For the thermal quenching of quantum well (QW) photoluminescence (PL) controversal de-activation energies have been reported. Values range from the total exciton (or electron-hole) binding energy Ex to half of Ex or to the binding energy of the shallower bound particle. We resolve this controversy by performing steady-state measurements both under high and extremely low (Iex≈l μW/mm2) excitation conditions on a series of multiple QW structures of the material systems InxGa1-xAs/GaAs and GaAs/AlyGa1-yAs. For high and low excitation, we find that the final de-activation step is associated with Ex. In an intermediate temperature range, the first decade of PL quenching is governed by a de-activation energy close to the binding energy of the shallower bound particle.
Also performed were temperature dependent photoluminescence excitation (PLE) measurements under high injection in InxGa1-xAs/GaAs double QWs with additional AlyGa1-yAs cladding barriers. Vertical transport between the QWs is observed and the underlying de-activation energies are found to be equal to the total exciton binding energies Ex We discuss our findings in the frame of a simple model for the thermalization of electrons and holes.