Low-temperature transport of excitons in type-II GaAs/AlAs quantum wells

Low-temperature transport of two-dimensional excitons in type-II GaAs/AlAs double quantum wells (DQW’s) with rough interfaces is considered. The limiting cases of zero magnetic field and the magnetic quantum limit are studied. We found that (1) the transport of excitons in DQW’s is mainly limited by the disorder at the external interfaces and (2) the transport relaxation time τ depends nonmonotonously on the quantum-well widths for electrons (AlAs QW) and holes (GaAs QW). In the magnetic quantum limit the exciton transport relaxation time decreases with magnetic field strength B approximately as τ∼${\mathit{B}}^{\mathrm{-}1/2}$.