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Yan J, Ma J, Wang A, Ma R, Wu L, Wu Z, Liu L, Bao L, Huan Q, Gao HJ. A time-shared switching scheme designed for multi-probe scanning tunneling microscope. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:103702. [PMID: 34717434 DOI: 10.1063/5.0056634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 09/11/2021] [Indexed: 06/13/2023]
Abstract
We report the design of a time-shared switching scheme, aiming to realize the manipulation and working modes (imaging mode and transport measurement mode) switching between multiple scanning tunneling microscope (STM) probes one by one with a shared STM control system (STM CS) and an electrical transport characterization system. This scheme comprises three types of switch units, switchable preamplifiers (SWPAs), high voltage amplifiers, and a main control unit. Together with the home-made software kit providing the graphical user interface, this scheme achieves a seamless switching process between different STM probes. Compared with the conventional scheme using multiple independent STM CSs, this scheme possesses more compatibility, flexibility, and expansibility for lower cost. The overall architecture and technique issues are discussed in detail. The performances of the system are demonstrated, including the millimeter scale moving range and atomic scale resolution of a single STM probe, safely approached multiple STM probes beyond the resolution of the optical microscope (1.1 µm), qualified STM imaging, and accurate electrical transport characterization. The combinational technique of imaging and transport characterization is also shown, which is supported by SWPA switches with ultra-high open circuit resistance (909 TΩ). These successful experiments prove the effectiveness and the usefulness of the scheme. In addition, the scheme can be easily upgraded with more different functions and numbers of probe arrays, thus opening a new way to build an extremely integrated and high throughput characterization platform.
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Affiliation(s)
- Jiahao Yan
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Jiajun Ma
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Aiwei Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Ruisong Ma
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Liangmei Wu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Zebin Wu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Li Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Lihong Bao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Qing Huan
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Hong-Jun Gao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
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2
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Electronic and Transport Properties of Epitaxial Graphene on SiC and 3C-SiC/Si: A Review. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10124350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The electronic and transport properties of epitaxial graphene are dominated by the interactions the material makes with its surroundings. Based on the transport properties of epitaxial graphene on SiC and 3C-SiC/Si substrates reported in the literature, we emphasize that the graphene interfaces formed between the active material and its environment are of paramount importance, and how interface modifications enable the fine-tuning of the transport properties of graphene. This review provides a renewed attention on the understanding and engineering of epitaxial graphene interfaces for integrated electronics and photonics applications.
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3
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Voigtländer B, Cherepanov V, Korte S, Leis A, Cuma D, Just S, Lüpke F. Invited Review Article: Multi-tip scanning tunneling microscopy: Experimental techniques and data analysis. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:101101. [PMID: 30399776 DOI: 10.1063/1.5042346] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/25/2018] [Indexed: 06/08/2023]
Abstract
In scanning tunneling microscopy, we witness in recent years a paradigm shift from "just imaging" to detailed spectroscopic measurements at the nanoscale and multi-tip scanning tunneling microscope (STM) is a technique following this trend. It is capable of performing nanoscale charge transport measurements like a "multimeter at the nanoscale." Distance-dependent four-point measurements, the acquisition of nanoscale potential maps at current carrying nanostructures and surfaces, as well as the acquisition of I - V curves of nanoelectronic devices are examples of the capabilities of the multi-tip STM technique. In this review, we focus on two aspects: How to perform the multi-tip STM measurements and how to analyze the acquired data in order to gain insight into nanoscale charge transport processes for a variety of samples. We further discuss specifics of the electronics for multi-tip STM and the properties of tips for multi-tip STM, and present methods for a tip approach to nanostructures on insulating substrates. We introduce methods on how to extract the conductivity/resistivity for mixed 2D/3D systems from four-point measurements, how to measure the conductivity of 2D sheets, and how to introduce scanning tunneling potentiometry measurements with a multi-tip setup. For the example of multi-tip measurements at freestanding vapor liquid solid grown nanowires, we discuss contact resistances as well as the influence of the presence of the probing tips on the four point measurements.
