Hot-exciton relaxation in (In,Ga)As-AlAs strained quantum wells

(In,Ga)As-AlAs strained-layer quantum-well samples have been grown by molecular-beam epitaxy and studied with use of photoluminescence and photoluminescence-excitation spectroscopy. The well width, barrier width, and indium fraction were chosen to illustrate the change in the band alignment from type I to type II. For an indium fraction of 0.04, we find the crossover from type I to type II to occur at an (In,Ga)As well width of {~}30 {}. In those samples that have a type-I alignment we see clear evidence in the excitation spectrum for features related to hot-exciton relaxation. Their appearance is correlated with an inferred increase in the number of nonradiative recombination centers introduced by depositing the layers at a low substrate temperature of 530 ^∘{}C.