Low energy carbonaceous and graphite phases on the surfaces of thermochemically polished chemical vapor deposited diamond films

Abstract

Micro-Raman spectroscopy was used to characterize chemical vapor deposition diamond films that were thermochemically polished at elevated temperatures. A continuous wave He–Ne laser and an argon ion laser both operated at a power of 10 mW on an area of 1 μm2 were used as excitation sources of the Raman setup. New Raman peaks were observed in a spectral range of 100–700 cm−1 in addition to the common graphite related features. These peaks are assumed to be related to carbonaceous phases formed on the surfaces of the films. A peculiarity of these new features is an increase in intensity with increasing laser exposure time. However, it was observed that the intensities of the amorphous and graphite Raman lines at 1326 and the 1577 cm−1, respectively, were independent of the laser exposure time. The temperature dependency of the intensities of the diamond and of the graphite Raman lines was investigated at different polishing temperatures. Low temperature (700 °C) polishing was also done to high temperature pre-polished samples to investigate the dissolution of nondiamond carbon in the polishing plate.