石墨烯形貌&物相

The characterization of grephene ￿班￿09￿材料三班 ￿￿￿ 朱杉（￿￿ 校稿） ￿强（文章撰写） 高厚仁（￿料收集） ￿宏翔（文章撰写） 开￿尔江（其他） 石墨石墨石墨石墨￿￿￿￿的表征方法的表征方法的表征方法的表征方法 1 Introduction ￿Graphene ￿ a two-dimensional, single-layer sheet of sp2-hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties. 1.1 Synthesis of graphene ￿Mechanical exfoliation ￿Chemical vapor deposition CVD ￿Chemically derived graphene ￿Other synthesis approaches 1.2 Properties and characterization ￿High electronic conductivity ￿Good thermal stability ￿Excellent mechanical strength 2 Morphology analysis ￿Atom Force Microscope （AFM） ￿Scanning Tunnel Microscope （STM） ￿Scanning Electron Microscope（SEM） ￿Optical Microscope （OM） 2.1 AFM ￿Preparation ￿Observation ￿Perance test Fig1. SEM images of early attempts at mechanical exfoliation using graphite pillars Fig2. 3D model of AFM tip/specimen contact Fig3. Mechanical exfoliation produced the very first single layer graphene flakes. Fig4.a 8 μm x8 μm AFM topography b Pseudo-3D representation Fig5. Schematic of AFM tip/specimen contact under negative and positive appliedloads. Fig6. Fig7 . AFM image of the graphene specimen, 2D profiles at the six different regions and the thickness at the six sites indicated on the image Fig8. AFM images of graphene specimen a before and b after wear test. Fig9. a AFM image of wear tracks and b the cross-sections of wear tracks. 2 Morphology analysis ￿￿Atom Force Microscope （AFM） ￿Scanning Tunnel Microscope （STM） ￿Scanning Electron Microscope（SEM） ￿Optical Microscope （OM） 2.2 STM Fig10. a STM image of graphite showing only the three carbons that eclipse a neighbor in the sheet directly below. b In contrast,all six carbons are equivalent and thus visible in mechanically exfoliated single-layer graphene. 2 Morphology analysis ￿￿Atom Force Microscope （AFM） ￿￿Scanning Tunnel Microscope （STM） ￿Scanning Electron Microscope（SEM） ￿Optical Microscope （OM） Fig11.Graphene nanofabric. SEM micrograph of a strongly crumpled graphene sheet on a Si wafer. Note that it looks just like silk thrown over a surface. Lateral size of the image is 20 microns. Si wafer is at the bottom-right corner. 2.3 SEM Fig12.abSEM image of graphene 1 Morphology analysis ￿￿Atom Force Microscope （AFM） ￿￿Scanning Tunnel Microscope （STM） ￿￿Scanning Electron Microscope（SEM） ￿Optical Microscope （OM） 2.4 OM Figure 13. The interference pattern we calculate can be convertedinto RGB colors a and the comparison with the experimentally observed colors b is good. The red c, green d, and blue e components from the same image reproduce the main features of our numerical result in Figure 2b. While image b was not modified in any way, contrast on panels c, d, and e was maximized for better visibility. f Large-scale atomic force scan for thickness reference. Figure 14. Image of big graphite flake containing regions of many different thicknesses. A ultrathin graphite region thickness below 2nm is highlighted by a dashed rectangle. aOM;bAFM;cSEM Fig15. Optical reflection and transmission schematic for a layered thin-film system consisting of a dielectric film Al2O3, SiO2,or Si3N4 on silicon wafer left part and graphene added on the dielectric film right part. 3 Phase analysis ￿X-Ray Diffraction（XRD） ￿Transmission Electron Microscope （TEM） 2.1 XRD Fig17.XRD patterns of graphitea、graphite oxideband graphenec Fig18. XRD patterns of a before the CVD growth and b after the CVD growth of graphene multi-layers. Open circles graphen multi-layers,open square Fe, solid circles Fe3C 3 Phase analysis ￿￿X-Ray Diffraction（XRD） ￿Transmission Electron Microscope （TEM） Fig 19 aTEM images to show an example of a graphene. Fig20.The relative SAED pattern of the graphene sample 3.2 TEM Fig21a,b High-resolution TEM images d,e Electron diffraction patterns taken from the positions of the d black and e white 500nm500nm Fig 22 aTEM images and SAED pattern together to show an example of a graphene grain. bBright field TEM image of two coalesced grains and SAED. The SAED patterns have been filtered Fig23.TEM image and SAED pattern of the GNS film a, b. TEM imageand SAED pattern of the a-CNP/GNS composite film c, d 4 Conclusion ￿With new access to 2D crystallites, experimentalists scrambled to confirm results long predicted by theory. Before they could do so, techniques needed to be developed for the characterization of deposited flakes. ￿In light of such collaborations, it is difficult to believe that the future for graphene is anything but bright. Thank youThank youThank youThank you. . . .