Observation of Localized Above-Barrier Excitons in Type-I Superlattices

This Letter reports experimental evidence for the existence of localized excitons at above-barrier energies in type-I superlattices. By using magnetoabsorption measurement on a series of ${\mathrm{Zn}}_{0.86}$ ${\mathrm{Cd}}_{0.14}$Se/${\mathrm{Zn}}_{0.75}$ ${\mathrm{Mn}}_{0.25}$Se superlattices, where the subbands localized in nonmagnetic and magnetic layers undergo drastically different Zeeman splittings, we show conclusively that above-barrier excitons are localized in the barrier rather than in the well regions.