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Duan Y, Xu W, Kong W, Wang J, Zhang J, Yang Z, Cai Q. Modification on Flower Defects and Electronic Properties of Epitaxial Graphene by Erbium. ACS OMEGA 2023; 8:37600-37609. [PMID: 37841144 PMCID: PMC10568997 DOI: 10.1021/acsomega.3c06523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 09/15/2023] [Indexed: 10/17/2023]
Abstract
Manipulating the topological defects and electronic properties of graphene has been a subject of great interest. In this work, we have investigated the influence of Er predeposition on flower defects and electronic band structures of epitaxial graphene on SiC. It is shown that Er atoms grown on the SiC substrate actually work as an activator to induce flower defect formation with a density of 1.52 × 1012 cm-2 during the graphitization process when the Er coverage is 1.6 ML, about 5 times as much as that of pristine graphene. First-principles calculations demonstrate that Er greatly decreases the formation energy of the flower defect. We have discussed Er promoting effects on flower defect formation as well as its formation mechanism. Scanning tunneling microscopy (STM) and Raman and X-ray photoelectron spectroscopy (XPS) have been utilized to reveal the Er doping effect and its modification to electronic structures of graphene. N-doping enhancement and band gap opening can be observed by using angle-resolved photoemission spectroscopy (ARPES). With Er coverage increasing from 0 to 1.6 ML, the Dirac point energy decreases from -0.34 to -0.37 eV and the band gap gradually increases from 320 to 360 meV. The opening of the band gap is attributed to the synergistic effect of substitution doping of Er atoms and high-density flower defects.
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Affiliation(s)
- Yong Duan
- State Key Laboratory of Surface
Physics and Department of Physics, Fudan
University, Shanghai 200433, People’s
Republic of China
| | - Wenting Xu
- State Key Laboratory of Surface
Physics and Department of Physics, Fudan
University, Shanghai 200433, People’s
Republic of China
| | - Wenxia Kong
- State Key Laboratory of Surface
Physics and Department of Physics, Fudan
University, Shanghai 200433, People’s
Republic of China
| | - Jianxin Wang
- State Key Laboratory of Surface
Physics and Department of Physics, Fudan
University, Shanghai 200433, People’s
Republic of China
| | - Jinzhe Zhang
- State Key Laboratory of Surface
Physics and Department of Physics, Fudan
University, Shanghai 200433, People’s
Republic of China
| | - Zhongqin Yang
- State Key Laboratory of Surface
Physics and Department of Physics, Fudan
University, Shanghai 200433, People’s
Republic of China
| | - Qun Cai
- State Key Laboratory of Surface
Physics and Department of Physics, Fudan
University, Shanghai 200433, People’s
Republic of China
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2
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Mendoza CD, Figueroa NS, Maia da Costa MEH, Freire FL. CVD graphene/Ge interface: morphological and electronic characterization of ripples. Sci Rep 2019; 9:12547. [PMID: 31467360 PMCID: PMC6715795 DOI: 10.1038/s41598-019-48998-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 08/14/2019] [Indexed: 11/23/2022] Open
Abstract
Graphene grown directly on germanium is a possible route for the integration of graphene into nanoelectronic devices as well as it is of great interest for materials science. The morphology of the interface between graphene and germanium influences the electronic properties and has not already been completely elucidated at atomic scale. In this work, we investigated the morphology of the single-layer graphene grown on Ge substrates with different crystallographic orientations. We determined the presence of sinusoidal ripples with a single propagation direction, zig-zag, and could arise due to compressive biaxial strain at the interface generated as a result of the opposite polarity of the thermal expansion coefficient of graphene and germanium. Local density of states measurements on the ripples showed a linear dispersion relation with the Dirac point slightly shifted with respect to the Fermi energy indicating that these out-of-plane deformations were n-doped, while the graphene regions between the highs were undoped.
