The Study Of Synthesis Of Large Area Graphene

In the recent few years, graphene has been widely reported. Because of its high strength, high conductivity, high electron mobility at room temperature and the special quantum Hall effect, the graphene device have great development space in the future. Excellent graphene devices require high-quality graphene. How to get high quality graphene is the hot topic for researchers. In this paper, we focused on the growth and characterization of graphene.Firstly, we investigated the preparation of graphene by conventional CVD process, in which clean Cu foil was utilized as a catalyst substrate. After completion of growth, the transferred graphene square resistance was 1422?/□.Secondly, we explored an innovative research to grow graphene on Si/SiO2 substrate directly by MWPCVD. We used Cu as catalyst to synthesize graphene in the new method at first, in particular, we analyzed the key parameters, including the ratio of methane, hydrogen flow rate, growth temperature and the growth time, how to influence the quality of graphene, then we optimized the parameters, and explored an optimized terms of the growth of graphene. Next, we investigated Ni was used as catalyst to product graphene directly, and we made out the best parameters. In the last, we investigated the catalyst performance of NiCu alloy for graphene growth directly, and the best growth parameters. The results show the high quality sample could be grown at a low temperature when we use Ni as catalyst to synthesize graphene.Thirdly, the resistivity and Raman Spectroscopy of the samples synthesized by different catalyst were characterized. The result showed that, when Cu was used for catalyst, the best parameters were: growth temperature of 950 ℃, CH4 flow rate of 25 sccm, H2 flow rate of 275 sccm and the growth time of 7 min. Optimized parameters for Ni as catalyst were: growth temperature of 700 ℃, CH4 flow rate of 10 sccm, H2 flow rate of 275 sccm, the growth time of 3 min. For NiCu catalyst, the optimized parameters were that temperature was set to 950 ℃, CH4 flow rate to 25 sccm, H2 flow rate to 275 sccm and the growth time to 7 min.Finally, the SEM images indicated a smooth surface morphology and less breakage in our synthesized graphene samples. The electron constituency diffraction patterns stated clearly that prepared graphene presented integrated lattice and less defects. The co ming optical permeability test results showed that transmittance is more than 95% at the wavenumber light range of 500 ~ 4000cm-1, indicating high optical permeability. Finally, the carrier mobility measure results display the graphene has high carrier transport characteristics.