Nanopatterning of surfaces by ion bombardment
Ion bombardment of solid surfaces very often leads to the development of highly periodic nanopatterns such as nanodots and ripple-like structures. Their characteristic features (orientation, periodicity, etc.) depend strongly on the material being bombarded and the ion-beam parameters (energy, angle of incidence, ion current density). Generally, these phenomena are believed to be related to (and caused by) the interplay between ion erosion and diffusion of adatoms (vacancies) which induces a surface re-organization. Several promising applications for such structures are envisaged.
In this context, the dynamic evolution of such nanostructures will be studied for various materials and a wide range of ion-beam parameters. Specifically, the temporal dynamics of these patterns as function of irradiation time (fluence) will be investigated for the different experimental parameters. These results should be evaluated with respect to current theoretical concepts of the ion-induced morphological evolution of surfaces.
The experiments will be performed in two setups:
(i) A dual-beam focused ion beam system (at IFOS) that comprises a scanning electron microscope (SEM) and highly focused ion beam. This combination enables an in situ observation by SEM of the surface morphology created by the ion beam.
(ii) An ultrahigh vacuum apparatus which is equipped with a low-energy ion source and a scanning tunneling microscope (STM). In this system, the temporal evolution of the formed nanopatterns can be studied by STM upon consecutive ion-irradiation steps.