Study of the Initial Stages of Deposition of Graphene-like Films by Sublimation of Amorphous Carbon

摘要

The initial stages of deposition of graphene-like thin films have been studied by X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectroscopy and ellipsometry. The deposition process has been performed by sublimation of amorphous carbon on 330 nm SiO_2/ (001) Si substrates with surface area of 15x 15 mm~2. The sublimation process was carried out in a quartz tube having an internal diameter of 25 mm at a temperature of 1050°C in which samples were placed in an argon flow of about 1 cm~3/s for 3 to 15 minutes. As a source of amorphous carbon, modified carbon blacks SPHERON 5000 were used. We established that an amorphous carbon film with thickness up to 3- 6 nm is always deposited on the SiO_2 after 3- 5 min deposition and the deposition of a few-layered defected graphene as well as nano-sized graphite occurs after 5- 6 min on the surface of substrate. Further on, after 8-10min deposition a non-continuous carbon film is formed and after 12- 13 min the substrate is covered by a smooth and continuous carbon film. The film has extremely low resistivity (ρ= 2.8 x 10~(-6)Ω.m) and consists of predominantly sp~2 hybridized carbon with a Raman spectrum similar to those of nano-sized graphene.