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Affiliation(s)
- Cesar D Mendoza
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900, Rio de Janeiro, RJ, Brazil.
| | - Neileth S Figueroa
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900, Rio de Janeiro, RJ, Brazil
| | - Marcelo E H Maia da Costa
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900, Rio de Janeiro, RJ, Brazil
| | - Fernando L Freire
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900, Rio de Janeiro, RJ, Brazil
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3
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Xu X, Liu C, Sun Z, Cao T, Zhang Z, Wang E, Liu Z, Liu K. Interfacial engineering in graphene bandgap. Chem Soc Rev 2018. [PMID: 29513306 DOI: 10.1039/c7cs00836h] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Graphene exhibits superior mechanical strength, high thermal conductivity, strong light-matter interactions, and, in particular, exceptional electronic properties. These merits make graphene an outstanding material for numerous potential applications. However, a graphene-based high-performance transistor, which is the most appealing application, has not yet been produced, which is mainly due to the absence of an intrinsic electronic bandgap in this material. Therefore, bandgap opening in graphene is urgently needed, and great efforts have been made regarding this topic over the past decade. In this review article, we summarise recent theoretical and experimental advances in interfacial engineering to achieve bandgap opening. These developments are divided into two categories: chemical engineering and physical engineering. Chemical engineering is usually destructive to the pristine graphene lattice via chemical functionalization, the introduction of defects, doping, chemical bonds with substrates, and quantum confinement; the latter largely maintains the atomic structure of graphene intact and includes the application of an external field, interactions with substrates, physical adsorption, strain, electron many-body effects and spin-orbit coupling. Although these pioneering works have not met all the requirements for electronic applications of graphene at once, they hold great promise in this direction and may eventually lead to future applications of graphene in semiconductor electronics and beyond.
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Affiliation(s)
- Xiaozhi Xu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
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4
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Georgi A, Nemes-Incze P, Carrillo-Bastos R, Faria D, Viola Kusminskiy S, Zhai D, Schneider M, Subramaniam D, Mashoff T, Freitag NM, Liebmann M, Pratzer M, Wirtz L, Woods CR, Gorbachev RV, Cao Y, Novoselov KS, Sandler N, Morgenstern M. Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field. NANO LETTERS 2017; 17:2240-2245. [PMID: 28211276 DOI: 10.1021/acs.nanolett.6b04870] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudomagnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudomagnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudomagnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene's pseudospin due to a strain induced pseudomagnetic field, in analogy to the alignment of a real spin in a magnetic field. We reveal this sublattice symmetry breaking by tunably straining graphene using the tip of a scanning tunneling microscope. The tip locally lifts the graphene membrane from a SiO2 support, as visible by an increased slope of the I(z) curves. The amount of lifting is consistent with molecular dynamics calculations, which reveal a deformed graphene area under the tip in the shape of a Gaussian. The pseudomagnetic field induced by the deformation becomes visible as a sublattice symmetry breaking which scales with the lifting height of the strained deformation and therefore with the pseudomagnetic field strength. Its magnitude is quantitatively reproduced by analytic and tight-binding models, revealing fields of 1000 T. These results might be the starting point for an effective THz valley filter, as a basic element of valleytronics.
