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Lin X, Deng J, Bai Y, Huo D, Zhu C, Pan Z, Jian T, Liu C, Zhang C. van der Waals Engineering of Charge Density Waves in One-Dimensional Nb 6Te 6 Nanowires. ACS NANO 2024; 18:13241-13248. [PMID: 38718159 DOI: 10.1021/acsnano.4c02379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
One-dimensional (1D) systems have played a crucial role in the development of fundamental physics and practical applications. Recently, transition metal monochalcogenide (TMM) wires based on molybdenum (Mo) and tungsten (W) have emerged as promising platforms for investigating 1D physics in pure van der Waals (vdW) platforms. Here, we report on the bottom-up fabrication of Nb6Te6 wires down to the single-wire limit. The unique properties of Nb6Te6 single wire enable the realization of 1D charge density wave (CDW) phases in an isolated single TMM wire. Moreover, we revealed the appealing regulation of 1D CDW orders by van der Waals interactions at either the 1D-2D interface (i.e., rotation of a single wire along its wire axis) or the 1D-1D interface. Two rotation angles (30° and 0°) give rise to 3 × 1 and zigzag chain CDW morphologies, respectively, which exhibit pronounced differences in atomic displacement by a factor of 2. The interwire vdW coupling overwhelms its counterpart at the 1D-2D interface, thus locking the rotation angle (at 0°) as well as the interwire atomic registries. In contrast, interestingly, the phases of the charge oscillations are independent of the adjacent wires. The ability to tailor 1D charge orders provides a crucial addition to the toll set of vdW integrations beyond two-dimensional materials.
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Affiliation(s)
- Xiaoyu Lin
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jinghao Deng
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Yusong Bai
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Da Huo
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Chao Zhu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Zemin Pan
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Tao Jian
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Chuansheng Liu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Chendong Zhang
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
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2
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Deng J, Huo D, Bai Y, Lin X, Cheng Z, Zhang C. Observations of Charge-Density-Wave States in W 6Te 6 Wires. NANO LETTERS 2023; 23:7831-7837. [PMID: 37616474 DOI: 10.1021/acs.nanolett.3c01373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Determining the electronic ground state of a one-dimensional system is crucial to understanding the underlying physics of electronic behavior. Here, we demonstrate the discovery of charge-density wave states in few-wire W6Te6 arrays using scanning tunneling microscopy/spectroscopy. We directly visualize incommensurate charge orders, energy gaps with prominent coherence peaks, and the picometer-scale lattice distortion in nearly disorder-free double-wire systems, thereby demonstrating the existence of Peierls-type charge density waves. In the presence of disorder-induced charge order fluctuations, the coherence peaks resulting from phase correlation disappear and gradually transform the system into the pseudogap states. The power-law zero-bias anomaly and quasi-particle interference analysis further suggest the Tomonaga-Luttinger liquid behavior in such pseudogap region. In addition, we explicitly determined the evolution of the CDW energy gap as a function of stacking-wire numbers. The present study demonstrates the existence of electron-phonon interactions in few-wire W6Te6 that can be tuned by disorders and van der Waals stacking.
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Affiliation(s)
- Jinghao Deng
- School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Da Huo
- School of Physics and Technology, Wuhan University, Wuhan, 430072, China
- Wuhan Institute of Quantum Technology, Wuhan, 430206, China
| | - Yusong Bai
- School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Xiaoyu Lin
- School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Zhengbo Cheng
- School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Chendong Zhang
- School of Physics and Technology, Wuhan University, Wuhan, 430072, China
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Fedorov G, Hafizi R, Semenenko V, Perebeinos V. Metal Contact Induced Unconventional Field Effect in Metallic Carbon Nanotubes. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13111774. [PMID: 37299677 DOI: 10.3390/nano13111774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/28/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023]
Abstract
One-dimensional carbon nanotubes (CNTs) are promising for future nanoelectronics and optoelectronics, and an understanding of electrical contacts is essential for developing these technologies. Although significant efforts have been made in this direction, the quantitative behavior of electrical contacts remains poorly understood. Here, we investigate the effect of metal deformations on the gate voltage dependence of the conductance of metallic armchair and zigzag CNT field effect transistors (FETs). We employ density functional theory calculations of deformed CNTs under metal contacts to demonstrate that the current-voltage characteristics of the FET devices are qualitatively different from those expected for metallic CNT. We predict that, in the case of armchair CNT, the gate-voltage dependence of the conductance shows an ON/OFF ratio of about a factor of two, nearly independent of temperature. We attribute the simulated behavior to modification of the band structure under the metals caused by deformation. Our comprehensive model predicts a distinct feature of conductance modulation in armchair CNTFETs induced by the deformation of the CNT band structure. At the same time, the deformation in zigzag metallic CNTs leads to a band crossing but not to a bandgap opening.
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Affiliation(s)
- Georgy Fedorov
- Institute of Photonics, University of Eastern Finland, 999018 Joensuu, Finland
| | - Roohollah Hafizi
- Department of Physics and Astronomy and Thomas Young Centre, University College London, London WC1E 6BT, UK
| | - Vyacheslav Semenenko
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Vasili Perebeinos
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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Zhao S, Kitaura R, Moon P, Koshino M, Wang F. Interlayer Interactions in 1D Van der Waals Moiré Superlattices. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2103460. [PMID: 34841726 PMCID: PMC8805582 DOI: 10.1002/advs.202103460] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 10/02/2021] [Indexed: 06/13/2023]
Abstract
Studying two-dimensional (2D) van der Waals (vdW) moiré superlattices and their interlayer interactions have received surging attention after recent discoveries of many new phases of matter that are highly tunable. Different atomistic registry between layers forming the inner and outer nanotubes can also form one-dimensional (1D) vdW moiré superlattices. In this review, experimental observations and theoretical perspectives related to interlayer interactions in 1D vdW moiré superlattices are summarized. The discussion focuses on double-walled carbon nanotubes (DWNTs), a model 1D vdW moiré system, and the authors highlight the new optical features emerging from the non-trivial strong interlayer coupling effect and the unique physics in 1D DWNTs. Future directions and questions in probing the intriguing physical phenomena in 1D vdW moiré superlattices such as, correlated physics in different 1D moiré systems beyond DWNTs are proposed and discussed.
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Affiliation(s)
- Sihan Zhao
- Interdisciplinary Center for Quantum InformationZhejiang Province Key Laboratory of Quantum Technology and DeviceState Key Laboratory of Silicon MaterialsDepartment of PhysicsZhejiang UniversityHangzhou310027China
| | - Ryo Kitaura
- Department of ChemistryNagoya UniversityNagoya464‐8602Japan
| | - Pilkyung Moon
- Arts and SciencesNYU ShanghaiShanghai200122China
- NYU‐ECNU Institute of Physics at NYU ShanghaiShanghai200062China
| | - Mikito Koshino
- Department of PhysicsOsaka UniversityToyonaka560‐0043Japan
| | - Feng Wang
- Department of PhysicsUniversity of California at BerkeleyBerkeleyCA94720USA
- Materials Science DivisionLawrence Berkeley National LaboratoryBerkeleyCAUSA
- Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National LaboratoryBerkeleyCA94720USA
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Bulmer JS, Kaniyoor A, Elliott JA. A Meta-Analysis of Conductive and Strong Carbon Nanotube Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2008432. [PMID: 34278614 DOI: 10.1002/adma.202008432] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/19/2021] [Indexed: 06/13/2023]
Abstract
A study of 1304 data points collated over 266 papers statistically evaluates the relationships between carbon nanotube (CNT) material characteristics, including: electrical, mechanical, and thermal properties; ampacity; density; purity; microstructure alignment; molecular dimensions and graphitic perfection; and doping. Compared to conductive polymers and graphitic intercalation compounds, which have exceeded the electrical conductivity of copper, CNT materials are currently one-sixth of copper's conductivity, mechanically on-par with synthetic or carbon fibers, and exceed all the other materials in terms of a multifunctional metric. Doped, aligned few-wall CNTs (FWCNTs) are the most superior CNT category; from this, the acid-spun fiber subset are the most conductive, and the subset of fibers directly spun from floating catalyst chemical vapor deposition are strongest on a weight basis. The thermal conductivity of multiwall CNT material rivals that of FWCNT materials. Ampacity follows a diameter-dependent power-law from nanometer to millimeter scales. Undoped, aligned FWCNT material reaches the intrinsic conductivity of CNT bundles and single-crystal graphite, illustrating an intrinsic limit requiring doping for copper-level conductivities. Comparing an assembly of CNTs (forming mesoscopic bundles, then macroscopic material) to an assembly of graphene (forming single-crystal graphite crystallites, then carbon fiber), the ≈1 µm room-temperature, phonon-limited mean-free-path shared between graphene, metallic CNTs, and activated semiconducting CNTs is highlighted, deemphasizing all metallic helicities for CNT power transmission applications.
