D- ground state binding energy in graded GaAs-(Ga,Al)As quantum well

The energy levers of the D-0 and D- confined in the graded GaAs/Ga1-xAlxAs quantum well with smooth variation of Al concentration c(z) in the well int erface regions, are calculated taking into account a dependence on c(z) of the confining potential, effective mass and dielectric constant. A consider able increase of the binding energies both for DO and for D- produced by va riation of material parameters is found for small well widths (L less than or equal to 100 Angstrom) whereas the effect of the soft-edge-barrier profi le is significant only for larger well widths (L less than or equal to 100 Angstrom).