  The influence of the oxide in Ga-assisted growth of GaAs nanowires on Si
substrates is investigated. Three different types of oxides with different
structure and chemistry are considered. We observe that the critical oxide
thicknesses needed for achieving nanowire growth depends on the nature of oxide
and how it is processed. Additionally, we find that different growth conditions
such as temperature and Ga rate are needed for successful nanowire growth on
different oxides. We generalize the results in terms of the characteristics of
the oxides such as surface roughness, stoichiometry and thickness. These
results constitute a step further towards the integration of GaAs technology on
the Si platform.
