Raman spectroscopic characterization of diamond films grown in a low-pressure flat flame

Diamond films produced in the low-pressure hat flame have been examined usi ng Raman spectroscopy. The effect of the oxy-acetylene gas mixture (R = O-2 /C2H2 gas ratio of 0.95 to 1.06) and substrate temperature (650-850 degrees 'C) on the form of the non-diamond carbon as well as the diamond phase pur ity and crystallinity. are reported. An assessment of the diamond crystalli nity was achieved by inspection of the full-width-at-half-maximum (FWHM) of the Raman line observed at 1332 +/- 0.5 cm(-1) representing sp(3)-bonded c arbon. This analysis revealed a FWHM as low as similar to4.3 cm(-1) for the optimum growth conditions of an R = 1.05 and substrate temperatures of 650 -750 degreesC. The broad non-diamond carbon component in the 1350cm(-1) to 1650cm(-1) range was deconvoluted into three distinct Gaussian peaks at 135 5 +/- 1.5cm(-1) 1470 +/- 7.5cm(-1), and 1550 +/- 4.0cm. These peaks remaine d in the same relative proportion regardless of the processing conditions, and the total area of the non-diamond peaks was found to correspond linearl y with the background luminescence. A relative comparison of the diamond an d non-diamond carbon was used to qualitatively estimate the diamond film ph ase purity. (C) 2001 Published by Elsevier Science B.V.