Abstract
This work reports the growth kinetics of amorphous nanowires (NWs) developed by the vapour–liquid–solid (VLS) mechanism. The model presented here incorporates all atomistic processes contributing to the growth of amorphous oxide NWs having diameters in the 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 NW solid (L–S) interface plays a central role in the kinetic analysis. The balance between the 2D Si layer crystallization and oxidation rate is quantitatively examined and compared with experimental values. The atomistic process dependencies of the NW growth rate, supersaturation (C/C0), desolvation energy (QD) barrier and NW diameter have been analyzed in detail. The model successfully predicts the reported NW growth rate to be in the range of 1–10 μm s−1. A novel seed/catalyst metal-based synthesis strategy for the preparation of amorphous silica NWs is reported. A nickel thin film on Si is used as a seed metal for the Au assisted VLS growth of silica NWs. The experimental results provide evidence of the creation of SiO under the given conditions 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 the literature and obtain similar growth rates. The technique presented here holds promise for the synthesis of sub-100 nm diameter NWs.
Highlights
IntroductionInorganic nanowires (NWs) with diameters < 100 nm are widely studied as they hold great potential for nanoelectronics,[1,2] sensors,[3,4] exible electronics,[5,6,7] energy generation,[8] energy storage,[9,10] etc., owing to their interesting physical and chemical properties.[11,12,13,14,15,16] For example, the rapid change in the resistance of ZnO NWs with exposure to UV light makes them ideal for wearable dosimeters.[17] Likewise, with photoluminescence (PL) bands in the range of 1.9–4.3 eV, the NWs of amorphous silica exhibit exciting optical properties, which could address the challenge related to blue light emission.[18,19] Such properties are o en exploited to develop novel sensors, IR detectors, efficient waveguides, etc
Synthesis of amorphous silica and germanium oxide NWs in the diameter range of 10–100 nm has been studied experimentally, and a phenomenological kinetic model has been developed for their synthesis via the vapour–liquid– solid (VLS) mechanism
The growth rate (0.5–1 mm sÀ1) of silica NWs was estimated for a diameter range of 10–100 nm and temperatures of 900 C and 1000 C
Summary
Inorganic nanowires (NWs) with diameters < 100 nm are widely studied as they hold great potential for nanoelectronics,[1,2] sensors,[3,4] exible electronics,[5,6,7] energy generation,[8] energy storage,[9,10] etc., owing to their interesting physical and chemical properties.[11,12,13,14,15,16] For example, the rapid change in the resistance of ZnO NWs with exposure to UV light makes them ideal for wearable dosimeters.[17] Likewise, with photoluminescence (PL) bands in the range of 1.9–4.3 eV, the NWs of amorphous silica exhibit exciting optical properties, which could address the challenge related to blue light emission.[18,19] Such properties are o en exploited to develop novel sensors, IR detectors, efficient waveguides, etc To this end, the NWs require laborious tailoring of dimensions, growth processes, site-speci c synthesis, etc. The analogous case of amorphous GeOx nanowire growth is considered (Fig. S1†)
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