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Hirata M, Kobayashi A, Berthier C, Kanoda K. Interacting chiral electrons at the 2D Dirac points: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2021; 84:036502. [PMID: 33059346 DOI: 10.1088/1361-6633/abc17c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 10/15/2020] [Indexed: 06/11/2023]
Abstract
The pseudo-relativistic chiral electrons in 2D graphene and 3D topological semimetals, known as the massless Dirac or Weyl fermions, constitute various intriguing issues in modern condensed-matter physics. In particular, the issues linked to the Coulomb interaction between the chiral electrons attract great attentions due to their unusual features, namely, the interaction is not screened and has a long-ranged property near the charge-neutrality point, in clear contrast to its screened and short-ranged properties in the conventional correlated materials. In graphene, this long-range interaction induces an anomalous logarithmic renormalization of the Fermi velocity, which causes a nonlinear reshaping of its Dirac cone. In addition, for strong interactions, it even leads to the predictions of an excitonic condensation with a spontaneous mass generation. The interaction, however, would seem to be not that large in graphene, so that the latter phenomenon appears to have not yet been observed. Contrastingly, the interaction is probably large in the pressurized organic materialα-(BEDT-TTF)2I3, where a 2D massless-Dirac-fermion phase emerges next to a correlated insulating phase. Therefore, an excellent testing ground would appear in this material for the studies of both the velocity renormalization and the mass generation, as well as for those of the short-range electronic correlations. In this review, we give an overview of the recent progress on the understanding of such interacting chiral electrons in 2D, by placing particular emphasis on the studies in graphene andα-(BEDT-TTF)2I3. In the first half, we briefly summarize our current experimental and theoretical knowledge about the interaction effects in graphene, then turn attentions to the understanding inα-(BEDT-TTF)2I3, and highlight its relevance to and difference from graphene. The second half of this review focusses on the studies linked to the nuclear magnetic resonance experiments and the associated model calculations inα-(BEDT-TTF)2I3. These studies allow us to discuss the anisotropic reshaping of a tilted Dirac cone together with various electronic correlations, and the precursor excitonic dynamics growing prior to a condensation. We see these provide unique opportunities to resolve the momentum dependence of the spin excitations and fluctuations that are strongly influenced by the long-range interaction near the Dirac points.
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Affiliation(s)
- Michihiro Hirata
- Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
- MPA-Q, Los Alamos National Laboratory, NM 87545, United States of America
| | - Akito Kobayashi
- Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Claude Berthier
- Laboratoire National des Champs Magnétiques Intenses, UPR 3228 CNRS, EMFL, UGA, UPS and INSA, Boite Postale 166, 38042 Grenoble Cedex 9, France
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
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Chen S, Chen X, Duijnstee EA, Sanyal B, Banerjee T. Unveiling Temperature-Induced Structural Domains and Movement of Oxygen Vacancies in SrTiO 3 with Graphene. ACS APPLIED MATERIALS & INTERFACES 2020; 12:52915-52921. [PMID: 33175485 PMCID: PMC7705893 DOI: 10.1021/acsami.0c15458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 11/03/2020] [Indexed: 06/11/2023]
Abstract
Heterointerfaces coupling complex oxides exhibit coexisting functional properties such as magnetism, superconductivity, and ferroelectricity, often absent in their individual constituent. SrTiO3 (STO), a canonical band insulator, is an active constituent of such heterointerfaces. Temperature-, strain-, or mechanical stress-induced ferroelastic transition leads to the formation of narrow domains and domain walls in STO. Such ferroelastic domain walls have been studied using imaging or transport techniques and, often, the findings are influenced by the choice and interaction of the electrodes with STO. In this work, we use graphene as a unique platform to unveil the movement of oxygen vacancies and ferroelastic domain walls near the STO surface by studying the temperature and gate bias dependence of charge transport in graphene. By sweeping the back gate voltage, we observe antihysteresis in graphene typically observed in conventional ferroelectric oxides. Interestingly, we find features in antihysteresis that are related to the movement of domain walls and of oxygen vacancies in STO. We ascertain this by analyzing the time dependence of the graphene square resistance at different temperatures and gate bias. Density functional calculations estimate the surface polarization and formation energies of layer-dependent oxygen vacancies in STO. This corroborates quantitatively with the activation energies determined from the temperature dependence of the graphene square resistance. Introduction of a hexagonal boron nitride (hBN) layer, of varying thicknesses, between graphene and STO leads to a gradual disappearance of the observed features, implying the influence of the domain walls onto the potential landscape in graphene.
