Picosecond Imaging of Photoexcited-Carrier Transport in GaAs/AlGaAs Multiple Quantum Wells

Spatial and time-resolved induced bleaching at the heavy-hole exciton in a multiple quantum well structure is used to study ambipolar diffusive transport of a quasi-2D electron-hole plasma. The diffusivity is found to depend on excess carrier energy, lattice temperature, and carrier density. We attribute the density dependence to effects of screening and degeneracy at high density.