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Affiliation(s)
- Bert Voigtländer
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich and JARA-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Vasily Cherepanov
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich and JARA-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Stefan Korte
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich and JARA-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Arthur Leis
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich and JARA-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - David Cuma
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich and JARA-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Sven Just
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich and JARA-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Felix Lüpke
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich and JARA-Fundamentals of Future Information Technology, 52425 Jülich, Germany
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4
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Momeni Pakdehi D, Aprojanz J, Sinterhauf A, Pierz K, Kruskopf M, Willke P, Baringhaus J, Stöckmann JP, Traeger GA, Hohls F, Tegenkamp C, Wenderoth M, Ahlers FJ, Schumacher HW. Minimum Resistance Anisotropy of Epitaxial Graphene on SiC. ACS APPLIED MATERIALS & INTERFACES 2018; 10:6039-6045. [PMID: 29377673 DOI: 10.1021/acsami.7b18641] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We report on electronic transport measurements in rotational square probe configuration in combination with scanning tunneling potentiometry of epitaxial graphene monolayers which were fabricated by polymer-assisted sublimation growth on SiC substrates. The absence of bilayer graphene on the ultralow step edges of below 0.75 nm scrutinized by atomic force microscopy and scanning tunneling microscopy result in a not yet observed resistance isotropy of graphene on 4H- and 6H-SiC(0001) substrates as low as 2%. We combine microscopic electronic properties with nanoscale transport experiments and thereby disentangle the underlying microscopic scattering mechanism to explain the remaining resistance anisotropy. Eventually, this can be entirely attributed to the resistance and the number of substrate steps which induce local scattering. Thereby, our data represent the ultimate limit for resistance isotropy of epitaxial graphene on SiC for the given miscut of the substrate.
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Affiliation(s)
- D Momeni Pakdehi
- Physikalisch-Technische Bundesanstalt , Bundesallee 100, 38116 Braunschweig, Germany
| | - J Aprojanz
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstraße 2, 30167 Hannover, Germany
| | - A Sinterhauf
- IV. Physikalisches Institut der Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC) der Universität Göttingen , 37077 Göttingen, Germany
| | - K Pierz
- Physikalisch-Technische Bundesanstalt , Bundesallee 100, 38116 Braunschweig, Germany
| | - M Kruskopf
- Physikalisch-Technische Bundesanstalt , Bundesallee 100, 38116 Braunschweig, Germany
| | - P Willke
- IV. Physikalisches Institut der Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - J Baringhaus
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstraße 2, 30167 Hannover, Germany
| | - J P Stöckmann
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstraße 2, 30167 Hannover, Germany
| | - G A Traeger
- IV. Physikalisches Institut der Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - F Hohls
- Physikalisch-Technische Bundesanstalt , Bundesallee 100, 38116 Braunschweig, Germany
| | - C Tegenkamp
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstraße 2, 30167 Hannover, Germany
- Institute of Physics of Technische Universität Chemnitz , Reichenhainer Straße 70, 09126 Chemnitz, Germany
| | - M Wenderoth
- IV. Physikalisches Institut der Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC) der Universität Göttingen , 37077 Göttingen, Germany
| | - F J Ahlers
- Physikalisch-Technische Bundesanstalt , Bundesallee 100, 38116 Braunschweig, Germany
| | - H W Schumacher
- Physikalisch-Technische Bundesanstalt , Bundesallee 100, 38116 Braunschweig, Germany
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5
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Kruskopf M, Elmquist RE. Epitaxial graphene for quantum resistance metrology. METROLOGIA 2018; 55:10.1088/1681-7575/aacd23. [PMID: 30996479 PMCID: PMC6463316 DOI: 10.1088/1681-7575/aacd23] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Graphene-based quantised Hall resistance standards promise high precision for the unit ohm under less exclusive measurement conditions, enabling the use of compact measurement systems. To meet the requirements of metrological applications, national metrology institutes developed large-area monolayer graphene growth methods for uniform material properties and optimized device fabrication techniques. Precision measurements of the quantized Hall resistance showing the advantage of graphene over GaAs-based resistance standards demonstrate the remarkable achievements realized by the research community. This work provides an overview over the state-of-the-art technologies in this field.
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Affiliation(s)
- Mattias Kruskopf
- National Institute of Standards and Technology, Fundamental Electrical Measurements, 100 Bureau Drive, Gaithersburg, MD, United States of America
- University of Maryland, Joint Quantum Institute, College Park, MD, United States of America
| | - Randolph E Elmquist
- National Institute of Standards and Technology, Fundamental Electrical Measurements, 100 Bureau Drive, Gaithersburg, MD, United States of America
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6
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Ma R, Huan Q, Wu L, Yan J, Zou Q, Wang A, Bobisch CA, Bao L, Gao HJ. Upgrade of a commercial four-probe scanning tunneling microscopy system. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:063704. [PMID: 28668010 DOI: 10.1063/1.4986466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Upgrade of a commercial ultra-high vacuum four-probe scanning tunneling microscopy system for atomic resolution capability and thermal stability is reported. To improve the mechanical and thermal performance of the system, we introduced extra vibration isolation, magnetic damping, and double thermal shielding, and we redesigned the scanning structure and thermal links. The success of the upgrade is characterized by its atomically resolved imaging, steady cooling down cycles with high efficiency, and standard transport measurement capability. Our design may provide a feasible way for the upgrade of similar commercial systems.
