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,whereas 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.