A model for thin film texture evolution driven by surface energy effects

A model was developed in order to calculate the texture evolution of a growing film with large atomic diffusion on the surface. The tendency for lowest surface energy was taken as the driving force for the evolution. The orientation dependent surface energy y was approximated by a function with a sharp minimum in two crystallographic directions. The texture evolution was calculated, starting from various initial situations. With realistic assumptions it was found that a texture without preferential orientations evolved to a bimodal texture, and finally to a situation with only lowest y planes parallel to the substrate. For some initial situations a texture turn over from one crystallographic direction to another one can be expected. In all cases a sharpening of the angular distribution of the texture is found near the directions of a local minimum for y. For sufficiently large times the mean top diameter of the columns always increases with layer thickness. The calculated effects describe well a number of experimentally observed phenomena.