Proposal for the Undergraduate Research Award Title of the Activity : Controlled Growth of Graphene by Chemical Vapor Deposition

Graphene, firstly isolated in 2004, is a new type of carbon materials, which contains a singleor few-layered sheet of Sp2-bonded carbon atoms. This special atomic structure gives graphene rich physical properties and wide potential applications. It has excellent electrical, mechanical, thermal and optical properties and has wide applications in nanoeletronic devices, transparent conductive films, power storage, composites materials et al. In our program, CVD method will be used to fabricate large area and high quality graphene, which will pave the way for its applications. We will also investigate the growth mechanism of graphene on different metal substrates. Background: Graphene is a kind of magical materials which combines special 2D structure and diverse outstanding performance. The electron mobility of graphene is about 100 times faster than silicon, exhibiting the ballistic transport properties in submicron-scale at room temperature. Graphene is almost transparent with only 2.3% photoabsorption in a wide excitation range. Besides, graphene is about 100 times as strong as steel, excellent flexibility and ductility, up to 2600m2/g specific surface area. Its thermal conductivity is 10 times faster than copper. With these excellent physical properties, graphene has wide application in many fields. For instance, with its super-high electron mobility it can be used as high frequency transistor; with its high conductivity, high transmission and flexibility, it can be used as flexible transparent conductive films which is frequently used in touch screen and solar cell, etc; with its high strength and high thermal conductivity, it can improve the performance of traditional materials; and with its high specific surface area, it can be used as electrode materials for high performance lithium battery and super capacitor. The preparation of graphene is the premise and basis of understanding its physics and realizing its application. Mechanical cleavage of graphite is the earliest way to prepare graphene with high quality and excellent electrical properties, which has been widely used in studying graphene's physical properties and apparatus. However, this method is inefficient, with big randomicity and low productivity, which is difficult to realize large-scale production. Hereafter, the epitaxial growth based on SiC single crystal and metal single crystal, chemical exfoliation, chemical vapor deposition (CVD) and organic synthesis have been developed. Epitaxial growth based on SiC can obtain relative high quality graphene, but the preparation condition is demanding, and it need high level vacuum, meanwhile, the cost is high and the productivity is low. Chemical exfoliation can be used for large-scale preparation, however it has numerous defects. Recently, CVD is a kind of new way to prepare graphene, the process is simple and the quality is high, which can also be used in large-scale production, meanwhile, it can be easily transferred to other substrate. Therefore, CVD graphene is widely used in making nano-electronic devices and transparent conducive films, and it gradually becomes the primary ways to prepare high quality grapheme films. Recently, researchers focused on large area preparation of graphene by CVD. Nickel and Copper substrates are most widely used. The grain size of Nickel is small and the number of graphene layers achieved was difficult to be controlled. Copper substrates were used to prepared single-layered graphene. Recently, 30 inches of graphene films was prepared on Copper substrate and the quality and conductivity were improved correspondingly. However, how to further improve the quality, i.e. single crystal domain size, and the controllability of graphene thickness is still a tough issue and research interest, which restricts the application of graphene. Research plan: In this program, we will investigate the growth mechanism of graphene on different metal substrates and the effect of growth condition on graphene structure by CVD method. We will prepare large area, high quality graphene with good controllability, which will pave the way for applications. First, we will search the references on CVD graphene and be familiar with the CVD growth method. We will then build CVD furnace and prepare graphene on different substrates(Cu, Ni, and their allys). We will use substrate corrosion method to remove the metal substrate and transfer graphene to SiO2/Si substrates. Optical microscope will be used to observe the uniformity. Raman spectrum will be used to investigate the layer number, defects, and doping effect. Conductivity will be measured by four point method. Finally, we will systematically study the effect of substrate, reacting temperature, gas concentration, growing time, reacting gas atmosphere on graphene structure. We are aim to clarify the growth mechanism and control the growth of graphene. Time schedule: 2012 Jan.-Mar.: Search and read references. 2012 Apr.-Aug.: Systematically study about the effect of substrate structure, growth temperature, gas concentration, growth time, reacting gas atmosphere on graphene structure. We will optimize the transfer process, characterize the sample and obtain the optimal growth conditions. 2012 Sep.-Oct.: Prepare project final report. 2012 Nov.-Dec.: Summary our work and submit final report. Results to be expected: We will prepare graphene with different thickness, large area, continuous and uniformly distributed, which will provide the basis for application in nanoelctronic devices and photoelectronic devices. Budget Materials (carbon source, gas, etc.) $1,000.00 Substrates (copper, nickel, etc.) $500.00