The applicability of near-field scanning optical microscopy (NSOM) for optical characterization of semiconductors is discussed. The NSOM technique and some of its properties relevant to real-time in-situ measurements are reviewed. Several optical characterization methods widely used in the far-field, including reflectance, reflectance-difference spectroscopy, Raman spectroscopy, ellipsometry, and carrier lifetime, are evaluated for their use with NSOM. Experimental data are included for some of these methods. It is concluded that several, but not all, of the standard optical characterization methods can be coupled with NSOM to provide higher spatial resolution. The applicability of NSOM real-time in-situ probe shares some of the problems of other proximal probe methods, but offers enough new capabilities to warrant its application.
