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 evol ution. The orientation dependent surface energy gamma 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 wit hout preferential orientations evolved to a bimodal texture, and final ly to a situation with only low est gamma planes parallel to the subst rate. For some initial situations a texture turn over from over crysta llographic direction to another one can be expected. In all cases a sh arpening of the angular distribution of tile texture is found near the directions of a local minimum for gamma. For sufficiently large times the mean top diameter of the columns always increases with layer thic kness. The calculated effects describe well a number of experimentally observed phenomena.