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Zou F, Cong Y, Song W, Liu H, Li Y, Zhu Y, Zhao Y, Pan Y, Li Q. Interfacial Properties of Anisotropic Monolayer SiAs Transistors. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:238. [PMID: 38334509 PMCID: PMC10856446 DOI: 10.3390/nano14030238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/10/2024]
Abstract
The newly prepared monolayer (ML) SiAs is expected to be a candidate channel material for next-generation nano-electronic devices in virtue of its proper bandgap, high carrier mobility, and anisotropic properties. The interfacial properties in ML SiAs field-effect transistors are comprehensively studied with electrodes (graphene, V2CO2, Au, Ag, and Cu) by using ab initio electronic structure calculations and quantum transport simulation. It is found that ML SiAs forms a weak van der Waals interaction with graphene and V2CO2, while it forms a strong interaction with bulk metals (Au, Ag, and Cu). Although ML SiAs has strong anisotropy, it is not reflected in the contact property. Based on the quantum transport simulation, ML SiAs forms n-type lateral Schottky contact with Au, Ag, and Cu electrodes with the Schottky barrier height (SBH) of 0.28 (0.27), 0.40 (0.47), and 0.45 (0.33) eV along the a (b) direction, respectively, while it forms p-type lateral Schottky contact with a graphene electrode with a SBH of 0.34 (0.28) eV. Fortunately, ML SiAs forms an ideal Ohmic contact with the V2CO2 electrode. This study not only gives a deep understanding of the interfacial properties of ML SiAs with electrodes but also provides a guide for the design of ML SiAs devices.
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Affiliation(s)
- Feihu Zou
- College of Physics, Qingdao University, Qingdao 266071, China
| | - Yao Cong
- State Key Laboratory of Heavy Oil Processing, Institute of New Energy, College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Weiqi Song
- College of Physics, Qingdao University, Qingdao 266071, China
| | - Haosong Liu
- State Key Laboratory of Heavy Oil Processing, Institute of New Energy, College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Yanan Li
- State Key Laboratory of Heavy Oil Processing, Institute of New Energy, College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Yifan Zhu
- State Key Laboratory of Heavy Oil Processing, Institute of New Energy, College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Yue Zhao
- College of Physics, Qingdao University, Qingdao 266071, China
| | - Yuanyuan Pan
- College of Physics, Qingdao University, Qingdao 266071, China
| | - Qiang Li
- College of Physics, Qingdao University, Qingdao 266071, China
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2
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Yuan J, Dai JQ, Liu YZ, Zhao MW. Polarization-tunable interfacial properties in monolayer-MoS 2 transistors integrated with ferroelectric BiAlO 3(0001) polar surfaces. Phys Chem Chem Phys 2023; 25:25177-25190. [PMID: 37712428 DOI: 10.1039/d3cp02866f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
With the explosion of data-centric applications, new in-memory computing technologies, based on nonvolatile memory devices, have become competitive due to their merged logic-memory functionalities. Herein, employing first-principles quantum transport simulation, we theoretically investigate for the first time the electronic and contact properties of two types of monolayer (ML)-MoS2 ferroelectric field-effect transistors (FeFETs) integrated with ferroelectric BiAlO3(0001) (BAO(0001)) polar surfaces. Our study finds that the interfacial properties of the investigated partial FeFET devices are highly tunable by switching the electric polarization of the ferroelectric BAO(0001) dielectric. Specifically, the transition from quasi-Ohmic to the Schottky contact, as well as opposite contact polarity of respective n-type and p-type Schottky contact under two polarization states can be obtained, suggesting their superior performance metrics in terms of nonvolatile information storage. In addition, due to the feature of (quasi-)Ohmic contact in some polarization states, the explored FeFET devices, even when operating in the regular field-effect transistor (FET) mode, can be extremely significant in realizing a desirable low threshold voltage and interfacial contact resistance. In conjunction with the formed van der Waals (vdW) interfaces in ML-MoS2/ferroelectric systems with an interlayer, the proposed FeFETs are expected to provide excellent device performance with regard to cycling endurance and memory density.
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Affiliation(s)
- Jin Yuan
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, P. R. China.
| | - Jian-Qing Dai
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, P. R. China.
| | - Yu-Zhu Liu
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, P. R. China.
| | - Miao-Wei Zhao
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, P. R. China.
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3
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Lyu J, Gong J. Simulation of a Steep-Slope p- and n-Type HfS 2/MoTe 2 Field-Effect Transistor with the Hybrid Transport Mechanism. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:649. [PMID: 36839017 PMCID: PMC9961691 DOI: 10.3390/nano13040649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 06/18/2023]
Abstract
The use of a two-dimensional (2D) van der Waals (vdW) metal-semiconductor (MS) heterojunction as an efficient cold source (CS) has recently been proposed as a promising approach in the development of steep-slope field-effect transistors (FETs). In addition to the selection of source materials with linearly decreasing density-of-states-energy relations (D(E)s), in this study, we further verified, by means of a computer simulation, that a 2D semiconductor-semiconductor combination could also be used as an efficient CS. As a test case, a HfS2/MoTe2 FET was studied. It was found that MoTe2 can be spontaneously p-type-doped by interfacing with n-doped HfS2, resulting in a truncated decaying hot-carrier density with an increasing p-type channel barrier. Compared to the conventional MoTe2 FET, the subthreshold swing (SS) of the HfS2/MoTe2 FET can be significantly reduced to below 60 mV/decade, and the on-state current can be greatly enhanced by more than two orders of magnitude. It was found that there exists a hybrid transport mechanism involving the cold injection and the tunneling effect in such a p- and n-type HfS2/MoTe2 FET, which provides a new design insight into future low-power and high-performance 2D electronics from a physical point of view.