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Affiliation(s)
- Ruisong Ma
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Qing Huan
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Liangmei Wu
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Jiahao Yan
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Qiang Zou
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Aiwei Wang
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | | | - Lihong Bao
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Hong-Jun Gao
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
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7
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Yang Y, Cheng G, Mende P, Calizo IG, Feenstra RM, Chuang C, Liu CW, Liu CI, Jones GR, Hight Walker AR, Elmquist RE. Epitaxial graphene homogeneity and quantum Hall effect in millimeter-scale devices. CARBON 2017; 115:229-236. [PMID: 28924301 PMCID: PMC5600207 DOI: 10.1016/j.carbon.2016.12.087] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Quantized magnetotransport is observed in 5.6 × 5.6 mm2 epitaxial graphene devices, grown using highly constrained sublimation on the Si-face of SiC(0001) at high temperature (1900 °C). The precise quantized Hall resistance of [Formula: see text] is maintained up to record level of critical current Ixx = 0.72 mA at T = 3.1 K and 9 T in a device where Raman microscopy reveals low and homogeneous strain. Adsorption-induced molecular doping in a second device reduced the carrier concentration close to the Dirac point (n ≈ 1010 cm-2), where mobility of 18760 cm2/V is measured over an area of 10 mm2. Atomic force, confocal optical, and Raman microscopies are used to characterize the large-scale devices, and reveal improved SiC terrace topography and the structure of the graphene layer. Our results show that the structural uniformity of epitaxial graphene produced by face-to-graphite processing contributes to millimeter-scale transport homogeneity, and will prove useful for scientific and commercial applications.
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Affiliation(s)
- Yanfei Yang
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | - Guangjun Cheng
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | - Patrick Mende
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA
| | - Irene G. Calizo
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | - Randall M. Feenstra
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA
| | - Chiashain Chuang
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | - Chieh-Wen Liu
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
- Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan
| | - Chieh-I. Liu
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
- Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan
| | - George R. Jones
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | | | - Randolph E. Elmquist
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
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8
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Unveiling the carrier transport mechanism in epitaxial graphene for forming wafer-scale, single-domain graphene. Proc Natl Acad Sci U S A 2017; 114:4082-4086. [PMID: 28373575 DOI: 10.1073/pnas.1620176114] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Graphene epitaxy on the Si face of a SiC wafer offers monolayer graphene with unique crystal orientation at the wafer-scale. However, due to carrier scattering near vicinal steps and excess bilayer stripes, the size of electrically uniform domains is limited to the width of the terraces extending up to a few microns. Nevertheless, the origin of carrier scattering at the SiC vicinal steps has not been clarified so far. A layer-resolved graphene transfer (LRGT) technique enables exfoliation of the epitaxial graphene formed on SiC wafers and transfer to flat Si wafers, which prepares crystallographically single-crystalline monolayer graphene. Because the LRGT flattens the deformed graphene at the terrace edges and permits an access to the graphene formed at the side wall of vicinal steps, components that affect the mobility of graphene formed near the vicinal steps of SiC could be individually investigated. Here, we reveal that the graphene formed at the side walls of step edges is pristine, and scattering near the steps is mainly attributed by the deformation of graphene at step edges of vicinalized SiC while partially from stripes of bilayer graphene. This study suggests that the two-step LRGT can prepare electrically single-domain graphene at the wafer-scale by removing the major possible sources of electrical degradation.
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9
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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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10
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Ni-Co-Se nanoparticles modified reduced graphene oxide nanoflakes, an advance electrocatalyst for highly efficient hydrogen evolution reaction. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.07.133] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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11
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El Fatimy A, Myers-Ward RL, Boyd AK, Daniels KM, Gaskill DK, Barbara P. Epitaxial graphene quantum dots for high-performance terahertz bolometers. NATURE NANOTECHNOLOGY 2016; 11:335-338. [PMID: 26727199 DOI: 10.1038/nnano.2015.303] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 11/20/2015] [Indexed: 06/05/2023]
Abstract
Light absorption in graphene causes a large change in electron temperature due to the low electronic heat capacity and weak electron-phonon coupling. This property makes graphene a very attractive material for hot-electron bolometers in the terahertz frequency range. Unfortunately, the weak variation of electrical resistance with temperature results in limited responsivity for absorbed power. Here, we show that, due to quantum confinement, quantum dots of epitaxial graphene on SiC exhibit an extraordinarily high variation of resistance with temperature (higher than 430 MΩ K(-1) below 6 K), leading to responsivities of 1 × 10(10) V W(-1), a figure that is five orders of magnitude higher than other types of graphene hot-electron bolometer. The high responsivity, combined with an extremely low electrical noise-equivalent power (∼2 × 10(-16) W Hz(-1/2) at 2.5 K), already places our bolometers well above commercial cooled bolometers. Additionally, we show that these quantum dot bolometers demonstrate good performance at temperature as high as 77 K.
