  A model for realistic InAs quantum dot composition profile is proposed and
analyzed, consisting of a double region scheme with an In-rich internal core
and an In-poor external shell, in order to mimic the atomic scale phenomena
such as In-Ga intermixing and In segregation during the growth and overgrowth
with GaAs. The parameters of the proposed model are derived by reproducing the
experimentally measured polarization data. Further understanding is developed
by analyzing the strain fields which suggests that the two-composition model
indeed results in lower strain energies than the commonly applied uniform
composition model.
