Spontaneous structural pattern formation at the nanometre scale in kinetically restrictedhomoepitaxy on vicinal surfaces

Abstract

The concept of spontaneous pattern formation in epitaxial growth is currentlyactively explored as a promising pathway for lateral nanostructuring of surfaces.Often, the origin of self-organization is traced back to the presence of an excessenergy barrier for adatom diffusion associated with asymmetric features in thecrystalline structure, the Ehrlich–Schwöbel barrier. Upon growth of Cu on vicinal Cusurfaces at moderate substrate temperatures a step-meandering instability develops,resulting in an in-plane patterning of the surfaces at the nanometre scale with atemperature- and flux-dependent characteristic wavelength. This meandering instability issuperseded by a step-bunching instability during growth at higher temperatures.Specifically, the meandering instability acts as a precursor to the bunching instability,indicating that a one-dimensional treatment of bunching in step flow growth is notsufficient. These nanostructured surfaces might be used as templates in order toguide the growth of materials which do not show spontaneous self-organization.