GIANT OSCILLATOR-STRENGTHS OF IONIZED DONOR BOUND EXCITONS IN SEMICONDUCTOR QUANTUM CRYSTALLITES

We study the influence of the quantum confinement on the oscillator st rength for the dipole absorption of an exciton bound to an ionized hyd rogenic donor impurity placed at the centre of a semiconductor spheric al quantum well as a function of the sphere radius R and of the mass r atio sigma of the electron and hole using our previously obtained enve lope wave function. We assume infinite conduction and valance band off sets within the envelope function approximation. We show that the quan tum confinement gives rise to a ''giant'' oscillator strength per impu rity, contrary to what happens in bulk materials where a ''giant'' osc illator strength results only in the case of a high doping. Copyright (C) Elsevier Science Ltd