Raman microscopy using a scanning near-field optical probe

Abstract

A scanning near-field optical microscope (SNOM) has been coupled to a commercial Raman spectrometer to produce an instrument capable of obtaining Raman spectra with a spatial resolution of 100–200 nm. This resolution is three to ten times greater than is typically possible using a conventional diffraction limited system. Sub-micron resolution Raman images of a damaged silicon wafer have been obtained and the position of the peak analysed to produce a high resolution map of stress around a micron sized scratch. The results are compared with data obtained with a conventional Raman microscope. The current performance limits of the Raman SNOM instrument are discussed and possible technical improvements suggested; the latter indicate that near-field Raman spectroscopy will be a feasible technique for high spatial resolution characterisation of semiconductor surfaces.