Date of Award

Spring 2010

Project Type

Dissertation

Program or Major

Materials Science

Degree Name

Doctor of Philosophy

First Advisor

James M E Harper

Abstract

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.

Download

Share

COinS