Bound-exciton states of multiple-quantum-well structures in external fields

The bound states of excitons of all quantum numbers are calculated for different lattice sizes of the multiple-quantum-well structure GaAs/${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Al}}_{\mathrm{x}}$As in an external field. The Coulomb interactions in the same well and different wells are included in the Kronig-Penney model. The results show that the single-well model calculation is not accurate as the size becomes smaller. A detailed comparison of earlier works is given for the field dependence of the binding energy of various states.