THE NATURE OF THE LIGHT-HOLE POTENTIAL PROFILE IN GAAS-INGAAS DOUBLE-QUANTUM-WELL STRUCTURES

We report on a study of the optical properties of a (0 0 1) oriented G aAs-InxGa1-xAs double quantum well structure. In the photoluminescence excitation spectra we observe a transition associated with the quantu m wells at an energy greater than the bulk GaAs exciton. Circular pola risation excitation experiments show that this transition involves a l ight hole state. For confinement effects to increase the energies of t he lowest lying electron and light hole states such that their effecti ve energy gap is larger than the energy of the bulk GaAs exciton, the two carriers cannot be confined in the same layer of material. Thus th e observed electron to light bulk hole transition must be type II in n ature. (C) 1998 Elsevier Science Ltd. All rights reserved.