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Affiliation(s)
- John S Bulmer
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
| | - Adarsh Kaniyoor
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
| | - James A Elliott
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
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Gao J, Zhu Z, Shen B, Bai Y, Sun S, Wei F. Bandgap-Coupled Template Autocatalysis toward the Growth of High-Purity sp 2 Nanocarbons. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2003078. [PMID: 33854884 PMCID: PMC8025012 DOI: 10.1002/advs.202003078] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/29/2020] [Indexed: 06/12/2023]
Abstract
Extraordinary properties and great application potentials of carbon nanotubes (CNT) and graphene fundamentally rely on their large-scale perfect sp2 structure. Particularly for high-end applications, ultralow defect density and ultrahigh selectivity are prerequisites, for which metal-catalyzed chemical vapor deposition (CVD) is the most promising approach. Due to their structure and peculiarity, CNTs and graphene can themselves provide growth templates and nonlocal dual conductance, serving as template autocatalysts with tunable bandgap during the CVD. However, current growth kinetics models all focus on the external factors and edges. Here, the growth kinetics of sp2 nanocarbons is elaborated from the perspective of template autocatalysis and holistic electronic structure. After reviewing current growth kinetics, various representative works involving CVD growth of different sp2 nanocarbons are analyzed, to reveal their bandgap-coupled kinetics and resulting selective synthesis. Recent progress is then reviewed, which has demonstrated the interlocking between the atomic assembly rate and bandgap of CNTs, with an explicit volcano dependence whose peak would be determined by the environment. In addition, the topological protection for perfect sp2 structure and the defect-induced perturbation for the interlocking are discussed. Finally, the prospects for the kinetic selective growth of perfect nanocarbons are proposed.
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Affiliation(s)
- Jun Gao
- Beijing Key Laboratory of Green Chemical Reaction Engineering and TechnologyDepartment of Chemical EngineeringTsinghua UniversityBeijing100084China
| | - Zhenxing Zhu
- Beijing Key Laboratory of Green Chemical Reaction Engineering and TechnologyDepartment of Chemical EngineeringTsinghua UniversityBeijing100084China
| | - Boyuan Shen
- Beijing Key Laboratory of Green Chemical Reaction Engineering and TechnologyDepartment of Chemical EngineeringTsinghua UniversityBeijing100084China
| | - Yunxiang Bai
- Beijing Key Laboratory of Green Chemical Reaction Engineering and TechnologyDepartment of Chemical EngineeringTsinghua UniversityBeijing100084China
| | - Silei Sun
- Beijing Key Laboratory of Green Chemical Reaction Engineering and TechnologyDepartment of Chemical EngineeringTsinghua UniversityBeijing100084China
| | - Fei Wei
- Beijing Key Laboratory of Green Chemical Reaction Engineering and TechnologyDepartment of Chemical EngineeringTsinghua UniversityBeijing100084China
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Edwards PJ, Wang B, Cronin SB, Bushmaker AW. Direct Measurement of Water-Assisted Ion Desorption and Solvation on Isolated Carbon Nanotubes. ACS NANO 2020; 14:16854-16863. [PMID: 33202132 DOI: 10.1021/acsnano.0c05638] [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
We have investigated the change in mean residence time of gaseous ions adsorbed on the surface of suspended carbon nanotube field-effect transistors (CNT-FETs) with and without native surface water layers that exists in atmospheric conditions. Devices were characterized electrically before and after dehydration by thermal, dry gas, and vacuum desiccation and in each scenario were found to have substantially higher mean ion residence times. It is proposed that water molecules native to the CNT surface in ambient conditions provide a reduction pathway for incoming gaseous ions, yielding hydronium ions (H3O+). This is supported by the appearance of frequent clustered readsorption events in the presence of surface water, caused by the rapid hopping of H+ between the device surface and the lowest water layer, which are not present in data collected from desiccated devices. After desiccation of the device, a thermal trial was conducted to determine the adsorption energy of N2+ ions on the CNT surface. This work has profound implications for our understanding of wetting in one-dimensional systems and the chemistry of ion chemisorption and solvation on the surfaces of materials in general.
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Affiliation(s)
- Patrick J Edwards
- Department of Physics, The University of Southern California, 825 Bloom Walk, Los Angeles, California 90089, United States
- Physical Sciences Laboratories, The Aerospace Corporation, 355 S. Douglas Street, El Segundo, California 90245, United States
| | - Bo Wang
- Department of Physics, The University of Southern California, 825 Bloom Walk, Los Angeles, California 90089, United States
| | - Stephen B Cronin
- Department of Electrical Engineering, The University of Southern California, 3601 W. Way, Los Angeles, California 90089, United States
| | - Adam W Bushmaker
- Physical Sciences Laboratories, The Aerospace Corporation, 355 S. Douglas Street, El Segundo, California 90245, United States
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8
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Wang B, Yang S, Wang Y, Ahsan R, He X, Kim Y, Htoon H, Kapadia R, John DD, Thibeault B, Doorn SK, Cronin SB. Auger Suppression of Incandescence in Individual Suspended Carbon Nanotube pn-Junctions. ACS APPLIED MATERIALS & INTERFACES 2020; 12:11907-11912. [PMID: 32083460 DOI: 10.1021/acsami.9b17519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
There are various mechanisms of light emission in carbon nanotubes (CNTs), which give rise to a wide range of spectral characteristics that provide important information. Here we report suppression of incandescence via Auger recombination in suspended carbon nanotube pn-junctions generated from dual-gate CNT field-effect transistor (FET) devices. By applying equal and opposite voltages to the gate electrodes (i.e., Vg1 = -Vg2), we create a pn-junction within the CNT. Under these gating conditions, we observe a sharp peak in the incandescence intensity around zero applied gate voltage, where the intrinsic region has the largest spatial extent. Here, the emission occurs under high electrical power densities of around 0.1 MW/cm2 (or 6 μW) and arises from thermal emission at elevated temperatures above 800 K (i.e., incandescence). It is somewhat surprising that this thermal emission intensity is so sensitive to the gating conditions, and we observe a 1000-fold suppression of light emission between Vg1 = 0 and 15 V, over a range in which the electrical power dissipated in the nanotube is roughly constant. This behavior is understood on the basis of Auger recombination, which suppresses light emission by the excitation of free carriers. Based on the calculated carrier density and band profiles, the length of the intrinsic region drops by a factor of 7-25× over the range from |Vg| = 0 to 15 V. We, therefore, conclude that the light emission intensity is significantly dependent on the free carrier density profile and the size of the intrinsic region in these CNT devices.
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Affiliation(s)
| | | | | | | | - Xiaowei He
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Younghee Kim
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Han Htoon
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | | | - Demis D John
- Nanotech, Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Brian Thibeault
- Nanotech, Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Stephen K Doorn
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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9
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Rate-selected growth of ultrapure semiconducting carbon nanotube arrays. Nat Commun 2019; 10:4467. [PMID: 31578325 PMCID: PMC6775125 DOI: 10.1038/s41467-019-12519-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 09/10/2019] [Indexed: 11/24/2022] Open
Abstract
Carbon nanotubes (CNTs) are promising candidates for smart electronic devices. However, it is challenging to mediate their bandgap or chirality from a vapor-liquid-solid growth process. Here, we demonstrate rate-selected semiconducting CNT arrays based on interlocking between the atomic assembly rate and bandgap of CNTs. Rate analysis confirms the Schulz-Flory distribution which leads to various decay rates as length increases in metallic and semiconducting CNTs. Quantitatively, a nearly ten-fold faster decay rate of metallic CNTs leads to a spontaneous purification of the predicted 99.9999% semiconducting CNTs at a length of 154 mm, and the longest CNT can be 650 mm through an optimized reactor. Transistors fabricated on them deliver a high current of 14 μA μm−1 with on/off ratio around 108 and mobility over 4000 cm2 V−1 s−1. Our rate-selected strategy offers more freedom to control the CNT purity in-situ and offers a robust methodology to synthesize perfectly assembled nanotubes over a long scale. Carbon nanotubes are considered promising materials for microelectronics, but it is challenging to separate semiconducting tubes from their metallic counterparts. Here, the authors report a self-purification growth process that allows them to obtain long, highly pure semiconducting carbon nanotubes.
