MICROWAVE PLASMA CHEMICAL VAPOR-DEPOSITION OF DIAMOND - ITS GROWTH AND CHARACTERIZATION

Abstract

Diamond was deposited in both film and particle forms by microwave plasma chemical vapour deposition (CVD) from both CH4-H2 and CO-H2 systems with additive gases of O2 and CO2. The products were comparatively characterized by X-ray diffraction, scanning electron microscopy observation, and Raman and cathodoluminescence spectroscopy. Deposition parameters employed were a power input of 220 W, an H2 flow of 100 cm3 min-1, and a pressure of 3.3 kPa. The addition of O2 or CO2 gas resulted in increasing deposition rates of diamond, up to six times as high as the cases where no additives were used. The addition also resulted in improved crystallinity, so some were comparable with the naturally occurring type IIa diamond. The most favourable results obtained with the system CO-CO2-H2 make the combination appear to be the most promising for diamond synthesis by the microwave plasma CVD process. A possible mechanism of deposition from those gases is suggested.