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Dong X, Hou Y, Deng C, Wu J, Fu H. Bi 3O 2.5Se 2: a two-dimensional high-mobility polar semiconductor with large interlayer and interfacial charge transfer. NANOSCALE 2024; 16:14766-14774. [PMID: 38973699 DOI: 10.1039/d4nr01758g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Two-dimensional semiconductors with large intrinsic polarity are highly attractive for applications in high-speed electronics, ultrafast and highly sensitive photodetectors and photocatalysis. However, previous studies mainly focus on neutral layered polar 2D materials with limited vertical dipoles and electrostatic potential difference (typically <1.5 eV). Here, using the first-principles calculations, we systematically investigated the polarity of few-layer Bi3O2.5Se2 semiconductors with ultrahigh predicted room-temperature carrier mobility (1790 cm2 V-1 s-1 for the monolayer). Thanks to its unique non-neutral layered structure, few-layer Bi3O2.5Se2 contributes to a substantial interlayer charge transfer (>0.5 e-) and almost the highest electrostatic potential difference (ΔΦ) of ∼4 eV among the experimentally attainable 2D layered materials. More importantly, positioning graphene on different charged layers ([Bi2O2.5]+ or [BiSe2]-) switches the charge transfer direction, inducing selective n-doping or p-doping. Furthermore, we can use polar Bi3O2.5Se2 as an exemplary assisted gate to gain additional holes or electrons except for the external electric field, thus breaking the traditional limitations of gate tunability (∼1014 cm-2) observed in experimental settings. Our work not only expands the family of polar 2D semiconductors, but also makes a conceptual advance on using them as an assisted gate in transistors.
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Affiliation(s)
- Xinyue Dong
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, P. R. China.
| | - Yameng Hou
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, P. R. China.
| | - Chaoyue Deng
- Center of Quantum Materials and Devices, College of Physics, Chongqing University, Chongqing 401331, P. R. China.
| | - Jinxiong Wu
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, P. R. China.
| | - Huixia Fu
- Center of Quantum Materials and Devices, College of Physics, Chongqing University, Chongqing 401331, P. R. China.
- Chongqing Key Laboratory for Strongly Coupled Physics, Chongqing University, Chongqing 401331, P. R. China
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Zhao J, Jin X, Yao C, Zeng H. First-principles study of O-functionalized two-dimensional AsP monolayers: electronic structure, mechanical, piezoelectric, and optical properties. NANOTECHNOLOGY 2022; 34:015201. [PMID: 36162330 DOI: 10.1088/1361-6528/ac94db] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
Using density functional theory, we investigated the geometrical properties, electronic structures, carrier mobilities, piezoelectric coefficients, and optical absorption behaviors of three O-functionalizedβ-phase AsP structures (b-AsPO-FO, b-AsPO-As-SO and b-AsPO-P-SO). It is shown that three O-functionalized monolayers are all indirect semiconductors with bandgaps of 0.21, 0.67, and 0.80 eV, respectively. Our calculations demonstrated that the pristine AsP monolayer and these O-functionalized AsP monolayers have strongly anisotropic carrier mobilities, allowing their potential applications for in-plane anisotropic electronic device. The bandgaps of three functionalized nanomaterials exhibit non-monotonic variations under the biaxial strains changing from -0.10 to +0.10, all experiencing metal-indirect bandgap-direct bandgap transition. The calculated in-plane Young's modulus results suggest that they are fairly flexible to allow the application of large elastic strains on the chemically functionalized AsP monolayers. Furthermore, the b-AsPO-FO monolayer exhibits excellent anisotropic light-harvesting behavior (absorption peak: 2.36 and 2.76 eV alongxand 2.37 eV alongydirection) in visible light region. The b-AsPO-As-SO and b-AsPO-P-SO monolayers have strong absorption peak at 2.60 eV and 2.87 eV, respectively. The tunable electronic structures, anisotropic carrier mobility, and excellent optical absorption properties may facilitate practical applications of O-functionalized b-AsP monolayers in nanoelectronics and photovoltaics.
