Gradual transitions in morphology of diamond films grown by using N2 admixtures of CH4+H2 gas in a hot filament assisted chemical vapour deposition system

With the increase of admixture of N2 fraction, in contrast to earlier studies, the morphology was observed first to gradually change from {111}-faceted crystallites texture to that of an intermediate cubo-octahedral crystallite texture and then gradually but finally to transform completely into that of {100}-faceted crystallites.

The threshold nitrogen concentration, [N2]thr, required to bring about the said transition in morphology was much larger than it was reported previously. Moreover, the morphology transition required a larger [N2]thr when a large fraction of methane was employed. Further additions of nitrogen, that just exceeded the [N2]thr, resulted in growth of films containing slightly bigger {100}-multi-layered grains or isolated planar {100}-platelets.