Spectroscopic study on the evolution of graphite ablation plume in ECR argon plasma during the deposition of diamond-like carbon films

A spectroscopic study of carbon plume produced by pulsed laser ablation of a graphite target in argon plasma generated by electron cyclotron resonance (ECR) microwave discharge has been carried out in an attempt to clarify the processes involved in ECR argon plasma assisted pulsed laser deposition of diamond-like carbon (DLC) films. Optical emission spectroscopy measurements show that the plume exhibits different behaviors in its space distribution and time evolution when produced and expanding in argon plasma compared with the plume in vacuum or low-pressure argon ambient. In vacuum or low-pressure argon ambient, lines from carbon atoms and ions dominate the plume emission. In argon plasma, the emission evolves from consisting of lines from carbon atoms and ions to being dominated by bands from dimer C2, with the strong C2 bands governing the plume emission at the later stages of the plume expansion. The differences in the plume emission reveal the different gaseous species composing the plumes expanding in different environments, suggesting the different gaseous precursors for film deposition by PLD with or without the assistance of argon plasma. It was also found that the emissions of C2 Swan bands and C2 Deslandres D'Azembuja bands exhibit different space distribution.