  The fabrication of more and more miniaturized electronic and photonic devices
relies on new, ingenious methods for the fabrication of spatially controlled
nanostructures. Examples are electronic devices based on semiconducting
nanowires and photonic devices based on chains of metallic nanoclusters that
guide light by coupled surface plasmons. In this contribution a
template-directed ion beam synthesis of nanowires and regular nanocluster
chains will be presented. As templates, V-grooves etched in (001)Si and
subsequently oxidized are used. High fluence Ge+ implantation is carried out
into the SiO2 layer at 70 keV. Thereby, the implanted Ge enriches themselves in
the V-groove bottom to a critical amount, which may result in nanowire
formation by nucleation, growth and coalescence during subsequent thermal
treatment. TEM investigations indicate the formation of a nanowire buried in
the SiO2 at the V-groove bottom.
  Kinetic lattice Monte Carlo simulations of the nanowire formation process
were performed in order to understand the phase separation mechanism and
results are compared to TEM images. Furthermore, it is shown that even ideal
nanowires show a instability and form during long-lasting annealing
equal-spaced and equal-sized nanoclusters ("nanocluster chains") by
self-organization.
