Excitonic properties in ZnSe/${\mathrm{ZnS}}_{\mathit{x}}$${\mathrm{Se}}_{1\mathrm{-}\mathit{x}}$ strained-layer superlattices by one- and two-photon spectroscopy

Excitonic properties of ZnSe/${\mathrm{ZnS}}_{0.18}$ ${\mathrm{Se}}_{0.82}$ strained-layer superlattices have been investigated by means of one- and two-photon absorption spectroscopy. Heavy- and light-hole excitons associated with n=1,2 subbands have been observed and experimental evidence of 2s states in these systems has been obtained. Experimental exciton transition energies have been found to be in good agreement with theoretical predictions considering strain and confinement effects. The different selection rules governing linear and nonlinear absorption processes have been verified and some violations of them have been observed. Furthermore, exciton binding energy has been measured and compared with the result of a recent theoretical model.