1
|
Graziotto L, Macheda F, Venanzi T, Marchese G, Sotgiu S, Ouaj T, Stellino E, Fasolato C, Postorino P, Metzelaars M, Kögerler P, Beschoten B, Calandra M, Ortolani M, Stampfer C, Mauri F, Baldassarre L. Infrared Resonance Raman of Bilayer Graphene: Signatures of Massive Fermions and Band Structure on the 2D Peak. NANO LETTERS 2024; 24:1867-1873. [PMID: 38306119 DOI: 10.1021/acs.nanolett.3c03502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Few-layer graphene possesses low-energy carriers that behave as massive Fermions, exhibiting intriguing properties in both transport and light scattering experiments. Lowering the excitation energy of resonance Raman spectroscopy down to 1.17 eV, we target these massive quasiparticles in the split bands close to the K point. The low excitation energy weakens some of the Raman processes that are resonant in the visible, and induces a clearer frequency-separation of the substructures of the resonance 2D peak in bi- and trilayer samples. We follow the excitation-energy dependence of the intensity of each substructure, and comparing experimental measurements on bilayer graphene with ab initio theoretical calculations, we trace back such modifications on the joint effects of probing the electronic dispersion close to the band splitting and enhancement of electron-phonon matrix elements.
Collapse
Affiliation(s)
- Lorenzo Graziotto
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Francesco Macheda
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, 16163 Genoa, Italy
| | - Tommaso Venanzi
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Guglielmo Marchese
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Simone Sotgiu
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Taoufiq Ouaj
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Elena Stellino
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Claudia Fasolato
- Institute for Complex Systems, National Research Council (ISC-CNR), 00185 Rome, Italy
| | - Paolo Postorino
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Marvin Metzelaars
- Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany
| | - Paul Kögerler
- Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany
| | - Bernd Beschoten
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Matteo Calandra
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, 16163 Genoa, Italy
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Italy
| | - Michele Ortolani
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Christoph Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Francesco Mauri
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, 16163 Genoa, Italy
| | - Leonetta Baldassarre
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| |
Collapse
|
2
|
Mendoza CD, Freire FL. Single-Layer Graphene/Germanium Interface Representing a Schottky Junction Studied by Photoelectron Spectroscopy. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2166. [PMID: 37570483 PMCID: PMC10420948 DOI: 10.3390/nano13152166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/19/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023]
Abstract
We investigated the interfacial electronic structure of the bidimensional interface of single-layer graphene on a germanium substrate. The procedure followed a well-established approach using ultraviolet (UPS) and X-ray (XPS) photoelectron spectroscopy. The direct synthesis of the single-layer graphene on the surface of (110) undoped Ge substrates was conducted via chemical vapor deposition (CVD). The main graphitic properties of the systems were identified, and it was shown that the Ge substrate affected the electronic structure of the single-layer graphene, indicating the electronic coupling between the graphene and the Ge substrate. Furthermore, the relevant features associated with the Schottky contact's nature, the energy level's alignments, and the energy barrier's heights for electron and hole injection were obtained in this work. The results are useful, given the possible integration of single-layer graphene on a Ge substrate with the complementary metal-oxide-semiconductor (CMOS) technology.
Collapse
Affiliation(s)
- Cesar D. Mendoza
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro 22451-900, RJ, Brazil;
| | | |
Collapse
|
3
|
Venanzi T, Graziotto L, Macheda F, Sotgiu S, Ouaj T, Stellino E, Fasolato C, Postorino P, Mišeikis V, Metzelaars M, Kögerler P, Beschoten B, Coletti C, Roddaro S, Calandra M, Ortolani M, Stampfer C, Mauri F, Baldassarre L. Probing Enhanced Electron-Phonon Coupling in Graphene by Infrared Resonance Raman Spectroscopy. PHYSICAL REVIEW LETTERS 2023; 130:256901. [PMID: 37418733 DOI: 10.1103/physrevlett.130.256901] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 05/15/2023] [Indexed: 07/09/2023]
Abstract
We report on resonance Raman spectroscopy measurements with excitation photon energy down to 1.16 eV on graphene, to study how low-energy carriers interact with lattice vibrations. Thanks to the excitation energy close to the Dirac point at K, we unveil a giant increase of the intensity ratio between the double-resonant 2D and 2D^{'} peaks with respect to that measured in graphite. Comparing with fully ab initio theoretical calculations, we conclude that the observation is explained by an enhanced, momentum-dependent coupling between electrons and Brillouin zone-boundary optical phonons. This finding applies to two-dimensional Dirac systems and has important consequences for the modeling of transport in graphene devices operating at room temperature.
