Photoluminescence studies on very high-density quasi-two-dimensional electron gases in pseudomorphic modulation-doped quantum wells

Photoluminescence studies on highly dense quasi‐two‐dimensional electron gases (2DEGs) in selectively Si δ‐doped GaAs/In0.15Ga0.85As/Al0.25Ga0.75As quantum wells (Ns=4.24×1012 cm−2) are presented. Five well‐resolved photoluminescence lines centered at 1.4194, 1.4506, 1.4609, 1.4695, and 1.4808 eV were observed, which are attributed to the recombinations of 2DEG with holes in the n=1 heavy‐hole sub‐band. The sub‐band separations clearly exhibit the feature of the investigated quantum wells structure. The linewidths of these peaks are in the range of 2.2–3.4 meV, indicating the high quality of the structures. The reason for discrepancy between the calculated and observed linewidth is given. Their dependence on the excitation intensity and temperatures are also discussed.