Growth Dynamics of Nanocrystalline Diamond Thin Films Deposited by Hot Filament Chemical Vapor Deposition: Influence of Low Sticking and Renucleation Processes

Nanocrystalline diamond (NCD) thin films are being progressively more employed in different applications. However, the current understanding of their growth mechanisms, which becomes important to properly tune their properties, is still very limited. In this context, we have studied by atomic force microscopy the growth dynamics of NCD thin films grown on micro- and nanoseeded silicon substrates by hot filament chemical vapor deposition for different methane/hydrogen gas mixtures. The NCD film growth dynamics displays two regimes regardless of the gas mixture and type of seeding. The initial regime determines the film roughness and operates for submicrometer length scales, being strongly associated with gas mixture-dependent renucleation processes. The asymptotical second growth regime, which determines the saturation in film roughness over the micrometer scale, is the consequence of the very low sticking probability of the main growth species. As the gas mixture and seeding do affect to the nature and the lateral length extent of the first regime, respectively, they determine the film roughness.