistry and film properties of lanthanum zirconium oxide (LZO) and zirconium aluminum oxide (ZAO), respectively. The functionality of these dielectrics as device components is also demonstrated. Second, the impact of steam annealing on the evolution of aqueous-derived films is reported. Chapter V demonstrates that steam annealing lowers processing temperatures by effectively reducing residual counterion content, improving film stability with respect to water absorption, and enhancing dielectric properties of LZO films. Third, density and composition inhomogeneities in aqueous-derived films are investigated. Chapters VI and VII examine density inhomogeneities in single- and multi-metal component thin films, respectively, and show that these density inhomogeneities are related to inhomogeneous metal component distributions. This dissertation includes previously published coauthored material.

The main aim of this thesis work is to investigate the electrical, optical and thermal impact characteristics of cobalt oxide doped antimony tin oxide (CoO-ATO) in the form of thin films and nanofiber membranes. CoO-ATO is a novel composite material that has the potential to be used as reinforced aircraft coatings, military garment coatings, or more specifically as an anti-reflective (AR) top coating for photovoltaic (PV) cells. This work will be critical in determining the effectiveness of using a CoO-ATO layer in these applications. Electrospun nanofibers and spin coated thin films consisting of a polymeric solution of CoO-ATO will be used. Thin films are created using spin coating techniques, and nanofiber membranes are created using an electrospinning technique. Polystyrene (PS) will be used as a solute, and chloroform as a solvent, to create the solution. It is hypothesized that coatings of this material will have improved optical characteristics as compared to traditional ATO coatings and minimum impact from thermal cycling making it a favorable candidate for PV cells. This work will do an electrical, optical and thermal cycling impact characterization of CoO-ATO thin films and nanofiber membranes for a doping range of x% CoO where x ranged from 0.2

La pérennisation de la valorisation agricole des boues résiduaires passe par une optimisation des techniques d'épandage. Dans le cas présent, nous nous sommes focalisés sur les phénomènes intervenant sur les disques qui constituent la table d'épandage, en tenant compte à la fois des caractéristiques rhéologiques du matériau à épandre et des réglages mécaniques du matériel. On montre d'abord par des expériences de rhéométrie qu'aux faibles contraintes, les boues ne peuvent s'écouler de manière stable: la déformation totale du matériau résulte d'une compétition entre la restructuration pendant la phase de repos précédant le cisaillement et la déstructuration due au cisaillement. De plus, lors du cisaillement avec une surface lisse, un glissement apparaît dans la même gamme de contrainte, à partir d'une déformation critique. Il se forme une fine couche de liquide newtonien entre la surface qui induit le cisaillement et le reste du matériau dans l'entrefer. Au delà d'une contrainte critique, l'écoulement devient homogène, quelque soit la nature de la surface, lisse ou rugueuse. A partir de travaux sur maquette, nous avons analysé la déformation d'un échantillon de fluide à seuil engendrée par l'application d'une force centrifuge d'intensité croissante, en accélérant progressivement la vitesse de rotation du disque. On montre que la dynamique de l'étalement se résume en trois phases distinctes. Aux faibles vitesses de rotation, le matériau se comporte comme un solide viscoélastique et subit de faibles déformations élongationnelles. Quand la vitesse de rotation dépasse une valeur critique, la déformation n'est plus homogène: le matériau se comporte comme un liquide en périphérie, et comme un solide au centre de l'échantillon. Seule la partie liquide s'étale en formant un bourrelet. On montre ainsi que les paramètres viscoélastiques du matériau et l'initiation de l'écoulement sont étroitement liés: plus le seuil de contrainte est élevé, plus la vitesse critique est grande. Enfin, l'étalement se localise au sein de digitations qui se forment à partir du bourrelet. Finalement, on montre qu'au cours de l'épandage les paquets de boues arrivant sur la table d'épandage ne sont pas cisaillés sous l'action de la force centrifuge, mais ils subissent une élongation puis une fragmentation avant d'être projeté à la sortie du disque. On démontre au passage que les pâles n'ont aucune utilité sur le procédé d'émiettement.