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Affiliation(s)
- Jun Zhao
- New Energy Technology Engineering Laboratory of Jiangsu Province & School of Science, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210023, People's Republic of China
| | - Xuehu Jin
- New Energy Technology Engineering Laboratory of Jiangsu Province & School of Science, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210023, People's Republic of China
| | - Can Yao
- New Energy Technology Engineering Laboratory of Jiangsu Province & School of Science, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210023, People's Republic of China
| | - Hui Zeng
- School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, People's Republic of China
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Bertel R, Mora-Ramos M, Correa J. Effects of van der Waals interaction on the adsorption of H2 on MoS2 monolayers and nanoribbons. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Chang H, Wang H, Song KK, Zhong M, Shi LB, Qian P. Origin of phonon-limited mobility in two-dimensional metal dichalcogenides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:013003. [PMID: 34714257 DOI: 10.1088/1361-648x/ac29e1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
Metal dichalcogenides are novel two-dimensional (2D) semiconductors after the discovery of graphene. In this article, phonon-limited mobility for six kinds of 2D semiconductors with the composition of MX2is reviewed, in which M (Cr, Mo and W) is the transition metal, and X (S and Se) is the chalcogen element. The review is divided into three parts. In the first part, we briefly introduce the calculation method of mobility, including the empirical model and Boltzmann transport theory (BTE). The application scope, merits and limitations of these methods are summarized. In the second part, we explore empirical models to calculate the mobility of MX2, including longitudinal acoustic phonon, optical phonon (OP) and polar optical phonon (POP) models. The contribution of multi-valley to mobility is reviewed in the calculation. The differences between static and high-frequency dielectric constants (Δϵ) are only 0.13 and 0.03 for MoS2and WS2. Such a low value indicates that the polarization hardly changes in the external field. So, their mobility is not determined by POP, but by deformation potential models. Different from GaAs, POP scattering plays a decisive role in its mobility. Our investigations also reveal that the scattering from POP cannot be ignored in CrSe2, MoSe2and WSe2. In the third parts, we investigate the mobility of MX2using electron-phonon coupling matrix element, which is based on BTE from the framework of a many-body quantum-field theory. Valence band splitting of MoS2and WS2is induced by spin-orbit coupling effect, which leads to the increase of hole mobility. In particular, we review in detail the theoretical and experimental results of MoS2mobility in recent ten years, and its mobility is also compared with other materials to deepen the understanding.
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Affiliation(s)
- Hao Chang
- College of Physical Science and Technology, Bohai University, Jinzhou 121013, People's Republic of China
| | - Hao Wang
- College of Physical Science and Technology, Bohai University, Jinzhou 121013, People's Republic of China
| | - Ke-Ke Song
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, People's Republic of China
| | - Min Zhong
- Liaoning Key Laboratory of Optoelectronic Functional Materials Testing and Technology, College of Chemical and Material Engineering, Bohai University, Jinzhou 121013, People's Republic of China
| | - Li-Bin Shi
- College of Physical Science and Technology, Bohai University, Jinzhou 121013, People's Republic of China
| | - Ping Qian
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, People's Republic of China
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Guo JX, Wu SY, Zhong SY, Zhang GJ, Yu XY, Wu LN. Exploring promising gas sensing and highly active catalysts for CO oxidation: transition-metal (Fe, Co and Ni) adsorbed Janus MoSSe monolayers. Phys Chem Chem Phys 2021; 23:11004-11014. [PMID: 33942039 DOI: 10.1039/d1cp00994j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
From first-principles calculations, the transition-metal (TM) atom (Fe, Co and Ni) adsorbed Janus MoSSe monolayer, toxic gas molecules (CO, NH3 and H2S) adsorbed on the Ni-MoSSe monolayer and CO catalytic oxidation on the Fe-MoSSe monolayer are systematically investigated. An increasing order (Fe-MoSSe < Co-MoSSe < Ni-MoSSe) is found for the stability and band gap of the TM atom adsorbed Janus MoSSe monolayer. These toxic gas molecules are found to be weakly physisorbed and strongly chemisorbed on the pristine and Ni-MoSSe monolayers, respectively. The electronic structure and gas molecular adsorption properties of the Janus MoSSe monolayer can be modulated by adsorbing different TM atoms and gas molecules. Particularly, the CO catalytic oxidation can be realized on the Fe-MoSSe monolayer in light of the more preferable Eley-Rideal (ER) mechanism with the two-step route (CO + O2 → OOCO → CO2 + Oads, CO + Oads → CO2) with highly exothermic processes in each step. The adsorption of TM atoms which may greatly enhance gas sensing performance and catalytic performance of CO oxidation based on the Janus MoSSe monolayer is further discussed.
