SCREENING EFFECT ON THE BINDING-ENERGIES OF SHALLOW DONORS, ACCEPTORSAND EXCITONS IN FINITE-BARRIER QUANTUM-WELLS

The conduction and valence subband energies in the presence of an elec tric field are calculated using the fifth-order Runge-Kutta method. Th e binding energies of shallow donors, accepters and excitons in finite -barrier GaAs/Ga1-xAlx As quantum wells are then obtained variationall y in the presence of a magnetic field. The effects of a spatially depe ndent screening function epsilon(r) On the calculation of binding ener gies are specifically investigated. The use of epsilon(r) in compariso n with the use of a constant epsilon(0) increases the binding energy o f accepters as the increase on shallow donors and excitons is quite sm all. (C) 1998 Academic Press Limited.