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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Fabrication and Characterization of Carbon Nanotubes-Zinc Oxide Structure by Drop-drying and Ink Jet Printing

January 2012 (has links)
abstract: This thesis elaborates the application of carbon nanotubes (CNTs) and it is discussed in two parts. In the first part of the thesis, two types of CNTs inks for inkjet materials printer are prepared. They are both chemical stable and printable, effective and easily made. The sheet resistance of printed films decreases exponentially as the number of layers increases. In the second part of this study, CNTs/ZnO composite structures are fabricated to understand the electronic and optical properties. The materials were deposited by two different methods: drop-drying and RF magnetic sputtering system on flexible polymer substrates. To further increase the conductivity of the various layers of deposited CNTs films, electrical and optical characterizations are also done. This study establishes CNTs as a multi-functional semitransparent conductor, which can be deposited at room-temperature with other transparent conductive oxide (TCO) composites for application in flexible electronics and printed circuit and sensors. / Dissertation/Thesis / M.S. Materials Science and Engineering 2012
12

Desenvolvimento de um sistema de imageamento usando a tomografia por coerência óptica no domínio temporal e de Fourier

de Barros Correia Kyotoku, Bernardo January 2006 (has links)
Made available in DSpace on 2014-06-12T18:06:32Z (GMT). No. of bitstreams: 2 arquivo7746_1.pdf: 2389621 bytes, checksum: 1af31849e955fb9c2078ec1ebd71fa6a (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Nesta dissertação, descrevemos a teoria básica e os detalhes de implementação experimental de três sistemas de tomografia por coerência óptica, dois no regime temporal e outro no regime espectral (Fourier). Tomografia por coerência óptica (TCO) é um método de imageamento óptico não invasivo, capaz de gerar imagens da seção transversal de materiais e tecidos biológicos. A técnica de TCO tem como base a interferência entre dois feixes de luz de baixa coerência, cuja resolução espacial longitudinal é determinada pela largura de banda espectral da fonte, e a profundidade de penetração na amostra é função dos coeficientes de espalhamento e absorção. Nos sistemas desenvolvidos neste trabalho, utilizamos como fonte de luz incidente em um interferômetro de Michelson (ar livre) um laser de Titânio-Safira com espectro alargado por efeitos não lineares em uma fibra óptica, obtendo-se uma largura espectral de 50 nm, centrado em 800nm, a partir do qual calculamos a resolução longitudinal de 5,6 mm. Para os sistemas operando no regime temporal, em umdos braços do interferômetro colocouse a amostra e no outro foram utilizadas duas linhas de atraso (não simultaneamente). Em um dos casos, a linha de atraso consistia de um espelhomóvelmontado em um transladador controlado por computador. No segundo caso, introduzimos uma linha de atraso de Fourier, composta de uma grade de difração, lente, um espelho montado sobre um motor galvo e um espelho fixo. A amostra a ser estudada foi fixada sobre uma base, que foi deslocada lateralmente durante a aquisição dos dados. No sistema de detecção, o sinal foi pré-processado e digitalizado. Todo o sistema de controle, deteção e geração de imagens foi desenvolvido usando o software Labview. Os tempos de aquisição de dados em uma única varredura em profundidade foram de 12 s e 50 ms para a primeira e segunda montagens, respectivamente. No sistema operando no domínio de Fourier, no lugar da linha de atraso, foi introduzido um espelho fixo e o sinal de interferência era dirigido a um espectrômetro. Um novo programa foi desenvolvido em Labview para controle de deslocamento lateral e aquisição de imagens, cujo tempo de aquisição de uma varredura em profundidade é de 500 ms. A sensibilidade foi de 98dB para uma potência incidente na amostra de 1 mW. O novo sistema também pode ser controlado remotamente, inclusive via internet, para aquisição de dados. Como exemplo de aplicação, os sistemas desenvolvidos foram utilizados para gerar imagens em dentes humanos in vitro, e as imagens obtidas foram bastante satisfatórias, quando comparadas com análises de microscopia óptica ou com outros resultados descritos na literatura
13

Influence of a Front Buffer Layer on the Performance of Flexible CdS/CdTe Solar Cells

Mahabaduge, Hasitha Padmika January 2013 (has links)
No description available.
14

Optimization and Characterization of Transparent Oxide Layers for CIGS solar cells fabrication

Liu, Qiudi January 2007 (has links)
No description available.
15

Etableringsprocessen på en tillväxtmarknad : En fallstudie om Scanias etableringsprocess på den indiska marknaden.

