LOCALIZED EXCITONIC TRANSITIONS IN A ZNSE-ZN0.75CD0.25SE DOUBLE-SUPERLATTICE GROWN BY MOLECULAR-BEAM EPITAXY

A group of well-defined exciton transitions from the localized states were observed in ZnSe-Zn0.75Cd0.25Se double-superlattice structure. Th e photoluminescence and photoreflectance have been employed to study t he subband transitions at low temperatures. At 1.4 K, except the two g round states and two higher subbands of n=1 light-hole and n=2 heavy-h ole excitonic transitions, other four peaks (A, B, C, and D) also were observed in wider-well superlattice, Those peaks were attributed to t he excitonic transitions from n=2 heavy-hole subband due to the fluctu ation of well-barrier interface. Another localized excitonic transitio n from narrower-well superlattice appeared as increasing the modulated intensity in photoreflectance spectra. (C) 1998 American Institute of Physics. [S0003-6951(98)02614-X].