Study Of Chemical Vapor Deposition Growth Of Graphene On Copper Surface

Graphene, a single layer film of carbon atoms, with the unique electrical properties, good flexibility and light transmission, has a broad application prospect in the fields of display devices, electronic devices, optoelectronic devices.Chemical Vapor Deposition (CVD) method, with many advantages such as homogeneous layers products, perfect structural integrity, favourable light-transmission, and potential application for mass production, has became a popular way for graphene preparation. In recent years, numbers of studies have been conducted on graphene preparation at low pressure, and its growth mechanism were researched. However, the stringent requirement on reaction condition and equipments limits its development. Whereas, graphene preparation at ambient pressure, with less requirement in equipments which can effectively reduce the cost of production, has an attractive application prospect.In the research, graphene films were grown on copper substrate at ambient pressure by chemical vapor deposition (CVD) firstly, with CH4as carbon source and Ar as carrier gas, and then the products were effectively transferred. In order to get a optimized parameter an understand the mechanization of graphene growth, Raman spectra, optical microscopy, scanning electron microscopy, and four-probe conductivity meter were used to character graphene growth under different hydrogen flow rates and temperatures.The result shows that, graphene can continuously grow into a complete film crossing copper grain boundaries and surface steps. The nucleation rate of graphene on the fabrication trace is higher. The fabrication trace also make the graphene have a trend to became thicker. It also found that growth temperature deeply affects the quality of graphene. At lower temperature, catalytic pyrolysis and diffusion rate of methane on copper surface are lower. As a result, the lower carbon concentration is conducive to the formation of single-layer graphene. But the defect of graphene tends to increase, due to the inhibition of graphitization. At higher temperature, catalytic pyrolysis and diffusion rate of methane on copper surface are higher, which make the carbon supply is more than the needs of graphene growth. So, the defect and layer of graphene tends to increase. And in the experiment1000℃is the optimal temperature to the graphene with little layer and defect. Hydrogen can catalyze the formation of the six-membered ring structure of graphene, inhibition the generated of amorphous carbon, but the increase of the hydrogen flow rate can reduce the growth rate of graphene. Moreover, H2flow rate also influences the conductivity of graphene. With H2flow rate increasing, the growth rate drop and the square resistance of graphene demonstrates an increasing trend.