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10
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Mironov GI. Electronic Structure and Optical Absorption Spectrum of Icosahedral Golden Fullerene Au32. RUSS J INORG CHEM+ 2019. [DOI: 10.1134/s0036023619100097] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Štrkalj A, Ferguson MS, Wolf TMR, Levkivskyi I, Zilberberg O. Tunneling into a Finite Luttinger Liquid Coupled to Noisy Capacitive Leads. PHYSICAL REVIEW LETTERS 2019; 122:126802. [PMID: 30978091 DOI: 10.1103/physrevlett.122.126802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/11/2019] [Indexed: 06/09/2023]
Abstract
Tunneling spectroscopy of one-dimensional interacting wires can be profoundly sensitive to the boundary conditions of the wire. Here, we analyze the tunneling spectroscopy of a wire coupled to capacitive metallic leads. Strikingly, with increasing many-body interactions in the wire, the impact of the boundary noise becomes more prominent. This interplay allows for a smooth crossover from standard 1D tunneling signatures into a regime where the tunneling is dominated by the fluctuations at the leads. This regime is characterized by an elevated zero-bias tunneling alongside a universal power-law decay at high energies. Furthermore, local tunneling measurements in this regime show a unique spatial dependence that marks the formation of plasmonic standing waves in the wire. Our result offers a tunable method by which to control the boundary effects and measure the interaction strength (Luttinger parameter) within the wire.
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Affiliation(s)
- Antonio Štrkalj
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
| | | | - Tobias M R Wolf
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Ivan Levkivskyi
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Oded Zilberberg
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
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12
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Margańska M, Schmid DR, Dirnaichner A, Stiller PL, Strunk C, Grifoni M, Hüttel AK. Shaping Electron Wave Functions in a Carbon Nanotube with a Parallel Magnetic Field. PHYSICAL REVIEW LETTERS 2019; 122:086802. [PMID: 30932614 DOI: 10.1103/physrevlett.122.086802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 01/25/2019] [Indexed: 06/09/2023]
Abstract
A magnetic field, through its vector potential, usually causes measurable changes in the electron wave function only in the direction transverse to the field. Here, we demonstrate experimentally and theoretically that, in carbon nanotube quantum dots combining cylindrical topology and bipartite hexagonal lattice, a magnetic field along the nanotube axis impacts also the longitudinal profile of the electronic states. With the high (up to 17 T) magnetic fields in our experiment, the wave functions can be tuned all the way from a "half-wave resonator" shape with nodes at both ends to a "quarter-wave resonator" shape with an antinode at one end. This in turn causes a distinct dependence of the conductance on the magnetic field. Our results demonstrate a new strategy for the control of wave functions using magnetic fields in quantum systems with a nontrivial lattice and topology.
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Affiliation(s)
- M Margańska
- Institute for Theoretical Physics, University of Regensburg, 93053 Regensburg, Germany
| | - D R Schmid
- Institute for Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - A Dirnaichner
- Institute for Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - P L Stiller
- Institute for Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Ch Strunk
- Institute for Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - M Grifoni
- Institute for Theoretical Physics, University of Regensburg, 93053 Regensburg, Germany
| | - A K Hüttel
- Institute for Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
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13
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Khivrich I, Clerk AA, Ilani S. Nanomechanical pump-probe measurements of insulating electronic states in a carbon nanotube. NATURE NANOTECHNOLOGY 2019; 14:161-167. [PMID: 30643270 DOI: 10.1038/s41565-018-0341-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 11/23/2018] [Indexed: 05/05/2023]
Abstract
Transport measurements have been an indispensable tool in studying conducting states of matter. However, there exists a large set of interesting states that are insulating, often due to electronic interactions or topology, and are difficult to probe via transport. Here, through an experiment on carbon nanotubes, we present a new approach capable of measuring insulating electronic states through their back action on nanomechanical motion. We use a mechanical pump-probe scheme, allowing the detection of shifts in both frequency and dissipation rate of mechanical vibrational modes, in an overall insulating system. As an example, we use this method to probe the non-conducting configurations of a double quantum dot, allowing us to observe the theoretically predicted signature of nanomechanical back action resulting from a coherently tunnelling electron. The technique opens a new way for measuring the internal electronic structure of a growing variety of insulating states in one- and two-dimensional systems.
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Affiliation(s)
- Ilya Khivrich
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Aashish A Clerk
- Institute for Molecular Engineering, University of Chicago, Chicago, IL, USA
| | - Shahal Ilani
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel.
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14
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Island JO, Ostermann M, Aspitarte L, Minot ED, Varsano D, Molinari E, Rontani M, Steele GA. Interaction-Driven Giant Orbital Magnetic Moments in Carbon Nanotubes. PHYSICAL REVIEW LETTERS 2018; 121:127704. [PMID: 30296145 DOI: 10.1103/physrevlett.121.127704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Indexed: 06/08/2023]
Abstract
Carbon nanotubes continue to be model systems for studies of confinement and interactions. This is particularly true in the case of so-called "ultraclean" carbon nanotube devices offering the study of quantum dots with extremely low disorder. The quality of such systems, however, has increasingly revealed glaring discrepancies between experiment and theory. Here, we address the outstanding anomaly of exceptionally large orbital magnetic moments in carbon nanotube quantum dots. We perform low temperature magnetotransport measurements of the orbital magnetic moment and find it is up to 7 times larger than expected from the conventional semiclassical model. Moreover, the magnitude of the magnetic moment monotonically drops with the addition of each electron to the quantum dot directly contradicting the widely accepted shell filling picture of single-particle levels. We carry out quasiparticle calculations, both from first principles and within the effective-mass approximation, and find the giant magnetic moments can only be captured by considering a self-energy correction to the electronic band structure due to electron-electron interactions.
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Affiliation(s)
- Joshua O Island
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - Marvin Ostermann
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - Lee Aspitarte
- Department of Physics, Oregon State University, Corvallis, Oregon 97331, USA
| | - Ethan D Minot
- Department of Physics, Oregon State University, Corvallis, Oregon 97331, USA
| | | | - Elisa Molinari
- CNR-NANO, Via Campi 213a, 41125 Modena, Italy
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche (FIM), Università degli Studi di Modena e Reggio Emilia, 41125 Modena, Italy
| | | | - Gary A Steele
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
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15
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Berkowitz E, Körber C, Krieg S, Labus P, Lähde TA, Luu T. Extracting the Single-Particle Gap in Carbon Nanotubes with Lattice Quantum Monte Carlo. EPJ WEB OF CONFERENCES 2018. [DOI: 10.1051/epjconf/201817503009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We show how lattice Quantum Monte Carlo simulations can be used to calculate electronic properties of carbon nanotubes in the presence of strong electron-electron correlations. We employ the path integral formalism and use methods developed within the lattice QCD community for our numerical work and compare our results to empirical data of the Anti-Ferromagnetic Mott Insulating gap in large diameter tubes.
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17
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Zhukov AA, Volk C, Winden A, Hardtdegen H, Schäpers T. Stability of charged density waves in InAs nanowires in an external magnetic field. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:475601. [PMID: 29094678 DOI: 10.1088/1361-648x/aa8d48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on magnetotransport measurements at [Formula: see text] K in a high-quality InAs nanowire ([Formula: see text] kΩ) in the presence of the charged tip of an atomic force microscope serving as a mobile gate. We demonstrate the crucial role of the external magnetic field on the amplitude of the charge density waves with a wavelength of 0.8 μm. The observed suppression rate of their amplitude is similar or slightly higher than the one for weak localization correction in our investigated InAs nanowire.
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Affiliation(s)
- A A Zhukov
- Institute of Solid State Physics, Russian Academy of Science, Chernogolovka, 142432, Russia
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18
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Abstract
Fifty years ago Walter Kohn speculated that a zero-gap semiconductor might be unstable against the spontaneous generation of excitons–electron–hole pairs bound together by Coulomb attraction. The reconstructed ground state would then open a gap breaking the symmetry of the underlying lattice, a genuine consequence of electronic correlations. Here we show that this excitonic insulator is realized in zero-gap carbon nanotubes by performing first-principles calculations through many-body perturbation theory as well as quantum Monte Carlo. The excitonic order modulates the charge between the two carbon sublattices opening an experimentally observable gap, which scales as the inverse of the tube radius and weakly depends on the axial magnetic field. Our findings call into question the Luttinger liquid paradigm for nanotubes and provide tests to experimentally discriminate between excitonic and Mott insulators. It has long been anticipated theoretically that semiconductors with small band gaps may form a correlated exciton insulator phase, but it has been difficult to find material realisations. Here, the authors predict numerically that zero-gap armchair carbon nanotubes could be exciton insulators.
