We have studied the low temperature photoluminescence and its excitation spectrum, and the LO-phonon resonant Raman scattering profile of a CdTe/ZnTe superlattice with d(CdTe) = 18 Å and d(ZnTe) = 12 Å. The excitation spectrum consists of a high energy part which is attributed to excitons in extended states and a low energy, exponentially decreasing tail, corresponding to localized exciton states. The Raman profile peaks in the transition region between extended and localized states and is due to the "incoming beam" resonance. It can be fitted by a model based on exciton damping which is strongly dependent on exciton energy.
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This study was supported by the United States—Israel Binational Science Foundation (BSF), Jerusalem, Israel. Two of us (E.C. and A.R.) thank the Fund for Promotion of Research at the Technion for its support.