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4
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Guan SY, Cai ZY, Ma ZW, Wu DY, Tian ZQ. Binding structure, breaking forces and conductance of Au-Octanedithiol-Au molecular junction under stretching processes: a DFT-NEGF study. NANOTECHNOLOGY 2022; 34:095401. [PMID: 36541478 DOI: 10.1088/1361-6528/aca617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 11/25/2022] [Indexed: 06/17/2023]
Abstract
Au-n-octanedithiol-Au molecular junction (Au-SC8S-Au) has been investigated using density functional theory combined with the nonequilibrium Green's function approach. Theoretically calculated results are used to build the relationship between the interface binding structures and single-molecule quantum conductance of n-octanedithiol (SC8S) embodied in a gold nanogap with or without stretching forces. To understand the electron transport mechanism in the single molecular nanojunction, we designed three types of Au-SC8S-Au nanogaps, including flat electrode through an Au atom connecting (Model I), top-pyramidal or flat electrodes with the molecule adsorbing directly (Model II), and top-pyramidal Au electrodes with Au atomic chains (Model III). We first determined the optimized structures of different Au-SC8S-Au nanogaps, and then predicted the distance-dependent stretching force and conductance in each case. Our calculated results show that in the Model I with an Au atom bridging the flat Au (111) gold electrodes and the SC8S molecule, the conductance decreases exponentially before the fracture of Au-Au bond, in a good agreement with the experimental conductance in the literature. For the top-pyramidal electrode Models II and III, the magnitudes of molecular conductance are larger than that in Model I. Our theoretical calculations also show that the Au-Au bond fracture takes place in Models I and III, while the Au-S bond fracture appears in Model II. This is explained due to the total strength of three synergetic Au-Au bonds stronger than an Au-S bond in Model II. This is supported from the broken force about 2 nN for the Au-Au bond and 3 nN for the Au-S bond.
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Affiliation(s)
- Si-Yuan Guan
- State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University Xiamen, 361005, People's Republic of China
| | - Zhuan-Yun Cai
- State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University Xiamen, 361005, People's Republic of China
| | - Zi-Wei Ma
- State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University Xiamen, 361005, People's Republic of China
| | - De-Yin Wu
- State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University Xiamen, 361005, People's Republic of China
| | - Zhong-Qun Tian
- State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University Xiamen, 361005, People's Republic of China
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5
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Dahal D, Gumbs G, Iurov A, Ting CS. Plasmon Damping Rates in Coulomb-Coupled 2D Layers in a Heterostructure. MATERIALS (BASEL, SWITZERLAND) 2022; 15:7964. [PMID: 36431452 PMCID: PMC9695106 DOI: 10.3390/ma15227964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 11/01/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
The Coulomb excitations of charge density oscillation are calculated for a double-layer heterostructure. Specifically, we consider two-dimensional (2D) layers of silicene and graphene on a substrate. From the obtained surface response function, we calculated the plasmon dispersion relations, which demonstrate how the Coulomb interaction renormalizes the plasmon frequencies. Most importantly, we have conducted a thorough investigation of how the decay rates of the plasmons in these heterostructures are affected by the Coulomb coupling between different types of two-dimensional materials whose separations could be varied. A novel effect of nullification of the silicene band gap is noticed when graphene is introduced into the system. To utilize these effects for experimental and industrial purposes, graphical results for the different parameters are presented.
