Strong interaction of Fermi-edge singularity and exciton related to N=2 subband in a modulation-doped AlxGa1-xAs/InyGa1-xAs/GaAs quantum well

We have investigated photoluminescence and photoluminescence excitation spectra from a one-side modulation-doped AlxGa1-xAs/In(y)Gal(1-y)As/GaAs single quantum well under a near-resonance condition between the N=2 subband and the Fermi level of the two-dimensional electron gas. Under such conditions, strong interaction between electrons at the Fermi edge and the exciton related to the N=2 subband can be observed. The Fermi-edge singularity (FES) is enhanced first, and then the FES and the N=2 exciton repel each other. Finally, the N=2 exciton is screened by excess electrons with increased excitation power. With an increase in temperature, the FES rapidly quenches, and the intensity of the N=2 exciton transition increases accompanied by a blueshift of its peak position.