Kinetics of free and bound excitons in GaAs/AlGaAs double heterostructures

The kinetics of free- and bound-exciton formation and decay in GaAs/AlGaAs double heterostructures is studied by picosecond luminescence spectroscopy. A delayed onset of the luminescence from the free as well as bound excitons is found at low temperatures (T approximately 10K) reflecting the thermalisation, relaxation, and trapping processes. The decay of the free-exciton luminescence is determined by trapping into bound excitons at low temperatures. At higher temperatures, where bound excitons are unstable, the free-exciton luminescence decays appreciably more slowly.