In-situ X-ray Scattering: A Tool for Investigation of Nanostructure Formation

Nowadays, the development of new materials is often associated with specific properties of functionalized nanostructures. X-ray investigations are a very important tool to find the link between the functional (magnetism, luminescence) and the corresponding structural properties (size, orientation etc.) that are generating this function and to explain the underlying physical processes. This knowledge makes it possible to design new materials with specific properties. We report on (in-situ) X-ray studies that are focused on ion-beam sputtering techniques (IBS) creating nanostructures either by ion beam erosion or by sputter deposition processes.
With IBS the roughness of solid surfaces can be modified on lateral scales of a few nanometers to micrometers or even further. In a defined parameter set IBS leads to a surface smoothing, whereas at other parameters the roughness is increased, leading eventually to periodic patterns, i.e. ripple and hexagonal dot patterns. In-situ measurements of the surface roughness during IBS of GaSb surfaces give insight into the detailed mechanisms; especially, if the early time regime is addressed. Modern synchrotron sources give us the possibility to study the nanostructure growth during deposition. A sputtering chamber mounted on a six-circle goniometer allows an insight into the growth of nanostructures using different scattering and diffraction methods. We have investigated the growth of FePt islands incorporated into an Ag matrix. The high brilliance of the synchrotron source had made it possible to obtain a reliable GISAXS signal and to control the cluster morphology during growth even at the initial stage. By depositing 6 nm Ag layer directly on the SiO2 substrate, we obtained well defined FePt clusters. FePt nanoislands have been achieved without degradation of the magnetic properties. We obtained a magnetic asymmetry with magnetic moments preferentially oriented parallel to the layer surface.