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Affiliation(s)
- Si Chen
- Zernike
Institute for Advanced Materials, University
of Groningen, 9747 AG Groningen, The Netherlands
| | - Xin Chen
- Department
of Physics and Astronomy, Uppsala University, P.O. Box 516, 751 20 Uppsala, Sweden
| | - Elisabeth A. Duijnstee
- Zernike
Institute for Advanced Materials, University
of Groningen, 9747 AG Groningen, The Netherlands
| | - Biplab Sanyal
- Department
of Physics and Astronomy, Uppsala University, P.O. Box 516, 751 20 Uppsala, Sweden
| | - Tamalika Banerjee
- Zernike
Institute for Advanced Materials, University
of Groningen, 9747 AG Groningen, The Netherlands
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Hwang J, Lee S, Lee JE, Kang M, Ryu H, Joo HJ, Denlinger J, Park JH, Hwang C. Tunable Kondo Resonance at a Pristine Two-Dimensional Dirac Semimetal on a Kondo Insulator. NANO LETTERS 2020; 20:7973-7979. [PMID: 33104350 DOI: 10.1021/acs.nanolett.0c02751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The proximity of two different materials leads to an intricate coupling of quasiparticles so that an unprecedented electronic state is often realized at the interface. Here, we demonstrate a resonance-type many-body ground state in graphene, a nonmagnetic two-dimensional Dirac semimetal, when grown on SmB6, a Kondo insulator, via thermal decomposition of fullerene molecules. This ground state is typically observed in three-dimensional magnetic materials with correlated electrons. Above the characteristic Kondo temperature of the substrate, the electron band structure of pristine graphene remains almost intact. As temperature decreases, however, the Dirac Fermions of graphene become hybridized with the Sm 4f states. Remarkable enhancement of the hybridization and Kondo resonance is observed with further cooling and increasing charge-carrier density of graphene, evidencing the Kondo screening of the Sm 4f local magnetic moment by the conduction electrons of graphene at the interface. These findings manifest the realization of the Kondo effect in graphene by the proximity of SmB6 that is tuned by the temperature and charge-carrier density of graphene.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics, Pusan National University, Busan 46241, South Korea
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Seungseok Lee
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Division of Advanced Material Science, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Ji-Eun Lee
- Department of Physics, Pusan National University, Busan 46241, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Minhee Kang
- Department of Physics, Pusan National University, Busan 46241, South Korea
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Hyun-Jeong Joo
- Department of Physics, Pusan National University, Busan 46241, South Korea
| | - Jonathan Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jae-Hoon Park
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Division of Advanced Material Science, Pohang University of Science and Technology, Pohang 37673, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan 46241, South Korea
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Dedkov Y, Voloshina E. Epitaxial graphene/Ge interfaces: a minireview. NANOSCALE 2020; 12:11416-11426. [PMID: 32458957 DOI: 10.1039/d0nr00185f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The recent discovery of the ability to perform direct epitaxial growth of graphene layers on semiconductor Ge surfaces led to a huge interest in this topic. One of the reasons for this interest is the chance to overcome several present-day drawbacks on the method of graphene integration in modern semiconductor technology. The other one is connected with the fundamental studies of the new graphene-semiconductor interfaces that might help with the deeper understanding of mechanisms, which governs graphene growth on different substrates as well as shedding light on the interaction of graphene with these substrates, whose range is now spread from metals to insulators. The present minireview gives a timely overview of the state-of-the-art field of studies of the graphene-Ge epitaxial interfaces and draws some conclusions in this research area.
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Affiliation(s)
- Yuriy Dedkov
- Department of Physics, Shanghai University, 200444 Shanghai, P. R. China. and Institute of Physical and Organic Chemistry, Southern Federal University, 344090 Rostov on Don, Russia
| | - Elena Voloshina
- Department of Physics, Shanghai University, 200444 Shanghai, P. R. China. and Institute of Physical and Organic Chemistry, Southern Federal University, 344090 Rostov on Don, Russia
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Zhai Z, Shen H, Chen J, Li X, Li Y. Metal-Free Synthesis of Boron-Doped Graphene Glass by Hot-Filament Chemical Vapor Deposition for Wave Energy Harvesting. ACS APPLIED MATERIALS & INTERFACES 2020; 12:2805-2815. [PMID: 31867953 DOI: 10.1021/acsami.9b17546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Property modulation of graphene glass by heteroatom doping such as boron (B) and nitrogen (N) is important to extend its practical applications. However, unlike N doping, research studies about the metal-free synthesis of B-doped graphene on glass through the chemical vapor deposition (CVD) method are rarely reported. Herein, we report a hot-filament CVD approach to prepare B-doped graphene glass using diborane (B2H6) as the B dopant. The synthesized B-doped graphene was uniform on a large-scale and composed of nanocrystalline graphene grains. By raising the B2H6 flow from 0 to 15 sccm, the B content of graphene was facilely modulated from 0 to 5.3 at. %, accompanied with the improvement of both transparency and conductivity. The B-doped graphene prepared on glass at 15 sccm B2H6 flow presented the optimal transparent conductive performance superior to those of most reported graphene glass fabricated by other state-of-the-art approaches. Furthermore, for the first time, the performance of graphene glass for wave energy harvesting has been elaborated. It was found that the output power produced by inserting graphene glass into 0.6 M sodium chloride (NaCl) solution could be improved by more than 6 times through B doping. The significant enhancement resulted from the higher waving voltage and smaller resistance of B-doped graphene on glass than the pristine ones. In addition, the waving voltage inversed the polarity after B doping, which was due to the opposite variation of surface potential of pristine and B-doped graphene after NaCl immersion. This work would pave ways for the metal-free preparation and expand the energy-harvesting applications of B-doped graphene materials.
