PLASMA CHEMISTRY IN THE CVD SYNTHESIS OF NANODIAMOND FILMS

摘要

We review some of the experimental findings related to the diagnostics of the plasmas used for growing nanodiamond films, discussing the possible nonequilibrium plasma chemistry modelling. The latter will be illustrated with the use of a kinetic model built by our group to investigate the influence of processing parameters such as the pressure (0.1-0.8 Torr), power (100-300 W) and argon content (5- 95 %) on the nonequilibrium plasma chemistry of radio frequency (RF) produced C_2H_2 (1 %)/H_2/Ar plasmas of interest for the CVD synthesis of nanodiamond thin films at room temperature. We found that the concentrations of the species C_2 (X~1∑_g~+), C_2 (a~3∏_u) and C_2H are not sensitive to variations in the power but they exhibit a significant increase when the pressure decreases at high argon content in the plasma. A reasonable agreement is found when comparing the model predictions with available experimental results. These findings provide a basic understanding of the plasma chemistry of hydrocarbon/Ar-rich piasma environments.