Study On The Preparation, Synthesis Mechanism And Laser Raman Characterization Of Graphene And It’s Composited Structure Fabricated By Plasma Technology

Graphene, one of the allotropes of elemental carbon, is a planar monolayer of carbon atoms arranged into a two-dimensional (2D) honeycomb lattice. Due to its unique structure, graphene contribute to very peculiar properties such as an anomalous quantum Hall effect and the absence of localization. Graphene has demonstrated a variety of intriguing properties including high electron mobility at room temperature exceptional thermal conductivity and superior mechanical properties. Its potential applications include single molecule gas detection, transparent conducting electrodes, composites and energy storage devices such as supercapacitors and lithium ion batteries. There are two common methods of synthesis of graphene, Oxidation-reduction method and chemical vapor deposition method. It is rarely studied that synthesis of graphene and it’s composite structure by plasma technology. Plasma technology is of great value to study because it can lower the synthesis temperature of graphene and improve its growth rate. In this paper, graphene and it’s composite structure was prepared by Radio Frequency sputtering and Microwave Plasma Enhanced CVD respectively. They was characterized by Raman spectroscopy and HR-TEM, was analysed of the growth mechanism.In the experiments, Graphene have been synthesized graphene without catalyst using Radio Frequency sputtering and Microwave Plasma Enhanced CVD (MW-PECVD). CNTs, Si wafers and diamond-like carbon (DLC) films are chosen as substrates. The effects of temperature、Output power (RF or MW)、carbon concentration、growth time on the nucleation density of graphene、size and thickness are explored. In addtion, the impacts of different substrates to the growth of graphene are studyed. As temperature and plasma density rise, graphene grows faster. When carbon concentration is increased, graphene is thicker and larger. Compared with the carbon nanotube array, it is easier for graphene to grow on flat substrate by Radio Frequency magnetron sputtering,which is contrary to the result of MW-PECVD. In the end,we analyse the structure of graphene by Raman spectroscopy and HR-TEM. It turns out that the product is multilayered. In low carbon concentration and low plasma energy density, the substrate morphology has a significant influence on the diffusion of activated carbon atoms, so the grow of graphene on plane surface is much faster than that of the growth of graphene on CNTS.In high concentration and high plasma energy density, the number of the defects of the substrate surface is primary factor which affect the growth of graphene, and the more defects, the faster graphene grow. So, in conclusion,graphene without catalyst originates from the competing ecffects of activated carbon atoms absorbed by defects and carbon atoms etched by H plasma.