SYNTHESIS AND PURIFICATION OF DIAMOND FILMS USING THE MICROWAVE PLASMA OF A CO-H2 SYSTEM

A variety of diamond films were deposited using the microwave plasma of a CO-H-2 system. Qualities of the synthesized films were correlated with the gas phase atomic hydrogen concentration monitored using optical emission spectroscopy. The amorphous components contained in the synthesized films were of a polyacetylene structure, which was possibly formed by the successive polymerization of C2H2 in the gas phase. Excess atomic hydrogen allowed highly crystallized diamond films to be deposited at high growth rates which included only a small amount of polyacetylene components. Two possible explanations for these results were proposed: the suppression of polyacetylene formation and the production of appropriate precursor (CH3) for diamond synthesis under the excess atomic hydrogen condition. Finally, the ratio I(H)/I(Ar) (where I is the optical emission intensity) was suggested as a decisive parameter indicating the suitability of the plasma conditions for the growth of pure diamond with good crystallinity.