Spatially and temporally resolved near-field spectroscopy of single GaAs quantum wires

Single GaAs quantum wires grown on patterned (311)A GaAs substrates are stu died by steady-state and time-resolved near-field optical spectroscopy with a spatial resolution of 250 nm. The photoluminescence and photoluminescenc e excitation spectra as well as lateral variations of the quasi-one-dimensi onal confinement potential of the quantum wire are determined by measuremen ts in the temperature range from 10 to 300 K. Diffusive transport of excito ns and trapping into the quantum wire are directly monitored in picosecond luminescence experiments, allowing a quantitative measurement of exciton mo bility. First near-field pump-probe experiments with femtosecond time resol ution demonstrate the potential of this technique for monitoring spatio-tem poral dynamics on ultrafast time scales.