Vapour-liquid-solid (VLS) techniques are popular routes for the scalable synthesis
of semiconductor nanowires. In this article, in-situ electron microscopy is used to
correlate the equilibrium content of ternary (Au 0.75 Ag 0.25 –Ge and Au 0.65 Ag 0.35 –Ge) metastable alloys with the kinetics, thermodynamics and diameter of Ge nanowires grown via a VLS mechanism. The shape and geometry of the heterogeneous interfaces between the liquid eutectic and solid Ge nanowires varies as a function of nanowire
diameter and eutectic alloy composition. The behaviour of the faceted heterogeneous liquid–solid interface correlates with the growth kinetics of the nanowires, where the main growth facet at the solid nanowire–liquid catalyst drop contact line lengthens for faster nanowire growth kinetics. Pronounced diameter dependent growth kinetics, as inferred from liquid–solid interfacial behaviour, is apparent for the synthesised nanowires. Direct in-situ microscopy observations facilitates the comparison between
the nanowire growth behaviour from ternary (Au–Ag–Ge) and binary (Au–Ge)
eutectic systems.