Size and flux of carbon nanoparticles synthesized by Ar + CH4 multi-hollow plasma chemical vapor deposition

Carbon nanoparticles (CNPs) were synthesized using Ar + CH4 multi-hollow plasma chemical vapor deposition. The deposition flux of CNPs to a substrate was studied as a function of the plasma discharge time t and the distance L between the plasma and the substrate. CNPs were not deposited for L = 60 and 80 mm, whereas they were deposited for L = 100, 120 and 140 mm. The mean diameter of CNPs was 25 nm irrespective of L. For L = 120 and 140 mm, the flux gradually increased until t = 30 min and then became constant, indicating that thermophoretic force drives CNPs' deposition. Raman spectroscopy showed that a-C:H films were formed for L <= 80 mm, while polymer CNPs were predominant deposits for L >= 100 mm.