Modification and control of the interface of high temperature cuprate superconductors using self-assembled monolayers
High temperature superconductors are plagued by numerous material problems that have hampered the commercial development of these complex copper oxides. One of the most problematic material characteristics is the propensity of the cuprates to undergo reduction in the presence of water, acids, CO and CO2. One of the solutions to prevent corrosion developed in the McDevitt lab entails protecting the material with a monolayer coating of alkylamine reagents. While previous work has shown that these monolayers hinder the corrosion of cuprate superconductors, the mechanism and energetics of the formation process is poorly understood. The goal of this dissertation is to examine the mechanism and kinetics of formation of self-assembled amine monolayers atop cuprate superconductors. This dissertation is organized as follows: In Chapter 1, the theory of the materials and thin film deposition processes used in this dissertation are described. The specifics of the methods and materials employed are described Chapter 2. In order to examine these phenomena, a new pulsed laser deposition system capable of generating larger quantities of corrosion free thin film superconductors has been built and optimized as described in Chapter 3. In Chapter 4, experimental evidence for the removal of previously exposed corroded material by the alkyl-amine monolayer reagent has been provided using x-ray photoelectron spectroscopy, atomic absorption spectroscopy, and scanning electron micrography. Evidence of the alkyl-amines role in planarizing the superconductors is also provided. Finally, in Chapter 5, the kinetics of adsorption have been examined using a redox active monolayer reagent, providing the first documentation of adsorption isotherms atop cuprate thin films.