OPTICAL MONITORING OF NUCLEATION AND GROWTH OF DIAMOND FILMS

Early stages of diamond film deposition on molybdenum substrates using dc arc discharge in CH4/H-2 gas mixtures were studied by in situ measurements of optical reflectivity of growing film. Ultrafine diamond grit of almost-equal-to 200 angstrom size was used for seeding to increase nucleation density up to 2 X 10(9) cm-2 and to produce smooth thin films. Evolution of He-Ne laser beam reflection at 0.63 mum wavelength is described in terms of Mie scattering by nonabsorbing dielectric spheres in the case of nucleated film and of light interference in the system of continuous diamond film on a metal substrate. During the deposition process the growth rate passes through a minimum at the moment when a minimum roughness is supposed to be achieved.