Time-resolved exciton transfer in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As double-quantum-well structures

Transfer of excitons through a barrier is studied by means of time-resolved photoluminescence in a biased GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As asymmetric double-quantum-well structure. By tuning the external electric field, the dynamics of the system is investigated in the vicinity of the resonance between the first conduction subbands of the two wells. The excitonic nature of the tunneling process at low temperature is demonstrated. A nonlinear behavior of the interwell transfer is also observed when the appearance of a crossed exciton induces a dipolar electric field. The experimental curves are quantitatively compared with a theoretical simulation of the exciton-assisted tunneling process.