Propagation of amorphous oxide nanowires via the VLS mechanism: growth kinetics

This work reports the growth kinetics of amorphous nanowires (NWs) developed by Vapour-liquid-solid (VLS) mechanism. The model presented here incorporates all atomistic processes contributing to the growth of amorphous oxide NWs having diameters in 5-100 nm range. The steady state growth condition has been described by balancing the key atomistic process steps. It is found that the 2D nano-catalyst liquid and NWs solid (L-S) interface play central role in the kinetic analysis. The balance between 2D Si layer crystallization and oxidation rate is quantitatively examined and compared with experimental values. The atomistic process dependencies of NWs growth rate, supersaturation (C/C0), desolvation energy (QD) barrier and NWs diameter etc. have been analyzed in detail. The model successfully predicts the reported NWs growth rate in range of 1-10 µm/s. A novel seed/catalyst metal-based synthesis strategy for the preparation of amorphous silica NWs is reported. Nickel thin film over Si is used as a seed metal for the Au assisted VLS growth of silica NWs. The experimental results provide evidence that the creation of SiO under given conditions and followed by Si injection in the Au-Si nano-catalyst solution. The usage of seed metal was observed to reduce the growth temperature compared to the methods reported in literature and obtain similar growth rates. The technique presented here holds promise for the synthesis of sub-100 nm diameter NWs