Femtosecond near-field spectroscopy of spatiotemporal carrier dynamics in locally disorder-patterned quantum wells

Summary form only given. The short length scales of semiconductor nanostructures increase the importance of transport processes in carrier dynamics. We report measurements which directly show how diffusive transport over nanometer distances affects carrier dynamics in locally disorder-patterned quantum wells on the picosecond time scale. The dependence of the spatiotemporal dynamics on the geometry of the disorder pattern and the diffusion within non-sinusoidal carrier distributions are investigated. These experiments have been made possible by a recently developed femtosecond near-field scanning optical microscope, which allows for pump-probe measurements with 150 nm spatial and 250 fs temporal resolution. The disorder patterns were written by focused ion beam implantation, leading to fast carrier trapping and reduced optical nonlinearity in the implanted areas.