Diffusion of electron-hole pairs in disordered quantum wires

The diffusivity of photogenerated electron-hole pairs in weakly disordered GaAs/AlGaAs V-groove quantum wires was measured using a photoluminescence (PL) time-of-flight technique. It is shown that the electron-hole pair diffusion is thermally activated above about 50 K. Exciton localization is observed in micro-PL (mu PL) spectra at low temperature. A reduction in the Stokes shift is found to accompany the increase in the diffusion coefficient. Nevertheless, localization-related features in the mu PL spectra disappear at intermediate temperatures, before measurable diffusion occurs.