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Affiliation(s)
- Dipendra Dahal
- Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX 77204, USA
| | - Godfrey Gumbs
- Department of Physics and Astronomy, Hunter College, City University of New York, 695 Park Avenue, New York, NY 10065, USA
| | - Andrii Iurov
- Department of Physics and Computer Science, Medgar Evers College, City University of New York, Brooklyn, NY 11225, USA
| | - Chin-Sen Ting
- Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX 77204, USA
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6
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Guan S, Cai Z, Liu J, Pang R, Wu D, Ulstrup J, Tian Z. Adsorption, Stretching, and Breaking Processes in Single‐Molecule Conductance of
para
‐Benzenedimethanethiol in Gold Nanogaps: A DFT‐NEGF Theoretical Study**. ChemElectroChem 2021. [DOI: 10.1002/celc.202100184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Si‐Yuan Guan
- State Key Laboratory of Physical Chemistry of Solid Surface Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 P. R. China
| | - Zhuan‐Yun Cai
- State Key Laboratory of Physical Chemistry of Solid Surface Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 P. R. China
| | - Jia Liu
- State Key Laboratory of Physical Chemistry of Solid Surface Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 P. R. China
| | - Ran Pang
- State Key Laboratory of Physical Chemistry of Solid Surface Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 P. R. China
| | - De‐Yin Wu
- State Key Laboratory of Physical Chemistry of Solid Surface Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 P. R. China
| | - Jens Ulstrup
- Department of Chemistry Technical University of Denmark 2800 Kongens Lyngby Denmark
| | - Zhong‐Qun Tian
- State Key Laboratory of Physical Chemistry of Solid Surface Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 P. R. China
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7
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Rezapour MR, Lee G, Kim KS. A high performance N-doped graphene nanoribbon based spintronic device applicable with a wide range of adatoms. NANOSCALE ADVANCES 2020; 2:5905-5911. [PMID: 36133856 PMCID: PMC9419213 DOI: 10.1039/d0na00652a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 11/09/2020] [Indexed: 06/14/2023]
Abstract
Designing and fabricating nanosize spintronic devices is a crucial task to develop information technology of the future. However, most of the introduced spin filters suffer from several limitations including difficulty in manipulating the spin current, incapability in utilizing a wide range of dopants to provide magnetism, or obstacles in their experimental realization. Here, by employing first principles calculations, we introduce a structurally simple and functionally efficient spin filter device composed of a zigzag graphene nanoribbon (ZGNR) with an embedded nitrogenated divacancy. We show that the proposed system, possessing a robust ferromagnetic (FM) ordering, exhibits perfect half metallic behavior in the absence of frequently used transition metals (TMs). Our calculations also show that the suggested system is compatible with a wide range of adatoms including basic metals, metalloids, and TMs. It means that besides d electron magnetism originating from TMs, p electrons of incorporated elements of the main group can also cause half metallicity in the electronic structure of the introduced system. Our system exploiting the robustness of doping-induced FM ordering would be beneficial for promising multifunctional spin filter devices.
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Affiliation(s)
- M Reza Rezapour
- Center for Superfunctional Materials, Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 Korea
| | - Geunsik Lee
- Center for Superfunctional Materials, Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 Korea
| | - Kwang S Kim
- Center for Superfunctional Materials, Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 Korea
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8
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Chen J, Cai S, Xiong R, Sa B, Wen C, Wu B, Sun Z. High-performance III-VI monolayer transistors for flexible devices. Phys Chem Chem Phys 2020; 22:7039-7047. [PMID: 32195511 DOI: 10.1039/d0cp00578a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Group III-VI family MX (M = Ga and In, and X = S, Se, and Te) monolayers have attracted global interest for their potential applications in electronic devices due to their unexpectedly high carrier mobility. Herein, via density functional theory calculations as well as ab initio quantum transport simulations, we investigated the performance limits of MX monolayer metal oxide semiconductor field-effect transistors (MOSFETs) at the sub-10 nm scale. Our results highlighted that the MX monolayers possessed good structural stability and mechanical isotropy with large ultimate strains and low Young's modulus, which are intensely anticipated in the next-generation flexible devices. More importantly, the MX monolayer MOSFETs show excellent device performance under optimal schemes. The on-state current, delay time, and power dissipation of the MX monolayer MOSFETs satisfy the International Technology Roadmap for Semiconductors (ITRS) 2013 requirements for high-performance devices. Interestingly, the sub-threshold swings were in a very low range from 68 mV dec-1 to 108 mV dec-1, which indicated the favorable gate control ability for fast switching. Therefore, we believe that our findings shed light on the design and application of MX monolayer-based MOSFETs in next-generation flexible electronic devices.
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Affiliation(s)
- Jianhui Chen
- Key Laboratory of Eco-materials Advanced Technology, College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, P. R. China.
| | - Shuchang Cai
- Key Laboratory of Eco-materials Advanced Technology, College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, P. R. China.
| | - Rui Xiong
- Key Laboratory of Eco-materials Advanced Technology, College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, P. R. China.
| | - Baisheng Sa
- Key Laboratory of Eco-materials Advanced Technology, College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, P. R. China.
| | - Cuilian Wen
- Key Laboratory of Eco-materials Advanced Technology, College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, P. R. China.
| | - Bo Wu
- Key Laboratory of Eco-materials Advanced Technology, College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, P. R. China.
| | - Zhimei Sun
- School of Materials Science and Engineering, and Center for Integrated Computational Materials Science, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, P. R. China.
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9
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Xu Y, Wang M, Fang C, Cui B, Ji G, Zhao W, Liu D, Wang C, Qin M. Lateral scaling and positioning effects of top-gate electrodes on single-molecule field-effect transistors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:285302. [PMID: 30952153 DOI: 10.1088/1361-648x/ab1680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Molecular electronics aims at integrating controllable molecular devices into circuits or machines to realize certain functions. According to device configuration, molecular field-effect transistors with top-gate electrodes have great advantages for integration. Nevertheless, from technical aspects, it is difficult to control lateral scale and position of a top-gate electrode precisely. Therefore, one problem arises in how lateral scaling and positioning effects of a top-gate electrode affect device performance. To solve this problem, the electronic transport properties of single-molecule field-effect transistor configurations modulated by a series of partial-scale top-gate electrodes with different lateral scales and positions are studied by using non-equilibrium Green's function in combination with density functional theory, and compared with those of the full gate electrode (can be considered as a bottom gate electrode). The results show that lateral scaling and positioning effects indeed have a great impact on electronic transport properties of single-molecule field-effect transistor configurations. For [Formula: see text]-saturated 1,12-dodecanedithiol devices, larger lateral scale of a partial-scale top-gate electrode obtains larger amplification coefficient [Formula: see text] (ratio of device conductances with/without a gate electrode), and even larger [Formula: see text] than that of the full gate electrode. While lateral positioning effect has little influence on this device. For [Formula: see text]-conjugated 1,3,5,7,9,11-dodehexaene-1,12-dithiol devices, performance of a partial-scale top-gate electrode mainly depends on locations of its two edges, i.e. the number of [Formula: see text] bonds that it breaks. These results will provide theoretical directions in device designing and manufacturing in the future.
