CHARACTERIZATION OF MATERIALS BY MICRO-RAMAN SPECTROSCOPY

When illuminating a sample with a laser through an optical microscope, before collecting the scattered light in the monochromator of a Raman spectrometer, micro-Raman spectra can be recorded from a surface area as small as 1 μm2. Thus the individual components of a heterogeneous sample of micrometre size can be selectively investigated. Vibrations and phonons observed in Raman spectra are directly connected with the structure and dynamics of the solids. Thus many useful correlations can be deduced. Raman polarization is also helpful in the determination of the orientations of solids and layers. Step-etched and bevelled samples of layers on substrates studied by micro-Raman spectroscopy can reveal local structural changes and new chemical bonds at the interfaces as well as the regularity of epitaxial layers as a function of their thickness. These and other advantages due to recent advances in micro-Raman technology will be illustrated by examples of new semiconductor and superconductor materials. © 1990.