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 areapplied to the chemical vapour deposition (CVD) of diamond by anoxyacetylene flame to visualize the distribution of CN in the gas phaseduring the diamond growth process. The obtained diamond deposits arecharacterized by optical as well as scanning electron microscopy (SEM)and cathodoluminescence topography (CL). Experiments are carried out inboth laminar and turbulent flames and show CN to be present mostly atthe outer edge of the flame, where ambient air interacts with flamegases. Clear relations are observed between the distribution of CN andthe local variation of the growth rate, the morphology, and the nitrogenincorporation as identified by CL in the deposited diamond layer. Theobserved differences between the laminar and turbulent flame can beattributed to enhanced diffusion of nitrogen into the latter.Significant differences are found between the results of experimentsperformed with acetylene gas bottles from two different suppliers.