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Affiliation(s)
- Yuqing Xu
- School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, People's Republic of China
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10
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Quhe R, Liu J, Wu J, Yang J, Wang Y, Li Q, Li T, Guo Y, Yang J, Peng H, Lei M, Lu J. High-performance sub-10 nm monolayer Bi 2O 2Se transistors. NANOSCALE 2019; 11:532-540. [PMID: 30543242 DOI: 10.1039/c8nr08852g] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A successful two-dimensional (2D) semiconductor successor of silicon for high-performance logic in the post-silicon era should have both excellent performance and air stability. However, air-stable 2D semiconductors with high performance were quite elusive until the air-stable Bi2O2Se with high electron mobility was fabricated very recently (J. Wu, H. Yuan, M. Meng, C. Chen, Y. Sun, Z. Chen, W. Dang, C. Tan, Y. Liu, J. Yin, Y. Zhou, S. Huang, H. Q. Xu, Y. Cui, H. Y. Hwang, Z. Liu, Y. Chen, B. Yan and H. Peng, Nat. Nanotechnol., 2017, 12, 530). Herein, we predict the performance limit of the monolayer (ML) Bi2O2Se metal oxide semiconductor field-effect transistors (MOSFETs) by using ab initio quantum transport simulation at the sub-10 nm gate length. The on-current, delay time, and power-delay product of the optimized n- and p-type ML Bi2O2Se MOSFETs can reach or nearly reach the high performance requirements of the International Technology Roadmap for Semiconductors (ITRS) until the gate lengths are scaled down to 2 and 3 nm, respectively. The large on-currents of the n- and p-type ML Bi2O2Se MOSFETs are attributed to either the large effective carrier velocity (n-type) or the large density of states near the valence band maximum and special shape of the band structure (p-type). A new avenue is thus opened for the continuation of Moore's law down to 2-3 nm by utilizing ML Bi2O2Se as the channel.
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Affiliation(s)
- Ruge Quhe
- State Key Laboratory of Information Photonics and Optical Communications and School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, P. R. China.
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11
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Mirza B, Soleimani-Amiri S, Mirza M. Reaching for [6]n
SiC-cyclacenes and [6]n
SiC-acenes: A DFT approach. J PHYS ORG CHEM 2017. [DOI: 10.1002/poc.3754] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Behrooz Mirza
- Department of Chemistry, Karaj branch; Islamic Azad University; Karaj Iran
| | | | - Maziar Mirza
- Department of Chemistry, Karaj branch; Islamic Azad University; Karaj Iran
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12
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Feng YP, Shen L, Yang M, Wang A, Zeng M, Wu Q, Chintalapati S, Chang CR. Prospects of spintronics based on 2D materials. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1313] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yuan Ping Feng
- Department of Physics; National University of Singapore; Singapore
- Centre for Advanced Two-dimensional Materials; National University of Singapore; Singapore
| | - Lei Shen
- Department of Mechanical Engineering; National University of Singapore; Singapore
- Engineering Science Programme; National University of Singapore; Singapore
| | - Ming Yang
- Institute of Materials Science and Engineering; A*STAR; Singapore
| | - Aizhu Wang
- Department of Physics; National University of Singapore; Singapore
- Department of Electrical and Computer Engineering; National University of Singapore; Singapore
| | | | - Qingyun Wu
- Department of Materials Science and Engineering; National University of Singapore; Singapore
| | - Sandhya Chintalapati
- Centre for Advanced Two-dimensional Materials; National University of Singapore; Singapore
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13
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Lin ZZ. Two-dimensional C 12Mn 2/C 12Cr 2 as a room-temperature half metal/antiferromagnetic semiconductor: a systematic study. Phys Chem Chem Phys 2017; 19:3394-3404. [PMID: 28092387 DOI: 10.1039/c6cp07374c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Ferromagnetism in half-metallic two-dimensional (2D) materials can lead to unique spintronics applications. In this paper, we report first-principle calculations that predict 2D single-layer C12Mn2 as a ferromagnetic half metal, and 2D single-layer C12Cr2 as an antiferromagnetic semiconductor. A systematic study is carried out to demonstrate the reliability of our research. We employ a bottom-up method to investigate the structural and magnetic stability of single, two and more Cr or Mn atoms on graphyne at room temperature. The very high Curie/Néel temperatures of 2D C12Mn2/C12Cr2, respectively, indicate the stability of room-temperature ferromagnetism/antiferromagnetism. With perfect spin filtering, 2D C12Mn2 would be a promising material for future spintronics design.
