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Orientador: Jacobus Willibrordus Swart / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-12T22:45:26Z (GMT). No. of bitstreams: 1 Dias_GuilhermeOsvaldo_D.pdf: 3822925 bytes, checksum: 25e0dd51fed5d5d3cb7dc334a0a61bb7 (MD5) Previous issue date: 2009 / Resumo: Analisamos amostras de óxido de silício rico em silício (SRSO) obtidas por um sistema de deposição química de vapor com ressonância ciclotrônica de elétrons (ECR-CVD). Propriedades estruturais, de composição, ópticas e elétricas foram estudadas por transformada de Fourier de absorção no infravermelho (FTIR), microscopia eletrônica de transmissão (TEM), espectroscopia de retro-espalhamento Rutherford (RBS), fotoluminescência (PL), elipsometria e medidas de capacitância-tensão (C-V). Através do ajuste dos índices de refração em função do fluxo de O2 para uma longa faixa de razões de fluxo, pudemos notar que o sistema ECR-CVD permite obter filmes com alto controle desses índices de refração. Isto sugere indiretamente a possibilidade do controle das características ópticas e elétricas dos nossos filmes, pois essas características, assim como o índice de refração, são dependentes da concentração de silício nos filmes. Na região de concentração de interesse em nosso trabalho, a razão de concentração atômica O/Si obtida por RBS correlaciona-se linearmente com o índice de refração. As intensidades e posições dos picos de PL e as curvas de histereses observadas através de medidas C-V, após os tratamentos térmicos, dependem das razões de fluxo O2/SiH4 utilizadas na deposição. Observamos que temperatura e tempo de tratamento térmico têm forte influência nas propriedades de PL das amostras selecionadas. No entanto, a influência destes parâmetros sobre as propriedades elétricas (C-V) não é tão significativa, principalmente para temperaturas de tratamentos acima de 1000 ºC. As propriedades de PL e C-V puderam ser relacionadas com a presença de nanoestruturas de silício imersas nos filmes SRSO, sendo que defeitos do tipo NBOHC e ODC, típicos do óxido de Si, também têm influência sobre essas propriedades. Comparando os dados de PL e FTIR de nossas amostras, bem como dados da literatura, concluímos que a cristalinidade das nanoestruturas de Si tem forte influência sobre a intensidade de PL. Por outro lado, a cristalinidade influencia muito pouco na capacidade de armazenamento de carga, como verificado pelas curvas de histerese nas medidas C-V. Assim, as características ópticas e elétricas de nossas amostras estão associadas principalmente à presença de nanoestruturas de silício dentro da matriz de óxido de Si. Nossas amostras demonstram alta potencialidade para aplicação em dispositivos optoeletrônicos e nanoeletrônicos. / Abstract: In this work we have analyzed samples of Silicon Rich Silicon Oxide (SRSO) obtained by an Electron Cyclotron Resonance Chemical Vapor Deposition system (ECR-CVD). Structural, compositional, electrical and optical properties were investigated by Fourier transform infrared (FTIR), transmission electron microscopy (TEM), Rutherford backscattering spectroscopy (RBS), capacitance-voltage (C-V), photoluminescence (PL) and ellipsometry. By fitting a long range refractive indices curve as a function of O2 flow, it can be seem that the ECR-CVD system is able to produce films with high control on the refractive indices, which, indirectly, suggest the possibility of control of the optical and electrical characteristics, since all these characteristics are dependent of Si concentration in the film, as refractive index. Into the region of interest for our work, the atomic concentration ratio O/Si obtained by RBS correlates linearly with the refractive indeces. The PL intensities and peak positions and the hysteresis curves observed by C-V characterizations, after thermal treatments, show dependence on O2/SiH4 flow ratios used in the work. We observed that temperature and time of thermal treatments have strong influence on PL properties of the selected samples. Nevertheless, the influence of these same parameters on electrical properties (C-V) are less significant than for PL properties, mainly for temperatures above 1000 oC. The PL and CV characteristics of our samples can be related to the presence of silicon nanostructures embedded inside SRSO films. On the other hand, typical silicon oxide defects, like NBOHC and ODC, have some influence on such optical and electrical properties. Comparing our PL and FTIR data, as well as data from literature, we can suppose that crystallinity has strong influence on PL intensity. On the other hand, crystallinity has just a weak influence on the charge storage capacity of our samples, as we had seen by the hysteresis curves in C-V measurements for samples treated at 1100 oC and 1150 oC. Finally, we conclude that optical and electrical characteristics of our samples are associated principally to the presence of silicon nanostructures embedded in a silicon oxide matrix. Our samples showed high potentiality to applications as optoelectronic and nanoelectronic devices. / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor Engenharia Elétrica

