Synthesis of Large-Area Single-Crystalline Graphene by Enclosure-Assisted Chemical Vapor Deposition
Date Issued
2015
Date
2015
Author(s)
Ling, Tzu-Justine
Abstract
Graphene has been highly paid attention to since its discovery because of the highly chemical stability, high carrier mobility, thermal conduction, and the unique optical properties. It is the candidate of the new 2D material and has the potential to replace the silicon transistor. As a result, synthesizing large-area and high-quality graphene has been the popular research recently. In our research, we synthesize large-area and high-quality single-crystalline graphene on copper foil by chemical vapor deposition. In order to enlarge the graphene domain size, the key point is to lower its nucleation density. We try several methods, including the copper pretreatment, device design and parameter adjustment during the graphene growth. In the part of copper pretreatment, we do electropolishing and oxidation. Because the active carbon species grow along the copper surface and the morphology of copper affects the quality of graphene, we do electropolishing to flatten the copper surface to lower the possibility of the graphene nucleation. On the other hand, we oxidize copper to form cuprous oxide(Cu2O) and cupric oxide(CuO2) on the surface. During the high temperature, carbon atoms will act with oxide and become carbon oxide(CO) and carbon dioxide(CO2) which leave the surface. This also helps to reduce the nucleation density. During synthesis, we design a special CVD reactor to allow the graphene to grow within a confined reaction space, which also reduces the nucleation density. Finally, we use optical microscope, electron microscope, Raman spectrometer and selected-area electron pattern(SAED) to identify the quality of graphene. From now on, we have successfully synthesized single-crystalline graphene with 700 μm in diagonal length.
Subjects
graphene
single crystalline
chemical vapor deposition(CVD)
electro-polishing
Type
thesis
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