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Affiliation(s)
- Zheng-Zhe Lin
- School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China.
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14
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Rezapour MR, Yun J, Lee G, Kim KS. Lower Electric Field-Driven Magnetic Phase Transition and Perfect Spin Filtering in Graphene Nanoribbons by Edge Functionalization. J Phys Chem Lett 2016; 7:5049-5055. [PMID: 27973868 DOI: 10.1021/acs.jpclett.6b02437] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Perfect spin filtering is an important issue in spintronics. Although such spin filtering showing giant magnetoresistance was suggested using graphene nanoribbons (GNRs) on both ends of which strong magnetic fields were applied, electric field controlled spin filtering is more interesting due to much easier precise control with much less energy consumption. Here we study the magnetic/nonmagnetic behaviors of zigzag GNRs (zGNRs) under a transverse electric field and by edge functionalization. Employing density functional theory (DFT), we show that the threshold electric field to attain either a half-metallic or nonmagnetic feature is drastically reduced by introducing proper functional groups to the edges of the zGNR. From the current-voltage characteristics of the edge-modified zGNR under an in-plane transverse electric field, we find a remarkable perfect spin filtering feature, which can be utilized for a molecular spintronic device. Alteration of magnetic properties by tuning the transverse electric field would be a promising way to construct magnetic/nonmagnetic switches.
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Affiliation(s)
- M Reza Rezapour
- Center for Superfunctional Materials and ‡Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil, Ulsan 44919, Korea
| | - Jeonghun Yun
- Center for Superfunctional Materials and ‡Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil, Ulsan 44919, Korea
| | - Geunsik Lee
- Center for Superfunctional Materials and ‡Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil, Ulsan 44919, Korea
| | - Kwang S Kim
- Center for Superfunctional Materials and ‡Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil, Ulsan 44919, Korea
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15
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Yun J, Lee G, Kim KS. Electron Transport in Graphene Nanoribbon Field-Effect Transistor under Bias and Gate Voltages: Isochemical Potential Approach. J Phys Chem Lett 2016; 7:2478-2482. [PMID: 27299184 DOI: 10.1021/acs.jpclett.6b00996] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Zigzag graphene nanoribbon (zGNR) of narrow width has a moderate energy gap in its antiferromagnetic ground state. So far, first-principles electron transport calculations have been performed using nonequilibrium Green function (NEGF) method combined with density functional theory (DFT). However, the commonly practiced bottom-gate control has not been studied computationally due to the need to simulate an electron reservoir that fixes the chemical potential of electrons in the zGNR and electrodes. Here, we present the isochemical potential scheme to describe the top/back-gate effect using external potential. Then, we examine the change in electronic state under the modulation of chemical potential and the subsequent electron transport phenomena in zGNR transistor under substantial top-/back-gate and bias voltages. The gate potential can activate the device states resulting in a boosted current. This gate-controlled current-boosting could be utilized for designing novel zGNR field effect transistors (FETs).
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Affiliation(s)
- Jeonghun Yun
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, Korea
- Department of Chemistry, Pohang University of Science and Technology , Pohang 37673, Korea
| | - Geunsik Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, Korea
| | - Kwang S Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, Korea
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Luo K, Sheng W. Bias voltage control of magnetic phase transitions in graphene nanojunctions. NANOTECHNOLOGY 2015; 26:345303. [PMID: 26242503 DOI: 10.1088/0957-4484/26/34/345203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The magnetic state of a spintronic device is usually controlled by magnetic contacts or a transverse electric field generated by side gates. In this work, we consider a graphene nanojunction in the presence of a bias voltage that leads to magnetic phase transitions in the system. Combining the non-equilibrium Green’s function with the Hubbard model, our self consistent calculation reveals that an increasing bias voltage induces consecutive transitions among antiferromagnetic and ferromagnetic states. It is further shown that the graphene nanojunction is turned off in the antiferromagnetic state when the bias voltage is low and can then be switched on to the ferromagnetic state by a high bias voltage. We therefore demonstrate that the magnetic state of the graphene system can be controlled by the bias voltage without resorting to any transverse gates.
