Kinetics of indirect photoluminescence in GaAs/AlxGa12xAs double quantum wells in a random potential with a large amplitude

The kinetics of indirect photoluminescence of GaAs/AlxGa12xAs double quantum wells, characterized by a random potential with a large amplitude ~the linewidth of the indirect photoluminescence is comparable to the binding energy of an indirect exciton! in magnetic fields B<12 T at low temperatures T>1.3 K is investigated. It is found that the indirectrecombination time increases with the magnetic field and decreases with increasing temperature. It is shown that the kinetics of indirect photoluminescence corresponds to singleexciton recombination in the presence of a random potential in the plane of the double quantum wells. The variation of the nonradiative recombination time is discussed in terms of the variation of the transport of indirect excitons to nonradiative recombination centers, and the variation of the radiative recombination time is discussed in terms of the variation of the population of optically active excitonic states and the localization radius of indirect excitons. The photoluminescence kinetics of indirect excitons, which is observed in the studied GaAs/AlxGa12xAs double quantum wells for which the random potential has a large amplitude, is qualitatively different from the photoluminescence kinetics of indirect excitons in AlAs/ GaAs wells and GaAs/AlxGa12xAs double quantum wells with a random potential having a small amplitude. The temporal evolution of the photoluminescence spectra in the direct and indirect regimes is studied. It is shown that the evolution of the photoluminescence spectra corresponds to excitonic recombination in a random potential. © 1999 American Institute of Physics. @S1063-7761~99!02605-0#