Early stages of diamond growth on substrates with different carbon diffusivity

In this work, nanocrystalline diamond was deposited with a direct-current micro-plasma device on substrates with different carbon diffusivity. No substrate pre-treatment was performed and the same deposition conditions were adopted for all substrates, with the intention to investigate the first stages of growth. Samples were grown with increasing deposition time. Scanning electron microscopy and visible Raman spectroscopy were used to derive morphological and structural information. The growth dynamics was found to be the same on all substrates, with the deposition of a graphite layer prior to diamond growth. This layer was extensively characterized and a link between the structure and morphology of this layer and the subsequent features of the diamond grown on it was found. Moreover, diamond tens of micrometers thick was deposited in few hours, opening the possibility of producing diamond samples of practical interest. Particularly, the growth of nanocrystalline diamond on iron without substrate pre-treatment or interlayer deposition is reported, showing the feasibility of depositing diamond even on ferrous materials.