Equilibration of two-dimensional excitons in an in-plane harmonic potential

In this paper we report on the equilibration dynamics of spatially indirect 2D excitons in a coupled quantum well structure, trapped by an in-plane harmonic potential. We use the size of the exciton cloud as a measure of the temperature of particles. We show that the repulsive exciton-exciton interaction plays a major role in the time-evolution of the cloud size, and that at low lattice temperatures the exciton temperature is higher than that of the lattice, even long after equilibrium has obviously been reached. In the final part of the paper we demonstrate how our results can also be used for determining the absolute exciton density. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)