In-plane transport of excitons in quantum well structures

We have investigated the in-plane transport of photoexcited carriers and excitons in Al0.3Ga0.7As/GaAs quantum well structures as a function of excitation photon energy and temperature at low carrier density (108 cm-2). We have discovered a strong correlation between the diffusivity and the excitation photon energy; the exciton diffusivity becomes quenched as the excitation photon energy decreases closer to the heavy-hole exciton state. We have also found significant enhancement of diffusivity when a light-hole exciton state is resonantly excited. We attribute the enhancement to the difference between exciton scattering and free carrier scattering. © 1993.