Electronic states in diffused quantum wells

Abstract

In the present study we calculate the energy values and the spatial distributions of the bound electronic states in some diffused quantum wells. The calculations are performed within the virtual crystal approximation, sp3s* spin dependent empirical tight-binding model and the surface Green function matching method. A good agreement is found between our results and experimental data obtained for AlGaAs/GaAs quantum wells with thermally induced changes in the profile at the interfaces. Our calculations show that for diffusion lengths LD=0−20 Å the optical transition between the ground electron and hole states is less sensitive to the LD changes than the optical transitions between the excited electron and hole states. For diffusion lengths LD=20−100 Å, the optical transition between the second excited states is not sensitive to the diffusion length, but the other optical transitions display large “blue shifts” as LD increases. The observed dependence is explained in terms of the bound states spatial distributions.