Self-Organization of Nanostructures With Ion Beams

Self-organized nanostructures produced by far-from-equilibrium processing of semiconductor materials with ion beams can be applied in microelectronics (e.g. nanocluster memories), optoelectronics (luminescence from Si nanocrystals) and photonics (plasmonic devices using Au nanoclusters). Our recent experimental, theoretical and computer simulation work, which aimed at optimization and improved fundamental understanding of these processes, will be reviewed.
Two different regimes of self-organization will be distinguished: (i) Relaxation regime: Ion implantation of impurity atoms may produce extremely supersaturated solid solutions. During subsequent annealing this far-from-equilibrium state relaxes towards equilibrium by phase separation (nucleation, growth) and minimization of interface energy (Ostwald ripening, coalescence). Self-organization phenomena (e.g. pattern formation during spinodal decomposition, Rayleigh or pearling instability during interface minimization) are observed. (ii) Driven system: Interfaces or compounds like SiO2 can be driven into a steady state far from equilibrium by ion irradiation. The steady state is established by a competition between collisional mixing, diffusion and re-formation of the compound. The application of resulting effects like nanocluster d-layer formation and ''inverse'' Ostwald ripening for devices will be discussed.