Fast Lateral Transport of Excitons in a GaAs/AlGaAs Quantum Well

Abstract
We have studied the lateral transport of excitons in a GaAs/AlGaAs single quantum well by the exciton time-of-flight technique. The lateral motion of excitons has been measured as a function of temperature (4 K to 40 K) and excitation density (≥108 cm-2). Our analysis shows that the exciton diffusivity at temperatures below 10 K becomes considerably enhanced, implying extremely long (several micrometers) exciton mean free paths. This behavior is discussed in terms of several scattering mechanisms including interaction with non-equilibrium phonons emitted during energy relaxation of carriers.