Growth feature of layered self-standing diamond films by DC arc plasma jet CVD

Layered self-standing diamond films, two-, three- and four-layered films, were fabricated by varying the ratio of methane to hydrogen in high-power DC arc plasma jet CVD. Results of scanning electronic microscopy (SEM) and Raman spectra showed that the layered films were constructed by the micro-crystalline grains layer/nano-crystalline grains layer. The residual stress within the films were balanced, and even diminished in the certain layer. The grain size was calculated by X-ray diffraction (XRD). The layer containing nanocrystalline grains due to a plenty of secondary nucleation can weakly inherit the columnar growth feature of the overlaid layer containing micro-crystalline grains. The grain size and growth orientation of the layer containing micro-crystalline grains can be adjusted by introduction of a mid-layer containing nano-crystalline grains. Growth rate was over 10 mm/h in layered film fabrication.