抄録
Diamond was deposited in both film and particle form by microwave plasma CVD from a CO-H2 system at a power input of 220W, an H2 flow of 100cm3/min., and a pressure of 3.3kPa. O2 and CO2 were used as additive gases. In deposition without additives, the rate reached a maximun at 50cm3 CO/min., while idiomorphism was apparent at CO concs<15cm3/min.; for the same CO flow with the O2 additive, the maximum occurred at 1cm3 O2/min. and the idiomorphism appeared at O2 cones>4cm3/min.; and for the same CO flow with CO2, the maximum occurred at 4cm3 CO2/min, and the idiomorphism appeared at CO2 cones>6 cm3/min. The highest deposition rates obtained in this study were 2.8 and 9.2μm/min, for the film and particles, respectively, with a CO-CO2-H2 system. The favorable results make this appear to be the most promising combination for diamond synthesis by microwave CVD.
Addition of either O2 or CO2 to this system can form diamond of higher crystallinity comparable to that of naturally occurring type II a.
A possible mechanism of deposition from those gases is also suggested.
