The internal stress and strain in boron-doped diamond films grown by microwave plasma chemical vapor deposition ͑MWCVD͒ and hot filament CVD ͑HFCVD͒ were studied as a function of boron concentration. The total stress ͑thermalϩintrinsic͒ was tensile, and the stress and strain increased with boron concentration. The stress and the strain measured in HFCVD samples were greater than those of MWCVD samples at the same boron concentration. The intrinsic tensile stress, 0.84 GPa, calculated by the grain boundary relaxation model, was in good agreement with the experimental value when the boron concentration in the films was below 0.3 at. %. At boron concentrations above 0.3 at. %, the tensile stress was mainly caused by high defect density, and induced by a node-blocked sliding effect at the grain boundary.

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The nucleation stage of diamond on silicon substrates was studied by atomic force microscopy. Samples were grown by hot filament chemical vapor deposition and substrate biases from -200 ν to +75 ν were investigated. The effects of the process on the substrate as well as on the morphology of the crystallites were observed using an atomic force microscope operating in tapping mode. It was observed that both the density and morphology of the diamond crystallites were greatly dependent on the applied bias values. The highest nucleation density was achieved for the -200 ν bias, when a plasma around the substrate holder was formed.