FORMATION OF PROTECTIVE CARBON FILM ON THE SURFACE OF GRAPHENE BY PLASMA DEPOSITION AND HEAT TREAT-MENT

ASGEOK

Abstract

A technique has been proposed for the formation of a protective carbon layer for graphene films based on a two-stage process, including the deposition of carbon atoms in methane plasma and heat treatment. A 200 W radio frequency inductively coupled plasma source was used to deposit carbon atoms. The duration of the deposition process in the methane plasma ranged from 3 to 6 minutes. Heat treatments were carried out in an inert gas atmosphere at temperatures from 750 °C to 800 °C for up to 25 minutes. To characterize the surface, methods of atomic force microscopy and Raman spectroscopy were used. Studies using atomic force microscopy have shown that the proposed technique makes it possible to successfully form carbon films several tens of nanometers thick on the surface of the original graphene film obtained by chemical vapor deposition. Etching the synthesized structure in oxygen plasma with a power of 200 W and a duration of up to 30 s leads to the formation of films with a thickness of several nanometers and a surface roughness of about 0.5 nm. Folds of the initial graphene film, which had a height of up to tens of nanometers, were not detected after the treatments. From the analysis of the Raman spectra it follows that after etching the synthesized structures in oxygen plasma to the initial thicknesses, the main graphene G- and 2D-peaks are restored. One can note a slight increase in the integral intensity of the D-band, due to the presence of defects and disturbances in the crystal lattice, which can be partially eliminated by heat treatment.