Silicon nanowires: Diameter dependence of growth rate and delay in growth

We grew Si nanowires by chemical vapor deposition, via the vapor liquid solid growth, using silane as gaseous precursor and gold as catalyst. The results show that the nanowire length depends on their diameter. For nanowires with diameter under 100 nm, the length increases when diameter increases, because of an increase in the growth velocity. For the thicker diameter (d>100 nm), length decreases when diameter increases, due to an apparent incubation time which is all the higher as the diameter is high. We propose a semiempirical model combining Gibbs-Thomson effect and incubation time, which shows good agreement with the experimental data.