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Affiliation(s)
- Zihao Zhai
- College of Materials Science & Technology, Jiangsu Provincial Key Laboratory of Materials and Technology for Energy Conversion , Nanjing University of Aeronautics & Astronautics , 29 Yudao Street , Nanjing 210016 , PR China
| | - Honglie Shen
- College of Materials Science & Technology, Jiangsu Provincial Key Laboratory of Materials and Technology for Energy Conversion , Nanjing University of Aeronautics & Astronautics , 29 Yudao Street , Nanjing 210016 , PR China
- Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering , Changzhou University , Changzhou 213164 , PR China
| | - Jieyi Chen
- College of Materials Science & Technology, Jiangsu Provincial Key Laboratory of Materials and Technology for Energy Conversion , Nanjing University of Aeronautics & Astronautics , 29 Yudao Street , Nanjing 210016 , PR China
| | - Xuemei Li
- College of Materials Science & Technology, Jiangsu Provincial Key Laboratory of Materials and Technology for Energy Conversion , Nanjing University of Aeronautics & Astronautics , 29 Yudao Street , Nanjing 210016 , PR China
| | - Yufang Li
- College of Materials Science & Technology, Jiangsu Provincial Key Laboratory of Materials and Technology for Energy Conversion , Nanjing University of Aeronautics & Astronautics , 29 Yudao Street , Nanjing 210016 , PR China
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Kang KT, Park J, Suh D, Choi WS. Synergetic Behavior in 2D Layered Material/Complex Oxide Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1803732. [PMID: 30589101 DOI: 10.1002/adma.201803732] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 09/18/2018] [Indexed: 05/28/2023]
Abstract
The marriage between a 2D layered material (2DLM) and a complex transition metal oxide (TMO) results in a variety of physical and chemical phenomena that cannot be achieved in either material alone. Interesting recent discoveries in systems such as graphene/SrTiO3 , graphene/LaAlO3 /SrTiO3 , graphene/ferroelectric oxide, MoS2 /SrTiO3 , and FeSe/SrTiO3 heterostructures include voltage scaling in field-effect transistors, charge state coupling across an interface, quantum conductance probing of the electrochemical activity, novel memory functions based on charge traps, and greatly enhanced superconductivity. In this context, various properties and functionalities appearing in numerous different 2DLM/TMO heterostructure systems are reviewed. The results imply that the multidimensional heterostructure approach based on the disparate material systems leads to an entirely new platform for the study of condensed matter physics and materials science. The heterostructures are also highly relevant technologically as each constituent material is a promising candidate for next-generation optoelectronic devices.
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Affiliation(s)
- Kyeong Tae Kang
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea
| | - Jeongmin Park
- Department of Energy Sciences, Sungkyunkwan University, Suwon, 16419, Korea
| | - Dongseok Suh
- Department of Energy Sciences, Sungkyunkwan University, Suwon, 16419, Korea
| | - Woo Seok Choi
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea
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Marchenko D, Evtushinsky DV, Golias E, Varykhalov A, Seyller T, Rader O. Extremely flat band in bilayer graphene. SCIENCE ADVANCES 2018; 4:eaau0059. [PMID: 30430134 PMCID: PMC6226281 DOI: 10.1126/sciadv.aau0059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 10/04/2018] [Indexed: 05/06/2023]
Abstract
We propose a novel mechanism of flat band formation based on the relative biasing of only one sublattice against other sublattices in a honeycomb lattice bilayer. The mechanism allows modification of the band dispersion from parabolic to "Mexican hat"-like through the formation of a flattened band. The mechanism is well applicable for bilayer graphene-both doped and undoped. By angle-resolved photoemission from bilayer graphene on SiC, we demonstrate the possibility of realizing this extremely flattened band (< 2-meV dispersion), which extends two-dimensionally in a k-space area around the K ¯ point and results in a disk-like constant energy cut. We argue that our two-dimensional flat band model and the experimental results have the potential to contribute to achieving superconductivity of graphene- or graphite-based systems at elevated temperatures.
