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 carrier–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. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)