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Affiliation(s)
- Jia-Xing Guo
- School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China.
| | - Shao-Yi Wu
- School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China.
| | - Si-Ying Zhong
- School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China.
| | - Gao-Jun Zhang
- School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China.
| | - Xing-Yuan Yu
- School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China.
| | - Li-Na Wu
- School of Sciences, Xi'an Technological University, Xi'an 710021, China
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Jang H, Dhakal KP, Joo KI, Yun WS, Shinde SM, Chen X, Jeong SM, Lee SW, Lee Z, Lee J, Ahn JH, Kim H. Transient SHG Imaging on Ultrafast Carrier Dynamics of MoS 2 Nanosheets. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1705190. [PMID: 29436068 DOI: 10.1002/adma.201705190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 12/10/2017] [Indexed: 05/17/2023]
Abstract
Understanding the collaborative behaviors of the excitons and phonons that result from light-matter interactions is important for interpreting and optimizing the underlying fundamental physics at work in devices made from atomically thin materials. In this study, the generation of exciton-coupled phonon vibration from molybdenum disulfide (MoS2 ) nanosheets in a pre-excitonic resonance condition is reported. A strong rise-to-decay profile for the transient second-harmonic generation (TSHG) of the probe pulse is achieved by applying substantial (20%) beam polarization normal to the nanosheet plane, and tuning the wavelength of the pump beam to the absorption of the A-exciton. The time-dependent TSHG signals clearly exhibit acoustic phonon generation at vibration modes below 10 cm-1 (close to the Γ point) after the photoinduced energy is transferred from exciton to phonon in a nonradiative fashion. Interestingly, by observing the TSHG signal oscillation period from MoS2 samples of varying thicknesses, the speed of the supersonic waves generated in the out-of-plane direction (Mach 8.6) is generated. Additionally, TSHG microscopy reveals critical information about the phase and amplitude of the acoustic phonons from different edge chiralities (armchair and zigzag) of the MoS2 monolayers. This suggests that the technique could be used more broadly to study ultrafast physics and chemistry in low-dimensional materials and their hybrids with ultrahigh fidelity.
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Affiliation(s)
- Houk Jang
- School of Electrical and Electronic Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Krishna P Dhakal
- School of Electrical and Electronic Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Kyung-Il Joo
- School of Electronics and Engineering, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Won Seok Yun
- Department of Emerging Materials Science, DGIST, Daegu, 42988, Republic of Korea
| | - Sachin M Shinde
- School of Electrical and Electronic Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Xiang Chen
- School of Electrical and Electronic Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Soon Moon Jeong
- Smart Textile Convergence Research Group, DGIST, Daegu, 42988, Republic of Korea
| | - Suk Woo Lee
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Zonghoon Lee
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - JaeDong Lee
- Department of Emerging Materials Science, DGIST, Daegu, 42988, Republic of Korea
| | - Jong-Hyun Ahn
- School of Electrical and Electronic Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Hyunmin Kim
- Companion Diagnostics and Medical Technology Research Group, DGIST, Daegu, 42988, Republic of Korea
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Dong Y, Zeng B, Xiao J, Zhang X, Li D, Li M, He J, Long M. Effect of sulphur vacancy and interlayer interaction on the electronic structure and spin splitting of bilayer MoS 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:125302. [PMID: 29485104 DOI: 10.1088/1361-648x/aaad3b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Molybdenum disulfide (MoS2) is one of the candidate materials for nanoelectronics and optoelectronics devices in the future. The electronic and magnetic properties of MoS2 can be regulated by interlayer interaction and the vacancy effect. Nevertheless, the combined effect of these two factors on MoS2 is not clearly understood. In this study, we have investigated the impact of a single S vacancy combined with interlayer interaction on the properties of bilayer MoS2. Our calculated results show that an S vacancy brings impurity states in the band structure of bilayer MoS2, and the energy level of the impurity states can be affected by the interlayer distance, which finally disappears in the bulk state when the layer distance is relatively small. Moreover, during the compression of bilayer MoS2, the bottom layer, where the S vacancy stays, gets an additional charge due to interlayer charge transfer, which first increases, and then decreases due to gradually forming the interlayer S-S covalent bond, as interlayer distance decreases. The change of the additional charge is consistent with the change of the total magnetic moment of the bottom layers, no magnetic moment has been found in the top layer. The distribution of magnetic moment mainly concentrates on the three Mo atoms around the S vacancy, for each of which the magnetic moment is very much related to the Mo-Mo length. Our conclusion is that the interlayer charge transfer and S vacancy co-determine the magnetic properties of this system, which may be a useful way to regulate the electronic and magnetic properties of MoS2 for potential applications.
