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Mesple F, Walet NR, Trambly de Laissardière G, Guinea F, Došenović D, Okuno H, Paillet C, Michon A, Chapelier C, Renard VT. Giant Atomic Swirl in Graphene Bilayers with Biaxial Heterostrain. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2306312. [PMID: 37615204 DOI: 10.1002/adma.202306312] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/10/2023] [Indexed: 08/25/2023]
Abstract
The study of moiré engineering started with the advent of van der Waals heterostructures, in which stacking 2D layers with different lattice constants leads to a moiré pattern controlling their electronic properties. The field entered a new era when it was found that adjusting the twist between two graphene layers led to strongly-correlated-electron physics and topological effects associated with atomic relaxation. A twist is now routinely used to adjust the properties of 2D materials. This study investigates a new type of moiré superlattice in bilayer graphene when one layer is biaxially strained with respect to the other-so-called biaxial heterostrain. Scanning tunneling microscopy measurements uncover spiraling electronic states associated with a novel symmetry-breaking atomic reconstruction at small biaxial heterostrain. Atomistic calculations using experimental parameters as inputs reveal that a giant atomic swirl forms around regions of aligned stacking to reduce the mechanical energy of the bilayer. Tight-binding calculations performed on the relaxed structure show that the observed electronic states decorate spiraling domain wall solitons as required by topology. This study establishes biaxial heterostrain as an important parameter to be harnessed for the next step of moiré engineering in van der Waals multilayers.
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Affiliation(s)
- Florie Mesple
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, 38000, France
| | - Niels R Walet
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PY, UK
| | - Guy Trambly de Laissardière
- Laboratoire de Physique Théorique et Modélisation (UMR 8089), CY Cergy Paris Université, CNRS, Cergy-Pontoise, 95302, France
| | - Francisco Guinea
- Imdea Nanoscience, Faraday 9, Madrid, 28015, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizábal 4, San Sebastián, 20018, Spain
| | | | - Hanako Okuno
- University Grenoble Alpes, CEA, IRIG-MEM, Grenoble, 38054, France
| | - Colin Paillet
- Université Côte d'Azur, CNRS, CRHEA, Rue Bernard Grégory, Valbonne, 06560, France
| | - Adrien Michon
- Université Côte d'Azur, CNRS, CRHEA, Rue Bernard Grégory, Valbonne, 06560, France
| | - Claude Chapelier
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, 38000, France
| | - Vincent T Renard
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, 38000, France
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Ben Jabra Z, Abel M, Fabbri F, Aqua JN, Koudia M, Michon A, Castrucci P, Ronda A, Vach H, De Crescenzi M, Berbezier I. Van der Waals Heteroepitaxy of Air-Stable Quasi-Free-Standing Silicene Layers on CVD Epitaxial Graphene/6H-SiC. ACS NANO 2022; 16:5920-5931. [PMID: 35294163 DOI: 10.1021/acsnano.1c11122] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Graphene, consisting of an inert, thermally stable material with an atomically flat, dangling-bond-free surface, is by essence an ideal template layer for van der Waals heteroepitaxy of two-dimensional materials such as silicene. However, depending on the synthesis method and growth parameters, graphene (Gr) substrates could exhibit, on a single sample, various surface structures, thicknesses, defects, and step heights. These structures noticeably affect the growth mode of epitaxial layers, e.g., turning the layer-by-layer growth into the Volmer-Weber growth promoted by defect-assisted nucleation. In this work, the growth of silicon on chemical vapor deposited epitaxial Gr (1 ML Gr/1 ML Gr buffer) on a 6H-SiC(0001) substrate is investigated by a combination of atomic force microscopy (AFM), scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy measurements. It is shown that the perfect control of full-scale almost defect-free 1 ML Gr with a single surface structure and the ultraclean conditions for molecular beam epitaxy deposition of silicon represent key prerequisites for ensuring the growth of extended silicene sheets on epitaxial graphene. At low coverages, the deposition of Si produces large silicene sheets (some hundreds of nanometers large) attested by both AFM and SEM observations and the onset of a Raman peak at 560 cm-1, very close to the theoretical value of 570 cm-1 calculated for free-standing silicene. This vibrational mode at 560 cm-1 represents the highest ever experimentally measured value and is representative of quasi-free-standing silicene with almost no interaction with inert nonmetal substrates. From a coverage rate of 1 ML, the silicene sheets disappear at the expense of 3D Si dendritic islands whose density, size, and thickness increase with the deposited thickness. From this coverage, the Raman mode assigned to quasi-free-standing silicene totally vanishes, and the 2D flakes of silicene are no longer observed by AFM. The experimental results are in very good agreement with the results of kinetic Monte Carlo simulations that rationalize the initial flake growth in solid-state dewetting conditions, followed by the growth of ridges surrounding and eventually covering the 2D flakes. A full description of the growth mechanism is given. This study, which covers a wide range of growth parameters, challenges recent results stating the impossibility to grow silicene on a carbon inert surface and is very promising for large-scale silicene growth. It shows that silicene growth can be achieved using perfectly controlled and ultraclean deposition conditions and an almost defect-free Gr substrate.
