SPATIAL-RESOLUTION OF LOCALIZED PHOTOLUMINESCENCE BY NEAR-FIELD SCANNING OPTICAL MICROSCOPY

A numerical model describing the spatial resolution limitations on loc alized band edge photoluminescence (PL) and trap-based luminescence, o btained through near-field scanning optical microscopy (NSOM), is pres ented. Calculations were carried out for NSOM measurements performed i n the tip illumination mode. Variations in surface recombination veloc ity, probe aperture, and the physical structure on the achievable spat ial resolution were investigated. These calculations indicate that the drift of photogenerated minority carriers to the surface narrows thei r lateral distribution, leading to improved spatial resolution. There is a weak dependence on the spatial resolution of the photoluminescenc e on the tip aperture. An order of magnitude reduction of the illumina ting tip aperture resulted in only a minor improvement in the lateral spatial resolution of the emitted FL. The spatial resolution of the lo calized trap luminescence is presented within the context of typical m aterial structures. (C) 1997 American Institute of Physics.