Analysis of particulates generated in a radiofrequencymethane plasma by laser light scattering and optical spectroscopy

The generation and the behavior of amorphous hydrogenated carbon particulates have been investigated in a pure methane low pressure radiofrequency discharge at 13.56 MHz. In the plasma, the formation and the presence of two kinds of particulates have been evidenced by use of laser light scattering. The study of the different forces acting on the particulates allowed us to understand their behavior in the discharge. Optical emission measurements have enabled us to correlate the evolutions of the emission lines (CH, Hα and H2) with the growth of amorphous hydrogenated carbon particulates and also with the results obtained by laser light scattering. The particulate sizes have been measured and a particulate number density of about 3.0 × 106 cm−3 has been determined.