Study On Structures And Properties Of Graphene Flims Prepared By DBD Plasmas

Graphene, the recent discovered two-dimensional carbon crystal has attracted wide attention because of its unique electrical and mechanical properties. The potential for applications in the electronic industry is recognized by scientists. However, the fabrication difficulty of a large area, high-quality graphene is a bottleneck for its application.In this paper, graphene was grown by DBD plasma enhanced chemical vapor deposition and the influences of processing parameters on graphene growth were studied. The as-deposited graphenes by DBD plasma were characterized by optical microscope, atomic force microscopy, scanning electron microscope and Raman spectroscopy, while its optical and electrical properties were also measured. From the experiments we got the following conclusions:(1) Substrates affect the graphene growth. Polished nickel plate and nickel-plated silicon substrate are used to prepare graphene, respectively. The size of graphene layer can reach the whole surface in nickel plate. It is noticed that the roughness of nickel plate and the thickness of nickel film on silicon substrate both play important role in graphene growth.(2) Find the primary process of graphene growth. The growth of graphene involves two processes:at the first stage carbon dissolved in the nickel substrate at high temperature, then due to a rapid quenching, the doped carbon atoms are out-diffused to the surface of the nickel substrate and form graphene layers. The increase in the proportion of methane, deposition time, discharge power provides more carbon at the growth process, which is conducive to the precipitation of carbon in the nickel surface. While the temperature increases the solubility of carbon in nickel, thus more carbon precipitation at the cooling stage. The essence of controlling graphene layers and the quality is to control the precipitation of carbon on the surface of the nickel, where the temperature, methane ratio, deposition time and discharge power play a significant role on the process.(3) The thickness of the catalyst on substrates is an important factor for graphene growth. For nickel-plated silicon substrates, the growth of graphene has a considerable relation to thickness of the nickel. If the nickel catalysts thinner, such as less than 50nm, nickel films easily accumulated to form particles and catalyze carbon nanotube growth, whereas a thicker layer of nickel can produce a good-quality graphene. (4) DBD plasma can fabricate a good property of graphene. Graphene is transferred to the glass substrates. The optical transmittance rate is more than 80% and the sheet resistance of graphene is 1000-5000Ω/□...