Hydrogen-free synthesis of graphene-graphitic films directly on Si substrate by plasma enhanced chemical vapor deposition

Carbon films with the thicknesses varying from 10 to 600 nm in the architecture range of carbonaceous graphene to graphitic bonding were synthesized on Si wafer. The films were prepared by radio frequency plasma enhanced chemical vapor deposition under 300 degrees C without any catalyst and hydrogen-assistant ambient as well. The films found to be composed of microcrystalline graphene and graphite inclusions with a maximum graphene film size of 2 mu m. Raman spectral characterization verified the bonding form of the graphene-graphitic films to be mostly sp(2). In this work, the complicated transfer printing process for carbon/silicon (C/Si) devices and the quality degradation of the hybrid films were avoided by the direct deposition of the carbonaceous films on Si substrate. The current-voltage feature of the devices manifested that the devices possess an excellent rectifying behavior in dark and the characteristic of photovoltaic in the illumination (known as solar cells).