ELECTRONIC STATES IN DIFFUSED QUANTUM-WELLS

In the present study we calculate the energy values and the spatial di stributions of the bound electronic states in some diffused quantum we lls. The calculations are performed within the virtual crystal approxi mation, sp(3)s spin dependent empirical tight-binding model and the s urface Green function matching method. A good agreement is found betwe en 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 L-D = 0-20 Angstrom the optical transition between the ground electron and hole states is less sensitive to the L-D changes than the optical transitions between the excited eb:tron and hole states. For diffusion lengths L-D = 20-1 00 Angstrom, the optical transition between the second excited states is not sensitive to the diffusion length, but the other optical transi tions display large ''blue shifts'' as L-D increases. The observed dep endence is explained in terms of the bound states spatial distribution s. (C) 1997 American Institute of Physics.