Collapse
Affiliation(s)
- Tommaso Venanzi
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Lorenzo Graziotto
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Francesco Macheda
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy
| | - Simone Sotgiu
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Taoufiq Ouaj
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Elena Stellino
- Department of Physics and Geology, University of Perugia, via Alessandro Pascoli, 06123 Perugia, Italy
| | - Claudia Fasolato
- Institute for Complex System, National Research Council (ISC-CNR), 00185 Rome, Italy
| | - Paolo Postorino
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Vaidotas Mišeikis
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy
- Istituto Italiano di Tecnologia, Center for Nanotechnology Innovation @NEST, Piazza San Silvestro, 12-56126 Pisa, Italy
| | - Marvin Metzelaars
- Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany
| | - Paul Kögerler
- Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany
| | - Bernd Beschoten
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Camilla Coletti
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy
- Istituto Italiano di Tecnologia, Center for Nanotechnology Innovation @NEST, Piazza San Silvestro, 12-56126 Pisa, Italy
| | - Stefano Roddaro
- Department of Physics, University of Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - Matteo Calandra
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Italy
| | - Michele Ortolani
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Christoph Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Francesco Mauri
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy
| | - Leonetta Baldassarre
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| |
Collapse
|
4
|
Zhang G, Lu G, Li X, Mei Z, Liang L, Fan S, Li Q, Wei Y. Reconfigurable Two-Dimensional Air-Gap Barristors. ACS NANO 2023; 17:4564-4573. [PMID: 36847653 DOI: 10.1021/acsnano.2c10593] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Reconfigurable logic circuits implemented by two-dimensional (2D) ambipolar semiconductors provide a prospective solution for the post-Moore era. It is still a challenge for ambipolar nanomaterials to realize reconfigurable polarity control and rectification with a simplified device structure. Here, an air-gap barristor based on an asymmetric stacking sequence of the electrode contacts was developed to resolve these issues. For the 2D ambipolar channel of WSe2, the barristor can not only be reconfigured as an n- or p-type unipolar transistor but also work as a switchable diode. The air gap around the bottom electrode dominates the reconfigurable behaviors by widening the Schottky barrier here, thus blocking the injection of both electrons and holes. The electrical performances can be improved by optimizing the electrode materials, which achieve an on/off ratio of 104 for the transistor and a rectifying ratio of 105 for the diode. A complementary inverter and a switchable AND/OR logic gate were constructed by using the air-gap barristors as building blocks. This work provides an efficient approach with great potential for low-dimensional reconfigurable electronics.
Collapse
Affiliation(s)
- Guangqi Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
| | - Gaotian Lu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
| | - Xuanzhang Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
| | - Zhen Mei
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
| | - Liang Liang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
| | - Shoushan Fan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
| | - Qunqing Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
| | - Yang Wei
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
| |
Collapse
|
5
|
Burton OJ, Winter Z, Watanabe K, Taniguchi T, Beschoten B, Stampfer C, Hofmann S. Putting High-Index Cu on the Map for High-Yield, Dry-Transferred CVD Graphene. ACS NANO 2023; 17:1229-1238. [PMID: 36594782 PMCID: PMC9878973 DOI: 10.1021/acsnano.2c09253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
Reliable, clean transfer and interfacing of 2D material layers are technologically as important as their growth. Bringing both together remains a challenge due to the vast, interconnected parameter space. We introduce a fast-screening descriptor approach to demonstrate holistic data-driven optimization across the entirety of process steps for the graphene-Cu model system. We map the crystallographic dependences of graphene chemical vapor deposition, interfacial Cu oxidation to decouple graphene, and its dry delamination across inverse pole figures. Their overlay enables us to identify hitherto unexplored (168) higher index Cu orientations as overall optimal orientations. We show the effective preparation of such Cu orientations via epitaxial close-space sublimation and achieve mechanical transfer with a very high yield (>95%) and quality of graphene domains, with room-temperature electron mobilities in the range of 40000 cm2/(V s). Our approach is readily adaptable to other descriptors and 2D material systems, and we discuss the opportunities of such a holistic optimization.
Collapse
Affiliation(s)
- Oliver J. Burton
- Department
of Engineering, University of Cambridge, CambridgeCB3 0FA, United Kingdom
| | - Zachary Winter
- 2nd
Institute of Physics A and JARA-FIT, RWTH
Aachen University, 52074Aachen, Germany
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki305-0044, Japan
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki305-0044, Japan
| | - Bernd Beschoten
- 2nd
Institute of Physics A and JARA-FIT, RWTH
Aachen University, 52074Aachen, Germany
| | - Christoph Stampfer
- 2nd
Institute of Physics A and JARA-FIT, RWTH
Aachen University, 52074Aachen, Germany
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425Jülich, Germany
| | - Stephan Hofmann
- Department
of Engineering, University of Cambridge, CambridgeCB3 0FA, United Kingdom
| |
Collapse
|
6
|
Picosecond energy transfer in a transition metal dichalcogenide-graphene heterostructure revealed by transient Raman spectroscopy. Proc Natl Acad Sci U S A 2022; 119:e2119726119. [PMID: 35380900 PMCID: PMC9169783 DOI: 10.1073/pnas.2119726119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Hot carrier–based energy harvesting is critically implied in the performances of optoelectronic devices based on van der Waals heterostructures composed by graphene (Gr) and monolayer transition metal dichalcogenides (TMD). The way electron–hole couples initially photogenerated in the TMD are converted into an electric current in Gr is a controversial issue. In this work we identify the interlayer interaction occurring during the first picoseconds following photoexcitation as an energy transfer process that is much faster than (other) photogating phenomena implied in optoelectronic applications. Intense light–matter interactions and unique structural and electrical properties make van der Waals heterostructures composed by graphene (Gr) and monolayer transition metal dichalcogenides (TMD) promising building blocks for tunneling transistors and flexible electronics, as well as optoelectronic devices, including photodetectors, photovoltaics, and quantum light emitting devices (QLEDs), bright and narrow-line emitters using minimal amounts of active absorber material. The performance of such devices is critically ruled by interlayer interactions which are still poorly understood in many respects. Specifically, two classes of coupling mechanisms have been proposed, charge transfer (CT) and energy transfer (ET), but their relative efficiency and the underlying physics are open questions. Here, building on a time-resolved Raman scattering experiment, we determine the electronic temperature profile of Gr in response to TMD photoexcitation, tracking the picosecond dynamics of the G and 2D Raman bands. Compelling evidence for a dominant role of the ET process accomplished within a characteristic time of ∼4 ps is provided. Our results suggest the existence of an intermediate process between the observed picosecond ET and the generation of a net charge underlying the slower electric signals detected in optoelectronic applications.
