Hydrogen-free synthesis of few-layer graphene film on different substrates by plasma enhanced chemical vapor deposition

Few layer graphene were synthesized on different substrates by radio frequency plasma enhanced chemical vapor deposition in the absence of any catalyst under 300 °C. Raman spectral characterization verified the bonding form of the films to be mostly sp2. The principal chemical mechanisms relevant to the growth of graphene from gaseous hydrogen and hydrocarbon species are presented. The kinetic processes during the activation and transport of the gaseous species are described. Furthermore, the effects of substrate treatment in the course of growth are analyzed. We demonstrated that the differences in growth conditions reveal different mechanisms of growth of graphene by chemical vapor deposition. Nevertheless, the overall thermodynamic and dynamics principles are identical. It is reasonable to obtain few layer graphene films by using methane alone without H2 as source gas. Moreover, graphene films of various feature and structures for different purposes can be achieved controllably by modulating the kinetic factors. Also, these graphene films can be used in many photoelectric devices such as solar cells and photodetectors.