Browsing by Subject "Thin Films"
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Item Electronic interactions between gold films and mn12-acetate(2009-05-15) Means, Joel LewisInteractions between Mn12?acetate molecular magnets and thin gold films have been explored in light of the theory of weak localization. Low-temperature measurements of the magnetoresistance of gold films of varying thicknesses, with and without the presence of a surface layer of Mn12?acetate, have been performed using a dilution refrigerator. Quantitative fits to the data using the predictions of weak localization theory were performed using a least-squares fit method in order to determine characteristic times for elastic, inelastic, spin-orbit and spin scattering events within the gold. These data indicate that the presence of Mn12?acetate on the surface of the gold film leads to a significant enhancement of the spin scattering within the gold films.Item Layer-by-layer assembly of electrically conductive polymer thin films(Texas A&M University, 2007-09-17) Jan, Chien Sy JasonLayer-by-layer (LbL) assembly was used to produce highly conductive thin films with carbon black (CB) and polyelectrolytes. The effects of sonication and pHadjustment of the deposition mixtures on the conductivity and transparency of deposited films were studied. Drying temperature was also evaluated with regard to thin film resistance. Sonication and oven drying at 70oC produced films with the lowest sheet resistance (~ 1500 ????/sq), which corresponds to a bulk resistivity of 0.2 ??????????cm for a 14- bilayer film that is 1.3 ????m thick. Increasing the pH of the PAA-stabilized mixture and decreasing the pH of the PEI-stabilized mixture resulted in films with 70% transparency due to thinner deposition from increased polymer charge density. Varying the number of bilayers allows both sheet resistance and optical transparency to be tailored over a broad range. Variation of deposition mixture composition led to further reduction of sheet resistance per bilayer. A 14 bilayer film, made from mixtures of 0.25wt% carbon black in 0.05wt% PAA and plain 0.1wt% PEI, was found to have a sheet resistance of approximately 325 ????/sq. Bulk resistivity was not improved due to the film being 8 ????m thick, but this combination of small thickness and low resistance is an order of magnitude better than carbon black filled composites made via traditional melt or solution processing. Applications for this technology lie in the areas of flexible electronics, electrostatic charge dissipation, and electromagnetic interference shielding.Item Wrinkling of Stiff Films on Stretched Compliant Films: Experimental and Theoretical Studies(2013-12-06) Yang, YiWrinkling of stiff film on semi-infinite compliant substrates has attracted attentions recently due to its important applications in stretchable electronics and micro-pattern metrology. However, wrinkling of a stiff film on a compliant thin film substrate has not been well understood. The composite bilayer comprised with a stiff film and a stretched film has a critical application in developing advanced thin film solar cells for long duration stratosphere balloons. The presented thesis focuses on wrinkling of stiff films with finite widths on stretched compliant thin sheet via experimental and theoretical approach. Polyester films and low density polyethylene films have been utilized as the surface films and substrate films, respectively. Flexible polyvinyl chloride films have also been employed to serve as the surface layer for better understanding the physics behind the phenomena. The experiments reveal wrinkling phenomena of the film on the stretched thin sheet are very similar to that of a stiff film on a semi-infinite elastic foundation. A theoretical model considering finite width effect is formulated based on the concept of effective elastic foundation observed from the experiments via variational approach and principle of minimum potential energy. The result predicted by the theoretical model is validated via experiments and the finite width effect is also investigated and discussed. In summary, the presented study shows the stretched film plays the role as a virtual semi-infinite elastic foundation for the surface film. The experimental ob- servations and theoretical prediction of the phenomena has been achieved. It may provide a physics-based foundation for technology adventures in thin-film solar cell powered scientific balloon.