Les diodes électroluminescentes hybrides organiques-inorganiques ou Quantum Dot- Light-Emitting Diodes (QD-LED) sont le parangon de dispositifs qui associeraient les propriétés semi-conductrices des matériaux organiques conjugués, ainsi que leur facilité de mise en oeuvre en couche mince, aux propriétés exceptionnelles (couleur accordable par la taille, bon rendement quantique de photoluminescence) des nanoparticules nanométriques de semi-conducteurs inorganiques, telles que CdSe/ZnS (TOPO). Diverses approches ont été explorées pour optimiser les QD-LEDs ; elles reposent sur la réalisation d'architectures diverses (uni, bi, tri couches) combinant matériaux organiques et QDs (en couche compacte ou dispersés dans une matrice), obtenues par diverses méthodes de dépôt (spin coating, tampon, impression jet d'encre). Dans ce travail de thèse, nous avons d'abord réalisé une structure originale sous forme de diodes comportant une couche hybride nanocomposite, obtenue en incorporant les QDs dans une matrice diélectrique de PMMA. Le but était de contrôler les flux de porteurs pour maximiser leur recombinaison sur les QDs. Les mesures des caractéristiques électriques, d'électro- et photoluminescence sont discutées, conjointement à des études de la morphologie des dépôts par AFM qui ont montré comment la microstructure dépendait des caractéristiques du, ou des, solvant(s) utilisé(s) pour le spin coating. D'une façon générale, les nanoparticules sont agrégées et la couche apparait inhomogène et rugueuse, ce qui permet des contacts entre les couches de transport. La faible électroluminescence résulterait de transferts d'excitation à partir d'états excités produits par les recombinaisons à ces endroits. Dans une seconde partie, nous avons déposé les QDs par spin coating à partir de solutions dans l'heptane, un solvant qui ne perturbe pas les couches organiques préalablement déposées. Les morphologies observées sont celles d'ilots compacts, avec des taux de couverture allant de 0 à 100%. La diminution, puis la disparition, de l'électroluminescence aux fortes couvertures confirme que l'émission des QDs provient exclusivement de transferts d'excitation à partir d'espèces excitées générées à l'interface organique-organique, en fonction de la nature des matériaux organiques. Les mécanismes d'injection des porteurs à la cathode, dépendant de la nature de celle-ci et de la couche de transport d'électrons, sont variables eux-aussi.

Organic polymer materials have been broadly applied in optical storage, optical communication and optical signal process. It has been revealed that these organic materials have some superior characteristics such as larger electro-optical (EO) coefficients, broader bandwidth and shorter response time, which make it good for EO modulator application. In our study, the goal is to study the EO coefficient of novel polymer material to be used in low driving voltage EO modulator. During the experiment, the dependence of the second harmonic generation (SHG) intensity on doping concentration of DR1/PMMA was observed and a reasonable explanation of the nonlinear dependency was given. We measured the EO coefficient of a new material, ASF/PMMA, using a Mach-Zehnder interferometer. We also observed the relaxation process of SHG intensity of this new material, which was compared with that of DR1/PMMA. Under the same measurement condition, we found that the EO coefficient of ASF/PMMA (13.1 pm/V) is significantly larger than that of DR1/PMMA (3 pm/V). It is also found that relaxation time of ASF/PMMA and DR1/PMMA are 22 and 8.5 seconds, respectively. Because of the superior characteristics of this material, it is suitable to be used in EO modulator.

A series of novel metallic nanoparticle and suspension were developed and synthesized for ink-jet printing and spin coating applications. Organic components, such as alkanethiols and amines, were used as new capping agent design. The suspension was characterized by NMR, ESCA, TEM, SEM, EDS, TGA, DTG, DSC, TA-MS for chemical composition and three-dimension SAMs desorption.