Collapse
|
7
|
Chen Z, Khaireddin Y, Swan AK. Identifying the charge density and dielectric environment of graphene using Raman spectroscopy and deep learning. Analyst 2022; 147:1824-1832. [DOI: 10.1039/d2an00129b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We built a CNN model to classify graphene Raman spectra. Compared to other deep learning models and machine learning algorithms studied in this work, the CNN model achieves a high accuracy of 99% and is less sensitive to the SNR of Raman spectra.
Collapse
Affiliation(s)
- Zhuofa Chen
- Department of Electrical and Computer Engineering, Boston University, Boston, USA
| | - Yousif Khaireddin
- Department of Electrical and Computer Engineering, Boston University, Boston, USA
| | - Anna K. Swan
- Department of Electrical and Computer Engineering, Boston University, Boston, USA
| |
Collapse
|
8
|
Zhang X, Makles K, Colombier L, Metten D, Majjad H, Verlot P, Berciaud S. Dynamically-enhanced strain in atomically thin resonators. Nat Commun 2020; 11:5526. [PMID: 33139724 PMCID: PMC7608634 DOI: 10.1038/s41467-020-19261-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 10/01/2020] [Indexed: 11/13/2022] Open
Abstract
Graphene and related two-dimensional (2D) materials associate remarkable mechanical, electronic, optical and phononic properties. As such, 2D materials are promising for hybrid systems that couple their elementary excitations (excitons, phonons) to their macroscopic mechanical modes. These built-in systems may yield enhanced strain-mediated coupling compared to bulkier architectures, e.g., comprising a single quantum emitter coupled to a nano-mechanical resonator. Here, using micro-Raman spectroscopy on pristine monolayer graphene drums, we demonstrate that the macroscopic flexural vibrations of graphene induce dynamical optical phonon softening. This softening is an unambiguous fingerprint of dynamically-induced tensile strain that reaches values up to ≈4 × 10−4 under strong non-linear driving. Such non-linearly enhanced strain exceeds the values predicted for harmonic vibrations with the same root mean square (RMS) amplitude by more than one order of magnitude. Our work holds promise for dynamical strain engineering and dynamical strain-mediated control of light-matter interactions in 2D materials and related heterostructures. Here, the authors use Raman spectroscopy on circular graphene drums to demonstrate dynamical softening of optical phonons induced by the macroscopic flexural motion of graphene, and find evidence that the strain in graphene is enhanced under non-linear driving.
Collapse
Affiliation(s)
- Xin Zhang
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France.
| | - Kevin Makles
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France
| | - Léo Colombier
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France
| | - Dominik Metten
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France
| | - Hicham Majjad
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France
| | - Pierre Verlot
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom.,Institut Universitaire de France, 1 rue Descartes, 05 75231, Paris Cedex, France
| | - Stéphane Berciaud
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France. .,Institut Universitaire de France, 1 rue Descartes, 05 75231, Paris Cedex, France.
| |
Collapse
|
9
|
Vejpravova J, Pacakova B, Dresselhaus MS, Kong J, Kalbac M. Coexistence of Van Hove singularities and pseudomagnetic fields in modulated graphene bilayer. NANOTECHNOLOGY 2020; 31:165705. [PMID: 31891936 DOI: 10.1088/1361-6528/ab6687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The stacking and bending of graphene are trivial but extremely powerful agents of control over graphene's manifold physics. By changing the twist angle, one can drive the system over a plethora of exotic states via strong electron correlation, thanks to the moiré superlattice potentials, while the periodic or triaxial strains induce discretization of the band structure into Landau levels without the need for an external magnetic field. We fabricated a hybrid system comprising both the stacking and bending tuning knobs. We have grown the graphene monolayers by chemical vapor deposition, using 12C and 13C precursors, which enabled us to individually address the layers through Raman spectroscopy mapping. We achieved the long-range spatial modulation by sculpturing the top layer (13C) over uniform magnetic nanoparticles (NPs) deposited on the bottom layer (12C). An atomic force microscopy study revealed that the top layer tends to relax into pyramidal corrugations with C3 axial symmetry at the position of the NPs, which have been widely reported as a source of large pseudomagnetic fields (PMFs) in graphene monolayers. The modulated graphene bilayer (MGBL) also contains a few micrometer large domains, with the twist angle ∼10°, which were identified via extreme enhancement of the Raman intensity of the G-mode due to formation of van Hove singularities (VHSs). We thereby conclude that the twist-induced VHSs coexist with the PMFs generated in the strained pyramidal objects without mutual disturbance. The graphene bilayer modulated with magnetic NPs is a non-trivial hybrid system that accommodates features of twist-induced VHSs and PMFs in environs of giant classical spins.
