CN DISTRIBUTION IN FLAME DEPOSITION OF DIAMOND AND ITS RELATION TO THE GROWTH-RATE, MORPHOLOGY, AND NITROGEN INCORPORATION OF THE DIAMOND LAYER

Two-dimensional laser-induced fluorescence (2D-LIF) measurements are a pplied to the chemical vapour deposition (CVD) of diamond by an oxyace tylene flame to visualize the distribution of CN in the gas phase duri ng the diamond growth process. The obtained diamond deposits are chara cterized by optical as well as scanning electron microscopy (SEM) and cathodoluminescence topography (CL). Experiments are carried out in bo th laminar and turbulent flames and show CN to be present mostly at th e outer edge of the flame, where ambient air interacts with flame gase s. Clear relations are observed between the distribution of CN and the local variation of the growth rate, the morphology, and the nitrogen incorporation as identified by CL in the deposited diamond layer. The observed differences between the laminar and turbulent flame can be at tributed to enhanced diffusion of nitrogen into the latter. Significan t differences are found between the results of experiments performed w ith acetylene gas bottles from two different suppliers. (C) 1998 Elsev ier Science S.A.