GROUND-STATE ENERGY OF AN EXCITON BOUND TO AN IONIZED DONOR IMPURITY IN SEMICONDUCTOR QUANTUM-WELLS

The ground state energy of an exciton bound to an ionized hydrogenic donor impurity placed at the centre of a semiconductor quantum well with finite barriers is calculated variationally as a function of the well width and the effective mass ratio of the electron and the hole within the envelope function approximation. For the GaAs/Ga1-x Alx As system with x = 0.15 and x = 0.30 the energy is minimum for a well width near 50 Angstroms. This minimum is comprised between the values obtained in the 2D and 3D limits.