Kanwal, Bushra, Flores Frias, Sandino January 2013 (has links)
Objective: The objective of this thesis is to investigate how Scania has attained success to establish on the Indian market and to inquire into the establishment process of Scania and their entrance in the Indian market. The thesis describes different factors such as the product, mode of entry, time of entry and choice of market that play a role when a company establishes and invest in a foreign market. Method: This thesis is limited to the process of establishing Scania on the Indian truck market. A qualitative approach has being utilized in this study, consisting of interviews with Staffan Sjöström, development manager at the R&D department, Koen Knoops, vice president at Financial Services and Henrik Fagrenius, former managing director for Scania in India. Data collection from various journals and articles have been conducted for the presentation of the number of sold newly registered trucks in comparison to the number of sold newly registered trucks in India by Volvo, Tata Motors and Ashok Leyland during 2010, 2011, 2012 and the first three quarters of 2013. Theory: With a starting-point in empirism, we have used a theoretical frame of reference to describe Scania´s establishment process. Scania makes use of an internationalization strategy, namely Market Selection, Time of Entry and Entry mode and the network model, which describes the process of establishing on a foreign market as a business association with various players on the market. Scania has made the choice to establish on the Indian growth market, which is still economically unexploited in many aspects since it is a young and growing market and has positive opportunities for profitability. Conclusions: The concept that Scania follows as it establishes on a growth market, be it an industrialized country or a newly industrialized country, is that supreme quality always should be the primary choice. Customers are interested in lower overall costs and not in low prices. Scania believes that entrepreneurs worldwide have the same need for high quality and that psychological distance, meaning cultural differences should not be an obstacle on the path of establishment. A cheap work force, improving infrastructure and political reforms have carved the path for Scania’s establishment on the Indian growth market. According to Fagrenius Scania has wasted no time on excessive observation although they have taken precautions in forming partnerships and creating a broad network before entering the Indian market.
16

Développement de la technique dépôt par couche atomique spatiale (SALD) pour la fabrication de couches minces type P d'oxyde de cuivre (I) conductrices / Development of the Spatial Atomic Layer Deposition (SALD) technique for the fabrication of p-type thin films of highly conductive copper (I) oxide

