Characteristics of Pristine and Doped Graphene Synthesized by Chemical Vapor Deposition

Chemical vapor deposition (CVD) is an extremely useful process for atomic layer deposition of extremely thin layers of material and for the synthesis of various kinds of nano-electronic materials. In this manuscript, among the various nanomaterials, graphene will mainly be described as an example. Controlling the properties of graphene is a very important and attractive issue in graphene research. As we know, graphene is obtained from natural graphite or artificially synthesized; the latter case is easier than the former for manipulating the properties of graphene. Based on this motivation, we investigated the synthesis conditions of pristine and doped graphene when using CVD with various organic precursors, such as methane (CH4), pyridine (C5H5N), liquid petroleum (LPG) and so on. For the synthesis of high-quality graphene, the growth condition was optimized by controlling the CVD parameters. As a result, we were able to grow successfully graphene and doped graphene in a very short time that was 10 times faster than the typical growth time when using CVD with methane (CH4). In the Raman spectra, the 2D/G and the D/G ratios for the samples were significantly different, depending on the supply source. Especially, in the case of N-doped graphene grown using a pyridine source, the D-peak intensity was increased, the G-peak was blue shifted and the 2D-peak intensity was suppressed. In the X-ray photoelectron spectra, the pristine graphene exhibited clear C1s-peaks while the N-doped graphene exhibited an asymmetric broad C1s-peak due to the C-N bond and a N1s-peak due to the graphitic-N bond. In addition, based on these recipes, we developed a roll-to-roll CVD system for continuous growth. The system can produce a 10-m-long graphene film within 1 h by using this technique.