Theoretische Untersuchungen zu Wachstum, Stabilität und Funktionalität von Nanodrähten

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Nanowires have fascinating optical, electrical and magnetic properties which can differ significantly from macroscopic systems. Also the kind and strength of driving forces for their structural evolution can be completely different, thus opening new routes for their synthesis. Additionally, nanowires are thermodynamically instable and form frequently self-organized nanostructures during their decay. This project aims at the fundamental understanding of (i) the synthesis of nanowires, (ii) their shape evolution during treatments, and (iii) the fabrication of functional structures. Systematic theoretical studies will be performed to understand under which conditions 1D precursor structures (e.g. implantation profiles; stripes of deposited material) evolve towards nanowires. Concerning the shape evolution the aim is twofold: On the one hand, it will be studied how nanowires withstand thermal treatments without decay (Rayleigh instability). On the other hand, we search for a control of the pearling instability to produce functional structures like quantum dot chains. In this connection, for monocrystalline wires like CoSi2 in Si the impact of crystal orientation on nanowire stabilization/destabilization is an important issue to be studied for the first time by atomistic simulations. For specific experiments (ion-track-wires at GSI, FIB-wires at FZR) predictions of atomistic simulations will serve as guidelines for nanowire synthesis and modifications. The simulations will be performed with a well-established unique 3D kinetic lattice Monte Carlo program package.