Abstract

The short length scales of semiconductor nanostructures increase the importance of transport processes in carrier dynamics.^1,2,3 We report measurements which directly show how diffusive transport over nanometer distances affects carrier dynamics in locally disorder-patterned guantum 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,⁴ which allows for pump-probe measurements with 150 nm spatial and 250 fs temporal resolution.⁵ The disorder patterns were written by focused ion beam (FIB) implantation, leading to fast carrier trapping and reduced optical nonlinearity in the implanted areas.

© 1999 Optical Society of America