Pulsed electromagnetic inductive plasma-enhanced chemical-vapor deposition of amorphous carbon films

A pulsed electromagnetic inductive methane discharge process was developed to form amorphous carbon thin films. In order to estimate the methane plasma state in the pulsed plasma process, the time-resolved excitation temperature was measured by means of relative spectral intensity method. At the high electromagnetic compression phase the pulsed plasma has an excitation temperature of the same order (20 000-50 000 K) as in the conventional rf glow discharges. The deposited thin films are transparent in the IR and adhere well to room-temperature substrates. The optical energy gap and the electrical conductivity of the amorphous carbon films are investigated and compared with the amorphous carbon films prepared with rf glow plasma chemical vapor deposition. The optical gap is observed to decrease from 1.26 to 1.14 eV as the deposition temperature and the charging voltage increase. It is shown that dynamic pulsed plasma flows affect the phase transition from a diamondlike structure to a graphitic structure.