RADIATIVE RECOMBINATION PROCESSES AND FERMI EDGE SINGULARITY IN MODULATION DOPED N-TYPE GAINAS ALINAS MULTIPLE QUANTUM-WELLS

We report the results of a detailed spectroscopic investigation of the optical properties of modulation doped GaInAs/AlInAs multiple quantum wells. The radiative recombination processes involve electronic states from the confined free carrier plasma and the photogenerated holes at k=0. The absorption edge is blue-shifted to the Fermi level of the electron plasma. A simple model for the calculation of the emission line-shape reveals information on the energy parameters of the optical transitions and on the band gap renormalization. The occurrence of a Fermi edge singularity in the photoluminscence excitation spectra due to the enhanced electronic correlation in the two-dimensional plasma is discussed. Finally, the effects of the transition from one component (electron) plasma to two component (electron-hole) plasma are studied under intense photoexcitation, showing optical amplification of the free carrier luminescence. © 1990.