(Color online) Raman spectra taken from two points on the sample showing graphene-related D, G, and 2-D bands. The inset shows the bands of the TO and LO of SiC at lower wave numbers, indicating the polycrystalline nature of the 3 C-SiC substrate. The curves are vertically offset for clarity.
(Color online) Graphene on polycrystalline 3 C-SiC. (a) Large scale STM image (1250 × 1250 nm2, VT = 2.1 V) showing the global topography. (b) Topographic and corresponding differentiated (c) STM images (110 × 110 nm2, VT = 2.8 V) showing grain boundaries and moiré patterns (∼2.8 nm in Region I and ∼5.0 nm in Region II) on a terrace. The bead-like domain boundaries are highlighted by green dash-dotted curves. Graphene between two beads is continuous, highlighted by the yellow square. A boundary between discontinous graphene (Regions I and II) is highlighted by a yellow oval. (d) Atomically resolved STM image (15 × 15 nm2, VT = 0.5 V) showing the (√3 x √3) R30° superstructure arising from intervalley scattering at the domain boundary.
(Color online) STM images in high resolution. (a) STM image (60 × 60 nm2, VT = 3.4 V) showing three kinds of graphene with different appearances: A, monolayer graphene on 3 × 3 reconstructed SiC surface; B, few layers of graphene with complex moiré pattern; C, normal graphene in AB stacking. (b) STM image (25 × 25 nm2, VT = 2.5 V) showing Area A with a Kagome lattice. (c) Proposed model of the Kagome structure. (d) Zoomed-in STM image (5 × 5 nm2, VT = 0.2 V) showing the honeycomb structure, highlighted by a blue hexagon, of monolayer graphene on the 3 × 3 reconstructed SiC surface. (e) STM image (20 × 10 nm2, VT = 0.2 V) showing the complex moiré pattern in Area B at atomic scale.
(Color online) dI/dV − VT spectra acquired from Areas A, B, and C in Fig. 3(a), respectively. Each spectrum is spatially averaged on 20 points. Setpoint: I = 150 pA, VT = 0.4 V. The spectra are offset vertically for clarity.
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