The influence of grain boundary (GB) on stability of poly-silicon thin film transistor (TFT) have been investigated in this work. The work was supported by the National Science Council of the Republic of China and AUO. We used ac stress and dc stress conditions to stress different TFTs, and investigate the influence of grain boundary by use of electrical analysis. The SLS poly-Si TFT which does contain GB perpendicular to the channel direction owns the higher ability against dc stress and poorer ability against ac stress than the poly-Si TFT which does not contain GB. The physical mechanism for these results has been reasonably deduced by use of TFT device simulation tool (ise-tcad).

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Presented diploma thesis deals with preparation of bioresorbable polyurethanes (PUR) and their characterization. The theoretical part describes the feedstocks used for the PUR preparation and summarizes the knowledge about PUR used in medical applications. Experimental part presents characterization of bioresorbable PUR films prepared by reactive casting in one step without the use of organic solvents. The absence of solvents represents a great advantage due to their toxicity and subsequent removal from the resulting product. The synthesis of PUR was conducted under an inert atmosphere by polyaddition reaction of hydrophobic poly(e-caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) with hexamethylene diisocyanate (HDI). Synthesis under an inert atmosphere was necessary due to a side reaction of isocyanate with atmospheric humidity, which causes the formation of porous films instead of continuous ones. Prepared PUR films were characterized for different PCL/PEG ratios and different isocyanate index (ratio of NCO/OH reacted groups). PUR (isocyanate index 1.05) with PCL content 90 wt. % and higher demonstrated tought behavior in mechanical tests. Increase of isocyanate index and decrease of PCL content under 90 wt. % caused fragile sample behavior. The reason of such behavior was the different ability of PCL to crystallize in the structure of the polyurethane network. Increasing the PEG content has improved the ability of PUR films to absorb water and enhanced the rate of hydrolytic degradation. By adjusting the PCL/PEG ratio and the amount of isocyanate, solvent free bioresorbable PUR with suitable mechanical (flexibility, toughness) and physical properties (swelling, degradation) can be obtained. Prepared PUR films could be used in biomedicine e.g. as vascular grafts.

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Le présent travail a porté sur l’élaboration d’électrodes à base de polymère conducteur et d’un tapis de nanotubes de carbone alignés pour les applications de supercondensateur.Dans la première partie de ce travail, nous avons porté notre attention sur le choix de nos matériaux et nous avons pu déterminer leur comportement électrochimique en milieu liquide ionique. Les deux polymères choisis : le poly(3-méthylthiophène) et le poly(3,4-diméthylthiophène) possèdent des propriétés très différentes en terme de capacitance, de potentiel d’oxydation, de résistance ou de cyclabilité. Afin d’allier ces propriétés entre elles, nous avons réalisé la synthèse de copolymères obtenus par voie électrochimique en milieu liquide ionique aprotique. Cette électro-co-polymérisation nous a permis d’obtenir une large gamme de matériaux aux propriétés variables selon la composition du polymère.Dans la deuxième partie de ce travail, nous avons optimisé la synthèse électrochimique d’un nanocomposite poly(3-méthylthiophène)/nanotubes de carbone alignés en milieu liquide ionique. Les matériaux obtenus offrent la propriété d’être « auto-supportés » et permettent ainsi de s’affranchir de collecteur de courant. La nanostructuration grâce aux nanotubes et l’absence de collecteur de courant nous ont permis d’améliorer d’un facteur 3 la capacitance spécifique de nos électrodes. Une optimisation des conditions d’élaboration des nanocomposites permettent d’atteindre une capacitance de 180F.g-1 dans EMITFSI à 30°C. / The present work concerned the elaboration of electrodes containing electronic conducting polymer and a carpet of aligned carbon nanotubes for supercapacitor applications. In the first part of this work, we put our attention on the choice of our materials and we were able to determine their electrochemical behavior in ionic liquid. Both chosen polymers : poly(3-méthylthiopène) and poly(3.4-diméthylthiophène) possess very diffrent properties in term of capacitance, oxidation potential, resistance or cyclability. In the second part of this work, we optimized the electrochemical synthesis of a nanocomposite poly(3-méthyltiophène)/aligned carbon nanotubes in ionic liquid. The obtained materials offer the property to be "self-supported" and allow using themselves without current collector. And optimization of the conditions of nanocomposites elaboration allows reaching a capacitance of 180 F.g-1 in EMITFSI in 30°C.

ABSTRACT In this study, the rf magnetron sputtering was used to deposit (Ba0.8Sr0.2)(Ti0.9Zr0.1)O3 (BSTZ) ferroelectric thin films on SiO2/Si substrates, and MFIS structure was also fabricated. The effects of various sputtering parameters effects on the characteristics of BSTZ thin films, such as the oxygen concentrations, deposition temperature, rf power, chamber pressure and deposition time were be discussed. As deposited on Pt/Ti/SiO2/Si substrate, the electrical and physical properties of BSTZ thin films after RTA and CTA thermal treatment were be also discussed. In XRD and SEM analysis, the crystal structure and grain size of as-deposited BSTZ thin film could be observed. From the C-V and J-E curves obtained, the memory window and leakage current density of MFIS structure were about 9.5V and 2.76¡Ñ 10-9 A/cm2, respectively. After RTA and CTA post-treatment, the capacitances of MFM structure were about 2.06nF and 1.93nF. We found that dielectric constant of as-deposited BSTZ thin film increased to 183 and 194, respectively. In addition, the leakage current density of RTA and CTA treated BSTZ films were about 3.82¡Ñ 10-6 A/cm2 and 1.16¡Ñ 10-6 A/cm2. Finally, the one-transistor-capacitor (1TC) structure of ferroelectric random access memory (FeRAM) with the gate oxide of BSTZ thin films on the polysilicon TFT structure have been fabricated and investigated.From the experimental results, the on/off drain current ratio is two orders, and its value is much smaller than those of the most reported bottom-gated TFTs devices by using different ferroelectric materials as gate oxide. From these results in this study, the BSTZ thin films for top-gate polysilicon thin-film transistor will be an excellent candidate to fabricate higher storage capacitance ferroelectric random access memory (FeRAM) devices for system on panel (SOP) applications.

The synthesis and investigation of new types of poly(paraphenyleneethynylene)s, PPEs, is presented. PPEs which are Jacketed are there by shielded from electronic and plararization effects in the solid state. Other PPEs contain pendent groups which may functionalized before or after polymerization to afford two versitle routes to newly functionalized polymeric materials. Based on the PPE structure, metals may be introduced and these polymers may be used as precursors for other types of materials such as ceramics.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2007. / Committee Chair: Sheldon W. May ; Committee Members: Donald F. Doyle, Leslie T. Gelbaum, Stanley H. Pollock, and James Powers. Part of the SMARTech Electronic Thesis and Dissertation Collection.