Exciton-spin relaxation in weakly confining quantum dots due to spin–orbit interaction

In weakly confining quantum structures such as interfacial islands or quantum disks the exciton-spin relaxation is governed by two independent electron and hole spin flip processes between the optically active and dark states. A microscopic theory for these transitions is presented which is based on second order spin-orbit and corrier-phonon interaction processes. We found that the sequential relaxation between bright and -dark states leads to much faster exciton-spin relaxation than for strongly confining ("small") quantum dots where the dominant process stems from electron-hole exchange interaction plus hole deformation potential coupling. In addition, the fast exciton spin relaxation implies that the (exciton-bound) electron spin flip time is also much shorter than for a single electron.