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Bazrafshan MA, Khoeini F. Flexible thermoelectrics in crossed graphene/hBN composites. Sci Rep 2024; 14:1079. [PMID: 38212539 PMCID: PMC10784592 DOI: 10.1038/s41598-024-51652-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 01/08/2024] [Indexed: 01/13/2024] Open
Abstract
Nanostructures exhibit unusual properties due to the dominance of quantum mechanical effects. In addition, the geometry of a nanostructure can have a strong influence on its physical properties. Using the tight-binding and force-constant approaches with the help of the non-equilibrium Green's function method, the transport and thermoelectric properties of cross-shaped (X-shaped) composite heterostructures are studied in two cases: Mixed graphene and h-BN (HETX-CBN) and all graphene (HETX-C) cross-shaped structures. Our numerical results show that an X-shaped structure helps to manipulate its electronic and phononic properties. The transport energy gap can be tuned in the range of ~ 0.8 eV by changing one arm width. Due to the drastic decrease in the electronic conductance of HETX-CBN and the dominance of the phononic thermal conductance, the ZT performance is degraded despite the high Seebeck coefficient value (in the order of meV). However, HETX-C has better ZT performance due to better electronic conductance and lower phononic/electronic thermal ratio, it can enhance the ZT ~ 2.5 times compared to that of zigzag graphene nanoribbon. The thermoelectric properties of the system can be tuned by controlling the size of the arms of the device and the type of its atoms.
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Affiliation(s)
- M Amir Bazrafshan
- Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, Iran
| | - Farhad Khoeini
- Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, Iran.
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Bo W, Zou Y, Wang J. Novel electrical properties and applications in kaleidoscopic graphene nanoribbons. RSC Adv 2021; 11:33675-33691. [PMID: 35497508 PMCID: PMC9042372 DOI: 10.1039/d1ra05902e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 09/30/2021] [Indexed: 01/25/2023] Open
Abstract
As one of the representatives of nano-graphene materials, graphene nanoribbons (GNRs) have more novel electrical properties, highly adjustable electronic properties, and optoelectronic properties than graphene due to their diverse geometric structures and atomic precision configurations. The electrical properties and band gaps of GNRs depend on their width, length, boundary configuration and other elemental doping, etc. With the improvement of the preparation technology and level of GNRs with atomic precision, increasing number of GNRs with different configurations are being prepared. They all show novel electrical properties and high tunability, which provides a broad prospect for the application of GNRs in the field of microelectronics. Here, we summarize the latest GNR-based achievements in recent years and summarize the latest electrical properties and potential applications of GNRs.
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Affiliation(s)
- Wenjing Bo
- College of Science, Liaoning Petrochemical University Fushun 113001 China
| | - Yi Zou
- College of Science, Liaoning Petrochemical University Fushun 113001 China
| | - Jingang Wang
- College of Science, Liaoning Petrochemical University Fushun 113001 China
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Fischer MM, de Sousa LE, Luiz E Castro L, Ribeiro LA, de Sousa RT, Magela E Silva G, de Oliveira Neto PH. Effective Mass of Quasiparticles in Armchair Graphene Nanoribbons. Sci Rep 2019; 9:17990. [PMID: 31784579 PMCID: PMC6884564 DOI: 10.1038/s41598-019-54319-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 10/10/2019] [Indexed: 11/08/2022] Open
Abstract
Armchair graphene nanoribbons (AGNRs) may present intrinsic semiconducting bandgaps, being of potential interest in developing new organic-based optoelectronic devices. The induction of a bandgap in AGNRs results from quantum confinement effects, which reduce charge mobility. In this sense, quasiparticles' effective mass becomes relevant for the understanding of charge transport in these systems. In the present work, we theoretically investigate the drift of different quasiparticle species in AGNRs employing a 2D generalization of the Su-Schrieffer-Heeger Hamiltonian. Remarkably, our findings reveal that the effective mass strongly depends on the nanoribbon width and its value can reach 60 times the mass of one electron for narrow lattices. Such underlying property for quasiparticles, within the framework of gap tuning engineering in AGNRs, impact the design of their electronic devices.
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Affiliation(s)
| | | | | | - Luiz Antonio Ribeiro
- Institute of Physics, University of Brasilia, 70.919-970, Brasilia, Brazil.
- University of Brasília, PPG-CIMA, Campus Planaltina, 73345-010, Brasília, DF, Brazil.
| | - Rafael Timóteo de Sousa
- Department of Electrical Engineering, University of Brasília, CP04455, Brasília, 70919-970, Brazil
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Abergel DSL. Robustness of topologically protected transport in graphene-boron nitride lateral heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:075303. [PMID: 28032604 DOI: 10.1088/1361-648x/aa51e6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Previously, graphene nanoribbons set in lateral heterostructures with hexagonal boron nitride were predicted to support topologically protected states at low energy. We investigate how robust the transport properties of these states are against lattice disorder. We find that forms of disorder that do not couple the two valleys of the zigzag graphene nanoribbon do not impact the transport properties at low bias, indicating that these lateral heterostructures are very promising candidates for chip-scale conducting interconnects. Forms of disorder that do couple the two valleys, such as vacancies in the graphene ribbon, or substantial inclusions of armchair edges at the graphene-hexagonal boron nitride interface will negatively affect the transport. However, these forms of disorder are not commonly seen in current experiments.
