Nanoscale mapping of confinement potentials in single semiconductor quantum wires by near-field optical spectroscopy

The quasi-one-dimensional confinement potential and its influence on carrier transport in a GaAs quantum wire structure are directly mapped by low-temperature near-field scanning optical spectroscopy with subwavelength spatial resolution. Shallow asymmetric potential barriers in the vicinity of the quantum wire are detected, and their height and width are determined quantitatively. We demonstrate the strong influence of such local barriers on carrier transport and trapping into the quantum wire, suppressing carrier trapping at low temperature.