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Efroni Y, Ilani S, Berg E. Topological Transitions and Fractional Charges Induced by Strain and a Magnetic Field in Carbon Nanotubes. PHYSICAL REVIEW LETTERS 2017; 119:147704. [PMID: 29053312 DOI: 10.1103/physrevlett.119.147704] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Indexed: 06/07/2023]
Abstract
We show that carbon nanotubes (CNT) can be driven through a topological phase transition using either strain or a magnetic field. This can naturally lead to Jackiw-Rebbi soliton states carrying fractionalized charges, similar to those found in a domain wall in the Su-Schrieffer-Heeger model, in a setup with a spatially inhomogeneous strain and an axial field. Two types of fractionalized states can be formed at the interface between regions with different strain: a spin-charge separated state with integer charge and spin zero (or zero charge and spin ±ℏ/2), and a state with charge ±e/2 and spin ±ℏ/4. The latter state requires spin-orbit coupling in the CNT. We show that in our setup, the precise quantization of the fractionalized interface charges is a consequence of the symmetry of the CNT under a combination of a spatial rotation by π and time reversal.
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Affiliation(s)
- Yonathan Efroni
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shahal Ilani
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Erez Berg
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
- Department of Physics, James Frank Institute, University of Chicago, Chicago, Illinois 60637, USA
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Aspitarte L, McCulley DR, Bertoni A, Island JO, Ostermann M, Rontani M, Steele GA, Minot ED. Giant modulation of the electronic band gap of carbon nanotubes by dielectric screening. Sci Rep 2017; 7:8828. [PMID: 28821825 PMCID: PMC5562844 DOI: 10.1038/s41598-017-09372-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/04/2017] [Indexed: 11/08/2022] Open
Abstract
Carbon nanotubes (CNTs) are a promising material for high-performance electronics beyond silicon. But unlike silicon, the nature of the transport band gap in CNTs is not fully understood. The transport gap in CNTs is predicted to be strongly driven by electron-electron (e-e) interactions and correlations, even at room temperature. Here, we use dielectric liquids to screen e-e interactions in individual suspended ultra-clean CNTs. Using multiple techniques, the transport gap is measured as dielectric screening is increased. Changing the dielectric environment from air to isopropanol, we observe a 25% reduction in the transport gap of semiconducting CNTs, and a 32% reduction in the band gap of narrow-gap CNTs. Additional measurements are reported in dielectric oils. Our results elucidate the nature of the transport gap in CNTs, and show that dielectric environment offers a mechanism for significant control over the transport band gap.
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Affiliation(s)
- Lee Aspitarte
- Department of Physics, Oregon State University, Corvallis, OR, 97331, USA
| | - Daniel R McCulley
- Department of Physics, Oregon State University, Corvallis, OR, 97331, USA
| | - Andrea Bertoni
- Istituto Nanoscienze-CNR, Via Campi 213a, I-41125, Modena, Italy
| | - Joshua O Island
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, Delft, 2628 CJ, The Netherlands
| | - Marvin Ostermann
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, Delft, 2628 CJ, The Netherlands
| | - Massimo Rontani
- Istituto Nanoscienze-CNR, Via Campi 213a, I-41125, Modena, Italy
| | - Gary A Steele
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, Delft, 2628 CJ, The Netherlands
| | - Ethan D Minot
- Department of Physics, Oregon State University, Corvallis, OR, 97331, USA.
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Konstantinidis NP. Capped carbon nanotubes with a number of ground state magnetization discontinuities increasing with their size. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:215803. [PMID: 28437255 DOI: 10.1088/1361-648x/aa6bd4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The classical ground state magnetic response of fullerene molecules that resemble capped carbon nanotubes is calculated within the framework of the antiferromagnetic Heisenberg model. It is found that the magnetic response depends subtly on spatial symmetry and chirality. Clusters based on armchair carbon nanotubes which are capped with non-neighboring pentagons and have D 5d spatial symmetry have a number of magnetization discontinuities which increases with their size. This occurs even though the model completely lacks magnetic anisotropy, and even though the only source of frustration are the two groups of six pentagons located at the ends of the molecules, which become more strongly outnumbered as the clusters are filled in the middle with more unfrustrated hexagons with increasing size. For the cluster with 180 vertices there are already seven magnetization and one susceptibility discontinuities. Contrary to that, similar molecules which have D 5h spatial symmetry reach a limit of one magnetization and two susceptibility ground state discontinuities, while fullerene molecules based on zigzag carbon nanotubes and capped by neighboring pentagons also reach a fixed number of discontinuities with increasing size.
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Karrasch C, Kennes DM, Heidrich-Meisner F. Thermal Conductivity of the One-Dimensional Fermi-Hubbard Model. PHYSICAL REVIEW LETTERS 2016; 117:116401. [PMID: 27661705 DOI: 10.1103/physrevlett.117.116401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Indexed: 06/06/2023]
Abstract
We study the thermal conductivity of the one-dimensional Fermi-Hubbard model at a finite temperature using a density matrix renormalization group approach. The integrability of this model gives rise to ballistic thermal transport. We calculate the temperature dependence of the thermal Drude weight at half filling for various interaction strengths. The finite-frequency contributions originating from the fact that the energy current is not a conserved quantity are investigated as well. We report evidence that breaking the integrability through a nearest-neighbor interaction leads to vanishing Drude weights and diffusive energy transport. Moreover, we demonstrate that energy spreads ballistically in local quenches with initially inhomogeneous energy density profiles in the integrable case. We discuss the relevance of our results for thermalization in ultracold quantum-gas experiments and for transport measurements with quasi-one-dimensional materials.
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Affiliation(s)
- C Karrasch
- Department of Physics, University of California, Berkeley, California 95720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - D M Kennes
- Institut für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information Technology, 52056 Aachen, Germany
| | - F Heidrich-Meisner
- Department of Physics and Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, 80333 München, Germany
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Shimizu S, Iizuka T, Kanahashi K, Pu J, Yanagi K, Takenobu T, Iwasa Y. Thermoelectric Detection of Multi-Subband Density of States in Semiconducting and Metallic Single-Walled Carbon Nanotubes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:3388-3392. [PMID: 27191367 DOI: 10.1002/smll.201600807] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 04/17/2016] [Indexed: 06/05/2023]
Abstract
Thermoelectric detection of a multi-subband density of states in semiconducting and metallic single-walled carbon nanotubes is demonstrated by scanning the Fermi energy from electron-doped to hole-doped regions. The Fermi energy is systematically controlled by utilizing the strong electric field induced in electric-double-layer transistor configurations, resulting in the optimization of the thermoelectric power factor.
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Affiliation(s)
- Sunao Shimizu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Takahiko Iizuka
- Quantum Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Kaito Kanahashi
- Department of Applied Physics, Waseda University, Tokyo, 169-8555, Japan
| | - Jiang Pu
- Department of Applied Physics, Waseda University, Tokyo, 169-8555, Japan
| | - Kazuhiro Yanagi
- Department of Physics, Tokyo Metropolitan University, Tokyo, 192-0397, Japan
| | - Taishi Takenobu
- Department of Applied Physics, Waseda University, Tokyo, 169-8555, Japan
| | - Yoshihiro Iwasa
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
- Quantum Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
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Qiu M, Xie Y, Gao X, Li J, Deng Y, Guan D, Ma L, Yuan C. Band gap opening and semiconductor-metal phase transition in (n, n) single-walled carbon nanotubes with distinctive boron-nitrogen line defect. Phys Chem Chem Phys 2016; 18:4643-51. [PMID: 26794602 DOI: 10.1039/c5cp06853c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Band gap opening and modulating are critical in dictating the functionalities of single walled carbon nanotubes (SWCNTs) in a broad array of nano-devices. Using first-principles density functional theory calculations, a class of semiconducting armchair SWCNTs with a distinctive BN line defect are studied, showing a super capacity to open the band gap of (4, 4) SWCNT to as large as 0.86 eV, while the opened band gap are found decreasing with the increasing diameters of SWCNTs. The opened band gap of SWCNTs can also be successfully modulated through both mechanical and electrical approaches by applying compressive uniaxial strain and electric field. This study provides novel insights into the large band gap opening and modulating of SWCNTs and could be useful in facilitating future applications of SWCNTs in electronic, optical and thermoelectric devices.