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Affiliation(s)
- D S L Abergel
- Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-106 91 Stockholm, Sweden. Center for Quantum Materials, KTH and Nordita, Roslagstullsbacken 11, SE-106 91 Stockholm, Sweden
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Szczȩśniak D, Khater A, Ba̧k Z, Szczȩśniak R, Ghantous MA. Quantum conductance of silicon-doped carbon wire nanojunctions. NANOSCALE RESEARCH LETTERS 2012; 7:616. [PMID: 23130998 PMCID: PMC3598495 DOI: 10.1186/1556-276x-7-616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Accepted: 10/11/2012] [Indexed: 06/01/2023]
Abstract
Unknown quantum electronic conductance across nanojunctions made of silicon-doped carbon wires between carbon leads is investigated. This is done by an appropriate generalization of the phase field matching theory for the multi-scattering processes of electronic excitations at the nanojunction and the use of the tight-binding method. Our calculations of the electronic band structures for carbon, silicon, and diatomic silicon carbide are matched with the available corresponding density functional theory results to optimize the required tight-binding parameters. Silicon and carbon atoms are treated on the same footing by characterizing each with their corresponding orbitals. Several types of nanojunctions are analyzed to sample their behavior under different atomic configurations. We calculate for each nanojunction the individual contributions to the quantum conductance for the propagating σ, Π, and σ∗electron incidents from the carbon leads. The calculated results show a number of remarkable features, which include the influence of the ordered periodic configurations of silicon-carbon pairs and the suppression of quantum conductance due to minimum substitutional disorder and artificially organized symmetry on these nanojunctions. Our results also demonstrate that the phase field matching theory is an efficient tool to treat the quantum conductance of complex molecular nanojunctions.
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Affiliation(s)
- Dominik Szczȩśniak
- Institute for Molecules and Materials UMR 6283, University of Maine, Ave. Olivier Messiaen, Le Mans, 72085, France
- Institute of Physics, Jan Długosz University in Czȩstochowa, Al. Armii Krajowej 13/15, Czȩstochowa, 42200, Poland
| | - Antoine Khater
- Institute for Molecules and Materials UMR 6283, University of Maine, Ave. Olivier Messiaen, Le Mans, 72085, France
| | - Zygmunt Ba̧k
- Institute of Physics, Jan Długosz University in Czȩstochowa, Al. Armii Krajowej 13/15, Czȩstochowa, 42200, Poland
| | - Radosław Szczȩśniak
- Institute of Physics, Czȩstochowa University of Technology, Al. Armii Krajowej 19, Czȩstochowa, 42200, Poland
| | - Michel Abou Ghantous
- Department of Physics, Texas A&M University, Education City, PO Box 23874, Doha, Qatar
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Kumar M, Bagga A, Neeleshwar S. Tailoring of Seebeck coefficient with surface roughness effects in silicon sub-50-nm films. NANOSCALE RESEARCH LETTERS 2012; 7:169. [PMID: 22390685 PMCID: PMC3395578 DOI: 10.1186/1556-276x-7-169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 03/05/2012] [Indexed: 05/31/2023]
Abstract
The effect of surface roughness on the Seebeck coefficient in the sub-50-nm scale silicon ultra thin films is investigated theoretically using nonequilibrium Green's function formalism. For systematic studies, the surface roughness is modelled by varying thickness periodically with square wave profile characterized by two parameters: amplitude (A 0) and wavelength (λ). Since high Seebeck coefficient is obtained if the temperature difference between the ends of device produces higher currents and higher induced voltages, we investigate how the generated current and induced voltage is affected with increasing A 0 and λ. The theoretical investigations show that pseudoperiodicity of the device structure gives rise to two effects: firstly the threshold energy at which the transmission of current starts is shifted towards higher energy sides and secondly transmission spectra of current possess pseudobands and pseudogaps. The width of the pseudobands and their occupancies determine the total generated current. It is found that current decreases with increasing A 0 but shows a complicated trend with λ. The trends of threshold energy determine the trends of Seebeck voltage with roughness parameters. The increase in threshold energy makes the current flow in higher energy levels. Thus, the Seebeck voltage, i.e. voltage required to nullify this current, increases. Increase in Seebeck voltage results in increase in Seebeck coefficient. We find that threshold energy increases with increasing A 0 and frequency (1/λ). Hence, Seebeck voltage and Seebeck coefficient increase vice versa. It is observed that Seebeck coefficient is tuneable with surface roughness parameters.
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Affiliation(s)
- Manoj Kumar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016, India
| | - Anjana Bagga
- University School of Basic and Applied Sciences, GGS Indraprastha University, Dwarka, New Delhi-110075, India
| | - S Neeleshwar
- University School of Basic and Applied Sciences, GGS Indraprastha University, Dwarka, New Delhi-110075, India
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Chin SK, Lam KT, Seah D, Liang G. Quantum transport simulations of graphene nanoribbon devices using Dirac equation calibrated with tight-binding π-bond model. NANOSCALE RESEARCH LETTERS 2012; 7:114. [PMID: 22325480 PMCID: PMC3368727 DOI: 10.1186/1556-276x-7-114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 02/10/2012] [Indexed: 05/31/2023]
Abstract
We present an efficient approach to study the carrier transport in graphene nanoribbon (GNR) devices using the non-equilibrium Green's function approach (NEGF) based on the Dirac equation calibrated to the tight-binding π-bond model for graphene. The approach has the advantage of the computational efficiency of the Dirac equation and still captures sufficient quantitative details of the bandstructure from the tight-binding π-bond model for graphene. We demonstrate how the exact self-energies due to the leads can be calculated in the NEGF-Dirac model. We apply our approach to GNR systems of different widths subjecting to different potential profiles to characterize their device physics. Specifically, the validity and accuracy of our approach will be demonstrated by benchmarking the density of states and transmissions characteristics with that of the more expensive transport calculations for the tight-binding π-bond model.
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Affiliation(s)
- Sai-Kong Chin
- Institute of High Performance Computing, A*STAR, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - Kai-Tak Lam
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Dawei Seah
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Gengchiau Liang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
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