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Affiliation(s)
- D. Marchenko
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Corresponding author.
| | - D. V. Evtushinsky
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - E. Golias
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A. Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Th. Seyller
- Institut für Physik, Technische Universität Chemnitz, Reichenhainer Str. 70, 09126 Chemnitz, Germany
| | - O. Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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8
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Hwang J, Kim K, Ryu H, Kim J, Lee JE, Kim S, Kang M, Park BG, Lanzara A, Chung J, Mo SK, Denlinger J, Min BI, Hwang C. Emergence of Kondo Resonance in Graphene Intercalated with Cerium. NANO LETTERS 2018; 18:3661-3666. [PMID: 29761696 DOI: 10.1021/acs.nanolett.8b00784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interaction between a magnetic impurity, such as cerium (Ce) atom, and surrounding electrons has been one of the core problems in understanding many-body interaction in solid and its relation to magnetism. Kondo effect, the formation of a new resonant ground state with quenched magnetic moment, provides a general framework to describe many-body interaction in the presence of magnetic impurity. In this Letter, a combined study of angle-resolved photoemission (ARPES) and dynamic mean-field theory (DMFT) on Ce-intercalated graphene shows that Ce-induced localized states near Fermi energy, EF, hybridized with the graphene π-band, exhibit gradual increase in spectral weight upon decreasing temperature. The observed temperature dependence follows the expectations from the Kondo picture in the weak coupling limit. Our results provide a novel insight how Kondo physics emerges in the sea of two-dimensional Dirac electrons.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Kyoo Kim
- Max Planck-POSTECH/Hsinchu Center for Complex Phase Materials , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Hyejin Ryu
- Department of Physics , Pusan National University , Busan 46241 , Korea
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Center for Spintronics , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Jingul Kim
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Ji-Eun Lee
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Sooran Kim
- Max Planck-POSTECH/Hsinchu Center for Complex Phase Materials , Pohang University of Science and Technology , Pohang 37673 , Korea
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Minhee Kang
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Byeong-Gyu Park
- Pohang Accelerator Laboratory , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Alessandra Lanzara
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Physics , University of California , Berkeley , California 94720 , United States
| | - Jinwook Chung
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
- Department of Physics and Photon Science , Gwangju Institute of Science and Technology , Gwangju 61005 , Korea
| | - Sung-Kwan Mo
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Jonathan Denlinger
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Byung Il Min
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Choongyu Hwang
- Department of Physics , Pusan National University , Busan 46241 , Korea
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Tesch J, Paschke F, Fonin M, Wietstruk M, Böttcher S, Koch RJ, Bostwick A, Jozwiak C, Rotenberg E, Makarova A, Paulus B, Voloshina E, Dedkov Y. The graphene/n-Ge(110) interface: structure, doping, and electronic properties. NANOSCALE 2018; 10:6088-6098. [PMID: 29546912 DOI: 10.1039/c8nr00053k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The implementation of graphene in semiconducting technology requires precise knowledge about the graphene-semiconductor interface. In our work the structure and electronic properties of the graphene/n-Ge(110) interface are investigated on the local (nm) and macro (from μm to mm) scales via a combination of different microscopic and spectroscopic surface science techniques accompanied by density functional theory calculations. The electronic structure of freestanding graphene remains almost completely intact in this system, with only a moderate n-doping indicating weak interaction between graphene and the Ge substrate. With regard to the optimisation of graphene growth it is found that the substrate temperature is a crucial factor, which determines the graphene layer alignment on the Ge(110) substrate during its growth from the atomic carbon source. Moreover, our results demonstrate that the preparation route for graphene on the doped semiconducting material (n-Ge) leads to the effective segregation of dopants at the interface between graphene and Ge(110). Furthermore, it is shown that these dopant atoms might form regular structures at the graphene/Ge interface and induce the doping of graphene. Our findings help to understand the interface properties of the graphene-semiconductor interfaces and the effect of dopants on the electronic structure of graphene in such systems.
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Affiliation(s)
- Julia Tesch
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - Fabian Paschke
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - Mikhail Fonin
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - Marko Wietstruk
- SPECS Surface Nano Analysis GmbH, Voltastraße 5, 13355 Berlin, Germany
| | - Stefan Böttcher
- SPECS Surface Nano Analysis GmbH, Voltastraße 5, 13355 Berlin, Germany
| | - Roland J Koch
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Chris Jozwiak
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Eli Rotenberg
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Anna Makarova
- Institut für Festkörperphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - Beate Paulus
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Elena Voloshina
- Department of Physics and International Centre for Quantum and Molecular Structures, Shanghai University, Shangda Road 99, 200444 Shanghai, China.
| | - Yuriy Dedkov
- Department of Physics and International Centre for Quantum and Molecular Structures, Shanghai University, Shangda Road 99, 200444 Shanghai, China. and Materials Genome Institute, Shanghai University, Shangda Road 99, Shanghai 200444, China.
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