SPECTROSCOPIC INVESTIGATIONS OF PHOTOINDUCED CHANGES OF THE SPATIAL-DISTRIBUTION OF CHARGE-CARRIERS IN MODULATION-DOPED QUANTUM-WELL STRUCTURES

We investigated the photoinduced changes of the spatial distribution o f the free holes in p-type modulation-doped GaAs/AlxGa1-xAs heterostru ctures by measuring the energy of the quantum-well luminescence, which is conditioned by the many-particle effect of band-gap renormalizatio n and the excitonic interactions between the electrons and holes. A co nventional chopper technique with millisecond time resolution permitte d us to study the dynamics of the hole density variations in the quant um wells. The strength of excitonic effects on the luminescence signal s could be estimated by application of a magnetic field oriented paral lel to the growth direction of the samples.