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Zhang ZH, Yang LZ, Qin HJ, Liao WA, Liu H, Fu J, Zeng H, Zhang W, Fu YS. Direct Observations of Spontaneous In-Plane Electronic Polarization in 2D Te Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2405590. [PMID: 39194389 DOI: 10.1002/adma.202405590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 08/15/2024] [Indexed: 08/29/2024]
Abstract
Single-element polarization in low dimensions is fascinating for constructing next-generation nanoelectronics with multiple functionalities, yet remains difficult to access with satisfactory performance. Here, spectroscopic evidences are presented for the spontaneous electronic polarization in tellurium (Te) films thinned down to bilayer, characterized by low-temperature scanning tunneling microscopy/spectroscopy. The unique chiral structure and centrosymmetry-breaking character in 2D Te gives rise to sizable in-plane polarization with accumulated charges, which is demonstrated by the reversed band-bending trends at opposite polarization edges in spatially resolved spectra and conductance mappings. The polarity of charges exhibits intriguing influence on imaging the moiré superlattice at the Te-graphene interface. Moreover, the plain spontaneous polarization robustly exists for various film thicknesses, and can universally preserve against different epitaxial substrates. The experimental validations of considerable electronic polarization in Te multilayers thus provide a realistic platform for promisingly facilitating reliable applications in microelectronic devices.
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Affiliation(s)
- Zhi-Hao Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Lian-Zhi Yang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hao-Jun Qin
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Wen-Ao Liao
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Heng Liu
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China
- CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, China
| | - Jun Fu
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China
- CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, China
| | - Hualing Zeng
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China
- CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, China
| | - Wenhao Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ying-Shuang Fu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
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2
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Gao W, Zhi G, Zhou M, Niu T. Growth of Single Crystalline 2D Materials beyond Graphene on Non-metallic Substrates. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2311317. [PMID: 38712469 DOI: 10.1002/smll.202311317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/14/2024] [Indexed: 05/08/2024]
Abstract
The advent of 2D materials has ushered in the exploration of their synthesis, characterization and application. While plenty of 2D materials have been synthesized on various metallic substrates, interfacial interaction significantly affects their intrinsic electronic properties. Additionally, the complex transfer process presents further challenges. In this context, experimental efforts are devoted to the direct growth on technologically important semiconductor/insulator substrates. This review aims to uncover the effects of substrate on the growth of 2D materials. The focus is on non-metallic substrate used for epitaxial growth and how this highlights the necessity for phase engineering and advanced characterization at atomic scale. Special attention is paid to monoelemental 2D structures with topological properties. The conclusion is drawn through a discussion of the requirements for integrating 2D materials with current semiconductor-based technology and the unique properties of heterostructures based on 2D materials. Overall, this review describes how 2D materials can be fabricated directly on non-metallic substrates and the exploration of growth mechanism at atomic scale.
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Affiliation(s)
- Wenjin Gao
- Tianmushan Laboratory, Hangzhou, 310023, China
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | | | - Miao Zhou
- Tianmushan Laboratory, Hangzhou, 310023, China
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | - Tianchao Niu
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
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3
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Chen SB, Guo SD, Yan WJ, Chen XR, Geng HY. Equibiaxial strain regulates the electronic structure and mechanical, piezoelectric, and thermal transport properties of the 2H-phase monolayers CrX 2 (X = S, Se, Te). Phys Chem Chem Phys 2024; 26:3159-3167. [PMID: 38190261 DOI: 10.1039/d3cp04604d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
A superior piezoelectric coefficient and diminutive lattice thermal conductivity are advantageous for the application of a two-dimensional semiconductor in piezoelectric and thermoelectric devices, whereas an imperfect piezoelectric coefficient and large lattice thermal conductivity limit the practical application of the material. In this study, we investigate how the equibiaxial strain regulates the electronic structure, and mechanical, piezoelectric, and thermal transport properties. Tensile strain can deduce the bandgap of the monolayer CrX2 (X = S, Se, Te), whereas compressive strain has an opposite effect. Additionally, the transition from a semiconductor to a metal state and the transition between direct and indirect band gaps will occur at appropriate strain values, so the electronic structure can be effectively regulated. The reason is the different sensitivities of the energy corresponding to K and Γ on the valence band to the strain due to the changes in different orbital overlaps. The tensile strain can effectively improve the flexibility of monolayers CrX2, which provides a possibility for the application of flexible electronic devices. Furthermore, the tensile strain can improve the piezoelectric strain coefficient of monolayers CrX2. Using Slacks formulation, we calculate the lattice thermal conductivity, and the tensile biaxial strain can reduce the lattice thermal conductivity. Our research provides a strategy to enhance the piezoelectric and flexible electronic applications and decrease the lattice thermal conductivity, which can benefit the thermoelectric applications.