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Affiliation(s)
- Alexander Georgi
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University , 52062 Aachen, Germany
| | - Peter Nemes-Incze
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University , 52062 Aachen, Germany
| | - Ramon Carrillo-Bastos
- Facultad de Ciencias, Universidad Autónoma de Baja California , 21100 Mexicali, Baja California México
- Department of Physics and Astronomy, Ohio University , Athens, Ohio 45701, United States
| | - Daiara Faria
- Instituto Politécnico, Universidade do Estado de Rio de Janeiro , 28625-570 Nova Friburgo, Brasil
- Instituto de Física, Universidade Federal Fluminense , Niterói, 24210-340 Rio de Janeiro Brazil
| | - Silvia Viola Kusminskiy
- Dahlem Center for Complex Quantum Systems and Institut für Theoretische, Freie Universität Berlin , 14195 Berlin, Germany
- Institute for Theoretical Physics II, University of Erlangen-Nüremberg , 91058 Erlangen, Germany
| | - Dawei Zhai
- Department of Physics and Astronomy, Ohio University , Athens, Ohio 45701, United States
| | - Martin Schneider
- Dahlem Center for Complex Quantum Systems and Institut für Theoretische, Freie Universität Berlin , 14195 Berlin, Germany
| | - Dinesh Subramaniam
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University , 52062 Aachen, Germany
| | - Torge Mashoff
- Johannes Gutenberg-Universität , 55122 Mainz, Germany
| | - Nils M Freitag
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University , 52062 Aachen, Germany
| | - Marcus Liebmann
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University , 52062 Aachen, Germany
| | - Marco Pratzer
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University , 52062 Aachen, Germany
| | - Ludger Wirtz
- Physics and Materials Science Research Unit, University of Luxembourg , L-1511 Luxembourg, Luxembourg
| | - Colin R Woods
- School of Physics and Astronomy, University of Manchester , Manchester M13 9PL, United Kingdom
| | - Roman V Gorbachev
- School of Physics and Astronomy, University of Manchester , Manchester M13 9PL, United Kingdom
| | - Yang Cao
- School of Physics and Astronomy, University of Manchester , Manchester M13 9PL, United Kingdom
| | - Kostya S Novoselov
- School of Physics and Astronomy, University of Manchester , Manchester M13 9PL, United Kingdom
| | - Nancy Sandler
- Department of Physics and Astronomy, Ohio University , Athens, Ohio 45701, United States
| | - Markus Morgenstern
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University , 52062 Aachen, Germany
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5
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Zhao G, Li X, Huang M, Zhen Z, Zhong Y, Chen Q, Zhao X, He Y, Hu R, Yang T, Zhang R, Li C, Kong J, Xu JB, Ruoff RS, Zhu H. The physics and chemistry of graphene-on-surfaces. Chem Soc Rev 2017; 46:4417-4449. [DOI: 10.1039/c7cs00256d] [Citation(s) in RCA: 260] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This review describes the major “graphene-on-surface” structures and examines the roles of their properties in governing the overall performance for specific applications.
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Affiliation(s)
- Guoke Zhao
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Xinming Li
- Department of Electronic Engineering
- The Chinese University of Hong Kong
- China
| | - Meirong Huang
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Zhen Zhen
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Yujia Zhong
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Qiao Chen
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Xuanliang Zhao
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Yijia He
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Ruirui Hu
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Tingting Yang
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Rujing Zhang
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Changli Li
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
| | - Jing Kong
- Department of Electrical Engineering and Computer Sciences
- Massachusetts Institute of Technology
- Cambridge
- USA
| | - Jian-Bin Xu
- Department of Electronic Engineering
- The Chinese University of Hong Kong
- China
| | - Rodney S. Ruoff
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), and Department of Chemistry
- Ulsan National Institute of Science and Technology (UNIST)
- Ulsan
- Republic of Korea
| | - Hongwei Zhu
- State Key Lab of New Ceramics and Fine Processing
- School of Materials Science and Engineering, and Center for Nano and Micro Mechanics
- Tsinghua University
- Beijing 100084
- China
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6
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Al Balushi ZY, Wang K, Ghosh RK, Vilá RA, Eichfeld SM, Caldwell JD, Qin X, Lin YC, DeSario PA, Stone G, Subramanian S, Paul DF, Wallace RM, Datta S, Redwing JM, Robinson JA. Two-dimensional gallium nitride realized via graphene encapsulation. NATURE MATERIALS 2016; 15:1166-1171. [PMID: 27571451 DOI: 10.1038/nmat4742] [Citation(s) in RCA: 218] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 07/25/2016] [Indexed: 05/25/2023]
Abstract
The spectrum of two-dimensional (2D) and layered materials 'beyond graphene' offers a remarkable platform to study new phenomena in condensed matter physics. Among these materials, layered hexagonal boron nitride (hBN), with its wide bandgap energy (∼5.0-6.0 eV), has clearly established that 2D nitrides are key to advancing 2D devices. A gap, however, remains between the theoretical prediction of 2D nitrides 'beyond hBN' and experimental realization of such structures. Here we demonstrate the synthesis of 2D gallium nitride (GaN) via a migration-enhanced encapsulated growth (MEEG) technique utilizing epitaxial graphene. We theoretically predict and experimentally validate that the atomic structure of 2D GaN grown via MEEG is notably different from reported theory. Moreover, we establish that graphene plays a critical role in stabilizing the direct-bandgap (nearly 5.0 eV), 2D buckled structure. Our results provide a foundation for discovery and stabilization of 2D nitrides that are difficult to prepare via traditional synthesis.
