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Liu Y, Lew WS, Liu Z. Observation of Anomalous Resistance Behavior in Bilayer Graphene. NANOSCALE RESEARCH LETTERS 2017; 12:48. [PMID: 28097601 PMCID: PMC5241263 DOI: 10.1186/s11671-016-1792-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/14/2016] [Indexed: 05/07/2023]
Abstract
Our measurement results have shown that bilayer graphene exhibits an unexpected sharp transition of the resistance value in the temperature region 200~250 K. We argue that this behavior originates from the interlayer ripple scattering effect between the top and bottom ripple graphene layer. The inter-scattering can mimic the Coulomb scattering but is strongly dependent on temperature. The observed behavior is consistent with the theoretical prediction that charged impurities are the dominant scatters in bilayer graphene. The resistance increase with increasing perpendicular magnetic field strongly supports the postulate that magnetic field induces an excitonic gap in bilayer graphene. Our results reveal that the relative change of resistance induced by magnetic field in the bilayer graphene shows an anomalous thermally activated property.
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Affiliation(s)
- Yanping Liu
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 USA
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore
| | - Wen Siang Lew
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore
| | - Zongwen Liu
- School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, New South Wales (NSW) 2006 Australia
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Ben Gouider Trabelsi A, Kusmartsev FV, Gaifullin MB, Forrester DM, Kusmartseva A, Oueslati M. Morphological imperfections of epitaxial graphene: from a hindrance to the generation of new photo-responses in the visible domain. NANOSCALE 2017; 9:11463-11474. [PMID: 28580975 DOI: 10.1039/c6nr08999b] [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
We report the discovery of remarkable photo-physical phenomena with characteristics unique to epitaxial graphene grown on 6H-SiC (000-1). Surprisingly, the electrical resistance of graphene increases under light illumination in contrast to conventional materials where it normally decreases. The resistance shows logarithmic temperature dependences which may be attributed to an Altshuler-Aronov effect. We show that the photoresistance depends on the frequency of the irradiating light, with three lasers (red, green, and violet) used to demonstrate the phenomenon. The counterintuitive rise of the positive photoresistance may be attributed to a creation of trapped charges upon irradiation. We argue that the origin of the photoresistance is related to the texture formed by the graphene flakes. Photovoltage also exists and increases with light intensity. However, its value saturates quickly with irradiation and does not change with time. The saturation of the photovoltage may be associated with the formation of a quasi-equilibrium state of the excited electrons and holes associated with a charge redistribution between the graphene and SiC substrate. The obtained physical picture is in agreement with the photoresistance measurements: X-ray photoelectron spectrometry "XPS", atomic force microscopy "AFM", Raman spectroscopy and the magnetic dependence of photoresistance decay measurements. We also observed non-decaying photoresistance and linear magnetoresistance in magnetic fields up to 1 T. We argue that this is due to topological phases spontaneously induced by persistent current formation within the graphene flake edges by magnetic fields.
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Liu Y, Liu X, Zhang Y, Xia Q, He J. Effect of magnetic field on electronic transport in a bilayer graphene nanomesh. NANOTECHNOLOGY 2017; 28:235303. [PMID: 28516895 DOI: 10.1088/1361-6528/aa703e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the observation of an unexpected sudden increase of resistance in bilayer graphene nanomesh (GNM) in the temperature range 270 ∼ 300 K that is strongly dependent on the magnetic field strength. We conjecture that the sharp increase in resistance originates from ripple scattering as induced by substrate roughness. The observed result is evidence of extrinsic corrugation in bilayer GNM as an additional scattering source that contributes to significant resistance. The observed weak localization in the GNM indicates intervalley scattering induced by lattice defects acts as resonant scatterers attribute to the high D peak. Magnetotransport measurement strongly supports that the charge inhomogeneity related to the intrinsic disorder in bilayer GNM and the positive magnetoresistance shows a linear behavior with magnetic field strength. Potentially, the observed phenomena, therefore, point to a clear pathway towards practical application of bilayer GNM and to the design of a graphene magnetic sensor that can be manipulated by a magnetic field and a new generation of spintronics.
