Polycrystalline Ni thin films on nanopatterned Si substrates: from highly conformal isotropic to non-conformal anisotropic growth

Nanostructured thin films are of growing relevance for numerous applications including magnetic recording media[1] and photovoltaics.[2] Control of the film and substrate morphology at the submicron scale enables the fabrication of functional thin films with tailored magnetic,[3,4,5] optical,[6,7] chemical[8,9] or biological properties.[10] Various methods have been utilized to fabricate those nanostructured thin films with well defined morphology. In the past, most of these methods have been based on lithographic techniques such as electron beam,[4] nanosphere,[6] or colloidal lithography,[8] as well as on spontaneous pattern formation during epitaxial growth[5,10] or thermal annealing.[7] However, these methods often suffer from various shortcomings, e.g. low throughput, the need of high temperatures, or a restriction to isotropic patterns. An alternative approach for creating topological nanopatterns on solid surfaces that overcomes these shortcomings uses the self-organized formation of periodic nanopatterns during broad beam ion sputtering.