PHOTOLUMINESCENCE AND PHOTOLUMINESCENCE EXCITATION STUDIES ON GAAS AL0.25GA0.75AS ASYMMETRIC COUPLED DOUBLE-QUANTUM-WELL/

Photoluminescence (PL) and PL excitation (PLE) experiments on a GaAs/A l0.25Ga0.75As asymmetric coupled double quantum well are reported. In PLE, the seven peaks, four related to the heavy-hole coupled and the r est to the light-hole coupled excitonic states, are observed. The posi tions of seven peaks observed in PLE are in good agreement with the ca lculated results of multi-band envelope function approximation using t he transfer matrix method. The result of the temperature-dependent PL above 100 K shows that, even though the wavefunctions are localized in different wells separated by 8 monolayer barrier, the heavy-hole coup led excitons in the two lowest levels are in thermal equilibrium. The observed activation energy is equal to the difference between the two levels.