Confocal Raman imaging for the analysis of CVD diamond films

Raman imaging has been used to investigate the microstructure of some (100)-textured diamond films. Results have shown that different crystals within a film can give rise to different Raman line positions, intensities and line widths, with the result that the overall diamond line is the sum of all the individual contributions from all the different crystals. The images presented herein first show considerable variation in the distribution of amorphous carbon and defects producing the luminescence background. These defects were mostly detected within the grain boundaries, confirming most of the previous studies. These examples also emphasize the amount of variability that may be detected in the line shape of the Raman diamond line. In particular, line splitting was observed for all the samples examined, and in some particular cases was the most dominant feature that was observed. Such a line splitting has to be related to strain fields that exist within the crystals. However, it was impossible to correlate line shift or line splitting to the presence of defects such as amorphous carbon or point defects giving rise to the luminescence background. (C) 1999 Elsevier Science S.A. All rights reserved.