PHOTOLUMINESCENCE INTENSITY AND MULTIPLE PHONON RAMAN-SCATTERING IN QUANTUM DOTS - EVIDENCE OF THE BOTTLENECK EFFECT

We report a systematic study of photoluminescence efficiency in dry et ched quantum well dots. Luminescence degradation is observed on decrea sing the quantum dot lateral size. Furthermore, luminescence quenching is more pronounced in quantum dots with a thicker quantum well than t hose with a thinner one. This effect is attributed to the reduced carr ier relaxation in 0D system. Resonant Raman scattering and ''hot'' exc iton luminescence have also been observed in dry etched GaAs/AlGaAs qu antum dots in which quantum confinement effects are found with decreas ing dot sizes. Up to 4th-order multiphonon processes have been observe d through photoluminescence and photoluminescence excitation in quantu m dots. These results are direct evidence of the bottleneck effect. La teral patterning of quantum wells strongly localises excitons in three -dimensional quantum confinement regime (0D system). The observation o f resonant Raman scattering and hot exciton luminescence up to high te mperature demonstrates the high stability of localised excitons.