Fast Joule heating of carbon films formed by methane plasma deposition

The practical application of carbon nanomaterials drives the search for new methods of efficient synthesis. One promising approach is the production of graphene-like materials through fast (flash) Joule heating (or Ohmic heating) of a carbon-containing precursor. In this study, we investigated the effects of flash Joule heating on amorphous carbon films formed by deposition in methane plasma on Si/SiO 2 substrates. Joule heating was conducted via electric discharge through samples from a capacitor block with a total capacitance of 180 mF, charged to voltages ranging from 100 to 300 V. We used various methods, including Raman spectroscopy, scanning electron microscopy, X-ray energydispersive spectroscopy, and current-voltage characteristics. The findings revealed that the most ordered structure is the carbon film subjected to fast Joule heating at a discharge voltage of 160 V. Furthermore, flash heating significantly enhances both the electrical conductivity and hydrophobicity of the material. The highest values were observed for carbon films after the discharge of a capacitor bank charged to 160 V. These results can be attributed to the transition of the initial amorphous carbon film to a crystalline structure characterized by a predominance of sp²-hybridized bonds, which exhibit low electrical resistance. The emergence of water-repellent properties can be explained by the “lotus effect, the formation of spherical particles up to 1 μm in size and their larger conglomerates on the film surface. These findings can be used to synthesize graphene-like nanomaterials with high hydrophobicity and electrical conductivity from amorphous carbon. Such materials are particularly relevant for the development of designs for all-weather unmanned aerial vehicles.