CHARACTERIZATION OF DIAMOND FILMS DEPOSITED USING C3H6OX-H2 GAS-MIXTURES

Diamond films were synthesized using the vapour of hydrocarbon liquids,, such as C3H6O (propylene oxide), C3H6O2 (1,3-dioxolane) and C3H6O3 (dimethylcarbonate), diluted by a large amount of hydrogen as gas mixtures. The surface morphologies of the diamond films still possessed well-defined facets when the hydrocarbon concentrations were 1.2 vol.%, 0.5 vol.% and 0.3 vol.% for C3H6O3-H-2, C3H6O2-H-2 and C3H6O-H-2 gas mixtures respectively. Diamonds of good quality, according to Raman measurements, were obtained using C3H6O3-H-2, C3H6O2-H-2 and C3H6O-H-2 gas mixtures. Optical emission spectroscopy was used to examine the species in the plasma during the process of diamond growth. Our results show that the characteristics of diamond growth were related to the oxygen content, i.e. O-to-C ratios, of C3H6Ox (x = 1, 2, 3). We found that the diamond formation region could be extended to higher hydrocarbon concentrations for C3H6O3-H-2 mixtures than for C3H6O-H2 and C3H6O2-H2 MixtUreS because of the larger amounts of atomic hydrogen and oxygen-containing species, such as atomic oxygen, oxygen molecules and OH radicals, in the plasma of the C3H6O3-H-2 mixture. Obviously, there was a higher etching rate, resulting in a diamond formation region with a lower growth rate for the C3H6O3-H-2 mixture.