Characteristics of carbon-related materials deposited in electron-energy controlled CH4/H2 RF discharge plasmas

The influence of electron temperature Te on the production of carbon-related materials was investigated in a hollow-type magnetron radio-frequency (RF) CH4/H2 plasma. Here, the electron temperature decreased along the plasma column. Since the dissociation of CH4 is determined by the electron energy in plasmas, the density ratio of radicals CH2/CH3 can be varied by the electron temperature. Therefore, the change of the electron temperature is quite important for controlling the characteristics of carbon-related materials. In the experiment, the production of diamond microparticles in low Te plasma was detected. On the other hand, thin carbon films consisting of graphitic carbons were observed in the high Te plasma. Therefore, it is shown that control of the electron temperature in the plasma has a key effect on the film quality.

Research Highlights
► Control of electron temperature Te in CH4/H2 plasma is crucial for diamond growth.
► Dissociation of CH4 depends on Te. When Te is decreased to 1- 2 eV, we clearly observe a diamond formation.
► Only amorphous graphite or diamond-like carbon is deposited when Te = 3-4 eV.