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Affiliation(s)
- Abdel El Fatimy
- Department of Physics, Georgetown University, Washington, Washington DC 20057, USA
| | | | - Anthony K Boyd
- US Naval Research Laboratory, Washington, Washington DC 20375, USA
| | - Kevin M Daniels
- US Naval Research Laboratory, Washington, Washington DC 20375, USA
| | - D Kurt Gaskill
- US Naval Research Laboratory, Washington, Washington DC 20375, USA
| | - Paola Barbara
- Department of Physics, Georgetown University, Washington, Washington DC 20057, USA
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12
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Binder J, Urban JM, Stepniewski R, Strupinski W, Wysmolek A. In situ Raman spectroscopy of the graphene/water interface of a solution-gated field-effect transistor: electron-phonon coupling and spectroelectrochemistry. NANOTECHNOLOGY 2016; 27:045704. [PMID: 26655462 DOI: 10.1088/0957-4484/27/4/045704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a novel measurement approach which combines the electrical characterization of solution-gated field-effect transistors based on epitaxial bilayer graphene on 4H-SiC (0001) with simultaneous Raman spectroscopy. By changing the gate voltage, we observed Raman signatures related to the resonant electron-phonon coupling. An analysis of these Raman bands enabled the extraction of the geometrical capacitance of the system and an accurate calculation of the Fermi levels for bilayer graphene. An intentional application of higher gate voltages allowed us to trigger electrochemical reactions, which we followed in situ by Raman spectroscopy. The reactions showed a partially reversible character, as indicated by an emergence/disappearance of peaks assigned to C-H and Si-H vibration modes as well as an increase/decrease of the defect-related Raman D band intensity. Our setup provides a highly interesting platform for future spectroelectrochemical research on electrically-induced sorption processes of graphene on the micrometer scale.
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Affiliation(s)
- J Binder
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
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13
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Günes F, Arezki H, Pierucci D, Alamarguy D, Alvarez J, Kleider JP, Dappe YJ, Ouerghi A, Boutchich M. Tuning the work function of monolayer graphene on 4H-SiC (0001) with nitric acid. NANOTECHNOLOGY 2015; 26:445702. [PMID: 26457876 DOI: 10.1088/0957-4484/26/44/445702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Chemical doping of graphene is a key process for the modulation of its electronic properties and the design and fabrication of graphene-based nanoelectronic devices. Here, we study the adsorption of diluted concentrations of nitric acid (HNO3) onto monolayer graphene/4H-SiC (0001) to induce a variation of the graphene work function (WF). Raman spectroscopy indicates an increase in the defect density subsequent to the doping. Moreover, ultraviolet photoemission spectroscopy (UPS) was utilized to quantify the WF shift. UPS data show that the WF of the graphene layer decreased from 4.3 eV (pristine) down to 3.8 eV (30% HNO3) and then increased to 4.4 eV at 100% HNO3 concentration. These observations were confirmed using density functional theory (DFT) calculations. This straightforward process allows a large WF modulation, rendering the molecularly modified graphene/4H-SiC(0001) a highly suitable electron or hole injection electrode.
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Affiliation(s)
- Fethullah Günes
- GeePs, CNRS UMR8507, CentraleSupelec, Univ Paris-Sud, Sorbonne Universités-UPMC Univ Paris 06, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette Cedex, France. Department of Materials Science and Engineering, Izmir Kâtip Çelebi University Cigli Main Campus, 35620, IZMIR, Turkey
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14
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Kruskopf M, Pierz K, Wundrack S, Stosch R, Dziomba T, Kalmbach CC, Müller A, Baringhaus J, Tegenkamp C, Ahlers FJ, Schumacher HW. Epitaxial graphene on SiC: modification of structural and electron transport properties by substrate pretreatment. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:185303. [PMID: 25894386 DOI: 10.1088/0953-8984/27/18/185303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The electrical transport properties of epitaxial graphene layers are correlated with the SiC surface morphology. In this study we show by atomic force microscopy and Raman measurements that the surface morphology and the structure of the epitaxial graphene layers change significantly when different pretreatment procedures are applied to nearly on-axis 6H-SiC(0 0 0 1) substrates. It turns out that the often used hydrogen etching of the substrate is responsible for undesirable high macro-steps evolving during graphene growth. A more advantageous type of sub-nanometer stepped graphene layers is obtained with a new method: a high-temperature conditioning of the SiC surface in argon atmosphere. The results can be explained by the observed graphene buffer layer domains after the conditioning process which suppress giant step bunching and graphene step flow growth. The superior electronic quality is demonstrated by a less extrinsic resistance anisotropy obtained in nano-probe transport experiments and by the excellent quantization of the Hall resistance in low-temperature magneto-transport measurements. The quantum Hall resistance agrees with the nominal value (half of the von Klitzing constant) within a standard deviation of 4.5 × 10(-9) which qualifies this method for the fabrication of electrical quantum standards.
