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The spatiotemporal evolution of the bias plasma and the diamond coating in relation to the geometrical configuration of the bias device and the nature of the substrate holder was studied. Observations showed that the presence of the plasma was necessary. Based on these, a mechanism to explain the heterogenous deposit and the poor reproducibility was proposed. Results confirmed the proposed model and allowed homogenous diamond films elaborated with reproducible electrical parameters to be allowed.

We have improved the diamond nanoparticle seeding approach for chemical vapor deposition diamond growth in a novel process that consists of embedding the nanoparticles into a polymer matrix. We used a thin film of polyvinyl alcohol (PVA) doped with nanoparticles, which burns away during the initial stages of growth, leaving a stable distribution of nanoparticles on the substrate to initiate growth. The study shows that by varying the initial concentration of nanoparticles in the polymer preparation, it is possible to control the density of nanoparticles on the surface, over a wide range of densities. In some experimental conditions, the high densities of diamond seeding values obtained compare well with the highest values reported by the state-of-the-art. Moreover, the technique also opens up the route to very large area seeding, and this onto most types of substrates. In situ x-ray photoelectron spectroscopy (XPS) analyses showed that after pyrolysis of the polymer under H2 plasma, no significant residual carbon from the polymer was observed. Also, in the case of growth on silicon substrates, no silicon carbide was observed at the surface, showing that no reaction takes place between the polymer and the silicon surface itself. Finally, XPS also demonstrated that the polymer has not modified significantly the surface of the diamond nanoparticles after its pyrolysis. This approach improves the reproducibility of diamond nanoparticle seeding on flat surfaces and is more versatile as it may be applied to complex three-dimensional structures or cavities. [ABSTRACT FROM AUTHOR]

The present study deals with the interaction of C-terminated c(2×2) and Si-rich 3×2 3C-SiC (100) reconstructed surfaces with a microwave plasma chemical vapor deposition used for diamond growth. Pure hydrogen and hydrogen/methane exposures have been carried out. Their effects on the atomic ordering and the stoichiometry within the first planes have been studied in situ using low energy electron diffraction and electron spectroscopies: x-ray photoelectron spectroscopy, x-ray Auger electron spectroscopy, and ultraviolet photoelectron spectroscopy. 5 min plasma exposures result in a lost of the initial reconstructions, a postplasma oxygen contamination, and strong modifications of the stoichiometry within the first planes. Indeed, the stability of well defined 3C-SiC surfaces depends strongly on their termination: C-terminated surface exhibits a high inertia while the Si-rich surface undergoes partial etching. The three first silicon atomic planes involved in the 3×2 reconstruction are removed upon pure hydrogen plasma while a monolayer is preserved after hydrogen/methane exposure. [ABSTRACT FROM AUTHOR]