Photoluminescence Studies on Very High-Density Two-DimensonalElectron Gases in Pseudomorphic Modulation-Doped Quantum Wells

We present photoluminescence studies on highly dense two-dimensional electron gases in selectively Si δ-doped GaAs/ln_0.18Ga_0.82 As/Al_0.25 Ga_0.75,As quantum wells (N_s = 4.24 x 10¹² cm^-2). Five well-resolved photoluminescence lines centered at 1.4194, 1.4506, 1.4609, 1.4695 and 1.4808eV were observed, which are attributed to the subband exciton emission. The subband separations clearly exhibit the feature of a typical quantum well with triangle and square potential. These very intensive and sharp luminescence peaks with linewidths of 2.2 to 3.5meV indicate the high quality of the structures. Their dependence on the excitation intensity and temperatures are also discussed.