Nanosecond scale carrier dynamics of self-assembled InAs/AlAs quantum dots studied by time-resolved photoluminescence

Photo-excited carrier dynamics in the self-assembled InAs/AlAs quantum dot system are studied by time-resolved photoluminescence within the first two nanoseconds. Several unexpected energy shifts are observed, i.e., an initial redshift of ground state photoluminescence which is followed by a blueshift after ∼1 ns, and a continuous blueshift of the first excited states emission. Moreover, steady-state photoluminescence shows a continuous redshift of the ground state peak with increasing excitation intensity. Our data support the idea that for the carrier dynamics in the InAs/AlAs quantum dot system the existence of AlAs X-states, tunneling and scattering play an important role in the lateral carrier transfer in such a dense quantum dot system.