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Affiliation(s)
- Yanping Liu
- School of Physics and Electronics, Hunan Key Laboratory for Super-microstructure and Ultrafast Process, Central South University, Changsha, 932 South Lushan Road, Hunan 410083, People's Republic of China. Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States of America
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Do TN, Shih PH, Chang CP, Lin CY, Lin MF. Rich magneto-absorption spectra of AAB-stacked trilayer graphene. Phys Chem Chem Phys 2016; 18:17597-605. [PMID: 27305856 DOI: 10.1039/c6cp02275h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A generalized tight-binding model is developed to investigate the feature-rich magneto-optical properties of AAB-stacked trilayer graphene. Three intragroup and six intergroup inter-Landau-level (inter-LL) optical excitations largely enrich magneto-absorption peaks. In general, the former are much higher than the latter, depending on the phases and amplitudes of LL wavefunctions. The absorption spectra exhibit single- or twin-peak structures which are determined by quantum modes, LL energy spectra and Fermion distribution. The splitting LLs, with different localization centers (2/6 and 4/6 positions in a unit cell), can generate very distinct absorption spectra. There exist extra single peaks because of LL anti-crossings. AAB, AAA, ABA, and ABC stackings considerably differ from one another in terms of the inter-LL category, frequency, intensity, and structure of absorption peaks. The main characteristics of LL wavefunctions and energy spectra and the Fermi-Dirac function are responsible for the configuration-enriched magneto-optical spectra.
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Affiliation(s)
- Thi-Nga Do
- Department of Physics, National Cheng Kung University, Tainan, Taiwan.
| | - Po-Hsin Shih
- Department of Physics, National Cheng Kung University, Tainan, Taiwan.
| | - Cheng-Peng Chang
- Center for General Education, Tainan University of Technology, Tainan, Taiwan
| | - Chiun-Yan Lin
- Department of Physics, National Cheng Kung University, Tainan, Taiwan.
| | - Ming-Fa Lin
- Department of Physics, National Cheng Kung University, Tainan, Taiwan.
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Wu HC, Abid M, Wu YC, Coileáin CÓ, Syrlybekov A, Han JF, Heng CL, Liu H, Abid M, Shvets I. Enhanced Shubnikov-De Haas Oscillation in Nitrogen-Doped Graphene. ACS NANO 2015; 9:7207-7214. [PMID: 26061979 DOI: 10.1021/acsnano.5b02020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
N-doped graphene displays many interesting properties compared with pristine graphene, which makes it a potential candidate in many applications. Here, we report that the Shubnikov-de Haas (SdH) oscillation effect in graphene can be enhanced by N-doping. We show that the amplitude of the SdH oscillation increases with N-doping and reaches around 5k Ω under a field of 14 T at 10 K for highly N-doped graphene, which is over 1 order of magnitude larger than the value found for pristine graphene devices with the same geometry. Moreover, in contrast to the well-established standard Lifshitz-Kosevich theory, the amplitude of the SdH oscillation decreases linearly with increasing temperature and persists up to a temperature of 150 K. Our results also show that the magnetoresistance (MR) in N-doped graphene increases with increasing temperature. Our results may be useful for the application of N-doped graphene in magnetic devices.
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Affiliation(s)
- Han-Chun Wu
- †School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Mourad Abid
- ‡KSU-Aramco Center, King Saud University, Riyadh 11451, Saudi Arabia
| | - Ye-Cun Wu
- †School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Cormac Ó Coileáin
- †School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
- §CRANN, School of Physics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Askar Syrlybekov
- §CRANN, School of Physics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Jun Feng Han
- †School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Cheng Lin Heng
- †School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Huajun Liu
- ⊥Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Mohamed Abid
- ‡KSU-Aramco Center, King Saud University, Riyadh 11451, Saudi Arabia
| | - Igor Shvets
- §CRANN, School of Physics, Trinity College, University of Dublin, Dublin 2, Ireland
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Huang L, Yang R, Lai YC, Ferry DK. Lead-position dependent regular oscillations and random fluctuations of conductance in graphene quantum dots. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:085502. [PMID: 23343960 DOI: 10.1088/0953-8984/25/8/085502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Quantum interference causes a wavefunction to have sensitive spatial dependence, and this has a significant effect on quantum transport. For example, in a quantum-dot system, the conductance can depend on the lead positions. We investigate, for graphene quantum dots, the conductance variations with the lead positions. Since for graphene the types of boundaries, e.g., zigzag and armchair, can fundamentally affect the quantum transport characteristics, we focus on rectangular graphene quantum dots, for which the effects of boundaries can be systematically studied. For both zigzag and armchair horizontal boundaries, we find that changing the positions of the leads can induce significant conductance variations. Depending on the Fermi energy, the variations can be either regular oscillations or random conductance fluctuations. We develop a physical theory to elucidate the origin of the conductance oscillation/fluctuation patterns. In particular, quantum interference leads to standing-wave-like-patterns in the quantum dot which, in the absence of leads, are regulated by the energy-band structure of the corresponding vertical graphene ribbon. The observed 'coexistence' of regular oscillations and random fluctuations in the conductance can be exploited for the development of graphene-based nanodevices.
