Photoluminescence of Highly Excited GaAs/AlxGa1-xAs Quantum Wells

We report a comparative study of the luminescence properties of two- and three - dimensional electron-hole plasma obtained by simultaneous photogeneration in GaAs/AlxGa1-xAs quantum wells and in the GaAs buffer layer. The dependence of the luminescence on the optical excitation rate and on the temperature are studied by means of a lineshape analysis. The plasma luminescence in the quantum well results from the superposition of an excitonic emission, which does not shift with the excitation intensity, and of a free - carrier emission which shows a red shift with increasing excitation intensity. The observed shrinkage of the gap in the quantum well is in agreement with theoretical calculations