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Affiliation(s)
- Zakaria Y Al Balushi
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ke Wang
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ram Krishna Ghosh
- Department of Electrical Engineering, University of Norte Dame, Notre Dame, Indiana 46556, USA
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Rafael A Vilá
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Sarah M Eichfeld
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | | - Xiaoye Qin
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Yu-Chuan Lin
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | | - Greg Stone
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Shruti Subramanian
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Dennis F Paul
- Physical Electronics USA, 18725 Lake Drive East, Chanhassen, Minnesota 55317, USA
| | - Robert M Wallace
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Suman Datta
- Department of Electrical Engineering, University of Norte Dame, Notre Dame, Indiana 46556, USA
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Joan M Redwing
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Joshua A Robinson
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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7
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Rajput S, Li YY, Weinert M, Li L. Indirect Interlayer Bonding in Graphene-Topological Insulator van der Waals Heterostructure: Giant Spin-Orbit Splitting of the Graphene Dirac States. ACS NANO 2016; 10:8450-8456. [PMID: 27617796 DOI: 10.1021/acsnano.6b03387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
van der Waals (vdW) heterostructures of two-dimensional materials exhibit properties and functionalities that can be tuned by stacking order and interlayer coupling. Although direct covalent bonding is not expected at the heterojunction, the formation of an interface nevertheless breaks the symmetries of the layers, and the orthogonal requirement of the wave functions can lead to indirect interfacial coupling, creating new properties and functionalities beyond their constituent layers. Here, we fabricate graphene/topological insulator vdW heterostructure by transferring chemical vapor deposited graphene onto Bi2Se3 grown by molecular beam epitaxy. Using scanning tunneling microscopy/spectroscopy, we observe a giant spin-orbit splitting of the graphene Dirac states up to 80 meV. Density functional theory calculations further reveal that this splitting of the graphene bands is a consequence of the breaking of inversion symmetry and the orthogonalization requirement on the overlapping wave functions at the interface, rather than simple direct bonding. Our findings reveal two intrinsic characteristics-the symmetry breaking and orthogonalization of the wave functions at the interface-that underlines the properties of vdW heterostructures.
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Affiliation(s)
- Shivani Rajput
- Department of Physics, University of Wisconsin , Milwaukee, Wisconsin 53211, United States
| | - Yao-Yi Li
- Department of Physics, University of Wisconsin , Milwaukee, Wisconsin 53211, United States
| | - Michael Weinert
- Department of Physics, University of Wisconsin , Milwaukee, Wisconsin 53211, United States
| | - Lian Li
- Department of Physics, University of Wisconsin , Milwaukee, Wisconsin 53211, United States
- Department of Physics and Astronomy, West Virginia University , Morgantown, West Virginia 26506, United States
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8
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9
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Abstract
Graphene has intrigued the science community by many unique properties not found in conventional materials. In particular, it is the strongest two-dimensional material ever measured, being able to sustain reversible tensile elastic strain larger than 20%, which yields an interesting possibility to tune the properties of graphene by strain and thus opens a new field called "straintronics". In this article, the current progress in the strain engineering of graphene is reviewed. We first summarize the strain effects on the electronic structure and Raman spectra of graphene. We then highlight the electron-phonon coupling greatly enhanced by the biaxial strain and the strong pseudomagnetic field induced by the non-uniform strain with specific distribution. Finally, the potential application of strain-engineering in the self-assembly of foreign atoms on the graphene surface is also discussed. Given the short history of graphene straintronics research, the current progress has been notable, and many further advances in this field are expected.
