Exciton Binding Energy as a Function of Barrier Width in Coupled Quantum Well Structures

Excitons in a coupled quantum well structure (CQWS), consisting of two wells separated by a thick barrier, and in the two boundaries, the potential being infinite, are studied. The binding energy is calculated as a function of the barrier width. It is shown that there is a maximum in the binding energy as a function of the barrier width for an asymmetric CQWS, where as the binding energy is a monotonically decreasing function of the barrier width for a symmetric CQWS. Moreover, the binding energy in an asymmetric CQWS is larger than that in a symmetric CQWS.