  Crystal growth of semiconductor nanowires from a liquid droplet depends on
the stability of this droplet at the liquid-solid interface. By combining
in-situ transmission electron microscopy with theoretical analysis of the
surface energies involved, we show that truncation of the interface can
increase the stability of the droplet, which in turn increases the range of
parameters for which successful nanowire growth is possible. In addition to
determining the limits of nanowire growth, this approach allows us to
experimentally estimate relevant surface energies, such as the GaAs
$\{11\bar{2}0\}$ facet.