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Affiliation(s)
- Chen Si
- School of Materials Science and Engineering, and Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
| | - Zhimei Sun
- School of Materials Science and Engineering, and Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
| | - Feng Liu
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA. and Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
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10
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Vantasin S, Tanaka Y, Uemura S, Suzuki T, Kutsuma Y, Doujima D, Kaneko T, Ozaki Y. Characterization of SiC-grown epitaxial graphene microislands using tip-enhanced Raman spectroscopy. Phys Chem Chem Phys 2016; 17:28993-9. [PMID: 26456383 DOI: 10.1039/c5cp05014f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Single-layer graphene microislands with smooth edges and no visible grain boundary were epitaxially grown on the C-face of 4H-SiC and then characterized at the nanoscale using tip-enhanced Raman spectroscopy (TERS). Although these graphene islands appear highly homogeneous in micro-Raman imaging, TERS reveals the nanoscale strain variation caused by ridge nanostructures. A G' band position shift up to 9 cm(-1) and a band broadening up to 30 cm(-1) are found in TERS spectra obtained from nanoridges, which is explained by the compressive strain relaxation mechanism. The small size and refined nature of the graphene islands help in minimizing the inhomogeneity caused by macroscale factors, and allow a comparative discussion of proposed mechanisms of nanoridge formation.
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Affiliation(s)
- Sanpon Vantasin
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
| | - Yoshito Tanaka
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
| | - Shohei Uemura
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
| | - Toshiaki Suzuki
- UNISOKU Co. Ltd, 2-4-3 Kasugano, Hirakata, Osaka 573-0131, Japan
| | - Yasunori Kutsuma
- Department of Physics, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Daichi Doujima
- Department of Physics, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Tadaaki Kaneko
- Department of Physics, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Yukihiro Ozaki
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
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11
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Morán-Meza JA, Cousty J, Lubin C, Thoyer F. Understanding the STM images of epitaxial graphene on a reconstructed 6H-SiC(0001) surface: the role of tip-induced mechanical distortion of graphene. Phys Chem Chem Phys 2016; 18:14264-72. [DOI: 10.1039/c5cp07571h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Maxima in the STM images of epitaxial graphene (EG) on SiC(0001) (cyan) differ from topographic bumps in AFM images (green) by a separation distance of 1 nm, which is a result of two effects: the tip-induced distortion of EG and the asymmetric profile of the LDOS of the buffer layer.
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Affiliation(s)
| | - Jacques Cousty
- SPEC
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay 91191 Gif-sur-Yvette Cedex
| | - Christophe Lubin
- SPEC
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay 91191 Gif-sur-Yvette Cedex
| | - François Thoyer
- SPEC
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay 91191 Gif-sur-Yvette Cedex
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12
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Neng W, Shuang-ying L, Jun X, Matteo M, Yi-long Z, Shu W, Li-tao S, Qing-an H. Fullerene growth from encapsulated graphene flakes. NANOSCALE 2014; 6:11213-11218. [PMID: 25123407 DOI: 10.1039/c4nr03680h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The direct in situ observation of fullerene formation encapsulated within a graphene ridge has been made possible using an aberration corrected transmission electron microscope (AC-TEM). An atom-by-atom mechanism was proposed based on in situ AC-TEM observations. First principle calculations found a continuous energy decrease upon the addition of carbon atoms to the edge of the graphene flakes, which mimics the fullerene growth steps and supports the atom-by-atom mechanism. The ridged graphene structure worked as a container for pinning small graphene flakes and capturing carbon atoms, which increased the growth probability of the fullerene structure within the small encapsulated space.
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Affiliation(s)
- Wan Neng
- SEU-FEI Nano Pico center, Key Laboratory of MEMS of Ministry of Education, School of Electronics Science and Engineering, Southeast University, Nanjing, 210096, P. R. China.
