Magnetoluminescence study of many-body effects in a dense electron-hole plasma of strained ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs quantum wells

High-excitation luminescence spectra from a highly homogeneous electron-hole system have been investigated in strained undoped ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs quantum wells (QW’s) with nearly parabolic conduction and valence bands in magnetic fields H≤12 T. The spectra show well pronounced Landau levels which are shifted to lower energy with respect to separately measured magnetoexciton photoexcitation maxima in the empty QW. The shift depends on the carrier density, subband, and Landau-level number. For the dense (${\mathit{n}}_{\mathit{e}\mathrm{-}\mathit{h}}$>${10}^{12}$ ${\mathrm{cm}}^{\mathrm{-}2}$) magnetoplasma with electron temperature of the order of the cyclotron energy, a simple plasma approximation has been found to describe the Landau-level splitting. The band-gap shrinkage and reduced effective-mass ${\mathrm{\mu }}^{\mathrm{-}1}$=${\mathit{m}}_{\mathit{e}}^{\mathrm{-}1}$+${\mathit{m}}_{\mathit{e}}^{\mathrm{-}1}$ renormalization have been carefully measured and compared with those in the unstrained ${\mathrm{In}}_{0.53}$${\mathrm{Ga}}_{0.47}$As/InP QW’s. The difference has been revealed in the reduced effective-mass renormalization connected with renormalization of ${\mathit{m}}_{\mathit{h}}$ due to the change of the light-hole–heavy-hole subband splitting.