Midinfrared unipolar photoluminescence in InAs/GaAs self-assembled quantum dots

We have investigated the midinfrared unipolar photoluminescence in InAs/GaAs self-assembled quantum dots. Resonant emissions between confined levels are clearly observed at low temperature at around 10 μm wavelength. The unipolar emissions are polarized either in the layer plane or along the z growth axis of the quantum dots. The emissions are associated with hole transitions that involve the ground and the excited hole states. The quenching due to Pauli blocking of the unipolar emission lines involving the hole ground state is observed when this state is completely filled. An intradot nonradiative lifetime $\tau \approx 25$ ps is deduced for the different levels from the midinfrared emitted power.