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13
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Li YY, Chen MX, Weinert M, Li L. Direct experimental determination of onset of electron–electron interactions in gap opening of zigzag graphene nanoribbons. Nat Commun 2014; 5:4311. [DOI: 10.1038/ncomms5311] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 06/05/2014] [Indexed: 11/09/2022] Open
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14
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Flower-shaped domains and wrinkles in trilayer epitaxial graphene on silicon carbide. Sci Rep 2014; 4:4066. [PMID: 24513669 PMCID: PMC3920218 DOI: 10.1038/srep04066] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 01/27/2014] [Indexed: 11/08/2022] Open
Abstract
Trilayer graphene is of particular interest to the 2D materials community because of its unique tunable electronic structure. However, to date, there is a lack of fundamental understanding of the properties of epitaxial trilayer graphene on silicon carbide. Here, following successful synthesis of large-area uniform trilayer graphene, atomic force microscopy (AFM) showed that the trilayer graphene on 6H-SiC(0001) was uniform over a large scale. Additionally, distinct defects, identified as flower-shaped domains and isolated wrinkle structures, were observed randomly on the surface using scanning tunneling microscopy and spectroscopy (STM/STS). These carbon nanostructures formed during growth, has different structural and electronic properties when compared with the adjacent flat regions of the graphene. Finally, using low temperature STM/STS at 4K, we found that the isolated wrinkles showed an irreversible rotational motion between two 60° configurations at different densities of states.
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Rajput S, Chen M, Liu Y, Li Y, Weinert M, Li L. Spatial fluctuations in barrier height at the graphene–silicon carbide Schottky junction. Nat Commun 2013; 4:2752. [DOI: 10.1038/ncomms3752] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 10/11/2013] [Indexed: 01/10/2023] Open
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Abstract
We studied the thermophoretic motion of wrinkles formed in substrate-supported graphene sheets by nonequilibrium molecular dynamics simulations. We found that a single wrinkle moves along applied temperature gradient with a constant acceleration that is linearly proportional to temperature deviation between the heating and cooling sides of the graphene sheet. Like a solitary wave, the atoms of the single wrinkle drift upwards and downwards, which prompts the wrinkle to move forwards. The driving force for such thermophoretic movement can be mainly attributed to a lower free energy of the wrinkle back root when it is transformed from the front root. We establish a motion equation to describe the soliton-like thermophoresis of a single graphene wrinkle based on the Korteweg-de Vries equation. Similar motions are also observed for wrinkles formed in a Cu-supported graphene sheet. These findings provide an energy conversion mechanism by using graphene wrinkle thermophoresis.
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Affiliation(s)
- Yufeng Guo
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
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Hattab H, N'Diaye AT, Wall D, Klein C, Jnawali G, Coraux J, Busse C, van Gastel R, Poelsema B, Michely T, zu Heringdorf FJM, Horn-von Hoegen M. Interplay of wrinkles, strain, and lattice parameter in graphene on iridium. NANO LETTERS 2012; 12:678-82. [PMID: 22175792 DOI: 10.1021/nl203530t] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Following graphene growth by thermal decomposition of ethylene on Ir(111) at high temperatures we analyzed the strain state and the wrinkle formation kinetics as function of temperature. Using the moiré spot separation in a low energy electron diffraction pattern as a magnifying mechanism for the difference in the lattice parameters between Ir and graphene, we achieved an unrivaled relative precision of ±0.1 pm for the graphene lattice parameter. Our data reveals a characteristic hysteresis of the graphene lattice parameter that is explained by the interplay of reversible wrinkle formation and film strain. We show that graphene on Ir(111) always exhibits residual compressive strain at room temperature. Our results provide important guidelines for strategies to avoid wrinkling.
