Microstructural evolution of sputtered phase segregated metal composite thin films

In this thesis, we present the first comparative study of crystallographic texture development in three different types of metal thin film composites: fully miscible (Au-Ag), slightly immiscible (Cu-Ag) and immiscible (Au-SiO 2). Texture development refers to the distribution of orientations of crystallites in polycrystalline thin films, and is an important part of the microstructure that determines thin film properties. A material's crystallographic texture needs to be understood because of its sensitivity to the energetic growth conditions. By controlling the microstructure, a material can be tailored to specific applications. We investigated in comparison the texture and microstructure evolution in metal composite systems through x-ray diffraction pole figures. Our thin film materials were codeposited at room temperature by magnetron sputtering. Each of these composite metal systems shows a different behavior as determined by the phase diagram of the composites. The fully miscible fcc-fcc Au-Ag system shows a constant strong (111) fiber texture perpendicular to the substrate, that is also characteristic of each single phase in a pure state. The slightly immiscible fcc-fcc Cu-Ag system shows an unexpected increase in pole figure intensity in the alloy region compared with the pure metals. These Cu-Ag thin films were also evaluated for antimicrobial applications. The fully immiscible Au-SiO2 system is an fcc metal-insulator segregated composite, which shows a rapid drop in Au (111) pole figure intensity with the addition of a few percent SiO2. We interpret this as a pinning behavior and model the results using a phase-field simulation method.