Orientadores: Vitor Baranauskas, Alfredo Carlos Peterlevitz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-12T10:56:53Z (GMT). No. of bitstreams: 1 Manne_GustavoAndreMograo_M.pdf: 4900447 bytes, checksum: 96ac39c8d4903a68da74c3db411b33b1 (MD5) Previous issue date: 2008 / Resumo: Esta tese apresenta um estudo do crescimento e caracterização do diamante nanocristalino crescido por deposição química a partir da fase vapor (diamante CVD), com a introdução de boro durante o crescimento. Nosso objetivo foi de produzir amostras com boas propriedades para emissão de elétrons para o vácuo por efeito do campo elétrico (FEE). As amostras foram caracterizadas por Microscopia Eletrônica de Varredura de Emissão por Campo (FESEM), micro-espectroscopia Raman e emissão de elétrons por campo elétrico. Os resultados destas caracterizações são apresentados e discutidos. / Abstract: This thesis presents a study of the growth and characterization of nano crystalline diamonds produced by the hot-filament chemical vapor deposition (CVD) with the introduction of boron during the growth process. Our objective was to produce samples with good electrical properties for field induced emission of electrons (FEE) to the vacuum. Characterization of the samples by electron microscopy, Raman micro-spectroscopy, and Field Emission measurements are presented and discussed. / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

No description available.

This diploma thesis is focused on characterization of semiconductive nanowires. Theoretical part of thesis deals with basic physical properties of TiO2 and a search of selected properties of titanium dioxide nanostructures is preseted. The experimental part describes several spectroscopic measurements carried out with complex of TiO2 nanowires. The influence of gold nanoparticles (deposited on the nanowire surface) on sample properties is also tested. The final part of thesis is devoted to methodology for measurement of electrical properties. These experiments are carried out only with one nanowire. Focused electron beam induced deposition (resp. Focused ion beam induced deposition) and electron lithography are utilized.

Lead-based piezoelectric materials, such as PbZrxTi1-xO3 (PZT), have attracted considerable attention and have been widely used in actuators, sensors and transducers due to their excellent electric properties. However, considering the toxicity of lead and its oxides, environmentally friendly lead-free piezoelectric materials are attracting more attention as potential replacements for PZT. Among them, Bi0.5Na0.5TiO3 (BNT)-based materials exhibit good electrical properties and electromechanical coupling response. In this work, the 0.97Bi0.5Na0.5TiO3-0.03BiAlO3 (BNTBA) thin films (~120 nm thickness) were successfully prepared using the pulsed laser deposition (PLD) method on Pt/TiO2/SiO2/Si substrates. The effects of substrate temperature, oxygen pressure, laser repetition rate, and post-annealing treatment were investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) are used to study the structure of the films and the ferroelectric and dielectric properties are measured. The results show that it is necessary to introduce excess sodium and bismuth to compensate for their evaporation in further thermal treatment. The values of remnant polarization increase from 8.7 μC/cm2 to 12.3 μC/cm2 with the introduction BiAlO3. The dielectric constant increases from 600-550 to 710-600 and the dielectric loss increases from 4.2% to 6.7% at higher frequency when the oxygen pressure increases from 20 Pa to 30 Pa. / Blybaserade piezoelektriska material, såsom PbZrxTi1-xO3 (PZT), har väckt stor uppmärksamhet och har använts i stor utsträckning på grund av deras utmärkta elektriska egenskaper. Men med tanke på toxiciteten hos bly och dess oxider lockar miljövänliga blyfria piezoelektriska material mer uppmärksamhet från forskare som potentiella utbyten för PZT. Bland dem uppvisar Bi0.5Na0.5TiO3 (BNT) -baserade material bra elektriska egenskaper och elektromekanisk kopplingssvar. I detta arbete framställdes 0,97Bi0.5Na0.5TiO3-0.03BiAlO3 (BNTBA) tunna filmer (~ 120 nm tjocklek) med användning av pulserad laseravsättningsmetod på Pt / TiO2 / SiO2 / Si-substrat. Effekterna av substrattemperatur, syretryck, laserrepetitionshastighet och efterglödande behandling undersöktes. Röntgendiffraktions (XRD) och skanningelektronmikroskop (SEM) används för att studera filmens struktur och de ferroelektriska och dielektriska egenskaperna mäts. Resultaten visar att det är nödvändigt att införa överskott av natrium och vismut för att kompensera för deras avdunstning vid vidare termisk behandling. Värdena för återstående polarisation ökar från 8,7 μC / cm2 till 12,3 μC / cm2 med introduktionen BiAlO3. Den dielektriska konstanten ökar från 600-550 till 710-600 och den dielektriska förlusten ökar från 4,2% till 6,7% vid högre frekvens när syretrycket ökar från 20 Pa till 30 Pa.