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Rezapour MR, Rajan AC, Kim KS. Molecular sensing using armchair graphene nanoribbon. J Comput Chem 2014; 35:1916-20. [DOI: 10.1002/jcc.23705] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Revised: 07/21/2014] [Accepted: 07/27/2014] [Indexed: 01/25/2023]
Affiliation(s)
- Mohammad Reza Rezapour
- Department of Physics; Pohang University of Science and Technology; Pohang 790-784 Korea
- Department of Chemistry; School of Natural Science, Ulsan National Institute of Science and Technology (UNIST); Ulsan 689-798 Korea
| | - Arunkumar Chitteth Rajan
- Department of Chemistry; Pohang University of Science and Technology; Pohang 790-784 Korea
- Department of Chemistry; School of Natural Science, Ulsan National Institute of Science and Technology (UNIST); Ulsan 689-798 Korea
| | - Kwang S. Kim
- Department of Chemistry; School of Natural Science, Ulsan National Institute of Science and Technology (UNIST); Ulsan 689-798 Korea
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Chamani Z, Bayat Z, Mahdizadeh SJ. Theoretical study of the electronic conduction through organic nanowires. J STRUCT CHEM+ 2014. [DOI: 10.1134/s0022476614030226] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Rajan AC, Rezapour MR, Yun J, Cho Y, Cho WJ, Min SK, Lee G, Kim KS. Two dimensional molecular electronics spectroscopy for molecular fingerprinting, DNA sequencing, and cancerous DNA recognition. ACS NANO 2014; 8:1827-1833. [PMID: 24446806 DOI: 10.1021/nn4062148] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Laser-driven molecular spectroscopy of low spatial resolution is widely used, while electronic current-driven molecular spectroscopy of atomic scale resolution has been limited because currents provide only minimal information. However, electron transmission of a graphene nanoribbon on which a molecule is adsorbed shows molecular fingerprints of Fano resonances, i.e., characteristic features of frontier orbitals and conformations of physisorbed molecules. Utilizing these resonance profiles, here we demonstrate two-dimensional molecular electronics spectroscopy (2D MES). The differential conductance with respect to bias and gate voltages not only distinguishes different types of nucleobases for DNA sequencing but also recognizes methylated nucleobases which could be related to cancerous cell growth. This 2D MES could open an exciting field to recognize single molecule signatures at atomic resolution. The advantages of the 2D MES over the one-dimensional (1D) current analysis can be comparable to those of 2D NMR over 1D NMR analysis.
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Affiliation(s)
- Arunkumar Chitteth Rajan
- Department of Chemistry and ‡Department of Physics, Pohang University of Science and Technology , Pohang 790-784, Korea
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Atomic scale investigation of a graphene nano-ribbon based high efficiency spin valve. Sci Rep 2013; 3:2921. [PMID: 24132194 PMCID: PMC3797541 DOI: 10.1038/srep02921] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 09/19/2013] [Indexed: 11/28/2022] Open
Abstract
Graphene nanoribbons based electronic devices present many interesting physical properties. We designed and investigated the spin-dependent electron transport of a device configuration, which is easy to be fabricated, with an oxygen-terminated ZGNR central scatter region between two hydrogen-terminated ZGNR electrodes. According to the analysis based on non-equilibrium Green's function and density functional theory, the proposed device could maintain its good spin-filter performance (80% to 99%) and have a stable magneto resistance value up to 105%. The spin dependent electron transmission spectrum and space-resolve density of states are employed to investigate the physical origin of the spin-polarized current and magneto resistance.
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Hong K, Kim WY. Fano-Resonance-Driven Spin-Valve Effect Using Single-Molecule Magnets. Angew Chem Int Ed Engl 2013; 52:3389-93. [DOI: 10.1002/anie.201208816] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 12/21/2012] [Indexed: 11/08/2022]
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Hong K, Kim WY. Fano-Resonance-Driven Spin-Valve Effect Using Single-Molecule Magnets. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201208816] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Liang Y, Wang V, Mizuseki H, Kawazoe Y. Band gap engineering of silicene zigzag nanoribbons with perpendicular electric fields: a theoretical study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:455302. [PMID: 23085744 DOI: 10.1088/0953-8984/24/45/455302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The electronic properties of silicene zigzag nanoribbons with the presence of perpendicular fields are studied by using first-principles calculations and the generalized nearest neighboring approximation method. In contrast to the planar graphene, in silicene the Si atoms are not coplanar. As a result, by applying perpendicular fields to the two-dimensional silicene sheet, the on-site energy can be modulated and the band gap at the Dirac point is open. The buckled structure also creates a height difference between the two edges of the silicene zigzag nanoribbons. We find that the external fields can modulate the energies of spin-polarized edge states and their corresponding band gaps. Due to the polarization in the plane, the modulation effect is width dependent and becomes much more significant for narrow ribbons.
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Affiliation(s)
- Yunye Liang
- Institute for Materials Research, Tohoku University, Aobaku, Sendai 980-8577, Japan.
