Study on Morphologies and Strictures of Diamond Films Synthesized on Cemented Carbide Substrates

摘要

Morphologeis and structures of diamond films synthesized on cobalt cemented tungsten carbide substrates using DC plasma jet CVD (direct current plasma jet chemical vapor deposition) method were investigated by means of SEM, XRD, TEM and Raman spectroscopy. The results show that the high thermal gradient and the high concentration gradient of chemical species within plasma jet have large influence on morphologies and quality of diamond films deposited. There are residual compressive stresses with GPa order of magnitude in diamond films, and micro-stresses are quite small. Mosaic bloc sizes, being manometer order of magnitude, decrease with the increasing of methane concentrations. Average values of dislocation density within diamond films, estimated from the magnitude of mosaic block sizes, are at least 10~10 cm~-2 order of magnitude. This result is also confirmed by calculated value from TEM observation of diamond films. It is flown that both the lattice distortion tested by XRD and FWHM value of diamond Raman peak measured from Raman spectrum have a similar trend of change with methane concentration comparing the results of CRD and Raman spectra