Relation between gas phase CN radical distributions, nitrogen incorporation, and growth rate in flame deposition of diamond

Controlled amounts of nitrogen were added during oxyacetylene flame deposit ion of diamond to investigate the possible role of the CN radical in the ef fects of nitrogen addition. CN radical distributions were visualized using two-dimensional laser induced fluorescence (LIF) and compared with nitrogen incorporation into the layer and with the diamond growth rate, which were measured by means of cathodoluminescence (CL) and optical microscopy, respe ctively. For the studied range of nitrogen flows, it was found that the CN LIF signal in the center of the flame is linearly dependent on the added am ount of nitrogen. Diamond deposition in the central region is mainly influe nced by the deposition parameters, whereas deposition in the outer zone is largely determined by the interaction of the flame with the ambient; the an nulus of enhanced growth is affected by both the deposition parameters and the ambient. By a simple consideration, in which the growth rate is separat ed in nitrogen dependent and independent contributions, an observed positio nal difference between CN LIF and growth rate maxima can be explained. Comp arison of the CN LIF signal, the CL signal and the diamond deposition rate indicates that CN (or a closely related species) may be the species or one of the main species responsible for the effects of nitrogen addition during oxyacetylene flame deposition of diamond. (C) 2000 American Institute of P hysics. [S0021-8979(00)04717-4].