Slow spin relaxation observed in InGaN/GaN multiple quantum wells

We present the first experimental study of the exciton spin relaxation dyna mics in InGaN/GaN multiple quantum well structures after quasi-resonant pic osecond excitation with linearly polarized light. Whereas short spin-relaxa tion times are generally expected in GaN-based bulk structures, for multipl e quantum well structures we found long spin-relaxation times, around 100 p s, when the indium content was not too high. Our results suggest that the e nergy relaxation toward the radiative state can preserve the linear polariz ation of the exciton.