Measurement and analysis of diamond Raman bandwidths

Raman spectroscopy is an excellent technique for characterization of the crystalline quality of diamond films and the amount of graphite and amorphous carbon impurities in them. Most publications on diamond include Raman spectra to show the quality of the films through a measurement of the bandwidth (FWHM) of the feature at ca. 1332.5 cm(-1) characteristic of diamond. These measurements are often done directly on the spectra without correcting them for the instrumental contribution to the bandwidth. This can lead to meaningless comparisons of diamond bandwidth measurements across research groups. In order to show to what extent interpretations based on such raw measurements can be misled, we have characterized five CVD diamond films and a natural type IIa diamond using four different sets of instrumental parameters. We present a fitting procedure to obtain the Raman bandwidth corresponding to the material under study independent of the experimental parameters. This method permits absolute comparisons among Raman bandwidths obtained under different experimental conditions, providing they are corrected for the instrumental contribution. (C) 1998 Elsevier Science S.A.