NEAR-FIELD PHOTOCONDUCTIVITY - APPLICATION TO CARRIER TRANSPORT IN INGAASP QUANTUM-WELL LASERS

A new contrast method in near-field scanning optical microscopy in whi ch the near-field probe is used to excite photocurrent in a semiconduc tor sample is described and demonstrated. The use of near-field optics results in an order-of-magnitude improvement in spot size and a fivef old improvement in resolution over previous methods of photocurrent im aging. The application of this near-field photoconductivity technique to a multiquantum well laser provides direct visualization of carrier transport throughout the structure, yielding information on growth inh omogeneities, carrier leakage and isolation, and the overall quality o f p-n junctions. (C) 1994 American Institute of Physics.