Many-body effects of a dense two-dimensional electron-hole system in a strained ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum well

The photoluminescence (PL) of a dense quasi-two-dimensional (quasi-2D) electron-hole (e-h) system in a strained ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum well (QW) has been investigated. The QW is part of a selectively doped n-type ${\mathrm{Al}}_{\mathit{y}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{y}}$As/${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs heterostructure and PL measurements are made at excitation intensities up to ${10}^5$ W/${\mathrm{cm}}^2$ in a magnetic field, H≤8.4 T. A strong change in the emission spectra associated with many-body effects is found under conditions when the density of the photoexcited e-h pairs becomes comparable to or higher than that of the initial equilibrium electron concentration due to selective doping (∼${10}^{12}$ ${\mathrm{cm}}^{\mathrm{-}2}$). The damping of one-particle states is found to be a nonlinear function of energy (calculated from the Fermi level) and also depends on the e-h-pair density and the subband number. A common approximation of the rigid band shift in the dense plasma is found to be crude. The change in the effective mass due to the many-body effects, as high as 15%, has been discovered in addition to the band-gap renormalization.