Masse de la Huerta, César, Arturo 26 November 2019 (has links)
Pour concevoir avec succès l'instrumentation nécessaire aux nouvelles technologies de fabrication avec une précision nanométrique, la méthodologie de conception doit prendre en compte de nombreux sujets différents liés à la chimie, à la physique, à la mécanique, à l'électronique et à l'automatisation, travaillant ensemble pour atteindre l'objectif souhaité. Dans cette thèse, cette méthodologie de conception a été mise en œuvre avec un grand nombre d’outils et d’approches permettant d’optimiser avec succès une méthode de nanofabrication appelée dépôt par couche atomique spatiale (SALD) afin de déposer des couches minces d’un matériau potentiellement utile en tant que composant du dispositifs à énergie solaire non-silicium, séparateurs d’eau photoélectrochimiques et composants électroniques transparents à couche mince, entre autres: oxyde cuivreux (Cu2O).En ce qui concerne la technologie de fabrication et la conception mécatronique, SALD est une technique de fabrication prometteuse qui permet la fabrication de films minces avec une précision nanométrique et avec la capacité de contrôler leurs propriétés mécaniques, électriques et cristallographiques. De plus, l'approche SALD utilisée dans cette thèse et dans le Laboratoire des matériaux et du génie physique (LMGP) fonctionne à l'air libre (sans chambre de dépôt) et constitue donc potentiellement une approche compatible avec l'industrie pour les films minces homogènes de grande surface fabrication avec un débit élevé. De plus, SALD peut être utilisé dans des conditions qui le rendent compatible avec les substrats flexibles et avec les approches de rouleau à rouleau (R2R). Enfin, SALD offre une flexibilité sur le processus de dépôt afin qu’il puisse être ajusté pour obtenir différentes propriétés sur les films fabriqués avec un minimum de modification de l’instrumentation.À l'aide de simulations CFD (Computational Fluid Dynamics), les phénomènes de la mécanique des fluides qui se produisent pendant le processus de dépôt dans le système SALD ont été analysés pour différentes configurations du réacteur. L'influence sur les propriétés du film a été étudiée et une validation avec des dépôts expérimentaux a été effectuée. Ensuite, en utilisant les connaissances et les directives obtenues avec les simulations CFD, et afin de réduire le coût et la complexité de la modification de certains composants mécaniques du système, un flux de travail comprenant la conception assistée par ordinateur (CAO) et la fabrication additive (également appelé impression 3D) impression) a été mis en place au LMGP pour la fabrication de l’un des composants principaux du système SALD à LMGP: la tête de dépôt. Ici, c'est la première fois qu'une telle technique de fabrication innovante est appliquée aux processus de nanofabrication en couches minces, offrant de nombreuses applications potentielles dans le domaine. Dans cette thèse, un tel flux de travail est présenté et expliqué, ainsi que les directives apprises et les limitations découvertes également présentées.Enfin, couches minces de Cu2O ont été déposé avec succès avec la méthode SALD. Le Cu2O est l’un des rares matériaux aux propriétés électroniques prometteuses en tant que semi-conducteur transparent de type p. Ici, les films de Cu2O fabriqués utilisant le système SALD à LMGP sont rapportés et leur conductivité de type p et leur cristallographie sont analysées.Les résultats de ces travaux fournissent des directives initiales pour la conception industrielle d’un système de fabrication à haut débit basé sur la technologie SALD, dans lequel la conception de ses composants est optimisée pour chaque matériau souhaité. Cette approche de conception rend également ce travail utile pour augmenter la quantité de matériaux compatibles avec le SALD, ainsi que pour développer davantage la méthodologie SALD dans des processus de fabrication innovants de matériaux et de dispositifs. / To successfully design the instrumentation needed for new manufacturing technologies with nanoscale precision, the design methodology must take into account many different topics related to chemistry, physics, mechanics, electronics and automation, working together to achieve the desired goal. In this thesis, this design methodology has been implemented with a large number of tools and approaches to successfully optimize a nanofabrication method called spatial atomic layer deposition (SALD) in order to deposit thin films. a potentially useful material as a component of non-silicon solar energy devices, photoelectrochemical water separators and transparent thin-film electronic components, among others: cuprous oxide (Cu2O).With respect to manufacturing technology and mechatronics design, SALD is a promising manufacturing technique that enables the fabrication of thin films with nanoscale precision and the ability to control their mechanical, electrical and crystallographic properties. In addition, the SALD approach used in this thesis and in the Laboratoire des Matèriaux et du Génie Physique(LMGP) works in the open air (without a repository) and is therefore potentially an industry-compatible approach to film Thin homogeneous high-area manufacturing with high throughput. In addition, SALD can be used under conditions that make it compatible with flexible substrates and roll-to-roll approaches (R2R). Finally, SALD offers flexibility on the deposit process so that it can be adjusted to obtain different properties on films manufactured with a minimum of instrumentation modification.Using CFD (Computational Fluid Dynamics) simulations, the fluid mechanics phenomena that occur during the deposition process in the SALD system were analyzed for different reactor configurations. The influence on the properties of the film was studied and a validation with experimental deposits was carried out. Then, using the knowledge and guidance obtained with CFD simulations, and to reduce the cost and complexity of modifying certain mechanical components of the system, a workflow that includes computer-aided design (CAD) and manufacturing additive (also called 3D printing) printing) was set up at the LMGP for the manufacture of one of the main components of the LMGP SALD system: the deposit head. Here, it is the first time that such an innovative manufacturing technique has been applied to thin-film nanofabrication processes, offering many potential applications in the field. In this thesis, such a workflow is presented and explained, along with learned guidelines and discovered limitations also presented.Finally, thin layers of Cu2O have been successfully deposited with the SALD method. Cu2O is one of the few materials with promising electronic properties as a p-type transparent semiconductor. Here, Cu2O films made using the LMGP SALD system are reported and their p-type conductivity and crystallography are analyzed.The results of this work provide initial guidance for the industrial design of a high throughput manufacturing system based on SALD technology optimized for each desired material. This design approach also makes this work useful for increasing the amount of SALD compatible materials, as well as for further developing the SALD methodology in innovative materials and device manufacturing processes.
17

Une méthodologie d’aide à la décision pour l’optimisation de services aéronautiques basés sur la performance / A decision-support methodology for the optimisation of performance-based services

