Rapid Chemical Vapor Deposition Of High Quality Graphene On Liquid Copper

Graphene as novel two-dimensional single-walled carbon atom nanomaterials, which is prepared by mechanical exfoliation since 2004, causes extensive research boom because of its unique variety of electrical, optical and thermal properties. Currently there are many methods of preparing graphene, mainly are mechanical exfoliation, chemical vapor deposition, Si C epitaxial growth, chemical reduced oxide and so on, wherein the method of chemical vapor deposition is a controlled preparation of large-area graphene of high quality method. The method of chemical vapor deposition is easy and convenient to operate, and it can combine with the next step of graphene transferring and graphene application. Now the method of chemical vapor deposition has become the mainstream method of graphene growth. But most of the growth of graphene using conventional chemical vapor deposition method will take a few hours, limiting further application of graphene, so looking for a method for the rapid growth of high-quality graphene is imminent.In this thesis, graphene is grown using vertical cold wall CVD system that can quickly heating and cooling, thereby reducing the growth time of graphene, but the fast-growing single-crystal graphene grains on copper are relatively small and the defect density is relatively high. In order to solve this problem, the rapid growth of graphene on liquid copper to improve the area of graphene grains and reduce the defect density is studied. Due to the elimination of grain boundaries in the solid copper, the growth of graphene on liquid copper leads to a uniform, low-density, self-aligned distribution of nucleation. While the method for transferring graphene grown on copper foil was improved to make it more suitable for the transferring graphene grown on liquid copper.The main work of this thesis was as follows.(1) The graphene grown on liquid copper in different methane flow and different growth time are studied with the optical microscope, the scanning electron microscope, and the Raman spectroscopy to analyze the morphology, the defect density and quality of graphene. And simultaneously the graphene grown on liquid copper are compared with the graphene grown on solid copper. The case of innovative achievements of this thesis is the combination of the rapid growth system and the growth on liquid copper to grow high-quality graphene. The rapid growth of graphene on liquid copper which compared to the rapid growth of graphene on solid copper requires approximately same growth time(about 40 minutes) finally not only growed large-area graphene single crystals(diameter greater than 100?m) and a uniform continuous single-layer graphene, while the Raman spectrums show that this method can greatly reduce the defect density in the grown graphene. This research is significant for large-scale production and application of high-quality graphene.(2) Preparation of the back-gated graphene field effect device is an important method of studying the electrical properties of graphene(square resistance, mobility). In this thesis the preparation and the measurement of the back-gated graphene field effect transistor were studied. Graphene was transferred on the electrodes in the preparation of the back-gated graphene field effect transistor. This structure can reduce the damage to graphene during the preparation of device and improve the success rate of preparation. Since the water molecules and the gas molecules in the air are adsorbed on the surface of the graphene, thus the electrical properties of graphene are degraded. In order to solve this problem, when testing the back-gated graphene field effect transistor, the devices are heated to desorb the water molecules and the gas molecules adsorbed on the surface of graphene, thereby reducing the impact on the electrical properties of graphene. This research is significant for the production of high-performance graphene devices.