Peculiarities of photoluminescence in pseudomorphic modulation-doped ${\mathrm{Al}}_{0.2}{\mathrm{Ga}}_{0.8}{\mathrm{A}\mathrm{s}/\mathrm{I}\mathrm{n}}_{0.1}{\mathrm{Ga}}_{0.9}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ quantum wells

Peculiarities of photoluminescence (PL) spectra have been observed in the modulation-doped pseudomorphic strained-layer ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}{\mathrm{A}\mathrm{s}/\mathrm{I}\mathrm{n}}_y{\mathrm{Ga}}_{1-y}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ heterostructures $(x=0.2,\hspace{0.5em}\hspace{0.5em}y=0.1).\mathrm{}$ In particular, the character of PL spectra dramatically depends on the quantum well width, changing from excitoniclike in wider wells to (two-dimensional) electron–heavy-hole band transitions in narrower quantum wells. Low-energy structure in the photoluminescence is weakly observed in the ${\mathrm{In}}_y{\mathrm{Ga}}_{1-y}\mathrm{As}$ quantum well and interpreted in terms of a two-dimensional electron gas hole bound to acceptor transitions.