Fast lateral transport of excitons in a gaas/algaas quantum well

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. © 1993 The Japan Society of Applied Physics.