Effect of well width variation on type-I/type-II photoluminescence in GaAs/AlAs single quantum wells

We have investigated type-I/type-II transitions in MBE-grown 20, 35, and 50 Å GaAs/AlAs single quantum wells using photoluminescence (PL) spectroscopy. The 20 and 50 Å wells show a type-I peak, while the 35 Å well has PL peaks corresponding to both type-I and type-II transitions. Peak assignment for the 35 Å-well sample is based upon excitation intensity dependent measurements, and the strength of the type-II transition in this sample is attributed to Γ-X mixing. Superperiodicity has been put forth as a possible explanation for Γ-X mixing effects in superlattice structures, but the observation of this phenomenon in a single quantum well structure suggests that superperiodicity is not required for Γ-X mixing to occur. © 1997 Academic Press Limited