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Affiliation(s)
- Ming Qiu
- Department of Mechanical Engineering, University of Wisconsin Milwaukee, Wisconsin 53211, USA. and School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114, China
| | - Yuanyuan Xie
- Department of Mechanical Engineering, University of Wisconsin Milwaukee, Wisconsin 53211, USA.
| | - Xianfeng Gao
- Department of Mechanical Engineering, University of Wisconsin Milwaukee, Wisconsin 53211, USA.
| | - Jianyang Li
- Department of Mechanical Engineering, University of Wisconsin Milwaukee, Wisconsin 53211, USA.
| | - Yelin Deng
- Department of Mechanical Engineering, University of Wisconsin Milwaukee, Wisconsin 53211, USA.
| | - Dongsheng Guan
- Department of Mechanical Engineering, University of Wisconsin Milwaukee, Wisconsin 53211, USA.
| | - Lulu Ma
- Department of Mechanical Engineering, University of Wisconsin Milwaukee, Wisconsin 53211, USA.
| | - Chris Yuan
- Department of Mechanical Engineering, University of Wisconsin Milwaukee, Wisconsin 53211, USA.
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Steinigeweg R, Herbrych J, Zotos X, Brenig W. Heat Conductivity of the Heisenberg Spin-1/2 Ladder: From Weak to Strong Breaking of Integrability. PHYSICAL REVIEW LETTERS 2016; 116:017202. [PMID: 26799041 DOI: 10.1103/physrevlett.116.017202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Indexed: 06/05/2023]
Abstract
We investigate the heat conductivity κ of the Heisenberg spin-1/2 ladder at finite temperature covering the entire range of interchain coupling J(⊥), by using several numerical methods and perturbation theory within the framework of linear response. We unveil that a perturbative prediction κ∝J(⊥)(-2), based on simple golden-rule arguments and valid in the strict limit J(⊥)→0, applies to a remarkably wide range of J(⊥), qualitatively and quantitatively. In the large J(⊥) limit, we show power-law scaling of opposite nature, namely, κ∝J(⊥)(2). Moreover, we demonstrate the weak and strong coupling regimes to be connected by a broad minimum, slightly below the isotropic point at J(⊥)=J(∥). Reducing temperature T, starting from T=∞, this minimum scales as κ∝T(-2) down to T on the order of the exchange coupling constant. These results provide for a comprehensive picture of κ(J(⊥),T) of spin ladders.
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Affiliation(s)
- Robin Steinigeweg
- Department of Physics, University of Osnabrück, D-49069 Osnabrück, Germany
- Institute for Theoretical Physics, Technical University Braunschweig, D-38106 Braunschweig, Germany
| | - Jacek Herbrych
- Department of Physics, University of Crete, GR-71003 Heraklion, Greece
- Cretan Center for Quantum Complexity and Nanotechnology, University of Crete, GR-71003 Heraklion, Greece
| | - Xenophon Zotos
- Department of Physics, University of Crete, GR-71003 Heraklion, Greece
- Cretan Center for Quantum Complexity and Nanotechnology, University of Crete, GR-71003 Heraklion, Greece
- Foundation for Research and Technology-Hellas, GR-71110 Heraklion, Greece
- Institute of Plasma Physics, University of Crete, GR-71003 Heraklion, Greece
| | - Wolfram Brenig
- Institute for Theoretical Physics, Technical University Braunschweig, D-38106 Braunschweig, Germany
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26
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Chang SW, Hazra J, Amer M, Kapadia R, Cronin SB. A Comparison of Photocurrent Mechanisms in Quasi-Metallic and Semiconducting Carbon Nanotube pn-Junctions. ACS NANO 2015; 9:11551-11556. [PMID: 26498635 DOI: 10.1021/acsnano.5b03873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a comparative study of quasi-metallic (Eg ∼ 100 meV) and semiconducting (Eg ∼ 1 eV) suspended carbon nanotube pn-junctions introduced by electrostatic gating. While the built-in fields of the quasi-metallic carbon nanotubes (CNTs) are 1-2 orders of magnitude smaller than those of the semiconducting CNTs, their photocurrent is 2 orders of magnitude higher than the corresponding semiconducting CNT devices under the same experimental conditions. Here, the large exciton binding energy in semiconducting nanotubes (∼400 meV) makes it difficult for excitons to dissociate into free carriers that can contribute to an externally measured photocurent. As such, semiconducting nanotubes require a phonon to assist in the exciton dissociation process, in order to produce a finite photocurrent, while quasi-metallic nanotubes do not. The quasi-metallic nanotubes have much lower exciton binding energies (∼50 meV) as well as a continuum of electronic states to decay into and, therefore, do not require the absorption of a phonon in order to dissociate, making it much easier for these excitons to produce a photocurrent. We performed detailed simulations of the band energies in quasi-metallic and semiconducting nanotube devices in order to obtain the electric field profiles along the lengths of the nanotubes. These simulations predict maximum built-in electric field strengths of 2.3 V/μm for semiconducting and 0.032-0.22 V/μm for quasi-metallic nanotubes under the applied gate voltages used in this study.
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Affiliation(s)
| | | | - Moh Amer
- Department of Electrical Engineering University of California , Los Angeles, California 90095, United States
- King Abdulaziz City for Science and Technology , Riyadh 12612, Saudi Arabia
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Huang JW, Pan C, Tran S, Cheng B, Watanabe K, Taniguchi T, Lau CN, Bockrath M. Superior Current Carrying Capacity of Boron Nitride Encapsulated Carbon Nanotubes with Zero-Dimensional Contacts. NANO LETTERS 2015; 15:6836-6840. [PMID: 26390365 DOI: 10.1021/acs.nanolett.5b02716] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report fabrication and characterization of hexagonal boron nitride (hBN)-encapsulated carbon nanotube (CNT) field effect transistors, which are coupled to electrical leads via zero-dimensional contacts. Device quality is attested by the ohmic contacts and observation of Coulomb blockade with a single periodicity in small bandgap semiconducing nanotubes. Surprisingly, hBN-encapsulated CNT devices demonstrate significantly enhanced current carrying capacity; a single-walled CNT can sustain >180 μA current or, equivalently, a current density of ∼2 × 10(10) A/cm(2), which is a factor of 6-7 higher than devices supported on SiO2 substrates. Such dramatic enhancement of current carrying capacity arises from the high thermal conductivity of hBN and lower hBN-CNT interfacial thermal resistance and has implications for carbon electronic applications.
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Affiliation(s)
- Jhao-Wun Huang
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
| | - Cheng Pan
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
| | - Son Tran
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
| | - Bin Cheng
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
| | - Kenji Watanabe
- National Institute for Materials Science , 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science , 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Chun Ning Lau
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
| | - Marc Bockrath
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
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Pan D, Fuller EJ, Gül OT, Collins PG. One-Dimensional Poole-Frenkel Conduction in the Single Defect Limit. NANO LETTERS 2015; 15:5248-5253. [PMID: 26189911 DOI: 10.1021/acs.nanolett.5b01506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A single point defect surrounded on either side by quasi-ballistic, semimetallic carbon nanotube is a nearly ideal system for investigating disorder in one-dimensional (1D) conductors and comparing experiment to theory. Here, individual single-walled nanotubes (SWNTs) are investigated before and after the incorporation of single point defects. Transport and local Kelvin Probe force microscopy independently demonstrate high-resistance depletion regions over 1.0 μm wide surrounding one point defect in semimetallic SWNTs. Transport measurements show that conductance through such wide depletion regions occurs via a modified, 1D version of Poole-Frenkel field-assisted emission. Given the breadth of theory dedicated to the possible effects of disorder in 1D systems, it is surprising that a Poole-Frenkel mechanism appears to describe defect scattering and resistance in this semimetallic system.
