Exciton dynamics and spin-flip in tensile strained quantum wells

We have studied the exciton dynamics and spin-flip processes in tensile strained GaAs1 − yPy/Ga0.65Al0.35As quantum wells as a function of phosphorous composition and well width. The strain introduced by the presence of phosphorous modifies the valence band structure. This strongly affects the characteristic times of exciton formation and polarization decay. However, the recombination time is essentially determined by the light- or heavy-character of the excitonic ground state.