Figure 1.1. Graphene is an atomic-scale honeycomb lattice made of carbon atoms. 28

Figure 1.2. Hexagonal crystal lattice of graphene sheet 29

Figure 1.3. Graphene (top) consist of a 2D hexagonal lattice of carbon atoms. Each atom is covalently bonded to three others; but since carbon has four valence electrons, one is left free-allowing graphene to conduct electricity. Other well-know form of carbon all derive from graphene: graphite is stack of graphene layers (bottom right); carbon nanotubes are rolled-up... 30

Figure 1.4. Idealized structure proposed for graphene oxide (GO) 31

Figure 1.5. The band structure of graphene. The conduction band and valence band touch at the K point or six corners of the Brillouin zone. 33

Figure 1.6. QHE for massless Dirac fermions in single layer graphene. Hall conductivity (σxy) and longitudinal resistivity (ρxx) of graphene as a function of their concentration at B ＝ 14T and T ＝ 4K. The plateau occur half integer for high energy level results in a ladder of equidistant steps in Hall conductivity. Inset shows the σxy in...(이미지참조) 36

Figure 1.7. Quantum Hall effect in bilayer graphene. 37

Figure 1.8. (a) Photograph of a 50-μ m aperture partially covered by graphene and its bilayer. The line scan profile shows the intensity of transmitted white light along the yellow line. Inset shows the sample design: a 20-μm thick metal support structure has apertures 20, 30, and 50 μm in diameter with graphene flakes deposited over them; (b) Optical image of graphene flakes... 39

Figure 1.9. Mechanical exfoliation of graphene using scotch tape from HOPG. 43

Figure 1.10. (a) Schematic illustration of the graphene exfoliation process. Graphite flakes are combined with sodium cholate (SC) Horn-ultrasonication exfoliates few-layer graphene flakes that are encapsulated by SC micelles. (b) Photograph of 90 μmL-1 graphene dispersion in SC 6 weeks after it was prepared. (c) Schematic illustrating an...(이미지참조) 44

Figure 1.11. Schematic of (left side) thermal CVD and (right side) plasma-enhanced CVD (PECVD) 46

Figure 1.12. (a) Scheme showing the chemical route to the synthesis of aqueous graphene dispersions. (1) Oxidation of graphite (black blocks) to graphite oxide with greater interlayer distance. (2) Exfoliation of graphite oxide in water by sonication to obtain GO colloids that are stabilized by electrostatic repulsion. (3) Controlled conversion of GO colloids to conducting... 48

Figure 1.13. Unzipping of carbon nanotubes. (a, b) Representation of the gradual unzipping of a carbon nanotube by chemical attack method, and TEM image of a resulting nanoribbon. (c, d) The process to produce nanoribbons by plasma etching of nanotubes and an AFM image of a resulting nanoribbon. 49

Figure 2.1. (a) Graphene oxide colloid (1 mg/mL) and (b) the corresponding reduced graphene oxide colloid. 57

Figure 2.2. SEM images of (a) graphite powders (b) GO, (c) TEM image of GOand (d) AMF image of GO and the height profile in selected location 61

Figure 2.3 TEM image of RGO, the inset is the resultant SAED pattern, (b) two- and (c) three dimensional AFM images of the RGO-1100˚C film. 62

Figure 2.4. XRD patterns of raw graphite powder, GO, R-GO, thermally annealed GO and R-GO films at 1100˚C for 30min. 64

Figure 2.5. XRD patterns of raw graphitepowder, GO, R-GO, thermally annealed GO and R-GO films at 1100˚C for 30min. 66

Figure 2.6. UV-vis spectra of GO and R-GO, thermally annealed GO and R-GO films at 1100 ˚C for 30min. 67

Figure 2.7. FT-IR spectra of raw graphite material, dried GO, RGO and RGO filmsannealed at 1100˚C for 30 min 68

Figure 2.8. Raw XPS spectra of (a) GO, (b) RGO, (c) GO-1100oC and (d) RGO-1100˚C annealed for 30 min. 70

Figure 2.9. High resolution XPS spectra of (a) GO, (b) RGO, (c) GO and RGO annealed at 1100˚C for 30 min. 72

Figure 2.10. (a) Sheet resistance of GO and R-GO varied as a function of annealing temperature. (b) Variation sheet resistance of R-GO film with H₂ flow rate, annealing at 1100˚C for 30 min. (c) Sheet resistance of R-GO films as a function of annealing time. 74