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Affiliation(s)
- Mattias Kruskopf
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
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15
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High Electron Mobility in Epitaxial Graphene on 4H-SiC(0001) via post-growth annealing under hydrogen. Sci Rep 2014; 4:4558. [PMID: 24691055 PMCID: PMC3972502 DOI: 10.1038/srep04558] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 03/17/2014] [Indexed: 01/30/2023] Open
Abstract
We investigate the magneto-transport properties of epitaxial graphene single-layer on 4H-SiC(0001), grown by atmospheric pressure graphitization in Ar, followed by H2 intercalation. We directly demonstrate the importance of saturating the Si dangling bonds at the graphene/SiC(0001) interface to achieve high carrier mobility. Upon successful Si dangling bonds elimination, carrier mobility increases from 3 000 cm2V−1s−1 to >11 000 cm2V−1s−1 at 0.3 K. Additionally, graphene electron concentration tends to decrease from a few 1012 cm−2 to less than 1012 cm−2. For a typical large (30 × 280 μm2) Hall bar, we report the observation of the integer quantum Hall states at 0.3 K with well developed transversal resistance plateaus at Landau level filling factors of ν = 2, 6, 10, 14… 42 and Shubnikov de Haas oscillation of the longitudinal resistivity observed from about 1 T. In such a device, the Hall state quantization at ν = 2, at 19 T and 0.3 K, can be very robust: the dissipation in electronic transport can stay very low, with the longitudinal resistivity lower than 5 mΩ, for measurement currents as high as 250 μA. This is very promising in the view of an application in metrology.
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16
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Espinal AE, Yan Y, Zhang L, Espinal L, Morey A, Wells BO, Aindow M, Suib SL. Substrate control of anisotropic resistivity in heteroepitaxial nanostructured arrays of cryptomelane manganese oxide on strontium titanate. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:66-72. [PMID: 23894065 DOI: 10.1002/smll.201300713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Indexed: 06/02/2023]
Abstract
Resistivity and resistance measurements have been carried out for thin films of cryptomelane-type manganese oxide (OMS-2) grown onto (001), (110), and (111)STO single crystals substrates via pulsed laser deposition. While the symmetries of the (001) and (111)STO substrate surfaces give deposits consisting of multiple nanofiber arrays with isotropic in-plane resistivities, only a single nanofiber array is formed on (110)STO giving highly anisotropic electrical properties with very low resistivity values measured parallel to the fibers and similar to the lowest value ever reported.
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Affiliation(s)
- Anais E Espinal
- Institute of Materials Science, University of Connecticut, Storrs, CT, USA
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17
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Yue Z, Levchenko I, Kumar S, Seo D, Wang X, Dou S, Ostrikov KK. Large networks of vertical multi-layer graphenes with morphology-tunable magnetoresistance. NANOSCALE 2013; 5:9283-9288. [PMID: 23603856 DOI: 10.1039/c3nr00550j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report on the comparative study of magnetotransport properties of large-area vertical few-layer graphene networks with different morphologies, measured in a strong (up to 10 T) magnetic field over a wide temperature range. The petal-like and tree-like graphene networks grown by a plasma enhanced CVD process on a thin (500 nm) silicon oxide layer supported by a silicon wafer demonstrate a significant difference in the resistance-magnetic field dependencies at temperatures ranging from 2 to 200 K. This behaviour is explained in terms of the effect of electron scattering at ultra-long reactive edges and ultra-dense boundaries of the graphene nanowalls. Our results pave a way towards three-dimensional vertical graphene-based magnetoelectronic nanodevices with morphology-tuneable anisotropic magnetic properties.
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Affiliation(s)
- Zengji Yue
- Institute for Superconducting and Electronic Materials (ISEM), Faculty of Engineering, University of Wollongong, NSW 2522, Australia.
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18
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Nicotra G, Ramasse QM, Deretzis I, La Magna A, Spinella C, Giannazzo F. Delaminated graphene at silicon carbide facets: atomic scale imaging and spectroscopy. ACS NANO 2013; 7:3045-3052. [PMID: 23530467 DOI: 10.1021/nn305922u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Atomic-resolution structural and spectroscopic characterization techniques (scanning transmission electron microscopy and electron energy loss spectroscopy) are combined with nanoscale electrical measurements (conductive atomic force microscopy) to study at the atomic scale the properties of graphene grown epitaxially through the controlled graphitization of a hexagonal SiC(0001) substrate by high temperature annealing. This growth technique is known to result in a pronounced electron-doping (∼10(13) cm(-2)) of graphene, which is thought to originate from an interface carbon buffer layer strongly bound to the substrate. The scanning transmission electron microscopy analysis, carried out at an energy below the knock-on threshold for carbon to ensure no damage is imparted to the film by the electron beam, demonstrates that the buffer layer present on the planar SiC(0001) face delaminates from it on the (112n) facets of SiC surface steps. In addition, electron energy loss spectroscopy reveals that the delaminated layer has a similar electronic configuration to purely sp2-hybridized graphene. These observations are used to explain the local increase of the graphene sheet resistance measured around the surface steps by conductive atomic force microscopy, which we suggest is due to significantly lower substrate-induced doping and a resonant scattering mechanism at the step regions. A first-principles-calibrated theoretical model is proposed to explain the structural instability of the buffer layer on the SiC facets and the resulting delamination.
