Redeposition behavior of seeds in oblique cone evolution

Abstract

Cones developed on Cu surfaces bombarded with an obliquely incident Ar+ –ion beam, while simultaneously supplying Mo ‘‘seeds’’ by sputtering, were observed by scanning and transmission electron microscopy. Seed atoms were found to preferentially deposit on the cone slopes which received high fluxes of these species, forming crystalline thin layers there. The seed overlayers thus grown were ribbon-like in configuration and composed of Mo crystallites arranged in a preferred orientation. An explicit relationship was found between the crystallographic orientations of overlayer and substrate, but it was inconsistent with the existing model of epitaxy. Also, the cone population decreased with decreasing local seed flux and vice versa for the average cone dimension. This may indicate that the key role of seeds is to promote the nucleation of cones, not to enhance the development of nucleated cones.