TRANSMISSION ELECTRON-MICROSCOPY DETECTION OF MICROTEXTURE VARIATIONSAND THEIR EFFECTS ON THIN-FILM STABILITY

We have studied grain growth and the development of preferred orientat ion in thin gold films using transmission electron microscopy conical dark field imaging. The technique is capable of detecting texture vari ations characterized by mean orientation differences smaller than 5-de grees. We have observed microscopic regions with distinct [111] fiber textures that differ, primarily, in the mean azimuthal deviation from the fiber axis. For one texture, the [111] axes of individual grains a re found to have an average deviation of 1.5-degrees from the foil nor mal, a second is characterized by a mean deviation of 5-degrees, and a third is more nearly random with only a slight [111] orientation pref erence. The shapes of the differently oriented regions depend on the p reparation of the sodium chloride substrate before deposition. We have studied the dependence of preferential orientation development on sub strate surface topography and the evolution of microstructure in diffe rently textured regions. Hillock growth, observed only in nearly rando mly oriented regions of the films, cannot be explained by current theo ries of grain growth or hillock formation.