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Affiliation(s)
- Deng Pan
- Department of Physics and Astronomy, University of California at Irvine, Irvine, California 92697, United States
| | - Elliot J Fuller
- Department of Physics and Astronomy, University of California at Irvine, Irvine, California 92697, United States
| | - O Tolga Gül
- Department of Physics and Astronomy, University of California at Irvine, Irvine, California 92697, United States
| | - Philip G Collins
- Department of Physics and Astronomy, University of California at Irvine, Irvine, California 92697, United States
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Wang F, Stepanov P, Gray M, Lau CN, Itkis ME, Haddon RC. Ionic Liquid Gating of Suspended MoS2 Field Effect Transistor Devices. NANO LETTERS 2015; 15:5284-8. [PMID: 26181777 DOI: 10.1021/acs.nanolett.5b01610] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We demonstrate ionic liquid (IL) gating of suspended few-layer MoS2 transistors, where ions can accumulate on both exposed surfaces. Upon application of IL, all free-standing samples consistently display more significant improvement in conductance than substrate-supported devices. The measured IL gate coupling efficiency is up to 4.6 × 10(13) cm(-2) V(-1). Electrical transport data reveal contact-dominated electrical transport properties and the Schottky emission as the underlying mechanism. By modulating IL gate voltage, the suspended MoS2 devices display metal-insulator transition. Our results demonstrate that more efficient charge induction can be achieved in suspended two-dimensional (2D) materials, which with further optimization, may enable extremely high charge density and novel phase transition.
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Affiliation(s)
- Fenglin Wang
- †Department of Physics and Astronomy, ‡Department of Chemistry, and §Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Petr Stepanov
- †Department of Physics and Astronomy, ‡Department of Chemistry, and §Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Mason Gray
- †Department of Physics and Astronomy, ‡Department of Chemistry, and §Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Chun Ning Lau
- †Department of Physics and Astronomy, ‡Department of Chemistry, and §Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Mikhail E Itkis
- †Department of Physics and Astronomy, ‡Department of Chemistry, and §Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Robert C Haddon
- †Department of Physics and Astronomy, ‡Department of Chemistry, and §Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, California 92521, United States
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Amer MR, Chang SW, Cronin SB. Competing Photocurrent Mechanisms in Quasi-Metallic Carbon Nanotube pn Devices. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:3119-3123. [PMID: 25767070 DOI: 10.1002/smll.201403413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 02/07/2015] [Indexed: 06/04/2023]
Abstract
Photodetectors based on quasi-metallic carbon nanotubes exhibit unique optoelectronic properties. Due to their small bandgap, photocurrent generation is possible at room temperature. The origin of this photocurrent is investigated to determine the underlying mechanism, which can be photothermoelectric effect or photovoltaic effect, depending on the bandgap magnitude of the quasi-metallic nanotube.
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Affiliation(s)
- Moh R Amer
- Center of Excellence for Green Nanotechnologies, University of California Los Angeles, CA 90095, USA and King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
| | - Shun-Wen Chang
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, 90089, USA
| | - Stephen B Cronin
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, 90089, USA
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA, 90089, USA
- Department of Material Science, University of Southern California, Los Angeles, CA, 90089, USA
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31
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Sarpkaya I, Ahmadi ED, Shepard GD, Mistry KS, Blackburn JL, Strauf S. Strong Acoustic Phonon Localization in Copolymer-Wrapped Carbon Nanotubes. ACS NANO 2015; 9:6383-6393. [PMID: 26039893 DOI: 10.1021/acsnano.5b01997] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Understanding and controlling exciton-phonon interactions in carbon nanotubes has important implications for producing efficient nanophotonic devices. Here we show that laser vaporization-grown carbon nanotubes display ultranarrow luminescence line widths (120 μeV) and well-resolved acoustic phonon sidebands at low temperatures when dispersed with a polyfluorene copolymer. Remarkably, we do not observe a correlation of the zero-phonon line width with (13)C atomic concentration, as would be expected for pure dephasing of excitons with acoustic phonons. We demonstrate that the ultranarrow and phonon sideband-resolved emission spectra can be fully described by a model assuming extrinsic acoustic phonon localization at the nanoscale, which holds down to 6-fold narrower spectral line width compared to previous work. Interestingly, both exciton and acoustic phonon wave functions are strongly spatially localized within 5 nm, possibly mediated by the copolymer backbone, opening future opportunities to engineer dephasing and optical bandwidth for applications in quantum photonics and cavity optomechanics.
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Affiliation(s)
| | | | | | - Kevin S Mistry
- ‡National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Jeffrey L Blackburn
- ‡National Renewable Energy Laboratory, Golden, Colorado 80401, United States
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Wang F, Stepanov P, Gray M, Lau CN. Annealing and transport studies of suspended molybdenum disulfide devices. NANOTECHNOLOGY 2015; 26:105709. [PMID: 25697290 DOI: 10.1088/0957-4484/26/10/105709] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We fabricate suspended molybdenum disulfide (MoS2) field effect transistor devices and develop an effective gas annealing technique that significantly improves device quality and increases conductance by 3-4 orders of magnitude. Mobility of the suspended devices ranges from 0.01 to 46 cm(2) V(-1) s(-1) before annealing, and from 0.5 to 105 cm(2) V(-1) s(-1) after annealing. Temperature dependence measurements reveal two transport mechanisms: electron-phonon scattering at high temperatures and thermal activation over a gate-tunable barrier height at low temperatures. Our results suggest that transport in these devices is not limited by the substrates, but likely by defects, charge impurities and/or Schottky barriers at the metal-MoS2 interfaces. Finally, this suspended MoS2 device structure provides a versatile platform for other research areas, such as thermal, optical and mechanical studies.
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Affiliation(s)
- Fenglin Wang
- Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA
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Watanabe T, Sadki EHS, Yamaguchi T, Takano Y. Electrical transport properties of small diameter single-walled carbon nanotubes aligned on ST-cut quartz substrates. NANOSCALE RESEARCH LETTERS 2014; 9:374. [PMID: 25170326 PMCID: PMC4141659 DOI: 10.1186/1556-276x-9-374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/19/2014] [Indexed: 06/03/2023]
Abstract
A method is introduced to isolate and measure the electrical transport properties of individual single-walled carbon nanotubes (SWNTs) aligned on an ST-cut quartz, from room temperature down to 2 K. The diameter and chirality of the measured SWNTs are accurately defined from Raman spectroscopy and atomic force microscopy (AFM). A significant up-shift in the G-band of the resonance Raman spectra of the SWNTs is observed, which increases with increasing SWNTs diameter, and indicates a strong interaction with the quartz substrate. A semiconducting SWNT, with diameter 0.84 nm, shows Tomonaga-Luttinger liquid and Coulomb blockade behaviors at low temperatures. Another semiconducting SWNT, with a thinner diameter of 0.68 nm, exhibits a transition from the semiconducting state to an insulating state at low temperatures. These results elucidate some of the electrical properties of SWNTs in this unique configuration and help pave the way towards prospective device applications.
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Affiliation(s)
- Tohru Watanabe
- National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - El-Hadi S Sadki
- Physics Department, College of Science, United Arab Emirates University, Al Ain, Abu Dhabi, United Arab Emirates
| | - Takahide Yamaguchi
- National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Yoshihiko Takano
- National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan
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34
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Sarpkaya I, Zhang Z, Walden-Newman W, Wang X, Hone J, Wong CW, Strauf S. Prolonged spontaneous emission and dephasing of localized excitons in air-bridged carbon nanotubes. Nat Commun 2014; 4:2152. [PMID: 23845935 DOI: 10.1038/ncomms3152] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Accepted: 06/14/2013] [Indexed: 11/09/2022] Open
Abstract
The bright exciton emission of carbon nanotubes is appealing for optoelectronic devices and fundamental studies of light-matter interaction in one-dimensional nanostructures. However, to date, the photophysics of excitons in carbon nanotubes is largely affected by extrinsic effects. Here we perform time-resolved photoluminescence measurements over 14 orders of magnitude for ultra-clean carbon nanotubes bridging an air gap over pillar posts. Our measurements demonstrate a new regime of intrinsic exciton photophysics with prolonged spontaneous emission times up to T1=18 ns, about two orders of magnitude better than prior measurements and in agreement with values hypothesized by theorists about a decade ago. Furthermore, we establish for the first time exciton decoherence times of individual nanotubes in the time domain and find fourfold prolonged values up to T2=2.1 ps compared with ensemble measurements. These first observations motivate new discussions about the magnitude of the intrinsic dephasing mechanism while the prolonged exciton dynamics is promising for applications.