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19
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Liu YL, Yu CC, Fang CY, Chen HL, Chen CW, Kuo CC, Chang CK, Chen LC, Chen KH. Using Optical Anisotropy as a Quality Factor To Rapidly Characterize Structural Qualities of Large-Area Graphene Films. Anal Chem 2013; 85:1605-14. [DOI: 10.1021/ac302863w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | - Chun-Chiang Kuo
- Institute of Atomic and Molecular
Sciences, Academia Sinica, Taipei, Taiwan
| | | | | | - Kuei-Hsien Chen
- Institute of Atomic and Molecular
Sciences, Academia Sinica, Taipei, Taiwan
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20
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Bock C, Weingart S, Karaissaridis E, Kunze U, Speck F, Seyller T. Influence of structural properties on ballistic transport in nanoscale epitaxial graphene cross junctions. NANOTECHNOLOGY 2012; 23:395203. [PMID: 22971877 DOI: 10.1088/0957-4484/23/39/395203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this paper we investigate the influence of material and device properties on the ballistic transport in epitaxial monolayer graphene and epitaxial quasi-free-standing monolayer graphene. Our studies comprise (a) magneto-transport in two-dimensional (2D) Hall bars, (b) temperature- and magnetic-field-dependent bend resistance of unaligned and step-edge-aligned orthogonal cross junctions, and (c) the influence of the lead width of the cross junctions on ballistic transport. We found that ballistic transport is highly sensitive to scattering at the step edges of the silicon carbide substrate. A suppression of the ballistic transport is observed if the lead width of the cross junction is reduced from 50 nm to 30 nm. In a 50 nm wide device prepared on quasi-free-standing graphene we observe a gradual transition from the ballistic into the diffusive transport regime if the temperature is increased from 4.2 to about 50 K, although 2D Hall bars show a temperature-independent mobility. Thus, in 1D devices additional temperature-dependent scattering mechanisms play a pivotal role.
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Affiliation(s)
- Claudia Bock
- Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
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21
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Deng JH, Zheng RT, Zhao Y, Cheng GA. Vapor-solid growth of few-layer graphene using radio frequency sputtering deposition and its application on field emission. ACS NANO 2012; 6:3727-3733. [PMID: 22482928 DOI: 10.1021/nn300900v] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The carbon nanotube (CNT) and graphene hybrid is an attractive candidate for field emission (FE) because of its unique properties, such as high conductivity, large aspect ratio of CNT, and numerous sharp edges of graphene. We report here a vapor-solid growth of few-layer graphene (FLG, less than 10 layers) on CNTs (FLG/CNT) and Si wafers using a radio frequency sputtering deposition system. Based on SEM, TEM, and Raman spectrum analyses, a defect nucleation mechanism of the FLG growth was proposed. The FE measurements indicate that the FLG/CNT hybrids have low turn-on (0.956 V/μm) and threshold fields (1.497 V/μm), large field enhancement factor (∼4398), and good stability. Excellent FE properties of the FLG/CNT hybrids make them attractive candidates as high-performance field emitters.
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Affiliation(s)
- Jian-hua Deng
- Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, People's Republic of China
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22
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Lu B, Li T, Zhao H, Li X, Gao C, Zhang S, Xie E. Graphene-based composite materials beneficial to wound healing. NANOSCALE 2012; 4:2978-82. [PMID: 22453925 DOI: 10.1039/c2nr11958g] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We use electrospinning to prepare chitosan-PVA nanofibers containing graphene. The nanofibers can be directly used in wound healing: graphene, as an antibacterial material, can be beneficial for this. A possible antibacterial mechanism for graphene is presented.
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Affiliation(s)
- Bingan Lu
- School of Physical Science and Technology, Lanzhou University, Lanzhou, Gansu 730000 People's Republic of China.