A variety of nanostructures of tin (IV) oxide (TO) are synthesized using two fabrication methods: a solution spin-coating method followed by post-annealing in an oxygen flow and a newly developed catalyst-assisted pulsed laser deposition (PLD) technique. The spin-coating method is used to fabricate granular TO films with monodisperse, stable, ultra-small nanocrystallites (4-5 nm in size), the size of which is found to increase exponentially with post-anneal above 500??C. These nanocrystalline films are conductive and highly transparent, and their bandgap shows broadening due to a high carrier concentration. Their resistivity behavior as a function of temperature in the 50-280 K range can be explained by a two-medium transport model, i.e. transport through the crystalline grains and across the grain boundaries, and through the charge-depletion layer, where a potential barrier is found for transport across the grain boundaries. Electronic transport in these films follows a 3D-variable range hopping model, which reveals an increase in the localization length of carriers with increasing the TAnneal above the onset of exponential growth at TAnneal= 500??C. By homogenously doping Eu3+ in these nanocrystalline films up to a high doping level of ~ 8%, optical luminescence and magnetic orderings can be introduced into these nanocrystalline TO films. Both characteristic Eu3+ emission and defect-related TO emissions are observed in the otherwise transparent TO films upon UV-excitation. In spite of the non-magnetic nature of Eu3+ ions, magnetic orderings appear in the highly doped TO films below 50 K upon the emergence of Eu2Sn2O7 phase. In the second part of this work, we employ a layer of gold nanoislands with controlled sizes (10-50 nm) as catalysts for pulsed laser deposition of TO nanostructures. Highly crystalline TO nanobricks, cuboid nanoparticles, nanowires and nanobelts are obtained for the first time through vapour-solid or vapour-liquid-solid (VLS) mechanisms. Of particular interest are the micron long one-dimensional (1D) nanowires and nanobelts, with the smallest square and rectangular cross-sections, respectively, ever reported. These single-crystalline nanostructures are obtained at relatively low temperatures of 600??C, for nanowires, and 500??C, for nanobelts, and their cross-sectional sizes can be easily controlled by the size of the gold nanoislands. The nanobelts are found to grow along the [100] and [101] axes, while the nanowires appear to grow along the [100] axis. The growth evolution of the nanobelts are also investigated in detail revealing their VLS growth mode and their single-crystalline structure throughout the growth, which opens the prospect of controlling their growth axis and consequently their side-surface planes by pinning the base to the substrate at the desired crystalline orientation. Together, the two fabrication methods developed in the present work offer facile approaches to growing two scientifically and technologically important classes of TO nanostructures, i.e., nanocrystalline film and 1D nanostructures. Thorough characterization of the resulted nanostructured materials using advanced microscopic, spectroscopic and other techniques, including Helium Ion Microscopy, has been provided. Modification of structure, morphology and physical properties of these functional nanostructured materials are also illustrated by controlling the growth parameters and by (Eu-)doping, which pave the way for introducing new properties for applications in chemical sensing, (opto)electronics and displays.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-03-09Bitstream added on 2014-06-13T19:09:18Z : No. of bitstreams: 1 santos_cm_me_bauru.pdf: 3402403 bytes, checksum: 93b5430687fb5b726426e9016204d6ce (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho teve como objetivos a preparação e caracterização de filmes finos de YBa2Cu3O.7-x e La0.7Ca0.3MnO3 depositados sobre substratos de níquel metálico, silício, e substratos cerâmicos de MgO, SrTiO.3. As análises realizadas tiveram como objetivos o estudo da formação da fase, e a determinação do comportamento de condução elétrica e das propriedades magnéticas dos filmes finos. Nas deposições realizadas sobre substratos de níquel foi utilizada uma camada intermediária de Y.2O.3, para posterior deposição de YBa.2Cu.3O.7-x. As soluções precursoras dos filmes foram obtidas através do método dos precursores poliméricos, com a inclusão do ácido etilenodiaminotetraacético (EDTA) como agente complexante. As deposições ocorreram através da técnica Spin-Coating. As análises realizadas através da Espectroscopia de Fotoelétrons de Raios X (XPS) e Difração de Raios X (XRD) auxiliaram, na identificação dos elementos químicos presentes nos filmes finos, e a verificação da formação das fases cristalográficas desejadas. Estas técnicas permitiram comprovar a eficácia da camada intermediária (buffer layer) de Y.2O.3 utilizada para a deposição de YBa.2Cu.3O.7-x sobre substratos de níquel metálico, e comprovar a necessidade de uma camada buffer layer para a obtenção de filmes de YBa.2Cu.3O.7-x depositado sobre substrato de silício. Assim como na deposição realizada sobre substrato de níquel, foi verificada também a boa formação das fases desejadas sobre os substratos cerâmicos. As análises de condução elétrica e das propriedades magnéticas demonstraram a característica supercondutora dos filmes de YBa.2Cu.3.O.7-x depositados sobre substratos de níquel metálico, MgO e SrTiOI.3, e... / This paper aimed at preparing and characterizing YBa2Cu3O.7-x e La0.7Ca0.3MnO3 and thin films, deposited on metallic nickel substrates, silicon and MgO, SrTiO.3 and LaAIO.3 ceramic substrates. The analyses performed had as objectives to study the phase formation and to determine the electric conduction behavior and the magnetic properties of the thin films. In the depositions perfomed on nickel substrates, a YBa.2Cu.3O.7-x deposition. The precursory solutions of the films were obtained by means of the polymeric precursor method, with the inclusion of the ethylenediaminotetra acetic acid (EDTA), as complexant agent. The depositions occurred through the Spin-coating technique. The analyses performed by means of the X-ray Photoelectron Spectroscopy (XPS) and X-ray Diffraction (XRD) aided in the identification of the chemical elements present in the thin films and in the verification of the formation of the desired crystallographic phases. Such techniques allowed for confirming the Y.2O.3 buffer layer efficacy, utilized to the YBa.2Cu.3O.7-x deposition on metallic nickel substrates, and for confirming the need of a buffer layer in order to obtain the YBa.2Cu.3O.7-x films deposited on the silicon substrate. As in the deposition performed on the nickel substrate, it was also verified the good formation of the desired phases on the ceramic substrates. The analyses on electrical conduction and magnetic properties demonstrated the superconducting characteristic of the YBa.2Cu.3O.7-x films deposited on metallic nickel substrates, MgO and SrTiO.3, as well as the magnetic characteristic of the La.0.7Ca.0.3MNO.3 film deposited on the silicon substrate. The analyses performed by means of Scanning Electron Microscopy (SEM) showed a better ...(Complete abstract, click electronic address below)