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Affiliation(s)
- Ibrahim Sarpkaya
- Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
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35
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Amer MR, Chang SW, Dhall R, Qiu J, Cronin SB. Zener tunneling and photocurrent generation in quasi-metallic carbon nanotube pn-devices. NANO LETTERS 2013; 13:5129-5134. [PMID: 24127786 DOI: 10.1021/nl402334e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We investigate the electronic and optoelectronic properties of quasi-metallic nanotube pn-devices, which have smaller band gaps than most known bulk semiconductors. These carbon nanotube-based devices deviate from conventional bulk semiconductor device behavior due to their low-dimensional nature. We observe rectifying behavior based on Zener tunneling of ballistic carriers instead of ideal diode behavior, as limited by the diffusive transport of carriers. We observe substantial photocurrents at room temperature, suggesting that these quasi-metallic pn-devices may have a broader impact in optoelectronic devices. A new technique based on photocurrent spectroscopy is presented to identify the unique chirality of nanotubes in a functional device. This chirality information is crucial in obtaining a theoretical understanding of the underlying device physics that depends sensitively on nanotube chirality, as is the case for quasi-metallic nanotube devices. A detailed model is developed to fit the observed I-V characteristics, which enables us to verify the band gap from these measurements as well as the dimensions of the insulating tunneling barrier region.
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Affiliation(s)
- Moh R Amer
- Department of Electrical Engineering, ‡Department of Material Science, and §Department of Physics and Astronomy, University of Southern California , Los Angeles, California 90089, United States
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36
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Liu B, Wang C, Liu J, Che Y, Zhou C. Aligned carbon nanotubes: from controlled synthesis to electronic applications. NANOSCALE 2013; 5:9483-9502. [PMID: 23969970 DOI: 10.1039/c3nr02595k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Single-wall carbon nanotubes (SWNTs) possess superior geometrical, electronic, chemical, thermal, and mechanical properties and are very attractive for applications in electronic devices and circuits. To make this a reality, the nanotube orientation, density, diameter, electronic property, and even chirality should be well controlled. This Feature article focuses on recent achievements researchers have made on the controlled growth of horizontally aligned SWNTs and SWNT arrays on substrates and their electronic applications. Principles and strategies to control the morphology, structure, and properties of SWNTs are reviewed in detail. Furthermore, electrical properties of field-effect transistors fabricated on both individual SWNTs and aligned SWNT arrays are discussed. State-of-the-art electronic devices and circuits based on aligned SWNTs and SWNT arrays are also highlighted.
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Affiliation(s)
- Bilu Liu
- Department of Electrical Engineering and Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA.
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37
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Variability and Reliability of Single-Walled Carbon Nanotube Field Effect Transistors. ELECTRONICS 2013. [DOI: 10.3390/electronics2040332] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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38
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Waissman J, Honig M, Pecker S, Benyamini A, Hamo A, Ilani S. Realization of pristine and locally tunable one-dimensional electron systems in carbon nanotubes. NATURE NANOTECHNOLOGY 2013; 8:569-574. [PMID: 23912108 DOI: 10.1038/nnano.2013.143] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 06/19/2013] [Indexed: 06/02/2023]
Abstract
The ability to tune local parameters of quantum Hamiltonians has been demonstrated in experimental systems including ultracold atoms, trapped ions, superconducting circuits and photonic crystals. Such systems possess negligible disorder, enabling local tunability. Conversely, in condensed-matter systems, electrons are subject to disorder, which often destroys delicate correlated phases and precludes local tunability. The realization of a disorder-free and locally-tunable condensed-matter system thus remains an outstanding challenge. Here, we demonstrate a new technique for deterministic creation of locally-tunable, ultralow-disorder electron systems in carbon nanotubes suspended over complex electronic circuits. Using transport experiments we show that electrons can be localized at any position along the nanotube and that the confinement potential can be smoothly moved from location to location. The high mirror symmetry of transport characteristics about the nanotube centre establishes the negligible effects of electronic disorder, thus allowing experiments in precision-engineered one-dimensional potentials. We further demonstrate the ability to position multiple nanotubes at chosen separations, generalizing these devices to coupled one-dimensional systems. These capabilities could enable many novel experiments on electronics, mechanics and spins in one dimension.
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Affiliation(s)
- J Waissman
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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39
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Large spin-orbit coupling in carbon nanotubes. Nat Commun 2013; 4:1573. [DOI: 10.1038/ncomms2584] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 02/08/2013] [Indexed: 11/09/2022] Open
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40
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Hároz EH, Duque JG, Tu X, Zheng M, Hight Walker AR, Hauge RH, Doorn SK, Kono J. Fundamental optical processes in armchair carbon nanotubes. NANOSCALE 2013; 5:1411-39. [PMID: 23340668 DOI: 10.1039/c2nr32769d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Single-wall carbon nanotubes provide ideal model one-dimensional (1-D) condensed matter systems in which to address fundamental questions in many-body physics, while, at the same time, they are leading candidates for building blocks in nanoscale optoelectronic circuits. Much attention has been recently paid to their optical properties, arising from 1-D excitons and phonons, which have been revealed via photoluminescence, Raman scattering, and ultrafast optical spectroscopy of semiconducting carbon nanotubes. On the other hand, dynamical properties of metallic nanotubes have been poorly explored, although they are expected to provide a novel setting for the study of electron-hole pairs in the presence of degenerate 1-D electrons. In particular, (n,n)-chirality, or armchair, metallic nanotubes are truly gapless with massless carriers, ideally suited for dynamical studies of Tomonaga-Luttinger liquids. Unfortunately, progress towards such studies has been slowed by the inherent problem of nanotube synthesis whereby both semiconducting and metallic nanotubes are produced. Here, we use post-synthesis separation methods based on density gradient ultracentrifugation and DNA-based ion-exchange chromatography to produce aqueous suspensions strongly enriched in armchair nanotubes. Through resonant Raman spectroscopy of the radial breathing mode phonons, we provide macroscopic and unambiguous evidence that density gradient ultracentrifugation can enrich ensemble samples in armchair nanotubes. Furthermore, using conventional, optical absorption spectroscopy in the near-infrared and visible range, we show that interband absorption in armchair nanotubes is strongly excitonic. Lastly, by examining the G-band mode in Raman spectra, we determine that observation of the broad, lower frequency (G(-)) feature is a result of resonance with non-armchair "metallic" nanotubes. These findings regarding the fundamental optical absorption and scattering processes in metallic carbon nanotubes lay the foundation for further spectroscopic studies to probe many-body physical phenomena in one dimension.
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Affiliation(s)
- Erik H Hároz
- Department of Electrical and Computer Engineering, Rice University, 6100 Main St., MS-378, Houston, Texas 77005, USA
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41
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Sharf T, Kevek JW, Deborde T, Wardini JL, Minot ED. Origins of charge noise in carbon nanotube field-effect transistor biosensors. NANO LETTERS 2012; 12:6380-6384. [PMID: 23171196 DOI: 10.1021/nl303651t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Determining the major noise sources in nanoscale field-effect transistor (nanoFET) biosensors is critical for improving bioelectronic interfaces. We use the carbon nanotube (CNT) FET biosensor platform to examine the noise generated by substrate interactions and surface adsorbates, both of which are present in current nanoFET biosensors. The charge noise model is used as a quantitative framework to show that insulating substrates and surface adsorbates are both significant contributors to the noise floor of CNT FET biosensors. Removing substrate interactions and surface adsorbates reduces the power spectral density of background voltage fluctuations by 19-fold.
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Affiliation(s)
- Tal Sharf
- Department of Physics, Oregon State University, Corvallis, Oregon 97331-6507, United States
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42
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Amer MR, Bushmaker A, Cronin SB. The influence of substrate in determining the band gap of metallic carbon nanotubes. NANO LETTERS 2012; 12:4843-4847. [PMID: 22931184 DOI: 10.1021/nl302321k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report a detailed comparison of ultraclean suspended and on-substrate carbon nanotubes (CNTs) in order to quantify the effect of the substrate interaction on the effective band gap of metallic nanotubes. Here, individual CNTs are grown across two sets of electrodes, resulting in one segment of the nanotube that is suspended across a trench and the other segment supported on the substrate. The suspended segment shows a significant change in the conductance (ΔG/G = 0.84) with applied gate voltage, which is attributed to a small band gap. The on-substrate segment, however, only shows a change in the measured conductance of ΔG/G = 0.11. A Landauer model is used to fit the low bias conductance of these devices. From these fits, the band gaps in the suspended region range from 75 to 100 meV but are only 5-14.3 meV when the nanotube is in contact with the substrate. The decreased band gap is attributed to localized doping caused by trapped charges in the substrate that result in inhomogeneous broadening of the Fermi energy, which in turn limits the ability to modulate the conductance.
