Atom probe tomography study of wide bandgap semiconductor materials

This dissertation focuses on developing atom probe tomography (APT) for semiconductors. APT is quickly gaining interest in the field of material characterization because of its unique ability to provide 3D nanoscale studies. APT has been widely used in metals and conductive materials but design changes in the tool in recent years have made atom probe a suitable tool for semiconductor analysis. Because research in atom probe tomography of semiconductors is still in its infancy, it is still unclear whether this characterization method is suitable for semiconductor and how the added knowledge can be different than other accessible tools. This work will utilize APT as a characterization tool for wide bandgap semiconductors, specifically zinc oxide (ZnO) nanowires and GaN-based epitaxial sample. Wide bandgap semiconductor materials have attracted considerable attention in recent years because of the practical applications such as green and blue light emitting and laser diodes, solid-state lighting, photovoltaics, RF and microwave electronics, and gas sensors. Although silicon has remained the industry standard for many of these applications, its limitations have made way into the research of wide bandgap semiconductor materials, such as zinc oxide (ZnO) and gallium nitride (GaN). Because of their large direct bandgap, these materials show excellent promise in the field of optoelectronics, high frequency, high temperature and high power applications. First, we understand the behavior of the material to achieve field evaporation under APT conditions and the mechanisms behind, as well as ways to overcome the different artifacts introduced during sample preparation and data collection. Following this understanding, we can begin to apply APT to device structures to understand the effects of radiation on materials at the atomic scale, as well as the cluster formation of some of the elements along the material. At the conclusion of this dissertation, APT will deliver the results necessary to maximizing device efficiency as well as build the pathway for future APT analysis. (Published By University of Alabama Libraries