PMDA-ODA polyimide thin films can be formed by vapor co-deposition of the precursor molecules PMDA (pyromellitic dianhydride) and ODA (4, 4′-oxydianiline) if the resulting polyamic acid film is heated to a 473 to 573 K cure step. We have used laser Raman spectroscopy to study how dose composition, dose rate, and substrate temperature influence the properties of the resulting polyimide films. We find that only doses with excess PMDA produce high quality films. Doses with 1 : 1 stoichiometry or excess ODA produce thermally unstable films that contain imine bonds; these films decompose below 575 K. Dosing onto substrates below 315 K produces the polyamic acid precursor of polyimide. At higher substrate temperatures, films with high defect densities or decomposed films are produced. The equilibrium vapor pressures of ODA and PMDA are reported.

A new class of molecular composites of carbon black and an electronically conducting polymer, namely polypyrrole, has been synthesized by chemically polymerizing pyrrole in an aqueous dispersion of carbon black. The carbon black content of these composites can be varied from ∼5% to ∼85% (by weight). The surface area and density of these composites were compared to corresponding mixtures of carbon black and polypyrrole. The influence of carbon black on the efficiency of polymerization of pyrrole is described. The effect of carbon black content on the electronic conductivity of the composite has been mapped, and compared with the corresponding behavior of a mixture of carbon black and polyvinylchloride. The influence of the parent black characteristics (porosity, void volume, surface area) on the electronic conductivity of the resultant composite has been probed by comparing the behavior of composites derived from six commercial and experimental blacks. The temperature dependence of the composites has been studied as a function of the carbon black content. Finally, the application of these new materials is an environmental remediation scenario is demonstrated for Cr(vi) as a model pollutant.

In this article we present the results of a study aimed at developing hillock-free, pure-Al thin-film material suitable for the fabrication of gate and source lines in thin film transistor active-matrix liquid crystal displays. Strong Al(111) texture was shown to be a key attribute for achieving good resistance to hillock formation. To obtain this strong Al(111) texture, we explored the incorporation of a thin metal layer, under the Al film, and we showed that Ti could be an appropriate candidate for further optimization. Key variables affecting the quality of Al were found to be the roughness of the glass substrate, the thickness of the titanium, the background vacuum quality, and the sputtering temperature. By optimizing the deposition process for both Al and Ti layers, we showed that aluminum films with very strong (111) texture (rocking curve full width at half maximum 0.86°), very smooth surface (root mean square surface roughness 1.8 nm), and a uniform, columnar grain size (0.3–0.5 μm) could be deposited by dc magnetron sputtering. In addition to improving the aluminum microstructure, optimization of the gate dielectric process was also performed with the aim of reducing hillock formation. Combined optimization of the sputtering and gate dielectric deposition processes yielded an overall reduction in hillock density of 3.5–4 orders of magnitude, without the need for anodic oxidation or other means of capping the aluminum film. By combining Al/Ti dc sputtering, dry-etching technology for one-step patterning of the composite Al/Ti film, and gate insulator deposition at 300 °C we demonstrated, for the first time, gate metallization technology based on pure Al with excellent step coverage and ultralow hillock density (<103 cm−2).

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We present results for the electrical conductivity (σ) of thin films of poly(benzo[1,2-b:4,5- b']dithiophene-4,8-diyl vinylene) (PBDV) and poly (dodecylthiophene) (PDDT) as a function of temperature in the range 15-295K. The polymers were doped with FeC13 and PF6 which resulted in electrical conductivities differing by two orders of magnitude at room temperature. We examine three sets of σ(T)-data by using the variable-range hopping (VRH) model that predicts a linear relationship between ln(T1/2σ) and T1/4. We observe a change in the slope of the ln(T1/2σ) vs T14 relationship in all three samples at low temperatures. We also analyze the temperature dependence of the resistivity of PBDV by using the thermal fluctuation-induced tunneling model.