Pozzetti, André 22 April 2015 (has links)
Pour rester compétitives dans l'industrie aéronautique, les entreprises développent des stratégies diverses pour gagner un avantage concurrentiel comme l'augmentation du Coût Total de Possession (TCO) avec l'acquisition aéronautique complexe et des programmes de support. Les clients concentrent leurs besoins sur la disponibilité opérationnelle de tels systèmes et ne sont plus enclins à payer un prix supplémentaire pour un tel service, par conséquent le fournisseur est amené à minimiser le TCO tout en conservant un haut niveau de performance de flotte. Dans de tels accords, une partie du risque de performance opérationnelle est transférée vers le fournisseur sous forme de pénalité financière, engendrant ainsi un risque financier sur la rentabilité du contrat. Cette recherche aborde le problème du point de vue du fournisseur en considérant différentes options stratégiques pour la commercialisation de l'offre de services aéronautiques basés sur la performance, garantissant la disponibilité de la flotte. La méthodologie considère un système complexe, représentatif des systèmes aéronautiques actuels et les mécanismes de support rattachés, avec de multiples objectifs contradictoires à atteindre en tant que fournisseur. La méthodologie proposée couvre les catégories suivantes : disponibilité, fiabilité, maintenabilité et supportabilité. Elle considère le système complexe comme un tout incluant l'ensemble des interactions dans ce système et les relations entre la performance de disponibilité et le coût. D'autres facteurs de contribution additionnels sont aussi considérés dans ce mécanisme de support, comme les types d'incertitude de la performance du système, des données, des risques financiers et des coûts. Un modèle de pénalité pour l'utilisation avec les Services Basés sur la Performance (PBS) des offres dans l'industrie aéronautique est aussi fourni. Une méthodologie d'analyse de pénalité est proposée au travers de deux études de cas présentées dans cette thèse, offrant un avantage compétitif au fournisseur, de par la capacité de prévoir la distribution de probabilité de performance du système, et de quantifier le risque financier pour le modèle de pénalité en question. La méthodologie d'analyse démontre aussi que la capacité d'effectuer une analyse de risque sur des pénalités contractuelles est tout aussi importante pour le fournisseur que la capacité de prévoir la performance globale du système. Les conclusions montrent qu'il est tout à fait possible d'avoir une grande exposition de risque financier si un scénario de pénalité inadapté est choisi, même si la performance de disponibilité de la flotte prévue est au-dessus du taux ciblé ou contracté. / To remain competitive within the aeronautic industry, companies are developing various strategies to gain a competitive edge as the Total Cost of Ownership (TCO) increases with complex aeronautical acquisition and support programs. Customers are focusing their needs on the operational availability of such systems and are no longer willing to pay a premium for such a service, consequently the supplier is challenged to minimize the TCO whilst retaining a high level of fleet performance. In such accords, some of the operational performance risk is transferred back to the supplier and are usually in the form of financial penalties, which consequently creates a financial risk on the profitability of the contract for the supplier. This research addresses the problem from the point of the supplier when considering different strategic options for the sale and offer of performance-based aeronautic services that guarantee fleet availability. The methodology considers the complex system, as is typical with current aeronautic systems, relating support mechanisms, and the multiple yet contradictory objectives to achieve as a supplier. The methodology proposed covers the categories of Availability, Reliability, Maintainability and Supportability; it considers the complex system as a whole including the interactions within this system and the relationships between availability performance and cost. Additional other contributing factors are also considered within this support mechanism, such as the types of uncertainty on system performance, data, financial risks and costs. The introduction of a penalty model for use with Performance-Based Service (PBS) offers within the aeronautic industry is also provided. A methodology for penalty analysis is proposed through the two case studies presented in this thesis, giving the supplier a competitive advantage through the ability to predict the probability distribution of system performance and to quantify the financial risk for the penalty model in question. The analysis 5 methodology also demonstrates that the ability to perform risk analysis on contractual penalties is just as important to the supplier as the ability to predict overall system performance, as the findings present that it is quite possible to have a large financial risk exposure if the wrong penalty scenario is chosen even if the predicted Fleet Availability performance is above the targeted or contracted rate.
18

[en] LOGISTICAL COSTS MANAGEMENT BASED ON ACTIVITIES AND TOTAL COST OF OWNERSHIP / [pt] GESTÃO DE CUSTOS LOGÍSTICOS BASEADA EM ATIVIDADES E NO CUSTO TOTAL DE PROPRIEDADE

