Abstract
A diamond thin film was formed on the SiC substrate in hydrogen and methane mixed atmosphere by means of thermal CVD process. The structure of the deposits was analyzed by Raman spectroscopy and X-ray diffraction and reflective electron diffraction. The morphology was estimated by the SEM observation. It was confirmed that the deposits were diamond and i-carbon (amorphous carbon). Optimum condition for the formation of the diamond thin film in this experiment were as follows; substrate temperature of 700°C, filament temperature of 1900°C, the distance between filament and substrate; 5mm, CH4/(CH4+H2) =1 vol%, gas flow rate 20SCCM and gas pressure 4000Pa. The i-carbon in the deposites tended to increase with the increase of methane concentration at the temperature above 800°C and below 600°C, and the addition of cathodic voltage on the substrate. It was considered that these condition was concerned with the formation of methyl radical and hydrogen radical near the substrate and the hydrogen played a very important role for the diamond synthesis.