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23
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Nyakiti LO, Myers-Ward RL, Wheeler VD, Imhoff EA, Bezares FJ, Chun H, Caldwell JD, Friedman AL, Matis BR, Baldwin JW, Campbell PM, Culbertson JC, Eddy CR, Jernigan GG, Gaskill DK. Bilayer graphene grown on 4H-SiC (0001) step-free mesas. NANO LETTERS 2012; 12:1749-1756. [PMID: 22352833 DOI: 10.1021/nl203353f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We demonstrate the first successful growth of large-area (200 × 200 μm(2)) bilayer, Bernal stacked, epitaxial graphene (EG) on atomically flat, 4H-SiC (0001) step-free mesas (SFMs) . The use of SFMs for the growth of graphene resulted in the complete elimination of surface step-bunching typically found after EG growth on conventional nominally on-axis SiC (0001) substrates. As a result heights of EG surface features are reduced by at least a factor of 50 from the heights found on conventional substrates. Evaluation of the EG across the SFM using the Raman 2D mode indicates Bernal stacking with low and uniform compressive lattice strain of only 0.05%. The uniformity of this strain is significantly improved, which is about 13-fold decrease of strain found for EG grown on conventional nominally on-axis substrates. The magnitude of the strain approaches values for stress-free exfoliated graphene flakes. Hall transport measurements on large area bilayer samples taken as a function of temperature from 4.3 to 300 K revealed an n-type carrier mobility that increased from 1170 to 1730 cm(2) V(-1) s(-1), and a corresponding sheet carrier density that decreased from 5.0 × 10(12) cm(-2) to 3.26 × 10(12) cm(-2). The transport is believed to occur predominantly through the top EG layer with the bottom layer screening the top layer from the substrate. These results demonstrate that EG synthesized on large area, perfectly flat on-axis mesa surfaces can be used to produce Bernal-stacked bilayer EG having excellent uniformity and reduced strain and provides the perfect opportunity for significant advancement of epitaxial graphene electronics technology.
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Affiliation(s)
- L O Nyakiti
- U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA.
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24
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Morelos-Gómez A, Vega-Díaz SM, González VJ, Tristán-López F, Cruz-Silva R, Fujisawa K, Muramatsu H, Hayashi T, Mi X, Shi Y, Sakamoto H, Khoerunnisa F, Kaneko K, Sumpter BG, Kim YA, Meunier V, Endo M, Muñoz-Sandoval E, Terrones M. Clean nanotube unzipping by abrupt thermal expansion of molecular nitrogen: graphene nanoribbons with atomically smooth edges. ACS NANO 2012; 6:2261-2272. [PMID: 22360783 DOI: 10.1021/nn2043252] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report a novel physicochemical route to produce highly crystalline nitrogen-doped graphene nanoribbons. The technique consists of an abrupt N(2) gas expansion within the hollow core of nitrogen-doped multiwalled carbon nanotubes (CN(x)-MWNTs) when exposed to a fast thermal shock. The multiwalled nanotube unzipping mechanism is rationalized using molecular dynamics and density functional theory simulations, which highlight the importance of open-ended nanotubes in promoting the efficient introduction of N(2) molecules by capillary action within tubes and surface defects, thus triggering an efficient and atomically smooth unzipping. The so-produced nanoribbons could be few-layered (from graphene bilayer onward) and could exhibit both crystalline zigzag and armchair edges. In contrast to methods developed previously, our technique presents various advantages: (1) the tubes are not heavily oxidized; (2) the method yields sharp atomic edges within the resulting nanoribbons; (3) the technique could be scaled up for the bulk production of crystalline nanoribbons from available MWNT sources; and (4) this route could eventually be used to unzip other types of carbon nanotubes or intercalated layered materials such as BN, MoS(2), WS(2), etc.
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Affiliation(s)
- Aarón Morelos-Gómez
- Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-853, Japan
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25
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Hu H, Ruammaitree A, Nakahara H, Asaka K, Saito Y. Few-layer epitaxial graphene with large domains on C-terminated 6H-SiC. SURF INTERFACE ANAL 2012. [DOI: 10.1002/sia.4814] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Hailong Hu
- College of Physics and Information Engineering; Fuzhou University; Fuzhou 350002 China
| | | | - Hitoshi Nakahara
- Department of Quantum Engineering; Nagoya University; Nagoya 464-8603 Japan
| | - Koji Asaka
- Department of Quantum Engineering; Nagoya University; Nagoya 464-8603 Japan
| | - Yahachi Saito
- Department of Quantum Engineering; Nagoya University; Nagoya 464-8603 Japan
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26
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Ji SH, Hannon JB, Tromp RM, Perebeinos V, Tersoff J, Ross FM. Atomic-scale transport in epitaxial graphene. NATURE MATERIALS 2011; 11:114-119. [PMID: 22101814 DOI: 10.1038/nmat3170] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 10/13/2011] [Indexed: 05/31/2023]
Abstract
The high carrier mobility of graphene is key to its applications, and understanding the factors that limit mobility is essential for future devices. Yet, despite significant progress, mobilities in excess of the 2×10(5) cm(2) V(-1) s(-1) demonstrated in free-standing graphene films have not been duplicated in conventional graphene devices fabricated on substrates. Understanding the origins of this degradation is perhaps the main challenge facing graphene device research. Experiments that probe carrier scattering in devices are often indirect, relying on the predictions of a specific model for scattering, such as random charged impurities in the substrate. Here, we describe model-independent, atomic-scale transport measurements that show that scattering at two key defects--surface steps and changes in layer thickness--seriously degrades transport in epitaxial graphene films on SiC. These measurements demonstrate the strong impact of atomic-scale substrate features on graphene performance.
