This thesis reports the fabrication of nanophotonic structures by using electron beam lithography and using pattern transfer via self assembly with the aid of block copolymers. A theoretical and experimental basis was developed for fabricating anti-reflective coatings using block-copolymer pattern transfer. Block-copolymers were also used to fabricate plasmonic pattern arrays which form gold dots on glass surface. Electron-beam lithography was utilized to fabricate holey plasmonic structures from gold and silver films. Electron-beam exposure was used in block-copolymer lithography in selected regions. The exposure effects were studied for both thin and thick block-copolymer films. Reactive and ion beam etching techniques were used and optimized to fabricate those structures. This research required a great deal of development of new fabrication methods and key information is included in the body of the thesis.

Orientador: Francisco das Chagas Marques / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-12T20:56:17Z (GMT). No. of bitstreams: 1 Silva_DouglasSoaresda_M.pdf: 1607458 bytes, checksum: 64efea4eea6490352c0cec9182778a67 (MD5) Previous issue date: 2009 / Resumo: Nesta tese estamos propondo o uso de carbono amorfo como um possível candidato para uso como camada antirrefletora em células solares de silício cristalino. O carbono amorfo pode ser preparado com alta banda proibida e tem propriedades importantes como alta dureza, baixo coeficiente de atrito, preparado à temperatura ambiente, etc. Além disso, o carbono amorfo é um material abundante na natureza e seu uso em eletrônica poderia reduzir o consumo de materiais tóxicos, contribuindo para reduzir danos ao meio ambiente. Foram exploradas as propriedades óticas dos filmes de carbono e carbono de silício produzidos por diferentes métodos de deposição (RF Glow Discharge, RF Sputtering e FCVA_Filtered Cathodic Vacuum Arc) visando a aplicação como camadas antirrefletoras em células solares. O estudo de propriedades óticas dos filmes, como a banda proibida, índice de refração, coeficiente de absorção e reflexão integrada foram determinantes para as conclusões deste trabalho. Para isto foram importantes a fabricação de células solares e o estudo dos principais parâmetros fotovoltaicos: eficiência, corrente de curto circuito, tensão de circuito aberto e fator de preenchimento. As células solares de silício monocristalino foram desenvolvidas a partir da técnica amplamente difundida e conhecida através da difusão térmica de dopantes de fósforo, as chamadas homojunções pn. Diferentes estruturas antirrefletoras à base de carbono foram estudadas e comparadas. Assim, investigamos o uso de carbono tipo diamante (diamond-like carbon DLC), carbono tipo polimérico (polimeric-like carbon ¿ PLC), carbono tetraédrico (ta-C), carbeto de silício (a-CxS ix-1:H). Para efeito de comparação com camadas antirrefletoras convencionais, adotamos o dióxido de estanho (SnO2) depositado pela técnica de spray químico. Os resultados mostraram que filmes de carbono amorfo funcionam como camada antirefletora em células solares, embora não tenha sido possível encontrar em um único material todas as condições ideais para uma camada antirrefletora em silício cristalino. O carbeto de silício se mostrou bastante promissor como um composto à base de carbono e o próprio silício, sendo utilizado na fabricação do dispositivo e abundante na natureza. / Abstract: In this thesis we propose the use of amorphous carbon as a possible candidate for use as antireflective layer in crystalline silicon solar cells. The amorphous carbon can be prepared with high band gap and important properties such as high hardness, low coefficient of friction, prepared at room temperature, etc. Moreover, the amorphous carbon material is abundant in nature and its use in electronics could reduce the consumption of toxic materials, helping to reduce damage to the environment. We explored the optical properties of carbon films and carbon silicon produced by different methods of deposition (RF Glow Discharge, RF Sputtering and FCVA_Filtered Cathodic Vacuum Arc) to the application as antireflective coatings in solar cells. The study of optical properties of films, such as forbidden band, index of refraction, absorption coefficient and integrated reflection were crucial to the conclusions of this work. For that, it was important the manufacture of solar cells and the study of key photovoltaic parameters: efficiency, short-circuit current, open circuit voltage and fill factor. The single crystal silicon solar cells were developed from the widely known technique of thermal diffusion of phosphorus doping, the pn homojunctions. Different antireflective structures based on carbon were studied and compared. Thus, we investigated