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Georgakilas V, Otyepka M, Bourlinos AB, Chandra V, Kim N, Kemp KC, Hobza P, Zboril R, Kim KS. Functionalization of graphene: covalent and non-covalent approaches, derivatives and applications. Chem Rev 2012; 112:6156-214. [PMID: 23009634 DOI: 10.1021/cr3000412] [Citation(s) in RCA: 1829] [Impact Index Per Article: 152.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Kang HS. Spin-polarized transport through heterobilayers of graphene nanoribbons and ruthenium-porphyrin tapes. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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The structural and electronic properties of monovalent sidewall functionalized double-walled carbon nanotubes. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.04.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Cho WJ, Cho Y, Min SK, Kim WY, Kim KS. Chromium Porphyrin Arrays As Spintronic Devices. J Am Chem Soc 2011; 133:9364-9. [DOI: 10.1021/ja111565w] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Woo Jong Cho
- Department of Chemistry and Department of Physics, Pohang University of Science and Technology, San 31 Pohang, Republic of Korea
| | - Yeonchoo Cho
- Department of Chemistry and Department of Physics, Pohang University of Science and Technology, San 31 Pohang, Republic of Korea
| | - Seung Kyu Min
- Department of Chemistry and Department of Physics, Pohang University of Science and Technology, San 31 Pohang, Republic of Korea
| | - Woo Youn Kim
- Department of Chemistry, KAIST, Daejeon 305-701, Republic of Korea
| | - Kwang S. Kim
- Department of Chemistry and Department of Physics, Pohang University of Science and Technology, San 31 Pohang, Republic of Korea
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Min SK, Kim WY, Cho Y, Kim KS. Fast DNA sequencing with a graphene-based nanochannel device. NATURE NANOTECHNOLOGY 2011; 6:162-5. [PMID: 21297626 DOI: 10.1038/nnano.2010.283] [Citation(s) in RCA: 270] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 12/22/2010] [Indexed: 05/21/2023]
Abstract
Devices in which a single strand of DNA is threaded through a nanopore could be used to efficiently sequence DNA. However, various issues will have to be resolved to make this approach practical, including controlling the DNA translocation rate, suppressing stochastic nucleobase motions, and resolving the signal overlap between different nucleobases. Here, we demonstrate theoretically the feasibility of DNA sequencing using a fluidic nanochannel functionalized with a graphene nanoribbon. This approach involves deciphering the changes that occur in the conductance of the nanoribbon as a result of its interactions with the nucleobases via π-π stacking. We show that as a DNA strand passes through the nanochannel, the distinct conductance characteristics of the nanoribbon (calculated using a method based on density functional theory coupled to non-equilibrium Green function theory) allow the different nucleobases to be distinguished using a data-mining technique and a two-dimensional transient autocorrelation analysis. This fast and reliable DNA sequencing device should be experimentally feasible in the near future.
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Affiliation(s)
- Seung Kyu Min
- Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, Hyojadong, Namgu, Pohang 790-784, Korea
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Ding Z, Jiang J, Xing H, Shu H, Huang Y, Chen X, Lu W. The finite-size effect on the transport properties in edge-modified graphene nanoribbon-based molecular devices. J Comput Chem 2011; 32:1753-9. [PMID: 21351109 DOI: 10.1002/jcc.21760] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 12/29/2010] [Accepted: 12/30/2010] [Indexed: 11/11/2022]
Abstract
The size-dependence on the electronic and transport properties of the molecular devices of the edge-modified graphene nanoribbon (GNR) slices is investigated using density-functional theory and Green's function theory. Two edge-modifying functional group pairs are considered. Energy gap is found in all the GNR slices. The gap shows an exponential decrease with increasing the slice size of two vertical orientations in the two edge terminated cases, respectively. The tunneling probability and the number of conducting channel decreases with increasing the GNR-slices size in the junctions. The results indicate that the acceptor-donor pair edge modulation can improve the quantum conductance and decrease the finite-size effect on the transmission capability of the GNR slice-based molecular devices.
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Affiliation(s)
- Zongling Ding
- National Laboratory of Infrared Physics, Shanghai Institute for Technical Physics, Chinese Academy of Sciences, Yu Tian Road 500, Shanghai 200083, China
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Cho Y, Min SK, Kim WY, Kim KS. The origin of dips for the graphene-based DNA sequencing device. Phys Chem Chem Phys 2011; 13:14293-6. [DOI: 10.1039/c1cp20760a] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Carbon–nitrogen nanorings and nanoribbons: a theoretical approach for altering the ground states of cyclacenes and polyacenes. MONATSHEFTE FUR CHEMIE 2010. [DOI: 10.1007/s00706-010-0398-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lee EC, Choi YC, Kim WY, Singh NJ, Lee S, Shim JH, Kim KS. A Radical Polymer as a Two-Dimensional Organic Half Metal. Chemistry 2010; 16:12141-6. [DOI: 10.1002/chem.201000858] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Manna AK, Pati SK. Doping single-walled carbon nanotubes through molecular charge-transfer: a theoretical study. NANOSCALE 2010; 2:1190-1195. [PMID: 20648348 DOI: 10.1039/c0nr00124d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We study the effect of the molecular charge transfer on the electronic structure of metallic (5,5) and semiconducting (8,0) single-walled carbon nanotubes (SWNTs) induced by surface adsorption of various organic donor-acceptor molecules of different affinities using ab initio density functional theory. Our results, obtained from first-principles spin-polarized calculations show that the adsorption of molecules with different affinities reflects the difference in interaction strength that measure the overall energy of adsorption. Moderate values of the binding energy of these surface adsorbed molecular charge-transfer complexes suggest that the nature of interaction is in the physisorption regime, and mainly governs by Coulombic forces. We also find that the large band gap of semiconducting (8,0) SWNT can be tuned through the surface adsorption of selective organic molecules which gives rise to mid-gap localized molecular levels near the Fermi energy with tuning of band gap region. Interestingly, we find that the metallic (5,5) SWNT and semiconducting (8,0) SWNT turn into semiconducting and metallic nanotubes respectively in presence of selective surface adsorbed molecules, corroborating recent experimental findings. We also suggest that these charge transfer effect can be probed through optical conductivity measurement, as the low-frequency profiles are affected by charge transfer.