EDUARDO DA CUNHA MOREIRA 02 September 2008 (has links)
[pt] A correta avaliação dos custos logísticos de uma empresa permite uma melhor gestão destes custos e tomada de decisões mais precisas. Este trabalho aborda a apuração de custos logísticos através do método de custeio tradicional, indica os problemas que o tornam inadequado para esta tarefa e propõe a utilização de ferramentas contemporâneas. Apesar de considerar a importância da análise dos custos logísticos totais, o trabalho desenvolve a análise somente para os custos do transporte marítimo, pois estes são os mais relevantes para o caso em análise. Para solucionar as inadequações do método tradicional de custeio, é proposta a utilização do método de Custeio Baseado em Atividades, do inglês Activity-Based Costing (ABC). Este método visa atribuir os custos dos recursos de acordo com as atividades onde estes foram utilizados e traz bons resultados na avaliação gerencial dos custos logísticos. Além deste método, é proposta a utilização do Custo Total de Propriedade, do inglês Total Cost of Ownership (TCO), para a contratação de navios. Esta ferramenta avalia o custo de obtenção e uso de um bem ou serviço, incluindo outras variáveis além do preço. Os resultados do trabalho são favoráveis à utilização das ferramentas, mas há necessidade de um extenso trabalho interno no seu ambiente de aplicação para a sua implementação. / [en] The correct evaluation of the logistical costs of a company allows better management of these costs and a more accurate decision making process. This work addresses the obtainment of logistical costs through the traditional method of cost assignment, points out problems that make it unsuitable for this task, and suggests the use of contemporary tools. Despite considering the importance of the total logistical costs, this work develops the analysis only for the costs of shipping, since these are the most relevant to the case under approach. To solve the inadequacies of the traditional method of cost assignment, it is suggested the Activity-Based Costing method (ABC). This method allocates the cost of resources in accordance with the activities over which they were used and brings forth good results in the managerial evaluation of logistical costs. In addition to this method, it is suggested the use of Total Cost of Ownership (TCO) for hiring ships. This tool evaluates the cost of obtaining and using a good or service, including other variables besides price. The results of this work are favourable to the use of the tools, but there is the need of extensive internal work in its field of application to have it implemented.
19

Strukturuntersuchungen an Oxidkristalloberflächen mittels der streifenden Streuung schneller Atome

Meyer, Eric 19 February 2016 (has links)
Die Dissertation beschäftigt sich mit der Bestimmung der Oberflächenstruktur von Oxidkristallen. Die strukturelle Charakterisierung fand mittels der streifenden Streuung schneller Atome und Moleküle statt. Bei dieser Methode werden Atome oder Moleküle mit Energien im keV Bereich unter streifendem Einfall an einer Einkristalloberfläche gestreut. Sie werden unter axialer Gitterführung entlang niedrig-indizierter Kristallrichtungen gestreut und können mittels eines ortsauflösenden Detektors nachgewiesen werden. Bei hinreichend kleinen Energien werden Beugungserscheinungen beobachtet, die auf die Interferenz von Materiewellen zurückzuführen sind. Durch eine Analyse der Streuverteilung der Projektile, können Rückschlüsse auf das Wechselwirkungspotential und somit auf die Struktur der Oberfläche gezogen werden. Durch die Untersuchung der (100)- und (001)-Fläche konnten alle Gitterparameter des Ga2O3-Systems bestimmt werden. Die Messungen an der (100) Fläche lieferten Aufschluss über die Terminierung, für die ein alternatives Strukturmodell entwickelt wurde. Aufbauend auf der Entdeckung der longitudinalen Kohärenz bei der streifenden Streuung von Atomen an der Al2O3(11-20)-Fläche konnten die vorhandenen Messungen erweitert und ein effektives Auswerteprogramm entwickelt werden. Bei Messungen an der Al2O3(0001)-Fläche wurde ebenfalls das Auftreten einer longitudinalen Kohärenz beobachtet. Für beide Flächen wurden die jeweiligen Gitterparameter mit höchster Präzision bestimmt und die Intensitätsverteilung der Streubilder durch ein einfaches Modell beschrieben. Erstmalig in dieser Arbeitsgruppe konnte ein Wechselwirkungspotential für die Streuung von H2-Molekülen an einer KCl(001)-Fläche abgeleitet werden. Der im Experiment beobachtete drastische Unterschied in der Intensitätsmodulation der Beugungsreflexe mit der senkrecht-de Broglie Wellenlänge für gestreute Atome und Moleküle konnte mit Simulationen unter Verwendung des abgeleiteten Wechselwirkungspotentials erklärt werden. / This PhD thesis deals with the investigation of surface structures of oxide crystal surfaces. Therefore, the method of grazing scattering of fast atoms and molecules was applied. The projectiles are scattered with energies in the keV range under grazing incidence from a single crystal surface along low-indexed surface directions. They are recorded with a position sensitive detector. For sufficiently low energies diffraction patterns are observed that can be understood in terms of the interference of matter waves. By analyzing these patterns the interaction potential and in this manner the surface structure can be derived. The investigation of the (100) and (001) surface led to a determination of all lattice parameters of the Ga2O3 system so that it was possible to determine the termination of the (100) surface. An alternative structural model for this termination could be derived. After the discovery of a longithudinal coherence for the grazing scattering process on a Al2O3(11-20) surface, the existing measurements were expanded and an effective evaluation procedure was developed. In measurements on the Al2O3(0001) surface the longithudinal coherence was observed as well. For both surfaces, the lattice parameters could be determined with very high accuracy and the intensity distribution was described by a very simple model. For the first time in this working group the interaction potential for the scattering of H2 molecules from a KCl(001) surface could be deviated. The observed difference in the intensity distribution in dependence of the perpendicular de Broglie wavelength for scattered atoms and molecules could be explained by applying simulations using the deviated interaction potential.
20