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Affiliation(s)
- Liang Huang
- Institute of Computational Physics and Complex Systems and Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China.
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Hui YY, Tai G, Sun Z, Xu Z, Wang N, Yan F, Lau SP. n- and p-Type modulation of ZnO nanomesh coated graphene field effect transistors. NANOSCALE 2012; 4:3118-3122. [PMID: 22504661 DOI: 10.1039/c2nr30249g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Periodic zinc oxide (ZnO) nanomeshes of different thicknesses were deposited on single-layer graphene to form back-gated field effect transistors (GFETs). The GFETs exhibit tunable electronic properties, featuring n- and p-type characteristics by merely controlling the thickness of the ZnO nanomesh layer. Furthermore, the effect of thermal strain on the GFETs from the substrate is suppressed by the ZnO nanomesh, which improves the thermal stability of the GFETs. This nanopatterning technique could modulate the electronic properties of the GFETs effectively.
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Affiliation(s)
- Yeung Yu Hui
- Department of Applied Physics and Materials Research Centre, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
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Bittencourt C, Hitchock AP, Ke X, Van Tendeloo G, Ewels CP, Guttmann P. X-ray absorption spectroscopy by full-field X-ray microscopy of a thin graphite flake: Imaging and electronic structure via the carbon K-edge. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2012; 3:345-350. [PMID: 23016137 PMCID: PMC3388357 DOI: 10.3762/bjnano.3.39] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 04/06/2012] [Indexed: 05/29/2023]
Abstract
We demonstrate that near-edge X-ray-absorption fine-structure spectra combined with full-field transmission X-ray microscopy can be used to study the electronic structure of graphite flakes consisting of a few graphene layers. The flake was produced by exfoliation using sodium cholate and then isolated by means of density-gradient ultracentrifugation. An image sequence around the carbon K-edge, analyzed by using reference spectra for the in-plane and out-of-plane regions of the sample, is used to map and spectrally characterize the flat and folded regions of the flake. Additional spectral features in both π and σ regions are observed, which may be related to the presence of topological defects. Doping by metal impurities that were present in the original exfoliated graphite is indicated by the presence of a pre-edge signal at 284.2 eV.
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Affiliation(s)
- Carla Bittencourt
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, B-2020 Antwerp, Belgium
| | - Adam P Hitchock
- Chemistry & Chemical Biology, McMaster University, L8S4M1 Hamilton, ON, Canada
| | - Xiaoxing Ke
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, B-2020 Antwerp, Belgium
| | - Gustaaf Van Tendeloo
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, B-2020 Antwerp, Belgium
| | - Chris P Ewels
- Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, Nantes, France
| | - Peter Guttmann
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Soft Matter and Functional Materials, D-12489 Berlin, Germany
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Liu Y, Lew WS, Goolaup S, Liew HF, Wong SK, Zhou T. Observation of oscillatory resistance behavior in coupled Bernal and rhombohedral stacking graphene. ACS NANO 2011; 5:5490-8. [PMID: 21702483 DOI: 10.1021/nn200771e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We report on the first observation of an anomalous temperature-dependent resistance behavior in coupled Bernal and rhombohedral stacking graphene. At low-temperature regime (<50 K) the temperature-dependent resistance exhibits a drop while at high-temperature regions (>250 K), the resistance increases. In the transition region (50-250 K) an oscillatory resistance behavior was observed. This property is not present in any layered graphene structures other than five-layer. We propose that the temperature-dependent resistance behavior is governed by the interplay of the Coulomb and short-range scatterings. The origin of the oscillatory resistance behavior is the ABCAB and ABABA stacking configurations, which induces tunable bandgap in the five-layer graphene. The obtained results also indicate that a perpendicular magnetic field opens an excitonic gap because of the Coulomb interaction-driven electronic instabilities, and the bandgap of the five-layer graphene is thermally activated. Potentially, the observed phenomenon provides important transport information to the design of few-layer graphene transistors that can be manipulated by a magnetic field.
