CARRIER CAPTURE AND RELAXATION PROCESSES IN INAS GAAS QUANTUM DOTS/

Excited states and energy relaxation process are studied for self-orga nized InAs/GaAs quantum dots (QDs). Depending on the sample, excited s tate transitions or multi-LO-phonon resonances are found in photolumin escence excitation (PLE) spectra, revealing the size-dependent excited state splitting or the carrier relaxation mechanism, respectively. Ti me-resolved photoluminescence (PL) results indicate sample-dependent n on-radiative recombination, leading to a model for the observed PLE be havior, analogous to hot carrier relaxation in higher dimensional syst ems. Carrier relaxation in the self-organized InAs/GaAs QDs proceeds b y multi-10-phonon scattering on a 40 ps time scale, much shorter than radiative (> 500 ps) and non-radiative (> 100 ps) recombination times, accounting for the absence of a phonon bottleneck effect in PL spectr a.