Process optimization in the low-pressure flat flame growth of diamond

The influence of oxy-acetylene gas mixture (O-2/C2H2 gas ratio - 0.95:1.06) and substrate temperature (ranging from 650 to 850 degreesC) on diamond gr owth in the low-pressure flat flame is reported. Deconvolution of the Raman spectra was employed to qualitatively estimate the ratio of diamond-to-non -diamond carbon in the film deposits by an area comparison of these discrim inate peaks. The diamond crystallinity was assessed quantitatively by a det ermination of the full-width-at-half-maximum of the 1332 cm(-1) Raman line representing sp(3)-bonded carbon. An optimum oxygen/acetylene molar ratio o f similar to 1.05 and substrate temperature of 650-750 degreesC were observ ed for limiting both the non-diamond carbon content and a deterioration in the diamond crystallinity. The crystallite morphology was also evaluated as a function of this same parametric regime based on assignment of the param eter alpha describing growth rate competition between the {100} and {111} f aces. The collective data indicates the process conditions required to prod uce the optimum in film quality according to a desired him morphology. (C) 2001 Elsevier Science B.V. All rights reserved.