Collapse
Affiliation(s)
- Jana Vejpravova
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2, Czech Republic
| | | | | | | | | |
Collapse
|
10
|
Voylov DN, Bocharova V, Lavrik NV, Vlassiouk I, Polizos G, Volodin A, Shulga YM, Kisliuk A, Thiyagarajan T, Miller DD, Narayanan R, Sumpter BG, Sokolov AP. Noncontact tip-enhanced Raman spectroscopy for nanomaterials and biomedical applications. NANOSCALE ADVANCES 2019; 1:3392-3399. [PMID: 36133556 PMCID: PMC9419720 DOI: 10.1039/c9na00322c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 08/16/2019] [Indexed: 05/28/2023]
Abstract
Tip-enhanced Raman spectroscopy (TERS) has been established as one the most efficient analytical techniques for probing vibrational states with nanoscale resolution. While TERS may be a source of unique information about chemical structure and interactions, it has a limited use for materials with rough or sticky surfaces. Development of the TERS approach utilizing a non-contact scanning probe microscopy mode can significantly extend the number of applications. Here we demonstrate a proof of the concept and feasibility of a non-contact TERS approach and test it on various materials. Our experiments show that non-contact TERS can provide 10 nm spatial resolution and a Raman signal enhancement factor of 105, making it very promising for chemical imaging of materials with high aspect ratio surface patterns and biomaterials.
Collapse
Affiliation(s)
- Dmitry N Voylov
- Department of Mechanical Engineering, Tufts University Medford Massachusetts 02155 USA
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| | - Vera Bocharova
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| | - Nickolay V Lavrik
- Center for Nanophase Materials Sciences, Computational Sciences and Engineering Division, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| | - Ivan Vlassiouk
- Energy & Transportation Science Division, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| | - Georgios Polizos
- Energy & Transportation Science Division, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| | - Alexei Volodin
- Institute of Problems of Chemical Physics RAS Chernogolovka Moscow region 142432 Russia
| | - Yury M Shulga
- National University of Science and Technology MISIS Moscow 119049 Russia
| | - Alexander Kisliuk
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| | - Thirumagal Thiyagarajan
- Department of Medicine, University of Tennessee Health Science Center Memphis Tennessee 38103 USA
| | - Duane D Miller
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center Memphis Tennessee 38103 USA
| | - Ramesh Narayanan
- Department of Medicine, University of Tennessee Health Science Center Memphis Tennessee 38103 USA
| | - Bobby G Sumpter
- Center for Nanophase Materials Sciences, Computational Sciences and Engineering Division, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| | - Alexei P Sokolov
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| |
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
Pardanaud C, Merlen A, Gratzer K, Chuzel O, Nikolaievskyi D, Patrone L, Clair S, Ramirez-Jimenez R, de Andrés A, Roubin P, Parrain JL. Forming Weakly Interacting Multilayers of Graphene Using Atomic Force Microscope Tip Scanning and Evidence of Competition between Inner and Outer Raman Scattering Processes Piloted by Structural Defects. J Phys Chem Lett 2019; 10:3571-3579. [PMID: 31198044 DOI: 10.1021/acs.jpclett.9b00564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report on an alternative route based on nanomechanical folding induced by an AFM tip to obtain weakly interacting multilayer graphene (wi-MLG) from a chemical vapor deposition (CVD)-grown single-layer graphene (SLG). The tip first cuts and then pushes and folds graphene during zigzag movements. The pushed graphene has been analyzed using various Raman microscopy plots- AD/ AG × EL4 vs ΓG, ω2D vs Γ2D, Γ2D vs ΓG, ω2D+/- vs Γ2D+/-, and A2D-/ A2D+ vs A2D/ AG. We show that the SLG in-plane properties are maintained under the folding process and that a few tens of graphene layers are stacked, with a limited number of structural defects. A blue shift of about 20 cm-1 of the 2D band is observed. The relative intensity of the 2D- and 2D+ bands have been related to structural defects, giving evidence of their role in the inner and outer processes at play close to the Dirac cone.
