Interface kinetics and morphology on the nanoscale

Diffusion on the nanoscale in multilayer, thin films has many challenging features even if the role of structural defects can be neglected and ‘only’ the effects related to the nanoscale arise. Recently, we have discovered different examples for diffusional nanoscale effects, which are summarized in this contribution. Interface shift kinetics may be different from the ones predicted by continuum approximations (anomalous kinetics). Moreover we show that in solid state reactions, reaction layers form and start to grow highly non-stoichiometrically and an initially existing stoichiometric compound layer may dissolve then re-form non-stoichiometrically. Our findings are of primary importance for nanotechnologies where early stages of solid state reaction (SSR) are utilized. We also show that an initially diffused interface may sharpen even in completely miscible systems. This phenomenon could provide a useful tool for the improvement of interfaces and offer a way to fabricate, for example, better X-ray or neutron mirrors, microelectronic devices, or, multilayers with giant magnetic resistance.A variety of different UHV-based techniques (AES/XPS and synchrotron facilities) have been used to prove the above theoretical findings in different systems (e.g. Ni/Cu, Ni/Au, Si/Ge, Co/Si).