Carbon nanotube forests (CNTFs) are grown using an injection chemical vapor deposition method. Images of CNTFs are taken using a scanning electron microscope and are used to measure their height and density. Growth parameters are systematically varied to determine their effect on the height and density of CNTFs. Investigations of CNTF density as a function of distance from the growth substrate reveal that diffusion can be a limiting factor on CNTF growth. Our findings indicate that height and density are related and that each growth parameter has multi-dimensional effects.

Thesis theme were nanomaterials and its implementation to cementitious materials. Theoretical part has deal with description of carbon nanotubes types, their properties, production, ways of dispergation, nanotoxicity and CNT’s influence on silicate composites characteristics. Experimental part was divided to 5 stages. The first stages were focused on choosing appropriate carbon nanotubes and surfactants. In the next stage settings of US homogenizator were determinate (amplitude, US energy dosage, time). The part of US homogenizator setting process was observing influence of liquid environment characteristics (especially pH) on surface tension and particle distribution and influence of US energy on CNT walls damages through TEM. After dispergation parameters optimalization cement pastes were prepared and hydration temperature, hydration heat and viscosity were observed. Then testing specimens from cement mortar were prepared and tested form strength characteristics. Last stage was concrete production and their examination: compressive strength, flexural strength, static modulus of elasticity, dynamic modulus of elasticity, tensile splitting strength, depth of penetration of water under pressure, resistance of cement concrete surface to water and defrosting chemicals and determination of frost resistance of concrete. Samples with CNT addition had better strength characteristics and better resistance of penetration of water under pressure, water and defrosting chemicals resistance and frost resistance. Result of thesis is comprehensive study of CNT dispersion production and implementation CNT dispersion to concrete including testing specific concrete characteristics.

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It is reported that terahertz radiation from 0.69 to 2.54 THz has been sensitively detected in a device consisting of bundles of carbon nanotubes containing single wall metallic carbon nanotubes, quasi-optically coupled through a lithographically fabricated antenna, and a silicon lens. The measured data are consistent with a bolometric detection process in the metallic tubes and the devices show promise for operation well above 4.2 K. Microwave measurements have also been done up to 20GHz. Voltage responsivity got here is comparable to that of the Schottky diode detector. The detection at microwave frequencies are consistent with the diode detection mode. S11 parameters of different devices were measured using microwave probing, and de-embedding process has been done to get the impedances of the SWNTs. A circuit model was fitted based on the measurement data, and different values of the elements of the circuit are extracted. Frequency response from the circuit model is consistent with the experimental data.

Carbon based semiconductors such as conjugated polymer or single walled carbon nanotubes (SWNT) are promising materials for use next generation printable and wearable electronics. Thin film transistors (TFTs) are often viewed as a building block for more complex electronic device, however, lack of proper characterization of these devices using these novel carbon-based materials is preventing their large-scale adoption. This thesis has two sections; in the first section I explored and improved a novel electrical model originally developed for organic or polymer-based TFTs called the organic virtual source emission diffusion model (OVSED). I improved this model by adding a variable contact resistance parameter and effective gate voltages. I then found better agreement between model and experimental data using this improved OVSED model against the conventional MOSFET based models: the SH and Y-function models, for poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)) based OTFTs. The new model proved to be an efficient tool for benchmarking polymer based TFTs and provided an efficient way to characterize and reduce contact resistance in the devices. In the second section, I explore the effect of light on a series of conjugated polymer wrapped SWNT TFTs. A structure property relationship was established between the wrapping polymer structure and the exposure wavelength intensity. We demonstrated that SWNT TFTs can act as photodetectors after an initial light soak. Finally, we further characterized the SWNT TFTs using our OVSED model validating the observed structure property relationship. Overall this thesis demonstrates steps towards proper characterization of emerging carbon based semiconductors used in TFTs. -- Les semi-conducteurs à base de carbone, tels que les polymères conjugués ou les nanotubes de carbone à paroi simple (SWNT), sont des matériaux prometteurs pour la prochaine génération d'appareils électroniques imprimables et portables. Les transistors à couche mince (TFT) sont souvent considérés comme un élément de base pour des dispositifs électroniques plus complexes, mais la caractérisation incorrecte de ces dispositifs utilisant ces nouveaux matériaux à base de carbone empêche leur adoption à grande échelle. Cette thèse comporte deux sections ; dans la première, j'ai exploré et amélioré un nouveau modèle électrique développé à l'origine pour les TFT organiques ou à base de polymères, appelé le modèle de diffusion d'émission de source virtuelle organique (OVSED). J'ai amélioré ce modèle en ajoutant un paramètre de résistance de contact variable et des tensions de grille effectives. J'ai ensuite constaté une meilleure concordance entre le modèle et les données expérimentales en utilisant ce modèle OVSED amélioré par rapport aux modèles conventionnels basés sur les MOSFET : les modèles à fonction SH et Y, pour les OTFT à base de poly{[N,N'-bis(2-octyldodecyl)-naphtalène-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophène)} (P(NDI2OD-T2)). Le nouveau modèle s'est avéré être un outil efficace pour comparer les TFT à base de polymères et a fourni un moyen efficace de caractériser et de réduire la résistance de contact dans les dispositifs. Dans la deuxième partie, j'explore l'effet de la lumière sur une série de TFT à base de SWNT enveloppés de polymères conjugués. Une relation structure-propriété a été établie entre la structure du polymère enveloppant et l'intensité de la longueur d'onde d'exposition. Nous avons démontré que les SWNT TFT peuvent agir comme des photodétecteurs après une imprégnation initiale de lumière. Enfin, nous avons caractérisé les SWNT TFT à l'aide de notre modèle OVSED en validant la relation structure-propriété observée. Dans l'ensemble, cette thèse démontre les étapes vers une caractérisation appropriée des semi-conducteurs émergents à base de carbone utilisés dans les TFT.

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