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Keywords:

  • quantum dots;
  • excitons;
  • spin relaxation;
  • spin-orbit interaction;
  • phonons

Abstract

In this work, we study the temperature-dependent spin relaxation of exciton-bound carriers in (In,Ga)As/GaAs quantum dots. The exciton population mapped by a time-resolved differential transmission signal reveals a decay on two different time scales, reflecting the fractions of optically active and inactive excitons. The underlying exciton states are split from each other by the exchange interaction. The phonon-assisted spin-orbit interaction induces spin flips of an exciton-bound electron or hole which convert the exciton populations into each other. The temperature-dependent relaxation rate follows a thermal phonon distribution. Deviations indicate that two-phonon processes involving higher orbitals may contribute significantly to the total relaxation process. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)