Intersublevel dynamics of semiconductor nanostructures

In this contribution we present results for mid-infrared electroluminescence of InAs quantum dots (QDs) within a cascaded GaAs/AlAs structure. Based on ultrafast interband pump intraband probe spectroscopy we measure electron capture and relaxation times into the discrete dot energy levels within a few picoseconds and discuss possible relaxation mechanisms as well as their impact on a QD quantum cascade laser. Further we present an approach to rule out dot ensemble related effects within the time resolved measurements by combining interband microluminescence measurements with the intersublevel pump and probe spectroscopy. We show preliminary results for mid infrared induced direct electron transfer between electron intersublevels, which is monitored by changes in the interband luminescence of a single QD.