Strictly resonant excitation of carriers in self-assembled IuAs/GaAs quantum dots

We investigate the carrier dynamics in self-assembled InAs/GaAs quantum dots under strictly resonant excitation of the ground state. The spectral selectivity of the resonant excitation allows to study the physical properties of a class of dots characterized by an energy distribution comparable to the excitation laser spectrum. We detect no Stokes shift of the photoluminescence (PL) line. The PL decay time yields a straightforward determination of the radiative recombination time, tau(rad) similar to 650 ps. Finally we measure a very short rise time (< 1 ps) of the dots ground state PL after a resonant excitation of the first excited state, which indicates an extremely fast intra-dot energy relaxation.