We present a theoretical study of excitons in ZnSe-ZnS strained-layer superlattices within an effective-mass approximation. A simple description of excitons in a quantum well is adopted because of a good agreement of the calculated subband energy of the superlattice with that of the quantum well. We demonstrate the exciton effects on the optical gap of ZnSe-ZnS superlattices by a variational method. The calculated optical gap exhibits inverse-square dependence on the well width, which is consistent with recent experimental data.

• Received 14 November 1988

DOI:https://doi.org/10.1103/PhysRevB.39.8743