Collapse
Affiliation(s)
- C Pardanaud
- Aix Marseille Univ , CNRS, PIIM , Marseille , France
| | - A Merlen
- Aix Marseille Univ, Université de Toulon , CNRS, IM2NP , Marseille , France
| | - K Gratzer
- Aix Marseille Univ , CNRS, Centrale Marseille, iSm2 , Marseille , France
| | - O Chuzel
- Aix Marseille Univ , CNRS, Centrale Marseille, iSm2 , Marseille , France
| | - D Nikolaievskyi
- Aix Marseille Univ , CNRS, PIIM , Marseille , France
- Aix Marseille Univ , CNRS, Centrale Marseille, iSm2 , Marseille , France
| | - L Patrone
- Aix Marseille Univ, Université de Toulon , CNRS, IM2NP , Marseille , France
- ISEN Yncréa Méditerranée , CNRS, IM2NP UMR 7334 , Toulon , France
| | - S Clair
- Aix Marseille Univ, Université de Toulon , CNRS, IM2NP , Marseille , France
| | - R Ramirez-Jimenez
- Departamento de Física, Escuela Politecnica Superior , Universidad Carlos III de Madrid , Avenida Universidad 30 , Leganes, 28911 Madrid , Spain
- Instituto de Ciencia de Materiales de Madrid , Consejo Superior de Investigaciones Científicas , Cantoblanco, 28049 Madrid , Spain
| | - A de Andrés
- Instituto de Ciencia de Materiales de Madrid , Consejo Superior de Investigaciones Científicas , Cantoblanco, 28049 Madrid , Spain
| | - P Roubin
- Aix Marseille Univ , CNRS, PIIM , Marseille , France
| | - J-L Parrain
- Aix Marseille Univ , CNRS, Centrale Marseille, iSm2 , Marseille , France
| |
Collapse
|
13
|
Hu KM, Xue ZY, Liu YQ, Long H, Peng B, Yan H, Di ZF, Wang X, Lin L, Zhang WM. Tension-Induced Raman Enhancement of Graphene Membranes in the Stretched State. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1804337. [PMID: 30506848 DOI: 10.1002/smll.201804337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/14/2018] [Indexed: 06/09/2023]
Abstract
The intensity ratio of the 2D band to the G band, I2D /IG , is a good criterion in selecting high quality monolayer graphene samples; however, the evaluation of the ultimate value of I2D /IG for intrinsic monolayer graphene is a challenging yet interesting issue. Here, an interesting tension-induced Raman enhancement phenomenon is reported in supported graphene membranes, which show a transition from the corrugated state to the stretched state in the vicinity of wells. The I2D /IG of substrate-supported graphene membranes near wells are significantly enhanced up to 16.74, which is the highest experimental value to the best of knowledge, increasing by more than 600% when the testing points approach the well edges.The macroscopic origin of this phenomenon is that corrugated graphene membranes are stretched by built-in tensions. A lattice dynamic model is proposed to successfully reveal the microscopic mechanism of this phenomenon. The theoretical results agree well with the experimental data, demonstrating that tensile stresses can depress the amplitude of in-plane vibration of sp2 -bonded carbon atoms and result in the decrease in the G band intensity. This work can be helpful in furthering the development of the method of suppressing small ripples in graphene and acquiring ultraflat 2D materials.
Collapse
Affiliation(s)
- Kai-Ming Hu
- State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zhong-Ying Xue
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, China
| | - Yun-Qi Liu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, China
| | - Hu Long
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Bo Peng
- State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Han Yan
- State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zeng-Feng Di
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, China
| | - Xi Wang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, China
| | - Liwei Lin
- Berkeley Sensor and Actuator Center, University of California at Berkeley, 5101-B Etcheverry, Berkeley, CA, 94720-1774, USA
| | - Wen-Ming Zhang
- State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| |
Collapse
|
14
|
Wang X, Christopher JW, Swan AK. 2D Raman band splitting in graphene: Charge screening and lifting of the K-point Kohn anomaly. Sci Rep 2017; 7:13539. [PMID: 29051553 PMCID: PMC5648804 DOI: 10.1038/s41598-017-13769-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/29/2017] [Indexed: 11/10/2022] Open
Abstract
Pristine graphene encapsulated in hexagonal boron nitride has transport properties rivalling suspended graphene, while being protected from contamination and mechanical damage. For high quality devices, it is important to avoid and monitor accidental doping and charge fluctuations. The 2D Raman double peak in intrinsic graphene can be used to optically determine charge density, with decreasing peak split corresponding to increasing charge density. We find strong correlations between the 2D 1 and 2D 2 split vs 2D line widths, intensities, and peak positions. Charge density fluctuations can be measured with orders of magnitude higher precision than previously accomplished using the G-band shift with charge. The two 2D intrinsic peaks can be associated with the "inner" and "outer" Raman scattering processes, with the counterintuitive assignment of the phonon closer to the K point in the KM direction (outer process) as the higher energy peak. Even low charge screening lifts the phonon Kohn anomaly near the K point for graphene encapsulated in hBN, and shifts the dominant intensity from the lower to the higher energy peak.
