Visualizing the Mechanism Switching in High-Temperature Au-Catalyzed InAs Nanowire Growth

We use environmentaltransmission electron microscopyto observe in situ the switch from an axial vapor-liquid-solid(VLS) growth mechanism in Au-catalyzed InAs nanowires toward a radialvapor-solid (VS) one, dominated by layers nucleating at thetriple-phase line. At elevated temperatures, in addition to high V/IIIratios, the affinity for In in the Au catalyst will be greater thanthat of In in InAs, which in turn reduces the driving force and probabilityfor nucleation at the liquid-solid interface. Consequently,with increased temperature, the catalyst particle stops acting asa sink for incoming material and the decomposition of precursors awayfrom the catalyst increases, making radial vapor-solid growththe dominating growth mechanism. It is further observed that the growthproceeds through multistep propagation rather than a layer-by-layerpropagation under these conditions. Using in situ transmission electron microscopywe directly observe the switching from axial to radial growth in Au-catalyzedInAs nanowires and elucidate the mechanisms at play to limit vapor-liquid-solidgrowth.