Berlin 2005 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 50: Nanodr
ähte
HL 50.8: Vortrag
Dienstag, 8. März 2005, 12:30–12:45, TU P-N201
Theoretical study of reaction pathways of the formation and decay of 1D nanostructures — •Karl-Heinz Heinig und Lars Röntzsch — Forschungszentrum Rossendorf, Dresden
Nanowires have fascinating properties. Also the kind and strength of driving forces for their structural evolution differ from macroscopic systems, thus opening new routes for their synthesis. And, with respect to interface energy, nanowires are unstable, during their decay new self-organized 1D structures evolve.
This presentation summarizes reaction pathways of the formation and decay of 1D nanostructures predicted by atomistic computer simulations. It will be shown that nanowire synthesis by phase separation from supersaturated 1D traces relies on different time scales of different processes involved: (i) phase separation is faster than long-range diffusion, thus, initially small nanodroplets form. (ii) Short-range diffusion is fast, thus, lateron the minority phase is concentrated/unified to a wire (ripening, coalescence). (iii) On a long time scale, the wire lowers its surface energy by peristaltic undulations and decays finally into large droplets (Rayleigh instability). Each process can be governed in order to fabricated functional structures. For instance, crosspoints of nanowires accelerates the wire instability locally, which leads to a nanodot separated by nm gaps from the four nanowires. Such a Si structure embedded in SiO2 might operate as a room temperature single electron transistor.