Conception, élaboration et intégration d'électrodes transparentes optimisées pour l'extraction des charges dans des dispositifs photovoltaïques. / Conception, synthesis and integration of transparent electrodes optimized for charge collection in photovoltaic devices.

Tosoni, Olivier 18 December 2013 (has links)
Les oxydes transparents conducteurs (TCO) ont la rare propriété de concilier haute transparence et conductivité élevée, ce qui en fait des matériaux-clés pour de nombreuses applications requérant des électrodes transparentes comme les cellules photovoltaïques, les diodes organiques et les écrans plats. Avec une résistivité de l'ordre de 10^(-4) ohm.cm et une transmittance de 85% dans le domaine visible, l'oxyde d'indium dopé à l'étain (ITO) est le matériau privilégié. Toutefois, sa fragilité, son instabilité aux procédés plasma et son coût croissant du fait de sa haute teneur en indium sont autant de raisons de rechercher des matériaux alternatifs. Cette thèse a pour but de comprendre les points clefs permettant d'améliorer les performances d'une électrode transparente en oxyde de zinc dopé à l'aluminium (AZO) sur les plans optique, électrique et au niveau des interfaces ; des cellules photovoltaïques en silicium amorphe hydrogéné (a-Si:H) servent de dispositif-test à cette étude. Réalisées par pulvérisation cathodique magnétron sous des conditions de dépôt variées, les couches minces d'AZO obtenues ont une structure microcristalline et, pour des paramètres déterminés, des performances optoélectroniques approchant celles de l'ITO. Un modèle adapté d'après la théorie de Drude a permis de rendre compte du lien entre transparence et conduction et de confirmer la saturation en porteurs du matériau. L'efficacité d'une électrode au sein d'un dispositif dépend également très fortement de l'interface entre celle-ci et l'absorbeur, les porteurs devant être extraits rapidement pour ne pas se recombiner. Quelques voies ont été explorées pour réduire la barrière de potentiel entre le silicium amorphe et l'électrode tout en favorisant l'efficacité optique des cellules. Il ressort que l'insertion d'une couche tampon d'oxyde de titane ou de tungstène permet d'obtenir un gain notable dans les performances des cellules. / Because of their unique ability to reconcile high transparency with good electrical conductivity, transparent conductive oxides (TCOs) are key materials in many applications such as organic light-emitting diodes, photovoltaic solar cells or flat displays. With its resistivity of a few 10^(-4)$ ohm.cm and its 85% transmittance in the visible range, Indium Tin Oxide (ITO) dominates the TCO market. Yet, it is brittle, unstable to plasma processes and its cost is rising due to its high indium content, encouraging research on alternative materials. This thesis aims at understanding key points to improve the performance of an aluminum-doped zinc oxide (AZO) transparent electrode on the optical, electrical and interface levels; hydrogenated amorphous silicon (a-Si:H) photovoltaic solar cells serve as a test device in this study. We obtain microcrystalline AZO thin films by magnetron sputtering under various deposition conditions ; for certain parameters, performances are close to ITO. An adapted model after the Drude theory allowed to account for the link between transparency and conduction and to confirm that the material is saturated by charge carriers. The effectiveness of an electrode within a device also strongly depends on its interface with the absorber layer, since the charge carriers have to be rapidely extracted in order to avoid recombination. Some ways have been explored to reduce the potentiel barrier between amorphous silicon and the electrode, still favoring optical efficiency of the cells. It appears that the insertion of a buffer layer of titanium or tungsten oxide enables a sensible improvement in the cells' efficiencies.

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