Collapse
Affiliation(s)
- Xuanye Wang
- Department of Electrical and Computer Engineering, Photonics Center, Boston University, 8 St Mary's Street, Boston Massachusetts, 02215, United States of America
| | - Jason W Christopher
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, MA, 02215, United States of America
| | - Anna K Swan
- Department of Electrical and Computer Engineering, Photonics Center, Boston University, 8 St Mary's Street, Boston Massachusetts, 02215, United States of America. .,Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, MA, 02215, United States of America.
| |
Collapse
|
15
|
A General Route for Growing Metal Sulfides onto Graphene Oxide and Exfoliated Graphite Oxide. NANOMATERIALS 2017; 7:nano7090245. [PMID: 28858234 PMCID: PMC5618356 DOI: 10.3390/nano7090245] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 08/18/2017] [Accepted: 08/26/2017] [Indexed: 01/11/2023]
Abstract
Graphene-based materials are elective materials for a number of technologies due to their unique properties. Also, semiconductor nanocrystals have been extensively explored due to their size-dependent properties that make them useful for several applications. By coupling both types of materials, new applications are envisaged that explore the synergistic properties in such hybrid nanostructures. This research reports a general wet chemistry method to prepare graphene oxide (GO) sheets decorated with nanophases of semiconductor metal sulfides. This method allows the in situ growth of metal sulfides onto GO by using metal dialkyldithiocarbamate complexes as single-molecule precursors. In particular, the role of GO as heterogeneous substrate for the growth of semiconductor nanocrystals was investigated by using Raman spectroscopic and imaging methods. The method was further extended to other graphene-based materials, which are easily prepared in a larger scale, such as exfoliated graphite oxide (EGO).
Collapse
|
16
|
Phillipson R, Lockhart de la Rosa CJ, Teyssandier J, Walke P, Waghray D, Fujita Y, Adisoejoso J, Mali KS, Asselberghs I, Huyghebaert C, Uji-I H, De Gendt S, De Feyter S. Tunable doping of graphene by using physisorbed self-assembled networks. NANOSCALE 2016; 8:20017-20026. [PMID: 27883146 DOI: 10.1039/c6nr07912a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
One current key challenge in graphene research is to tune its charge carrier concentration, i.e., p- and n-type doping of graphene. An attractive approach in this respect is offered by controlled doping via well-ordered self-assembled networks physisorbed on the graphene surface. We report on tunable n-type doping of graphene using self-assembled networks of alkyl-amines that have varying chain lengths. The doping magnitude is modulated by controlling the density of the strong n-type doping amine groups on the surface. As revealed by scanning tunneling and atomic force microscopy, this density is governed by the length of the alkyl chain which acts as a spacer within the self-assembled network. The modulation of the doping magnitude depending on the chain length was demonstrated using Raman spectroscopy and electrical measurements on graphene field effect devices. This supramolecular functionalization approach offers new possibilities for controlling the properties of graphene and other two-dimensional materials at the nanoscale.
Collapse
Affiliation(s)
- Roald Phillipson
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
| | - César J Lockhart de la Rosa
- KU Leuven, Department of Metallurgy and Materials Engineering, Kasteelpark Arenberg 44, B-3001 Leuven, Belgium and imec, Kapeldreef 75, B-3001 Leuven, Belgium.
| | - Joan Teyssandier
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
| | - Peter Walke
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
| | - Deepali Waghray
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
| | - Yasuhiko Fujita
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
| | - Jinne Adisoejoso
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
| | - Kunal S Mali
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
| | | | | | - Hiroshi Uji-I
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium. and RIES, Hokkaido University, Sapporo, 001-0020, Japan
| | - Stefan De Gendt
- imec, Kapeldreef 75, B-3001 Leuven, Belgium. and KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Design and Synthesis, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Steven De Feyter
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
| |
Collapse
|
17
|
Heller EJ, Yang Y, Kocia L, Chen W, Fang S, Borunda M, Kaxiras E. Theory of Graphene Raman Scattering. ACS NANO 2016; 10:2803-2818. [PMID: 26799915 DOI: 10.1021/acsnano.5b07676] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Raman scattering plays a key role in unraveling the quantum dynamics of graphene, perhaps the most promising material of recent times. It is crucial to correctly interpret the meaning of the spectra. It is therefore very surprising that the widely accepted understanding of Raman scattering, i.e., Kramers-Heisenberg-Dirac theory, has never been applied to graphene. Doing so here, a remarkable mechanism we term"transition sliding" is uncovered, explaining the uncommon brightness of overtones in graphene. Graphene's dispersive and fixed Raman bands, missing bands, defect density and laser frequency dependence of band intensities, widths of overtone bands, Stokes, anti-Stokes anomalies, and other known properties emerge simply and directly.
Collapse
Affiliation(s)
- Eric J Heller
- Department of Physics, Harvard University , Cambridge, Massachusetts 02138, United States
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Yuan Yang
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Lucas Kocia
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Wei Chen
- Department of Physics, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Shiang Fang
- Department of Physics, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Mario Borunda
- Department of Physics, Oklahoma State University , Stillwater, Oklahoma 74078, United States
| | - Efthimios Kaxiras
- Department of Physics, Harvard University , Cambridge, Massachusetts 02138, United States
| |
Collapse
|
18
|
Neumann C, Reichardt S, Venezuela P, Drögeler M, Banszerus L, Schmitz M, Watanabe K, Taniguchi T, Mauri F, Beschoten B, Rotkin SV, Stampfer C. Raman spectroscopy as probe of nanometre-scale strain variations in graphene. Nat Commun 2015; 6:8429. [PMID: 26416349 PMCID: PMC4598719 DOI: 10.1038/ncomms9429] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/21/2015] [Indexed: 12/23/2022] Open
Abstract
Confocal Raman spectroscopy has emerged as a major, versatile workhorse for the non-invasive characterization of graphene. Although it is successfully used to determine the number of layers, the quality of edges, and the effects of strain, doping and disorder, the nature of the experimentally observed broadening of the most prominent Raman 2D line has remained unclear. Here we show that the observed 2D line width contains valuable information on strain variations in graphene on length scales far below the laser spot size, that is, on the nanometre-scale. This finding is highly relevant as it has been shown recently that such nanometre-scaled strain variations limit the carrier mobility in high-quality graphene devices. Consequently, the 2D line width is a good and easily accessible quantity for classifying the crystalline quality, nanometre-scale flatness as well as local electronic properties of graphene, all important for future scientific and industrial applications. Raman spectroscopy has become an invaluable tool for graphene characterisation, yet the nature of the broadening of the Raman 2D line remains unclear. Here, Stampfer et al. show that the Raman 2D line width is a measure of nanometre-scale strain variations in graphene on insulating substrates.