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Affiliation(s)
- Hichem Hattab
- Department of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany
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Vecchio C, Sonde S, Bongiorno C, Rambach M, Yakimova R, Raineri V, Giannazzo F. Nanoscale structural characterization of epitaxial graphene grown on off-axis 4H-SiC (0001). NANOSCALE RESEARCH LETTERS 2011; 6:269. [PMID: 21711803 PMCID: PMC3211332 DOI: 10.1186/1556-276x-6-269] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 03/29/2011] [Indexed: 05/27/2023]
Abstract
In this work, we present a nanometer resolution structural characterization of epitaxial graphene (EG) layers grown on 4H-SiC (0001) 8° off-axis, by annealing in inert gas ambient (Ar) in a wide temperature range (Tgr from 1600 to 2000°C). For all the considered growth temperatures, few layers of graphene (FLG) conformally covering the 100 to 200-nm wide terraces of the SiC surface have been observed by high-resolution cross-sectional transmission electron microscopy (HR-XTEM). Tapping mode atomic force microscopy (t-AFM) showed the formation of wrinkles with approx. 1 to 2 nm height and 10 to 20 nm width in the FLG film, as a result of the release of the compressive strain, which builds up in FLG during the sample cooling due to the thermal expansion coefficients mismatch between graphene and SiC. While for EG grown on on-axis 4H-SiC an isotropic mesh-like network of wrinkles interconnected into nodes is commonly reported, in the present case of a vicinal SiC surface, wrinkles are preferentially oriented in the direction perpendicular to the step edges of the SiC terraces. For each Tgr, the number of graphene layers was determined on very small sample areas by HR-XTEM and, with high statistics and on several sample positions, by measuring the depth of selectively etched trenches in FLG by t-AFM. Both the density of wrinkles and the number of graphene layers are found to increase almost linearly as a function of the growth temperature in the considered temperature range.
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Affiliation(s)
- Carmelo Vecchio
- CNR-IMM, Strada VIII, 5, Catania 95121, Italy
- Scuola Superiore di Catania, Via San Nullo, 5/i, Catania 95123, Italy
| | - Sushant Sonde
- CNR-IMM, Strada VIII, 5, Catania 95121, Italy
- Scuola Superiore di Catania, Via San Nullo, 5/i, Catania 95123, Italy
| | | | - Martin Rambach
- Centrotherm Thermal Solutions GmbH + Co. KG, Johannes-Schmid-Straße 8, Blaubeuren 89143, Germany
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Unarunotai S, Koepke JC, Tsai CL, Du F, Chialvo CE, Murata Y, Haasch R, Petrov I, Mason N, Shim M, Lyding J, Rogers JA. Layer-by-layer transfer of multiple, large area sheets of graphene grown in multilayer stacks on a single SiC wafer. ACS NANO 2010; 4:5591-5598. [PMID: 20843091 DOI: 10.1021/nn101896a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Here we report a technique for transferring graphene layers, one by one, from a multilayer deposit formed by epitaxial growth on the Si-terminated face of a 6H-SiC substrate. The procedure uses a bilayer film of palladium/polyimide deposited onto the graphene coated SiC, which is then mechanically peeled away and placed on a target substrate. Orthogonal etching of the palladium and polyimide leaves isolated sheets of graphene with sizes of square centimeters. Repeating these steps transfers additional sheets from the same SiC substrate. Raman spectroscopy, scanning tunneling spectroscopy, low-energy electron diffraction and X-ray photoelectron spectroscopy, together with scanning tunneling, atomic force, optical, and scanning electron microscopy reveal key properties of the materials. The sheet resistances determined from measurements of four point probe devices were found to be ∼2 kΩ/square, close to expectation. Graphene crossbar structures fabricated in stacked configurations demonstrate the versatility of the procedures.
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Affiliation(s)
- Sakulsuk Unarunotai
- Department of Chemistry, University of Illinois at Urbana−Champaign, 1206 West Green Street, Urbana, Illinois 61801, USA
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Ramesh P, Itkis ME, Bekyarova E, Wang F, Niyogi S, Chi X, Berger C, de Heer W, Haddon RC. Electro-oxidized Epitaxial Graphene Channel Field-Effect Transistors with Single-Walled Carbon Nanotube Thin Film Gate Electrode. J Am Chem Soc 2010; 132:14429-36. [DOI: 10.1021/ja101706j] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Palanisamy Ramesh
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Mikhail E. Itkis
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Elena Bekyarova
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Feihu Wang
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Sandip Niyogi
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Xiaoliu Chi
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Claire Berger
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Walt de Heer
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Robert C. Haddon
- Center for Nanoscale Science and Engineering, Departments of Chemistry, Chemical & Environmental Engineering, and Physics, University of California, Riverside, California 92521, CNRS - Institut Néel, Grenoble, France, and School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
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