Ultrafast carrier dynamics in size-controlled, self-assembled, InGaAs/GaAs quantum dots

Summary form only given. We describe measurements of carrier energy relaxation in a set of InGaAs/GaAs with various sizes resulting in energy level spacing (/spl Delta/E) ranging from /spl sim/65 meV to /spl sim/95 meV. We demonstrate that in all cases the relaxation is extremely rapid but slows with increasing /spl Delta/E. This behavior is highly suggestive of relaxation through phonon emission. Optical phonon energies of 29.6, 32.6, and 37.6 meV have been reported previously in InAs/GaAs self-assembled QDs. Thus, depending on the relative distribution of energy among the electron and hole levels, relaxation through single phonon emission (for both electrons and holes) is possible for /spl Delta/E /spl sim/65 meV, but multiphonon emission is required for /spl Delta/E /spl sim/95 meV. Phonon participation in the relaxation is also suggested by the temperature dependence of the measured relaxation rates and by measurements of the excited-state dynamics.