The nucleation and growth of (100) textured diamond films in presence of nitrogen

We have studied the influence of nitrogen addition in CH4/H2 gas mixtures on the nucleation, morphology and growth rate of polycrystalline diamond films prepared by hot filament chemical vapor deposition (HFCVD). The presence of nitrogen has little effect on diamond nucleation density, but is beneficial to enhance the growth rate and to stabilize (100) facets of diamond films. Optical emission spectroscopy was applied to detect the chemical radicals in the system. It is shown that the additional nitrogen makes the chemical radicals and surface activity of diamond films change tremendously. We believed that nitrogenous species abstract the atomic hydrogen on the diamond surface and speed up the desorption rate of H, so as to promote the diamond films deposition. Furthermore, the selective absorption of nitrogenous species causes chemical roughening of the (100) facets, which makes the growth rate of (100) facet higher than that of other facets and leads to the presence of (100) textured diamond films.