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Affiliation(s)
- Arun K Manna
- Theoretical Sciences Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Jakkur Campus, Bangalore-560064, India
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Shen X, Sun L, Benassi E, Shen Z, Zhao X, Sanvito S, Hou S. Spin filter effect of manganese phthalocyanine contacted with single-walled carbon nanotube electrodes. J Chem Phys 2010; 132:054703. [DOI: 10.1063/1.3302258] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kim WY, Kim KS. Tuning molecular orbitals in molecular electronics and spintronics. Acc Chem Res 2010; 43:111-20. [PMID: 19769353 DOI: 10.1021/ar900156u] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
With the advance of nanotechnology, a variety of molecules, from single atoms to large-scale structures such as graphene or carbon nanotubes, have been investigated for possible use as molecular devices. Molecular orbitals (MOs) are a key ingredient in determining the transport properties of molecules, because they contain all the quantum mechanical information of molecular electronic structures and offer spatial conduction channels for electron transport. Therefore, the delicate modulation of the MOs enables us to tune the performance of electron transport through the molecule. Electric and magnetic fields are powerful and readily accessible means for that purpose. In this Account, we describe the effects of external fields on molecular electronic and spintronic devices. Quantum transport through a molecule that connects source and drain electrodes depends strongly on the alignment of molecular energy levels with respect to the chemical potentials at both electrodes. This dependence results from the energy levels being exploited in resonant tunneling processes when the molecule is weakly coupled to the electrodes in the molecular junction. Molecular energy levels can be shifted by the Stark effect of an external electric field. For a molecule with no permanent dipole moment, the polarizability is the primary factor determining the energy shift of each MO, according to the second-order Stark effect; more polarizable MOs undergo a larger energy shift. Interestingly, even a small shift may lead to a completely nontrivial result. For example, we show a magnetic on-off switching phenomenon of a molecule controlled by an electric field. If a molecule has a nonmagnetic ground state but a highly polarizable magnetic excited state with an energy slightly above the ground state, the magnetic excited state can have lower energy than the ground state under a sufficiently strong electric field. A magnetic field is normally used to control spin orientation in a ferromagnetic system. Here we show that the magnetic field can also be used to control MOs. A graphene nanoribbon with zig-zag-shaped edges (ZGNR) has a ferromagnetic spin ordering along the edges, and the spin states have unique orbital symmetries. Both spin polarizations and orbital symmetries can simultaneously be controlled by means of an external magnetic field. The ZGNR spin-valve devices incorporating this effect are predicted to show an extreme enhancement (compared with conventional devices) of magnetoresistance due to the double spin-filtering process. In such a system, spins are filtered not only by spin matching-mismatching between both electrodes as in normal spin-valve devices, but also by the orbital symmetry matching-mismatching. Thus, a new type of magnetoresistance, and with extremely large values, so-called super-magnetoresistance (distinct from the conventional tunneling or giant magnetoresistance), is available with this method. MOs are at the heart of understanding and tuning transport properties in molecular systems. Therefore, investigating the effects of external fields on MOs is important not only for understanding fundamental quantum phenomena in molecular devices but also for practical applications in the development of interactive devices.
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Affiliation(s)
- Woo Youn Kim
- Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kwang S. Kim
- Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
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Manna AK, Pati SK. Tuning the Electronic Structure of Graphene by Molecular Charge Transfer: A Computational Study. Chem Asian J 2009; 4:855-860. [DOI: 10.1002/asia.200800486] [Citation(s) in RCA: 164] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Cho Y, Kim WY, Kim KS. Effect of Electrodes on Electronic Transport of Molecular Electronic Devices. J Phys Chem A 2009; 113:4100-4. [DOI: 10.1021/jp810467q] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yeonchoo Cho
- Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea
| | - Woo Youn Kim
- Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea
| | - Kwang S. Kim
- Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea
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Kim WY, Choi YC, Min SK, Cho Y, Kim KS. Application of quantum chemistry to nanotechnology: electron and spin transport in molecular devices. Chem Soc Rev 2009; 38:2319-33. [DOI: 10.1039/b820003c] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kim WY, Kim KS. Prediction of very large values of magnetoresistance in a graphene nanoribbon device. NATURE NANOTECHNOLOGY 2008; 3:408-412. [PMID: 18654564 DOI: 10.1038/nnano.2008.163] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 05/16/2008] [Indexed: 05/26/2023]
Abstract
Graphene has emerged as a versatile material with outstanding electronic properties that could prove useful in many device applications. Recently, the demonstration of spin injection into graphene and the observation of long spin relaxation times and lengths have suggested that graphene could play a role in 'spintronic' devices that manipulate electron spin rather than charge. In particular it has been found that zigzag graphene nanoribbons have magnetic (or spin) states at their edges, and that these states can be either antiparallel or parallel. Here we report the results of first-principles simulations that predict that spin-valve devices based on graphene nanoribbons will exhibit magnetoresistance values that are thousands of times higher than previously reported experimental values. These remarkable values can be linked to the unique symmetry of the band structure in the nanoribbons. We also show that it is possible to manipulate the band structure of the nanoribbons to generate highly spin-polarized currents.
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Kim WY, Choi YC, Kim KS. Understanding structures and electronic/spintronic properties of single molecules, nanowires, nanotubes, and nanoribbons towards the design of nanodevices. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b804359k] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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