Dynamics of excitons and biexcitons in one single quantum dot

The dynamics of quasi zero-dimensional excitons and biexcitons in a single quantum dot has been studied by time-resolved photoluminescence spectroscop y. The monoexponential decay of the biexciton and the plateau-like behaviou r of the exciton transient, are well described by a statistical treatment o f the dynamics, i.e. by taking into accout the discrete number of excitons allowed in the ground state of the quantum dot. Surprisingly, the radiative recombination lifetime of the biexciton is found to be comparable to the e xciton one. Model calculations demonstrate that this remarkable result is a consequence of the spin structure of the recombining particles and the spa tial separation of the holes in a quantum dot of finite extension.