| Summary: | 碩士 === 國立聯合大學 === 材料科學工程學系碩士班 === 105 === We used high-purity copper foil to grow graphene by chemical vapor deposition in this thesis. The parameters of substrate holder, gas flow rate, growth time, and temperature were adjusted to investigate the quality of graphene. SEM, OM, Raman, AFM and XRD were used to analysze the morphology and microstructure of the samples. The results show that the ratio of I2D/IG presented in Raman spectra can be up to 5.79, and most of the ID/IG were less than 0.4, showing that the single layer graphenes were synthesized successfully. On the other hand, according to the ratio of I2D/IG, few-layer graphen was obtained at 800 ℃. In addition, continuous layer of graphene with high coverage was observed in SEM as the growth temperature was high (1000 ℃), but films with crack was observed at lower temperature even the growth time was extended to more than 20 to 30 min. We found that the surface of copper foil was flattened at 900 ℃ and 1000 ℃, which is consist with the result of AFM, in which the Ra of copper foil can be reduced from 30.6 to 2.51 as the foil was annealed at 1000 ℃, which may reduce the nucleation sites to promote the growth of large-area graphene. Finally, we used XRD to investigate the effect of annealing on the orientation of copper foil, which is important to determine the shape and size of graphene layer. We found that the orientation of copper foil was transferred from (200) to (111), and then to (220) as the heating time was increased to 30 min. Triangle shape graphene with micrometer size was observed on the (111) surface, indicating that the substrate orientation affects the shape of graphene grain. More interesting, we found that SiO2 nanoparticles accompanied with the graphene, especially at high temperature. These nanoparticles may enhance the Raman scattering so that the I2D/IG can be larger than 5 for the graphene on copper. These nanoparticles may come from the etching of quartz tube or substrate holder by hydrogen gas, and we also assemble these nanoparticles via silicon nanostructure to create a novel nanoparticle foil in this thesis.
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