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Affiliation(s)
- Moh R Amer
- Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States
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43
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Cao Q, Han SJ, Tulevski GS, Franklin AD, Haensch W. Evaluation of field-effect mobility and contact resistance of transistors that use solution-processed single-walled carbon nanotubes. ACS NANO 2012; 6:6471-6477. [PMID: 22671996 DOI: 10.1021/nn302185d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Solution-processed single-walled carbon nanotubes (SWNTs) offer many unique processing advantages over nanotubes grown by the chemical vapor deposition (CVD) method, including capabilities of separating the nanotubes by electronic type and depositing them onto various substrates in the form of ultradensely aligned arrays at low temperature. However, long-channel transistors that use solution-processed SWNTs generally demonstrate inferior device performance, which poses concerns over the feasibility of using these nanotubes in high-performance logic applications. This paper presents the first systematic study of contact resistance, intrinsic field-effect mobility (μ(FE)), and conductivity (σ(m)) of solution-processed SWNTs based on both the transmission line method and the Y function method. The results indicate that, compared to CVD nanotubes, although solution-processed SWNTs have much lower μ(FE) for semiconducting nanotubes and lower σ(m) for metallic nanotubes due to the presence of a higher level of structural defects, such defects do not affect the quality of electric contacts between the nanotube and metal source/drain electrodes. Therefore, solution-processed SWNTs are expected to offer performance comparable to that of CVD nanotubes in ultimately scaled field-effect transistors, where contacts will dominate electron transport instead of electron scattering in the channel region. These results show promise for using solution-processed SWNTs for high-performance nanoelectronic devices.
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Affiliation(s)
- Qing Cao
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, United States.
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44
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Laird EA, Pei F, Tang W, Steele GA, Kouwenhoven LP. A high quality factor carbon nanotube mechanical resonator at 39 GHz. NANO LETTERS 2012; 12:193-197. [PMID: 22111547 DOI: 10.1021/nl203279v] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We measure the mechanical resonances of an as-grown suspended carbon nanotube, detected via electrical mixing in the device. A sequence of modes extending to 39 GHz is observed with a quality factor of 35,000 in the highest mode. This unprecedentedly high combination corresponds to a thermal excited state probability below 10(-8) and a relaxation time of 140 ns with microsecond relaxation times for lower modes. The effect of electron tunneling on the mechanical resonance is found to depend on frequency as the tunneling time becomes comparable to the vibration period.
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Affiliation(s)
- Edward A Laird
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
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45
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Micolich AP. What lurks below the last plateau: experimental studies of the 0.7 × 2e(2)/h conductance anomaly in one-dimensional systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:443201. [PMID: 21997403 DOI: 10.1088/0953-8984/23/44/443201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The integer quantised conductance of one-dimensional electron systems is a well-understood effect of quantum confinement. A number of fractionally quantised plateaus are also commonly observed. They are attributed to many-body effects, but their precise origin is still a matter of debate, having attracted considerable interest over the past 15 years. This review reports on experimental studies of fractionally quantised plateaus in semiconductor quantum point contacts and quantum wires, focusing on the 0.7 × 2e(2)/h conductance anomaly, its analogues at higher conductances and the zero-bias peak observed in the dc source-drain bias for conductances less than 2e(2)/h.
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Affiliation(s)
- A P Micolich
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
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46
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Kormondy KJ, Stokes P, Khondaker SI. High yield assembly and electron transport investigation of semiconducting-rich local-gated single-walled carbon nanotube field effect transistors. NANOTECHNOLOGY 2011; 22:415201. [PMID: 21914942 DOI: 10.1088/0957-4484/22/41/415201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report the fabrication and electron transport investigation of individual local-gated single-walled carbon nanotube field effect transistors (SWNT-FET) with high yield using a semiconducting-rich carbon nanotube solution. The individual semiconducting nanotubes were assembled at the selected position of the circuit via dielectrophoresis. Detailed electron transport investigations on 70 devices show that 99% display good FET behavior, with an average threshold voltage of 1 V, subthreshold swing as low as 140 mV/dec, and on/off current ratio as high as 8 × 10(5). The high yield directed assembly of local-gated SWNT-FET will facilitate large scale fabrication of CMOS (complementary metal-oxide-semiconductor) compatible nanoelectronic devices.
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Affiliation(s)
- Kristy J Kormondy
- Nanoscience Technology Center and Department of Physics, University of Central Florida, Orlando, FL 32826, USA
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47
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Farhat H, Berciaud S, Kalbac M, Saito R, Heinz TF, Dresselhaus MS, Kong J. Observation of electronic Raman scattering in metallic carbon nanotubes. PHYSICAL REVIEW LETTERS 2011; 107:157401. [PMID: 22107317 DOI: 10.1103/physrevlett.107.157401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Indexed: 05/31/2023]
Abstract
We present experimental measurements of the electronic contribution to the Raman spectra of individual metallic single-walled carbon nanotubes (MSWNTs). Photoexcited carriers are inelastically scattered by a continuum of low-energy electron-hole pairs created across the graphenelike linear electronic subbands of the MSWNTs. The optical resonances in MSWNTs give rise to well-defined electronic Raman peaks. This resonant electronic Raman scattering is a unique feature of the electronic structure of these one-dimensional quasimetals.
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Affiliation(s)
- H Farhat
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139, USA
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48
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Chandra B, Perebeinos V, Berciaud S, Katoch J, Ishigami M, Kim P, Heinz TF, Hone J. Low bias electron scattering in structure-identified single wall carbon nanotubes: role of substrate polar phonons. PHYSICAL REVIEW LETTERS 2011; 107:146601. [PMID: 22107221 DOI: 10.1103/physrevlett.107.146601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Indexed: 05/31/2023]
Abstract
We have performed temperature-dependent electrical transport measurements on known structure single wall carbon nanotubes at low bias. The experiments show a superlinear increase in nanotube resistivity with temperature, which is in contradiction with the linear dependence expected from nanotube acoustic-phonon scattering. The measured electron mean free path is also much lower than expected, especially at medium to high temperatures (>100 K). A theoretical model that includes scattering due to surface polar phonon modes of the substrates reproduces the experiments very well. The role of surface phonons is further confirmed by resistivity measurements of nanotubes on aluminum nitride.
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Affiliation(s)
- Bhupesh Chandra
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
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49
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Velasco J, Zhao Z, Zhang H, Wang F, Wang Z, Kratz P, Jing L, Bao W, Shi J, Lau CN. Suspension and measurement of graphene and Bi2Se3 thin crystals. NANOTECHNOLOGY 2011; 22:285305. [PMID: 21636884 DOI: 10.1088/0957-4484/22/28/285305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Coupling high-quality suspended atomic membranes to specialized electrodes enables the investigation of many novel phenomena, such as spin or Cooper pair transport in these two-dimensional systems. However, many electrode materials are not stable in the acids that are used to dissolve underlying substrates. Here we present a versatile and powerful multilevel lithographical technique to suspend thin crystals, which can be applied to the vast majority of substrate, crystal and electrode materials. Using this technique, we fabricated suspended graphene devices with Al electrodes and a mobility of 5500 cm(2) V(-1) s(-1). We also demonstrate, for the first time, fabrication and measurement of a free-standing thin Bi(2)Se(3) crystal, which has low contact resistance to electrodes and a mobility of approximately > 580 cm(2) V(-1) s(-1).
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Affiliation(s)
- Jairo Velasco
- Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA
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50
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Liu Z, Bushmaker A, Aykol M, Cronin SB. Thermal emission spectra from individual suspended carbon nanotubes. ACS NANO 2011; 5:4634-4640. [PMID: 21545117 DOI: 10.1021/nn200444x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We study the thermal emission spectra of individual suspended carbon nanotubes induced by electrical heating. Semiconducting and metallic devices exhibit different spectra, based on their distinctive band structures. These spectra are compared with the ideal blackbody emission spectrum. In the visible wavelength range, the thermal emission spectra of semiconducting devices agree well with Planck's law, while the spectra of metallic devices show an additional peak between 1.5 and 1.9 eV. In the near-infrared wavelength range, the semiconducting nanotubes exhibit a peak around 1 eV. These additional peaks are attributed to the E11M and E22SC transitions that are thermally driven under these high applied bias voltages. These peaks show a strong polarization dependence, while the blackbody tail is unpolarized, which provides further evidence for electron-hole recombination in thermal emission. For semiconducting devices, the temperature of the nanotube is fit to Planck's law and compared with the temperatures obtained from the G band and 2D band Raman downshifts, as well as the anti-Stokes/Stokes intensity ratio. For devices showing thermal non-equilibrium, the electron temperature agrees well with G+ downshift but deviates from G_ downshift.
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Affiliation(s)
- Zuwei Liu
- Department of Physics, University of Southern California, Los Angeles, California 90089, United States
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