  Semiconductor nanowire networks are essential elements for a variety of
gate-tunable quantum applications. Their relevance, however, depends critically
on the material quality. In this work we study selective area growth (SAG) of
highly lattice-mismatched InAs/In$_x$Ga$_{1-x}$As nanowires on insulating
GaAs(001) substrates and address two key challenges: crystalline quality and
compositional uniformity. We introduce optimization steps and show how misfit
dislocations are guided away from the InAs active region and how Ga-In
intermixing is kinetically limited with growth temperature. The optimization
process leads to a more than twofold increase in electron mobility and shows an
advancement toward realizing high quality gatable quantum wire networks.
