Diamond synthesis from CO-H2 mixed gas plasma

Abstract

Particulate or film-like diamond was prepared on silicon substrates from CO-H2 mixed gas using a microwave plasma technique. The growth rate of diamond without graphite and amorphous carbon, as measured by Raman spectroscopy, was 9Μm h−1 for particles and 4Μmh−1 for flims. These values were larger than those in other source gas systems, such as CH4-H2, CH4-H2-H2O and CH3OH-H2. The good formation rate and high quality of diamond in the CO-H2 system was attributed to acceleration of methyl radical formation by the reaction of excited CO and H2 molecules and removal of by-product graphite by OH radicals in the plasma.