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Affiliation(s)
- Yulan Dong
- Hunan Key Laboratory of Super Micro-structure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, People's Republic of China
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Li J, Yan H, Wei W, Meng L. Microwave-assisted mass synthesis of Mo1−xWxS2 alloy composites with a tunable lithium storage property. Dalton Trans 2018; 47:15148-15154. [DOI: 10.1039/c8dt03149e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mo1−xWxS2 (0 ≤ x ≤ 1) alloyed nanomaterials were successfully synthesized by a facile but high-efficiency one-pot microwave-assisted solvothermal method, and the relationship between structure of Mo1−xWxS2 and their properties such as characteristic Raman scattering, electronic conductivity and lithium storage properties are investigated as well.
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Affiliation(s)
- Jianhui Li
- School of Science; State Key Laboratory for Mechanical Behavior of Materials; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Materials
- Xi'an Jiaotong University
- Xi'an 710049
- P. R. China
| | - Haiting Yan
- School of Science; State Key Laboratory for Mechanical Behavior of Materials; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Materials
- Xi'an Jiaotong University
- Xi'an 710049
- P. R. China
| | - Wei Wei
- School of Science; State Key Laboratory for Mechanical Behavior of Materials; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Materials
- Xi'an Jiaotong University
- Xi'an 710049
- P. R. China
| | - Lingjie Meng
- School of Science; State Key Laboratory for Mechanical Behavior of Materials; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Materials
- Xi'an Jiaotong University
- Xi'an 710049
- P. R. China
- Instrumental Analysis Center
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Wang M, Ju P, Li W, Zhao Y, Han X. Ag2S nanoparticle-decorated MoS2 for enhanced electrocatalytic and photoelectrocatalytic activity in water splitting. Dalton Trans 2017; 46:483-490. [DOI: 10.1039/c6dt04079a] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Tight nanojunctions between Ag2S and MoS2 were constructed, which facilitates the separation of photogenerated charge carriers.
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Affiliation(s)
- Min Wang
- Laboratory of Clean Energy Chemistry and Materials
- Lanzhou Institute of Chemical Physics
- Chinese Academy of Sciences
- Lanzhou 730000
- PR China
| | - Peng Ju
- Laboratory of Clean Energy Chemistry and Materials
- Lanzhou Institute of Chemical Physics
- Chinese Academy of Sciences
- Lanzhou 730000
- PR China
| | - Wen Li
- Laboratory of Clean Energy Chemistry and Materials
- Lanzhou Institute of Chemical Physics
- Chinese Academy of Sciences
- Lanzhou 730000
- PR China
| | - Yun Zhao
- Laboratory of Clean Energy Chemistry and Materials
- Lanzhou Institute of Chemical Physics
- Chinese Academy of Sciences
- Lanzhou 730000
- PR China
| | - Xiuxun Han
- Laboratory of Clean Energy Chemistry and Materials
- Lanzhou Institute of Chemical Physics
- Chinese Academy of Sciences
- Lanzhou 730000
- PR China
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Li Q, Zhou Q, Niu X, Zhao Y, Chen Q, Wang J. Covalent Functionalization of Black Phosphorus from First-Principles. J Phys Chem Lett 2016; 7:4540-4546. [PMID: 27794604 DOI: 10.1021/acs.jpclett.6b02192] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The chemical functionalization is proven to be an effective and controllable approach to modify the properties of black phosphorus (BP), and improve the air-stability of BP and its nanoelectronic applications [Nat. Chem., 2016, 8, 597]. However, covalent functionalization of BP and related properties are poorly understood. Here we present a theoretical investigation on the electronic structure and transport property of chemically modified BP. Our calculations reveal that the molecule modification generates a rather flat energy band within the bandgap, which leads to a reduced hole mobility of BP. Alternatively, we propose to use polymers bonded to BP surface, aiming at a balance between functionality and carrier mobility. The polymer-BP composites preserve both electron and hole mobility of pristine BP. Meanwhile, the stability of polymer-BP composites in ambient condition is enhanced as well.
