Dr. Hanna Bishara
David Wang Auditorium, 3rd floor Dalia Meidan Bldg.
The impact of microstructural defects on the electrical properties of materials is generally captured as an accumulative effect of all the material’s defects. Despite the different atomic and mesoscopic structures of defects (even within same defect type e.g. grain boundaries – GBs), the impact of their structural characteristics on the resistivity is not yet understood. In this study, the resistivities of individual defect segments, having well-defined structures, are directly measured through novel high-resolution local electrical measurements in situ SEM. Specifically, the resistivities of GB segments in pure and Fe-alloyed Cu thin films are reported, and correlated with the GB structural characteristics and its thermodynamic excess properties. As well, the talk will discuss the preparation of GBs with the desired characters and the corresponding characterization techniques. In addition, the conductivity of near-surface dislocations in the ceramic oxide TiO2 is discussed. A single type of dislocations is obtained through a controlled nanoindentation, and consequently it locally enhances the oxide’s conductivity with a micrometer lateral resolution. The novel results contribute to a better understanding of the defects’ resistivity, which paves the way for knowledge-based defect engineering of conductors, functional materials and internal interfaces in devices.
Host: Asst. Prof. Joshua M. Grolman