Collapse
Affiliation(s)
- C Neumann
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - S Reichardt
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - P Venezuela
- Instituto de Fsica, Universidade Federal Fluminense, Niterói, 24210-346 Rio de Janeiro, Brazil
| | - M Drögeler
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - M Schmitz
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - K Watanabe
- National Institute for Materials Science,1-1 Namiki, Tsukuba 305-0044, Japan
| | - T Taniguchi
- National Institute for Materials Science,1-1 Namiki, Tsukuba 305-0044, Japan
| | - F Mauri
- IMPMC, UMR CNRS 7590, Sorbonne Universités-UPMC Univ. Paris 06, MNHN, IRD, 4 Place Jussieu, Paris 75005, France
| | - B Beschoten
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - S V Rotkin
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.,Department of Physics and Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| |
Collapse
|
19
|
Polyzos I, Bianchi M, Rizzi L, Koukaras EN, Parthenios J, Papagelis K, Sordan R, Galiotis C. Suspended monolayer graphene under true uniaxial deformation. NANOSCALE 2015; 7:13033-13042. [PMID: 26172517 DOI: 10.1039/c5nr03072b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
2D crystals, such as graphene, exhibit the higher strength and stiffness of any other known man-made or natural material. So far, this assertion has been primarily based on modelling predictions and on bending experiments in combination with pertinent modelling. True uniaxial loading of suspended graphene is not easy to accomplish; however such an experiment is of paramount importance in order to assess the intrinsic properties of graphene without the influence of an underlying substrate. In this work we report on uniaxial tension of graphene up to moderate strains of ∼0.8%. This has been made possible by sandwiching the graphene flake between two polymethylmethacrylate (PMMA) layers and by suspending its central part by the removal of a section of PMMA with e-beam lithography. True uniaxial deformation is confirmed by the measured large phonon shifts with strain by Raman spectroscopy and the indication of lateral buckling (similar to what is observed for thin macroscopic membranes under tension). Finally, we also report on how the stress is transferred to the suspended specimen through the adhesive grips and determine the value of interfacial shear stress that is required for efficient axial loading in such a system.
Collapse
Affiliation(s)
- Ioannis Polyzos
- Institute of Chemical Engineering Sciences, Foundation of Research and Technology-Hellas (FORTH/ICE-HT), Patras, Greece.
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Herziger F, Calandra M, Gava P, May P, Lazzeri M, Mauri F, Maultzsch J. Two-dimensional analysis of the double-resonant 2D Raman mode in bilayer graphene. PHYSICAL REVIEW LETTERS 2014; 113:187401. [PMID: 25396395 DOI: 10.1103/physrevlett.113.187401] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Indexed: 06/04/2023]
Abstract
By computing the double-resonant Raman scattering cross section completely from first principles and including the electron-electron interaction at the GW level, we unravel the dominant contributions for the double-resonant 2D mode in bilayer graphene. We show that, in contrast to previous works, the so-called inner processes are dominant and that the 2D-mode line shape is described by three dominant resonances around the K point. We show that the splitting of the transversal optical (TO) phonon branch in the Γ-K direction, as large as 12 cm(-1) in the GW approximation, is of great importance for a thorough description of the 2D-mode line shape. Finally, we present a method to extract the TO phonon splitting and the splitting of the electronic bands from experimental data.
Collapse
Affiliation(s)
- Felix Herziger
- Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Matteo Calandra
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités, UPMC Université Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
| | - Paola Gava
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités, UPMC Université Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
| | - Patrick May
- Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Michele Lazzeri
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités, UPMC Université Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
| | - Francesco Mauri
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités, UPMC Université Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
| | - Janina Maultzsch
- Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| |
Collapse
|
21
|
Berciaud S, Potemski M, Faugeras C. Probing electronic excitations in mono- to pentalayer graphene by micro magneto-Raman spectroscopy. NANO LETTERS 2014; 14:4548-4553. [PMID: 24955484 DOI: 10.1021/nl501578m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We probe electronic excitations between Landau levels in freestanding N-layer graphene over a broad energy range, with unprecedented spectral and spatial resolution, using micro magneto-Raman scattering spectroscopy. A characteristic evolution of electronic bands in up to five Bernal-stacked graphene layers is evidenced and shown to remarkably follow a simple theoretical approach, based on an effective bilayer model. (N > 3)-layer graphenes appear as appealing candidates in the quest for novel phenomena, particularly in the quantum Hall effect regime. Our work paves the way toward minimally invasive investigations of magneto-excitons in other emerging low-dimensional systems, with a spatial resolution down to 1 μm.
