Study of the initial stages of deposition of graphene-like films by sublimation of amorphous carbon

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 SiO2/ (001) Si substrates with surface area of 15× 15 mm2. 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 cm3/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 SiO2 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 × 10−6Ω.m) and consists of predominantly sp2 hybridized carbon with a Raman spectrum similar to those of nano-sized graphene.