Regular Chains Of Nanocrystals Fabricated from Nanowires – Predictions Based On Kinetic MC Simulations

The fabrication of regularly arranged nanostructures remains a challenge of today's materials research. In this contribution, Kinetic 3D Lattice Monte Carlo (MC) simulations of the shape evolution of single crystalline nanowires by thermally activated interface diffusion will be presented. Interface minimizations leads to the Rayleigh (or pearling) instability; during annealing nanowires develop peristaltic thickness undulations, which finally results in the decay of the wire into a regular chain of nanocrystals (NC’s). For temperatures above the roughening transition it could be shown that size and spacing of the NC’s are in good agreement with results of the classical stability analysis performed by Rayleigh and Mullins. The competition between peristaltic undulations having different wavelength (modes) results in the decay of the wire into equal-spaced NC’s due to self-selection of the fastest growing mode. This mode selection is demonstrated by the Fourier analysis of the MC results. Other than in the analytical stability analysis it has been found that short-wavelength modes develop first, whereas long-wavelength modes are missing initially. Below the roughening transition, the results differ quantitatively. The spacing between NC’s becomes larger and depend on the crystal orientation of the nanowire, which is due to the anisotropy of the interface energy.