Résumé:

We present the first experimental study of the exciton spin relaxation dynamics in InGaN/GaN multiple quantum well structures after quasi-resonant picosecond excitation with linearly polarized light. Whereas short spin-relaxation times are generally expected in GaN-based bulk structures, for multiple quantum well structures we found long spin-relaxation times, around 100 ps, when the indium content was not too high. Our results suggest that the energy relaxation toward the radiative state can preserve the linear polarization of the exciton.