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Affiliation(s)
- Qiang Li
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Qionghua Zhou
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Xianghong Niu
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Yinghe Zhao
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Qian Chen
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Jinlan Wang
- Department of Physics, Southeast University , Nanjing 211189, China
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Chung HC, Chang CP, Lin CY, Lin MF. Electronic and optical properties of graphene nanoribbons in external fields. Phys Chem Chem Phys 2016; 18:7573-616. [PMID: 26744847 DOI: 10.1039/c5cp06533j] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A review work is done for the electronic and optical properties of graphene nanoribbons in magnetic, electric, composite, and modulated fields. Effects due to the lateral confinement, curvature, stacking, non-uniform subsystems and hybrid structures are taken into account. The special electronic properties, induced by complex competitions between external fields and geometric structures, include many one-dimensional parabolic subbands, standing waves, peculiar edge-localized states, width- and field-dependent energy gaps, magnetic-quantized quasi-Landau levels, curvature-induced oscillating Landau subbands, crossings and anti-crossings of quasi-Landau levels, coexistence and combination of energy spectra in layered structures, and various peak structures in the density of states. There exist diverse absorption spectra and different selection rules, covering edge-dependent selection rules, magneto-optical selection rule, splitting of the Landau absorption peaks, intragroup and intergroup Landau transitions, as well as coexistence of monolayer-like and bilayer-like Landau absorption spectra. Detailed comparisons are made between the theoretical calculations and experimental measurements. The predicted results, the parabolic subbands, edge-localized states, gap opening and modulation, and spatial distribution of Landau subbands, have been identified by various experimental measurements.
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Affiliation(s)
- Hsien-Ching Chung
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan. and Center for Micro/Nano Science and Technology (CMNST), National Cheng Kung University, Tainan 70101, Taiwan
| | - Cheng-Peng Chang
- Center for General Education, Tainan University of Technology, Tainan 701, Taiwan
| | - Chiun-Yan Lin
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan.
| | - Ming-Fa Lin
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan.
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Uncovering edge states and electrical inhomogeneity in MoS2 field-effect transistors. Proc Natl Acad Sci U S A 2016; 113:8583-8. [PMID: 27444021 DOI: 10.1073/pnas.1605982113] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The understanding of various types of disorders in atomically thin transition metal dichalcogenides (TMDs), including dangling bonds at the edges, chalcogen deficiencies in the bulk, and charges in the substrate, is of fundamental importance for TMD applications in electronics and photonics. Because of the imperfections, electrons moving on these 2D crystals experience a spatially nonuniform Coulomb environment, whose effect on the charge transport has not been microscopically studied. Here, we report the mesoscopic conductance mapping in monolayer and few-layer MoS2 field-effect transistors by microwave impedance microscopy (MIM). The spatial evolution of the insulator-to-metal transition is clearly resolved. Interestingly, as the transistors are gradually turned on, electrical conduction emerges initially at the edges before appearing in the bulk of MoS2 flakes, which can be explained by our first-principles calculations. The results unambiguously confirm that the contribution of edge states to the channel conductance is significant under the threshold voltage but negligible once the bulk of the TMD device becomes conductive. Strong conductance inhomogeneity, which is associated with the fluctuations of disorder potential in the 2D sheets, is also observed in the MIM images, providing a guideline for future improvement of the device performance.
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Xiao J, Long M, Zhang X, Zhang D, Xu H, Chan KS. First-Principles Prediction of the Charge Mobility in Black Phosphorus Semiconductor Nanoribbons. J Phys Chem Lett 2015; 6:4141-7. [PMID: 26722789 DOI: 10.1021/acs.jpclett.5b01644] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We have investigated the electronic structure and carrier mobility of monolayer black phosphorus nanoribbons (BPNRs) using density functional theory combined with Boltzmann transport method with relaxation time approximation. It is shown that the calculated ultrahigh electron mobility can even reach the order of 10(3) to 10(7) cm(2) V(-1) s(-1) at room temperature. Owing to the electron mobility being higher than the hole mobility, armchair and diagonal BPNRs behave like n-type semiconductors. Comparing with the bare BPNRs, the difference between the hole and electronic mobilities can be enhanced in ribbons with the edges terminated by H atoms. Moreover, because the hole mobility is about two orders of magnitude larger than the electron mobility, zigzag BPNRs with H termination behave like p-type semiconductors. Our results indicate that BPNRs can be considered as a new kind of nanomaterial for applications in optoelectronics, nanoelectronic devices owing to the intrinsic band gap and ultrahigh charge mobility.
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Affiliation(s)
- Jin Xiao
- Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University , Changsha 410083, China
- School of Science, Hunan University of Technology , Zhuzhou 412007, China
| | - Mengqiu Long
- Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University , Changsha 410083, China
- Department of Physics and Materials Science, City University of Hong Kong , Hong Kong, China
| | - Xiaojiao Zhang
- Physical Science and Technology College of Yichun University , 576 Xuefu Road, Yuanzhou, Yichun 336000, China
| | - Dan Zhang
- Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University , Changsha 410083, China
| | - Hui Xu
- Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University , Changsha 410083, China
| | - Kwok Sum Chan
- Department of Physics and Materials Science, City University of Hong Kong , Hong Kong, China
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