Spin-polarized excitons in pseudomorphic, strained In(0.16)Ga(0.84)As/Al(0.29)Ga(0.71)As quantum wells on a GaAs substrate

Circularly polarized excitation light from a tunable Ti-doped sapphire laser has been used to produce spin-polarized excitons in strained, pseudomorphic Insub0.16Gasub0.84As/Alsub0.29Gasub0.71As quantum wells (QW's) grown on GaAs substrates. By analyzing the degree of circular polarization of the exciton luminescence and by studying the depolarization effect of a transverse magnetic field, the optical lifetime and the spinrelaxation time of excited carriers can be determined in relatively wide wells. We further show that circular excitation offers a relatively simple means to discriminate unambiguously between light- and heavy-hole excitons. We have thus made measurements that yield optically determined band offsets for the QW system under investigation.