Figure 2.11. Current-voltage curves of R-GO, thermally reduced GO and RGO films. 76

Figure 3.1. (a) Two-dimensional and (b) three-dimensional AFM images of N-doped graphene films 84

Figure 3.2. XRD patterns of graphite, intact GO and N-doped graphene at different temperatures. 85

Figure 3.3. Raw scan XPS spectra of graphite, GO and N-doped graphene at different temperatures. 87

Figure 3.4. High resolution C1s XPS spectra of graphite, intact GO and N-doped graphene at 600˚C, 700˚C, 800˚C and 900˚C. 89

Figure 3.5. N1s XPS spectra of graphite, intact GO and N-doped graphene at 600˚C, 700˚C, 800˚C and 900˚C. 90

Figure 3.6. FTIR spectra of graphite, intact GO, N-doping graphene at 600, 700, 800 and 900˚C. 92

Figure 3.7. Raman scattering spectra of graphite, intact GO, and N-doped graphene at different temperatures. 95

Figure 3.8. PL spectra of intact GO, 600oC-annealed GO, 700˚C-annealed GO, 800˚C-annealed GO, and 900˚C-annealed GO. 96

Figure 4.1. Raw scan XPS spectra of (a) graphite powders, (b) GO, (c) RGO and RGO annealed for (d) 0.5h, (e) 1h, (f) 2h, (g) 3h and (h) 4h; and their corresponding contents (bottom). 106

Figure 4.2. High resolution C1s XPS spectra of graphite and GO. 107

Figure 4.3. High resolution C1s XPS spectra of RGO and RGO annealed for different times at 1100˚C. 109

Figure 4.4. High resolution N1s XPS spectra of RGO and RGO annealed for different times at 1100˚C. 112

Figure 4.5. FTIR spectra of (a) graphite powders, (b) GO, (c) RGO and RGO annealed for (d) 0.5h, (e) 1h, (f) 2h, (g) 3h and (h) 4h at 1100˚C. 114

Figure 4.6. Raman spectra of (a) graphite powders, (b) GO, (c) RGO and RGO annealed for (d) 0.5h, (e) 1h, (f) 2h, (g) 3h and (h) 4h at 1100oC; and their corresponding intensity ratio ID/IG (bottom).(이미지참조) 116

Figure 4.7. XRD patterns of (a) graphite powders, (b) GO, (c) RGO and RGO annealed for (d) 0.5h, (e) 1h, (f) 2h, (g) 3h and (h) 4h at 1100˚C. 118

Figure 4.8. (a) Cross-section FE-SEM image of a graphene film on glass substrate, (b) optical microscopy image of the four-point probe measurement setup. The digital images of as-prepared GO, RGO, and N-doped RGO films (top right). 121

Figure 4.9. Current-voltage curves of (a) GO, (b) RGO and RGO annealed for (c) 0.5h, (d) 1h, (e) 2h, (f) 3h and (g) 4h at 1100˚C. 122

Figure 4.10. Room temperature PL spectrum of GO. 124

Figure 4.11. Room temperature PL spectra of RGO and RGO annealed for different times at 1100˚C. 127

Figure 5.1. (a) SEM images of GO, (b) TEM image of single layer GO and (c) HRTEM image of a single layer GO. 139

Figure 5.2. Non-contact mode AMF images of GO sheets deposited on Si wafer show the presence of single or bi-layer obtained from exfoliation in ethanol via sonication. 140

Figure 5.3. (a) Two-dimensional and (b) three-dimensional AFM images of B-dopedgraphene oxide films 141

Figure 5.4. XRD patterns of as-synthesized GO, 1100˚C-annealed GO, and B-doped GO. 142

Figure 5.5. (a) First-order Raman spectra of graphite, GO, 1100oC-annealed GO, and B-doped GO. (b) Second-order Raman spectrum of B-doped GO. 143

Figure 5.6. Raw scan XPS spectra of graphite, as-synthesized GO, 1100oC-annealed GO, and B-doped GO. 145

Figure 5.7. C1s XPS spectra of (a) graphite, (b) GO, (c) 1100oC-annealed GO, and (d) B-doped GO. 147

Figure 5.8. Figure 7 B1s XPS spectrum of B-doped GO. 148

Figure 5.9. FTIR spectra of GO, GO-annealed 1100oC and B-doped GO. 149

Figure 5.10. PL spectra of GO, 1100˚C-annealed GO, and B-doped GO. 152