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Affiliation(s)
| | - Mathieu Abel
- Aix Marseille University, CNRS, IM2NP, Marseille 13397, France
| | - Filippo Fabbri
- NEST, Istituto Nanoscienze-CNR, Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Jean-Noel Aqua
- Institut des Nanosciences de Paris, Sorbonne Université, CNRS, INSP, UMR 7588, 75005 Paris, France
| | - Mathieu Koudia
- Aix Marseille University, CNRS, IM2NP, Marseille 13397, France
| | - Adrien Michon
- Université Côte d'Azur, CNRS, CRHEA, Valbonne 06560, France
| | - Paola Castrucci
- Dipartimento di Fisica, Università di Roma Tor Vergata, Roma 00133, Italy
| | - Antoine Ronda
- Aix Marseille University, CNRS, IM2NP, Marseille 13397, France
| | - Holger Vach
- LPICM, CNRS, Ecole Polytechnique, IP Paris, Palaiseau 91128, France
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Gruart M, Feldberg N, Gayral B, Bougerol C, Pouget S, Bellet-Amalric E, Garro N, Cros A, Okuno H, Daudin B. Impact of kinetics on the growth of GaN on graphene by plasma-assisted molecular beam epitaxy. NANOTECHNOLOGY 2020; 31:115602. [PMID: 31774414 DOI: 10.1088/1361-6528/ab5c15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The growth of GaN on graphene by molecular beam epitaxy was investigated. The most stable epitaxial relationship, i.e. [00.1]-oriented grains, is obtained at high temperature and N-rich conditions, which match those for nanowire growth. Alternatively, at moderate temperature and Ga-rich conditions, several metastable orientations are observed at the nucleation stage, which evolve preferentially towards [00.1]-oriented grains. The dependence of the nucleation regime on growth conditions was assigned to Ga adatom kinetics. This statement is consistent with the calculated graphene/GaN in-plane lattice coincidence and supported by a combination of transmission electron microscopy, x-ray diffraction, photoluminescence, and Raman spectroscopy experiments.
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Affiliation(s)
- M Gruart
- Univ. Grenoble-Alpes, CEA-IRIG, PHELIQS, 17 av. des Martyrs, F-38000, Grenoble, France
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Sarno M, Galvagno S, Piscitelli R, Portofino S, Ciambelli P. Supercapacitor Electrodes Made of Exhausted Activated Carbon-Derived SiC Nanoparticles Coated by Graphene. Ind Eng Chem Res 2016. [DOI: 10.1021/acs.iecr.6b00737] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Maria Sarno
- Department
of Industrial Engineering DIIN and Research Centre NANO_MATES, University of Salerno, Via Giovanni
Paolo II, 132, 84084 Fisciano, (SA), Italy
| | - Sergio Galvagno
- Department
of
Environment, Global Change and Sustainable Development, C.R. ENEA
Portici, via Vecchio Macello loc. Granatello, 80055 Portici, NA, Italy
| | - Rosangela Piscitelli
- Department
of Industrial Engineering DIIN and Research Centre NANO_MATES, University of Salerno, Via Giovanni
Paolo II, 132, 84084 Fisciano, (SA), Italy
| | - Sabrina Portofino
- Department
of
Environment, Global Change and Sustainable Development, C.R. ENEA
Portici, via Vecchio Macello loc. Granatello, 80055 Portici, NA, Italy
| | - Paolo Ciambelli
- Department
of Industrial Engineering DIIN and Research Centre NANO_MATES, University of Salerno, Via Giovanni
Paolo II, 132, 84084 Fisciano, (SA), Italy
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X-Ray Diffraction and Raman Spectroscopy Study of Strain in Graphene Films Grown on 6H-SiC(0001) Using Propane-Hydrogen-Argon CVD. ACTA ACUST UNITED AC 2013. [DOI: 10.4028/www.scientific.net/msf.740-742.117] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have grown graphene films on 6H-SiC(0001) using propane CVD and evidenced the strong impact of the hydrogen/argon mixture used as the carrier gas on the graphene/SiC interface and on the orientation of graphene layers. By studying a set of samples grown with different hydrogen/argon mixture using Raman spectroscopy and grazing incidence X-ray diffraction, we evidence the links between graphene/SiC interface and strain in graphene.
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