the use of carbon type diamond (diamond-like carbon DLC), carbon type polymer (polimeric-like carbon - PLC), tetrahedral carbon (ta-C), silicon carbide (a-CxSix-1: H). For purposes of comparison with conventional antireflective layers, we adopted the tin dioxide (SnO2) deposited by chemical spray technique. The results showed that films of amorphous carbon layer acts as antireflective coatings in solar cells, although it was not possible to find a single material in all ideal conditions for an antireflective layer in crystalline silicon. The silicon carbide wasvery promising as a compound based on carbon and the silicon, been used in the manufacture of the device and abundant in nature. / Mestrado / Mestre em Física

La microscopie optique sur substrats antireflets est un outil de caractérisation simple et puissant qui a notamment permis l'isolation du graphène en 2004. Depuis, le domaine d'étude des matériaux bidimensionnels (2D) s'est rapidement développé, tant au niveau fondamental qu'appliqué. Ces matériaux ultraminces présentent des inhomogénéités (bords, joints de grains, multicouches, etc.) qui impactent fortement leurs propriétés physiques et chimiques. Ainsi leur caractérisation à l'échelle locale est primordiale. Cette thèse s'intéresse à une technique récente de microscopie optique à fort contraste, nommée BALM, basée sur l'utilisation originale de couches antireflets très minces (2-5 nm) et fortement absorbantes (métalliques). Elle a notamment pour but d'évaluer les mérites de cette technique pour l'étude des matériaux 2D et de leur réactivité chimique. Ainsi, les différents leviers permettant d'améliorer les conditions d'observation des matériaux 2D ont tout d'abord été étudiés et optimisés pour deux matériaux modèles : l'oxyde de graphène et les monocouches de MoS₂. L'étude de la dynamique de dépôt de couches moléculaires a notamment permis de montrer à la fois l'extrême sensibilité de BALM pour ce type de mesures et l'apport significatif des multicouches antireflets pour l'augmentation du contraste lors de l'observation des matériaux 2D. L'un des atouts principaux de BALM venant de sa combinaison à d'autres techniques, nous nous sommes particulièrement intéressés au couplage de mesures optiques et électrochimiques pour lesquelles le revêtement antireflet sert d'électrode de travail. Nous avons ainsi pu étudier optiquement la dynamique de réduction électrochimique de l'oxyde de graphène (GO), l'électro-greffage de couches minces organiques par réduction de sels de diazonium sur le GO et sa forme réduite (r-GO), ainsi que l'intercalation d'ions métalliques entre feuillets de GO. En combinant versatilité et fort-contraste, BALM est ainsi établi comme un outil prometteur pour l'étude des matériaux 2D et en particulier pour la caractérisation locale et in situ de leur réactivité chimique et électrochimique. / Optical microscopy based on anti-reflective coatings is a simple yet powerful characterization tool which notably allowed the first observation of graphene in 2004. Since then, the field of two-dimensional (2D) materials has developed rapidly both at the fundamental and applied levels. These ultrathin materials present inhomogeneities (edges, grain boundaries, multilayers, etc.) which strongly impact their physical and chemical properties. Thus their local characterization is essential. This thesis focuses on a recent enhanced-contrast optical microscopy technique, named BALM, based on ultrathin (2-5 nm) and strongly light-absorbing (metallic) anti-reflective layers. The goal is notably to evaluate the benefits of this technique for the study of 2D materials and their chemical reactivity. The various levers to improve 2D materials observation were investigated and optimized for two model materials: graphene oxide and MoS₂ monolayers. The investigation of molecular layer deposition dynamic notably showed the extreme sensitivity of BALM for such measurements and the significant contribution of multilayers anti-reflective coatings to enhance contrast during the observation of 2D materials. One of the main assets of BALM comes from its combination to other techniques. We particularly considered the coupling between optical measurements and electrochemistry for which the anti-reflective layer serves as working electrode. We investigated optically the dynamic of electrochemical reduction of Graphene Oxide (GO), the electrografting of organic layers by diazonium salts reduction on GO and its reduced form (rGO), as well as the intercalation of metallic ions within GO sheets. By combining versatility and high-contrast, BALM is established as a promising tool for the study of 2D materials, especially for the local and in situ characterization of their chemical and electrochemical reactivity.