  Selective area growth (SAG) of semiconductors is a scalable method for
fabricating gate-controlled quantum platforms. This letter reports on the
adatom diffusion, incorporation, and desorption mechanisms that govern the
growth rates of SAG nanowire (NW) arrays. We propose a model for the crystal
growth rates that considers two parameter groups: the crystal growth control
parameters and the design parameters. Using GaAs and InGaAs SAG NWs as platform
we show how the design parameters such as NW pitch, width, and orientation have
an impact on the growth rates. We demonstrate that by varying the control
parameters (i.e. substrate temperature and beam fluxes) source, balance, and
sink growth modes may exist in the SAG selectivity window. Using this model, we
show that inhomogeneous growth rates can be compensated by tuning the design
parameters.
