Field ion microscope studies of the propagation of substrate grain boundaries into an overgrowth

The roles of substrate grain boundaries and substrate surface topography in the nucleation and growth characteristics of thin and thick overgrowths were evaluated through field ion and transmission electron microscopy techniques. The results of these studies, utilizing both electrodeposited and vapor-deposited overgrowths, indicate that the substrate surface topography is generally continued in the overgrowths at thin coverages. Nucleation and growth characteristics are seen to be influenced more by surface asperities than by the existence of grain boundaries on substrate surfaces. Grain boundaries (or the interaction of grain boundaries with the substrate surface) are not observed to be sites for preferential nucleation and growth of thin films although they can act as a source for recrystallization and grain growth in thicker overgrowths (greater than 20μm).