COALESCED ORIENTED DIAMOND FILMS ON NICKEL

The growth of coalesced, highly oriented diamond films has been achiev ed on nickel substrates using a multistep process that consisted of (i ) seeding the Ni surface with 0.5 mu m diamond powder, (ii) annealing at 1100 degrees C in a hydrogen atmosphere, and (iii) growth at 900 de grees C in a mixture of hydrogen and 0.5% methane. Auger depth profile analysis of a sample quenched after the annealing stage showed the pr esence of significant amounts of carbon (6 at. %) close to the substra te surface and about 3 at. % deeper in the substrate. The loss of carb on into the substrate resulted in relatively low nucleation density. T he addition of methane into the gas phase during the annealing stage p roved very effective in compensating for the diffusion, An addition of 0.5% methane in the gas phase produced optimum results, as the nuclea tion density, orientation of diamond particles, and uniformity were su bstantially improved. Substrates nucleated under these conditions were grown our into coalesced, 30 mu m thick films. Both (100) and (111) o riented films showed a high degree of orientation and Raman spectra ob tained from these orientations showed intense and narrow diamond signa ture peaks with FWHM's of 5 and 8 cm(-1), respectively.