Near-field imaging of the photocurrent on a patterned Au/GaAs interface with various wavelengths and bias

This contribution presents an application of scanning near-field optical mi croscopy to the characterization of semi-conductors. It is based on the pho tocurrent mapping of a patterned Au/GaAs structure (Schottky barrier) under local illumination by the nanosource. The results obtained with different wavelengths, metallized or dielectric probes and different bias voltages ex hibit photocurrent variations independent of the topography and induced by interface defects. Finally, from this study of a patterned planar structure , we propose a method to determine the mean free path of the charge carrier s in the volume.