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Affiliation(s)
- Yanping Liu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore
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Liu Y, Lew WS, Sun L. Enhanced weak localization effect in few-layer graphene. Phys Chem Chem Phys 2011; 13:20208-14. [DOI: 10.1039/c1cp22250c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Liu Y, Goolaup S, Murapaka C, Lew WS, Wong SK. Effect of magnetic field on the electronic transport in trilayer graphene. ACS NANO 2010; 4:7087-92. [PMID: 21047066 DOI: 10.1021/nn101296x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The perpendicular magnetic field dependence of the longitudinal resistance in trilayer graphene at various temperatures has been systematically studied. For a fixed magnetic field, the trilayer graphene displays an intrinsic semiconductor behavior over the temperature range of 5-340 K. This is attributed to the parabolic band structure of trilayer graphene, where the Coulomb scattering is a strong function of temperature. The dependence of resistance on the magnetic field can be explained by the splitting of Landau levels (LLs). Our results reveal that the energy gap in the trilayer graphene is thermally activated and increases with √B.
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Affiliation(s)
- Yanping Liu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
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Lin J, Teweldebrhan D, Ashraf K, Liu G, Jing X, Yan Z, Li R, Ozkan M, Lake RK, Balandin AA, Ozkan CS. Gating of single-layer graphene with single-stranded deoxyribonucleic acids. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2010; 6:1150-1155. [PMID: 20473987 DOI: 10.1002/smll.200902379] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Patterning of biomolecules on graphene layers could provide new avenues to modulate their electrical properties for novel electronic devices. Single-stranded deoxyribonucleic acids (ssDNAs) are found to act as negative-potential gating agents that increase the hole density in single-layer graphene. Current-voltage measurements of the hybrid ssDNA/graphene system indicate a shift in the Dirac point and "intrinsic" conductance after ssDNA is patterned. The effect of ssDNA is to increase the hole density in the graphene layer, which is calculated to be on the order of 1.8 x 10(12) cm(-2). This increased density is consistent with the Raman frequency shifts in the G-peak and 2D band positions and the corresponding changes in the G-peak full width at half maximum. Ab initio calculations using density functional theory rule out significant charge transfer or modification of the graphene band structure in the presence of ssDNA fragments.
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Affiliation(s)
- Jian Lin
- Department of Mechanical Engineering, University of California-Riverside, Riverside, CA 92521, USA
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Zhou YB, Han BH, Liao ZM, Zhao Q, Xu J, Yu DP. Effect of contact barrier on electron transport in graphene. J Chem Phys 2010; 132:024706. [DOI: 10.1063/1.3292029] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Ujiie Y, Motooka S, Morimoto T, Aoki N, Ferry DK, Bird JP, Ochiai Y. Regular conductance fluctuations indicative of quasi-ballistic transport in bilayer graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:382202. [PMID: 21832362 DOI: 10.1088/0953-8984/21/38/382202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Quasi-periodic conductance fluctuations are observed in the low-temperature magneto-conductance of a bilayer graphene sample. The quasi-periodic nature of the fluctuations is confirmed by their Fourier power spectrum, which consists of just a small number of dominant frequency components. From an experimental study of these features, which are highly reminiscent of those reported previously for ballistic semiconductor quantum dots, we suggest that they are associated with the formation of an open quantum dot in the submicron graphene sample.
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Affiliation(s)
- Y Ujiie
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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