Abstract
By use of femtosecond differential absorption spectroscopy the electron-hole pair relaxation times have been determined in CdSe quantum dots with excited state energies larger than the LO-phonon energy. The fast energy relaxation within 500 fs is independent of the relation between level spacing and LO-phonon energy and shows no bottleneck effect. The population dynamics is mainly governed by the hole relaxation process. With increasing intensity, the formation of two-pair states (biexcitons) of various energies dominates the population dynamics due to the strong influence of Coulomb interaction in quantum dots even in the strong confinement. At high pair densities, the created two-pair states mediate a new relaxation path due to their stimulated decay into one photon and one electron-hole pair with lower energy.
- Received 20 May 1996
DOI:https://doi.org/10.1103/PhysRevB.54.17681
©1996 American Physical Society