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27
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Klarskov MB, Dam HF, Petersen DH, Hansen TM, Löwenborg A, Booth TJ, Schmidt MS, Lin R, Nielsen PF, Bøggild P. Fast and direct measurements of the electrical properties of graphene using micro four-point probes. NANOTECHNOLOGY 2011; 22:445702. [PMID: 21975563 DOI: 10.1088/0957-4484/22/44/445702] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present measurements of the electronic properties of graphene using a repositionable micro four-point probe system, which we show here to have unique advantages over measurements made on lithographically defined devices; namely speed, simplicity and lack of a need to pattern graphene. Measurements are performed in ambient, vacuum and controlled environmental conditions using an environmental scanning electron microscope (SEM). The results are comparable to previous results for microcleaved graphene on silicon dioxide (SiO(2)). We observe a pronounced hysteresis of the charge neutrality point, dependent on the sweep rate of the gate voltage; and environmental measurements provide insight into the sensor application prospects of graphene. The method offers a fast, local and non-destructive technique for electronic measurements on graphene, which can be positioned freely on a graphene flake.
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Affiliation(s)
- M B Klarskov
- Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Kongens Lyngby, Denmark
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28
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Strupinski W, Grodecki K, Wysmolek A, Stepniewski R, Szkopek T, Gaskell PE, Grüneis A, Haberer D, Bozek R, Krupka J, Baranowski JM. Graphene epitaxy by chemical vapor deposition on SiC. NANO LETTERS 2011; 11:1786-91. [PMID: 21438581 DOI: 10.1021/nl200390e] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We demonstrate the growth of high quality graphene layers by chemical vapor deposition (CVD) on insulating and conductive SiC substrates. This method provides key advantages over the well-developed epitaxial graphene growth by Si sublimation that has been known for decades. (1) CVD growth is much less sensitive to SiC surface defects resulting in high electron mobilities of ∼1800 cm(2)/(V s) and enables the controlled synthesis of a determined number of graphene layers with a defined doping level. The high quality of graphene is evidenced by a unique combination of angle-resolved photoemission spectroscopy, Raman spectroscopy, transport measurements, scanning tunneling microscopy and ellipsometry. Our measurements indicate that CVD grown graphene is under less compressive strain than its epitaxial counterpart and confirms the existence of an electronic energy band gap. These features are essential for future applications of graphene electronics based on wafer scale graphene growth.
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Affiliation(s)
- W Strupinski
- Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw, Poland.
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29
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Hite JK, Twigg ME, Tedesco JL, Friedman AL, Myers-Ward RL, Eddy CR, Gaskill DK. Epitaxial graphene nucleation on C-face silicon carbide. NANO LETTERS 2011; 11:1190-1194. [PMID: 21322598 DOI: 10.1021/nl104072y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The initial stages of epitaxial graphene growth were studied by characterization of graphene formed in localized areas on C-face 6H-SiC substrates. The graphene areas were determined to lie below the level of the surrounding substrate and showed different morphologies based on size. Employing electron channeling contrast imaging, the presence of threading screw dislocations was indicated near the centers of each of these areas. After the graphene was removed, these dislocations were revealed to lie within the SiC substrate. These observations suggest that screw dislocations act as preferred nucleation sites for graphene growth on C-face SiC.
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Affiliation(s)
- Jennifer K Hite
- U.S. Naval Research Laboratory , 4555 Overlook Avenue, SW, Washington, DC 20375, United States
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30
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Villegas CEP, Tavares MRS, Marques GE. Anisotropy induced localization of pseudo-relativistic spin states in graphene double quantum wire structures. NANOTECHNOLOGY 2010; 21:365401. [PMID: 20705968 DOI: 10.1088/0957-4484/21/36/365401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We study the single-particle properties of Dirac Fermions confined to a double quantum wire system based on graphene. We map out the spatial regions where electrons in a given subband display the largest occupation probability induced by spatial anisotropic effects associated to the interaction strength between the graphene wires and the substrate. Here, the graphene-substrate interaction is considered as an ad hoc parameter which destroys the zero-gap observed in the relativistic Dirac cone characteristic of graphene electronic energy dispersions. Furthermore, the results indicate that the character of quasi-extended spin states, viewed by multisubband probability density function, is highly sensitive to spatial asymmetries and to the graphene-substrate interaction strength.
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Affiliation(s)
- Cesar E P Villegas
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brazil
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