Four different catalysts, nano-Ni, diamond powder (250 ~ 350nm), mixture of nano-Ni/diamond powder, and ultrasonicated nanodiamond (50 nm) seed, on Si wafers were employed to investigate diamond film growth by hot filament CVD (HFCVD). Both front and back surfaces of as-grown diamond films were examined by XRD, Raman, transmission and scanning electron microscopy (TEM and SEM) and atomic force microscopy (AFM). The results indicated that diamond crystals were shown to grow directly on both large diamond powder and small nanodiamond seed, but a better crystallinity of diamond film was observed on the ultrasonicated nanodiamond seed. Nano-Ni nanocatalysts seem to promote the formation of amorphous and/or graphitic-like carbon phases at the initial growth of diamond films, and the subsequent nucleation and growth of diamond crystals on top of the amorphous carbon layer to generate the spherical diamond particles and clusters prior to coalescence into continuous diamond films. Moreover, the mixture of nano-Ni/diamond powder catalyst tend to promote the formation of a mixed of amorphous and crystallite diamond structures. For comparison, the plausible mechanisms for the initial growth of nano-Ni and/or diamond catalysts assisted diamond films by HFCVD and nanocrystalline diamond films by microwave plasma CVD will also be discussed.
Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2008: Materials, Fabrication, Particles, and Characterization – Technical Proceedings of the 2008 NSTI Nanotechnology Conference and Trade Show, Volume 1
Published: June 1, 2008
Pages: 90 - 93
Industry sector: Advanced Materials & Manufacturing
Topics: Carbon Nano Structures & Devices