Collapse
Affiliation(s)
- Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS , 23 rue du Lœss, BP43, 67034 Strasbourg Cedex 2, France
| | | | | |
Collapse
|
22
|
Trabelsi ABG, Kusmartsev FV, Robinson BJ, Ouerghi A, Kusmartseva OE, Kolosov OV, Mazzocco R, Gaifullin MB, Oueslati M. Charged nano-domes and bubbles in epitaxial graphene. NANOTECHNOLOGY 2014; 25:165704. [PMID: 24675237 DOI: 10.1088/0957-4484/25/16/165704] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
For the first time, new epitaxial graphene nano-structures resembling charged 'bubbles' and 'domes' are reported. A strong influence, arising from the change in morphology, on the graphene layer's electronic, mechanical and optical properties has been shown. The morphological properties of these structures have been studied with atomic force microscopy (AFM), ultrasonic force microscopy (UFM) and Raman spectroscopy. After initial optical microscopy observation of the graphene, a detailed description of the surface morphology, via AFM and nanomechanical UFM measurements, was obtained. Here, graphene nano-structures, domes and bubbles, ranging from a few tens of nanometres (150–200 nm) to a few μm in size have been identified. The AFM topographical and UFM stiffness data implied the freestanding nature of the graphene layer within the domes and bubbles, with heights on the order of 5–12 nm. Raman spectroscopy mappings of G and 2D bands and their ratio confirm not only the graphene composition of these structures but also the existence of step bunching, defect variations and the carrier density distribution. In particular, inside the bubbles and substrate there arises complex charge redistribution; in fact, the graphene bubble–substrate interface forms a charged capacitance. We have determined the strength of the electric field inside the bubble–substrate interface, which may lead to a minigap of the order of 5 meV opening for epitaxial graphene grown on 4H-SiC face-terminated carbon.
Collapse
|
23
|
Bissett MA, Tsuji M, Ago H. Strain engineering the properties of graphene and other two-dimensional crystals. Phys Chem Chem Phys 2014; 16:11124-38. [DOI: 10.1039/c3cp55443k] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
This perspective discusses recent advances in using strain to engineer the properties of thin-layer materials such as graphene and transition metal dichalcogenides (TMDs).
Collapse
Affiliation(s)
- Mark A. Bissett
- Institute for Materials Chemistry and Engineering
- Kyushu University
- Fukuoka, Japan
| | - Masaharu Tsuji
- Institute for Materials Chemistry and Engineering
- Kyushu University
- Fukuoka, Japan
| | - Hiroki Ago
- Institute for Materials Chemistry and Engineering
- Kyushu University
- Fukuoka, Japan
| |
Collapse
|
24
|
Chattrakun K, Huang S, Watanabe K, Taniguchi T, Sandhu A, LeRoy BJ. Gate dependent Raman spectroscopy of graphene on hexagonal boron nitride. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:505304. [PMID: 24275340 DOI: 10.1088/0953-8984/25/50/505304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Raman spectroscopy, a fast and nondestructive imaging method, can be used to monitor the doping level in graphene devices. We fabricated chemical vapor deposition (CVD) grown graphene on atomically flat hexagonal boron nitride (hBN) flakes and SiO2 substrates. We compared their Raman response as a function of charge carrier density using an ion gel as a top gate. The G peak position, the 2D peak position, the 2D peak width and the ratio of the 2D peak area to the G peak area show a dependence on carrier density that differs for hBN compared to SiO2. Histograms of two-dimensional mapping are used to compare the fluctuations in the Raman peak properties between the two substrates. The hBN substrate has been found to produce fewer fluctuations at the same charge density owing to its atomically flat surface and reduced charged impurities.
Collapse
|
25
|
Godel F, Pichonat E, Vignaud D, Majjad H, Metten D, Henry Y, Berciaud S, Dayen JF, Halley D. Epitaxy of MgO magnetic tunnel barriers on epitaxial graphene. NANOTECHNOLOGY 2013; 24:475708. [PMID: 24192567 DOI: 10.1088/0957-4484/24/47/475708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Epitaxial growth of electrodes and tunnel barriers on graphene is one of the main technological bottlenecks for graphene spintronics. In this paper, we demonstrate that MgO(111) epitaxial tunnel barriers, one of the prime candidates for spintronic application, can be grown by molecular beam epitaxy on epitaxial graphene on SiC(0001). Ferromagnetic metals (Fe, Co, Fe20Ni80) were epitaxially grown on top of the MgO barrier, thus leading to monocrystalline electrodes on graphene. Structural and magnetic characterizations were performed on these ferromagnetic metals after annealing and dewetting: they form clusters with a 100 nm typical lateral width, which are mostly magnetic monodomains in the case of Fe. This epitaxial stack opens the way to graphene spintronic devices taking benefits from a coherent tunnelling current through the epitaxial MgO/graphene stack.
Collapse
|