Raman Spectroscopy

Raman spectroscopy is an inelastic light scattering technique that measures the vibrational spectra of molecules and solids. A monochromatic light source (laser) is used to irradiate the sample. The photons from the laser interact with the molecular vibrations of the sample and cause the photon energy to shift up or down. The shift in energy is characteristic of specific bonds and can be used to generate a spectrum for the specific system being analyzed. The spectra provide detailed information about the character of the chemical bonds, e.g. graphitic bonding. Raman spectroscopy is typically used to identify organic compounds or to analyze solids such as polysilicon, metal silicides and strained silicon.

This technique is useful because it is non-destructive and relatively quick. By coupling the laser with a microscope we can achieve a lateral resolution of the incident beam on the order of 1 micron. However, the total collection volume depends on the light scattering properties of the material being analyzed. In addition to analysis on silicon, Raman can be used to identify some organic compounds.