Kinetics of indirect photoluminescence in GaAs/AlxGa1-xAs double quantum wells in a random potential with a large amplitude

The kinetics of indirect photoluminescence of GaAs/AlxGa1-xAs double quantu m wells, characterized by a random potential with a large amplitude (the li newidth of the indirect photoluminescence is comparable to the binding ener gy of an indirect exciton) in magnetic fields B less than or equal to 12 T at low temperatures T greater than or equal to 1.3 K is investigated. It is found that the indirect-recombination time increases with the magnetic fie ld and decreases with increasing temperature. It is shown that the kinetics of indirect photoluminescence corresponds to single-exciton recombination in the presence of a random potential in the plane of the double quantum we lls. The variation of the nonradiative recombination time is discussed in t erms of the variation of the transport of indirect excitons to nonradiative recombination centers, and the variation of the radiative recombination ti me is discussed in terms of the variation of the population of optically ac tive excitonic states and the localization radius of indirect excitons. The photoluminescence kinetics of indirect excitons, which is observed in the studied GaAs/AlxGa1-xAs double quantum wells for which the random potential has a large amplitude, is qualitatively different from the photoluminescen ce kinetics of indirect excitons in AlAs/GaAs wells and GaAs/AlxGa1-xAs dou ble quantum wells with a random potential having a small amplitude. The tem poral evolution of the photoluminescence spectra in the direct and indirect regimes is studied. It is shown that the evolution of the photoluminescenc e spectra corresponds to excitonic recombination in a random potential. (C) 1999 American Institute of Physics. [S1063-7761(99)02605-0].