| 1. |
- Coletti, C., et al.
(author)
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Revealing the electronic band structure of trilayer graphene on SiC: An angle-resolved photoemission study
- 2013
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 88:15
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Journal article (peer-reviewed)abstract
- In recent times, trilayer graphene has attracted wide attention owing to its stacking and electric-field-dependent electronic properties. However, a direct and well-resolved experimental visualization of its band structure has not yet been reported. In this paper, we present angle-resolved photoemission spectroscopy data which show with high resolution the electronic band structure of trilayer graphene obtained on alpha-SiC(0001) and beta-SiC(111) via hydrogen intercalation. Electronic bands obtained from tight-binding calculations are fitted to the experimental data to extract the interatomic hopping parameters for Bernal and rhombohedral stacked trilayers. Low-energy electron microscopy measurements demonstrate that the trilayer domains extend over areas of tens of square micrometers, suggesting the feasibility of exploiting this material in electronic and photonic devices. Furthermore, our results suggest that, on SiC substrates, the occurrence of a rhombohedral stacked trilayer is significantly higher than in natural bulk graphite.
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| 2. |
- Coletti, C., et al.
(author)
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Large area quasi-free standing monolayer graphene on 3C-SiC(111)
- 2011
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:8
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Journal article (peer-reviewed)abstract
- Large scale, homogeneous quasi-free standing monolayer graphene is obtained on cubic silicon carbide, i.e., the 3C-SiC(111) surface, which represents an appealing and cost effective platform for graphene growth. The quasi-free monolayer is produced by intercalation of hydrogen under the interfacial, (6 root 3 x 6 root 3)R30 degrees-reconstructed carbon layer. After intercalation, angle resolved photoemission spectroscopy reveals sharp linear pi-bands. The decoupling of graphene from the substrate is identified by x-ray photoemission spectroscopy and low energy electron diffraction. Atomic force microscopy and low energy electron microscopy demonstrate that homogeneous monolayer domains extend over areas of hundreds of square-micrometers. (C) 2011 American Institute of Physics. [doi:10.1063/1.3618674]
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| 3. |
- Forti, S., et al.
(author)
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Large-area homogeneous quasifree standing epitaxial graphene on SiC(0001): Electronic and structural characterization
- 2011
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 84:12
-
Journal article (peer-reviewed)abstract
- The growth of epitaxial graphene on SiC has been identified as one of the most promising techniques to produce graphene for electronic applications. In this paper, we present a systematic study of the electronic and structural properties of large-area quasifree standing epitaxial monolayer graphene grown on top of the SiC(0001) surface. For this purpose, we combine the thermal treatment of SiC in Ar atmosphere to achieve a homogeneous coverage of the surface with the hydrogen intercalation process, which leads to the removal of the interaction between the substrate and the carbon layer. The band structure in the vicinity of the (K) over bar point is measured using high-resolution angle-resolved photoelectron spectroscopy. A detailed analysis of the quasiparticle dynamics reveals a renormalization of the band velocity estimated to about 3% at energies around 200 meV below the Fermi level, which mainly originates from electron-phonon interaction. Further analysis of the momentum distribution curves leads to the formulation of a model for the doping reduction in such a system in the course of sample annealing above 650 degrees C. The uniformity and homogeneity of the graphene is demonstrated by means of low-energy electron microscopy (LEEM). Microphotoelectron spectroscopy data confirm the high structural quality and homogeneity of the quasifree standing graphene. Using LEEM and scanning tunneling microscopy, we demonstrate that the hydrogen desorption at elevated temperatures of approximately 750 degrees C sets in on the graphene terraces rather than via the step edges.
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| 4. |
- Forti, S., et al.
(author)
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Mini-Dirac cones in the band structure of a copper intercalated epitaxial graphene superlattice
- 2016
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In: 2D Materials. - : IOP Publishing. - 2053-1583. ; 3:3
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Journal article (peer-reviewed)abstract
- The electronic band structure of an epitaxial graphene superlattice, generated by intercalating a monolayer of Cu atoms, is directly imaged by angle-resolved photoelectron spectroscopy. The 3.2 nm lateral period of the superlattice is induced by a varying registry between the graphene honeycomb and the Cu atoms as imposed by the heteroepitaxial interface Cu/SiC. The carbon atoms experience a lateral potential across the supercell of an estimated value of about 65 meV. The potential leads to strong energy renormalization in the band structure of the graphene layer and the emergence of mini-Dirac cones. The mini-cones' band velocity is reduced to about half of graphene's Fermi velocity. Notably, the ordering of the interfacial Cu atoms can be reversibly blocked by mild annealing. The superlattice indeed disappears at∼220 °C.
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