Polymer-derived ceramics (PDCs) are a unique class of multifunctional materials synthesized by thermal decomposition of polymeric precursors. Due to their unique and excellent properties and flexible manufacturing capability, PDC is a promising technology to prepare ceramic fibers, coatings, composites and micro-sensors for high-temperature applications. However, the structure-property relationships of PDCs have not been well understood. The lack of such understandings drastically limited the further developments and applications of the materials. In this dissertation, the structure and properties of amorphous polymer-derived silicon carbonitride (SiCN) and silicoboron carbonitride (SiBCN) have been studied. The SiCN was obtained using commercially available polysilazane as pre-ceramic precursor, and the SiBCN ceramics with varied Si-to-B ratio were obtained from polyborosilazanes, which were synthesized by the hydroboration and dehydrocoupling reaction of borane and polysilazane. The structural evolution of polymer-derived SiCN and SiBCN ceramics from polymer to ceramics was investigated by NMR, FTIR, Raman, EPR, TG/DTA, and XRD. The results show a phaseseparation of amorphous matrix and a graphitization of “free” carbon phase, and suggest that the boron doping has a great influence on the structural evolution. The electric and dielectric properties of the SiCN and SiBCNs were studied by I-V curves, LCR Meter, and network analyzer. A new electronic conduction mechanism and structure model has been proposed to account for the relationships between the observed properties and microstructure of the materials. Furthermore, the SiBCN ceramics showed the improved dielectric properties at characterization iv temperature up to 1300 ºC, which allows the fabrication of ultrahigh-temperature wireless microsensors for extreme environments.

No description available.

Le but de ce projet est d'étudier les propriétés mécaniques et électriques d'une monocouche de phospholipide supportée sur silicium en vue de son utilisation comme diélectrique de grille dans un biocapteur à transistor à effet de champ. Ces monocouches de 3nm sont formées par fusion de vésicules. Les lipides utilisés possèdent des triples liaisons dans leurs chaînes alkyles permettant une polymérisation radicalaire. Nous montrons que la polymérisation stabilise la monocouche à l'air et améliore sa résistance mécanique. Les mesures ont été réalisées par mesure de force par AFM, la force de ‘rupture' de la monocouche par la pointe AFM augmentant après polymérisation. L'étude de la force en fonction de la vitesse d'approche de la pointe nous a permis de montrer que la rupture de la couche est un phénomène activé qui dépend de la vitesse. Nous avons pu ainsi déterminer pour chacune des deux surfaces, polymérisées ou pas, l'énergie d'activation de rupture de la couche du système couche/pointe et une estimation du module de Young. Ces grandeurs qui augmentent après polymérisation montrent une amélioration des propriétés mécaniques. Nous nous intéressons également aux propriétés électriques de ces monocouches. Nous avons réalisé des mesures Courant-Tension I(V) à partir desquelles nous avons pu déterminer la résistance de la couche, les densités de courant de fuite et la tension de claquage. Les résultats obtenus démontrent que ces monocouches ultrafines possèdent de très bonnes propriétés isolantes. De plus nous avons révélé la propriété très intéressante d'auto-régénération de la monocouche isolante après claquage à l'air, à température ambiante en quelques minutes seulement. / The main goal of this project was to study the electrical and mechanical properties of a solid supported lipid monolayer in order to use it as a dielectric insulator in a Field Effect Transistor based biosensor. The 3 nm lipid monolayer supported on silicon was obtained by the vesicle fusion method. DC8,9PC phospholipids containing acetylenic moiesties were selected. The lipid monolayer was stabilized on the substrate by two-dimensional polymerization in the plane of the layer. We demonstrate that this polymerization stabilizes the monolayer in air. Force measurements realized by AFM on both polymerized and non-polymerized layers demonstrated a net improvement of the nano-mechanical resistance of the layer after polymerization with a net increase of the force required to rupture the layer. Measurements realized at different loading rates have evidenced the fact that the monolayer rupture is an activated process that depends on the loading rate. For both types of layers, we have determined the intrinsic rupture activation energy of the tip–layer system as well as their Young modulus. These two physical quantities increase after polymerization and demonstrate a net improvement of the mechanical properties of the polymerized monolayer. The electrical properties of these layers have also been investigated. Current-Voltage measurements were done on the monolayer in the air at room temperature. The differential resistance, the leakage current, the breakdown voltages were measured and showed that the polymerized monolayer behaves as a good electric insulator. In addition, we demonstrated a very interesting property of autonomic self-healing after electrical breakdown.