Research On Large Area Monolayer Graphene And 3D-structured Graphene Prepared By APCVD

Graphene, a two-dimensional honeycomb lattice of sp2-bonded carbon atoms, has attracted worldwide interest and plays a decisive role in the field of material science since its experimental isolation from graphite. Due to its extremely high intrinsic carrier mobility, high transparency and remarkable tensile strength make graphene a promising material in a wide range of application, including electronics, spintronics, optoelectronics, sensors, batteries and supercapacitors. Especially in in the field of microelectronics, graphene is regarded as the best choice to instead of traditional silicon materials. But all this is on the premise of preparation of high-quality graphene in large batch. Considering various preparation methods, chemical vapor deposition method is considered to be the most promising method for the preparation of large area high-quality graphene.However, graphene prepared by chemical vapor deposition is still challenging. In most experiments, the growth of graphene needs low pressure environment, which makes the high cost of graphene. Moreover, the graphene grown on the metal substrate needs transferring for practical application. These problems still need further study.According to the present research, this thesis mainly carried on the following two aspects.In view of the defects of low pressure vapor deposition, we explore the best conditions of large area monolayer graphene on copper substrate by chemical vapor deposition under atmospheric pressure. Based on literature summary and continuous experimental optimization, the appropriate parameters are obtained after optimization. We also constructed a quasi-confined space by two ceramic boats. During the growth of graphene, the quasi-confined space ot only suppresses the evaporation loss of copper but also creates a stable air environment. Thus, large area high-quality monolayer graphene can be obtained under ambient pressure. The raman mapping proved the single layer coverage of the sample is above 95%.Because the graphene powder obtained by chemical preparation methods shows low quality and reunites easily, we prepared the three-dimensional graphene by using nickel foam as the substrate via APCVD (ambient pressure chemical vapor deposition). The three-dimensional (3D) graphene shows good quality and large specific surface area. Through optimization experiments, we obtained good quality 3D graphene under low hydrogen and methane flow. After removing the nickel, the three-dimensional structure of the sample is still remained. The raman results show that the three-dimensional graphene is about four-layer thick.