Messily grown nanowires: Simulation, geometrical characteristics and microstructural dynamics

The geometrical characteristics and microstructural dynamics of messily grown nanowires were investigated by the means of Monte Carlo simulations and fractal geometry. Firstly, the simulated morphologies of messily grown nanowires are generated by Monte Carlo simulations. The fractal dimensions of simulated morphologies were calculated and found to be significantly determined by the quantity, radius and length of the simulated nanowires. Then, factors called theoretical and actual area ratio were proposed to describe the structure of simulated morphologies. Based on the new factors and the simulation results, a series of empirical models describing the actual area ratio varying with nanowire growth time were proposed. Finally, the proposed model was used on the time varying morphologies of messily grown Si nanowires synthesized by experiments. Predictions provided by the model show good agreement with experiments. The best fits appear when the nanowire quantity shows the saturated growth mode. Further simulations also show that the growth dynamic of actual area ratio shares the S type growth and is influenced by the growth modes of nanowire length, quantity or radius.