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Affiliation(s)
- Shao-Bo Chen
- College of Electronic and Information Engineering, Anshun University, Anshun 561000, Peoples Republic of China.
| | - San-Dong Guo
- School of Electronic Engineering, Xian University of Posts and Telecommunications, Xian 710121, Peoples Republic of China
| | - Wan-Jun Yan
- College of Electronic and Information Engineering, Anshun University, Anshun 561000, Peoples Republic of China.
| | - Xiang-Rong Chen
- College of Physics, Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, Peoples Republic of China.
| | - Hua-Yun Geng
- National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, CAEP, Mianyang 621900, Peoples Republic of China
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Park MU, Kim M, Kim SH, Lee C, Lee KS, Jeong J, Cho MH, Kim DY, Yoo KH. Funnel Devices Based on Asymmetrically Strained Transition Metal Dichalcogenides. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209788. [PMID: 36750416 DOI: 10.1002/adma.202209788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/17/2023] [Indexed: 06/18/2023]
Abstract
The strain applied to transition metal dichalcogenides (TMDs) reduces their energy bandgap, and local strains result in a funnel-like band structure in which funneled excitons move toward the most strained region. Herein, a funnel device based on asymmetrically strained WS2 and MoS2 is reported. Asymmetric strains are induced by transferring the TMD flakes onto a fork-shaped SU-8 microstructure. Raman and photoluminescence spectra peaks are shifted according to the morphology of the SU-8 microstructure, indicating the application of asymmetric strains to the TMDs. To investigate whether funneled excitons can be converted to electrical currents, various devices are constructed by depositing symmetric and asymmetric electrodes onto the strained TMDs. The scanning photocurrent mapping images follow a fork-shaped pattern, indicating probable conversion of the funneled excitons into electrical currents. In the case of the funnel devices with asymmetric Au and Al electrodes, short-circuit current (ISC ) of WS2 is enhanced by the strains, whereas ISC of MoS2 is suppressed because the Schottky barrier lowers with increasing strain for the MoS2 . These results demonstrate that the funnel devices can be implemented using asymmetrically strained TMDs and the effect of strains on the Schottky barrier is dependent on the TMD used.
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Affiliation(s)
- Myung Uk Park
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
| | - Myeongjin Kim
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
| | - Sung Hyun Kim
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
| | - ChangJun Lee
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
| | - Kyo-Seok Lee
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
| | - Jaehun Jeong
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
| | - Mann-Ho Cho
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
| | - Dug Young Kim
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
| | - Kyung-Hwa Yoo
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
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5
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Rao G, Fang H, Zhou T, Zhao C, Shang N, Huang J, Liu Y, Du X, Li P, Jian X, Ma L, Wang J, Liu K, Wu J, Wang X, Xiong J. Robust Piezoelectricity with Spontaneous Polarization in Monolayer Tellurene and Multilayer Tellurium Film at Room Temperature for Reliable Memory. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204697. [PMID: 35793515 DOI: 10.1002/adma.202204697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/22/2022] [Indexed: 06/15/2023]
Abstract
Robust neuromorphic computing in the Big Data era calls for long-term stable crossbar-array memory cells; however, the elemental segregation in the switch unit and memory unit that inevitably occurs upon cycling breaks the compositional and structural stability, making the whole memory cell a failure. Searching for a novel material without segregation that can be used for both switch and memory units is the major concern to fabricate robust and reliable nonvolatile cross-array memory cells. Tellurium (Te) is found recently to be the only peculiar material without segregation for switching, but the memory function has not been demonstrated yet. Herein, apparent piezoelectricity is experimentally confirmed with spontaneous polarization behaviors in elementary 2D Te, even in monolayer tellurene (0.4 nm), due to the highly oriented polarization of the molecular structure and the non-centrosymmetric lattice structure. A large memory window of 7000, a low working voltage of 2 V, and high on switching current up to 36.6 µA µm-1 are achieved in the as-fabricated Te-based memory device, revealing the great promise of Te for both switching and memory units in one cell without segregation. The piezoelectric Te with spontaneous polarization provides a platform to build robust, reliable, and high-density logic-in-memory chips in neuromorphic computing.
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Affiliation(s)
- Gaofeng Rao
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Hui Fang
- School of Physics, Southeast University, Nanjing, 211189, China
| | - Ting Zhou
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Chunlin Zhao
- Department of Materials Science, Sichuan University, Chengdu, 6110064, China
- College of Materials Science and Engineering, Fuzhou University, Fuzhou, 350108, China
| | - Nianze Shang
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Jianwen Huang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Yuqing Liu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Xinchuan Du
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Peng Li
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Xian Jian
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Liang Ma
- School of Physics, Southeast University, Nanjing, 211189, China
| | - Jinlan Wang
- School of Physics, Southeast University, Nanjing, 211189, China
| | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Jiagang Wu
- Department of Materials Science, Sichuan University, Chengdu, 6110064, China
| | - Xianfu Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
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Wang G, Ding Y, Guan Y, Wang Y, Yang L. Tunable Electronic Properties of Few-Layer Tellurene under In-Plane and Out-of-Plane Uniaxial Strain. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:875. [PMID: 35269362 PMCID: PMC8912431 DOI: 10.3390/nano12050875] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/02/2022] [Accepted: 03/04/2022] [Indexed: 01/27/2023]
Abstract
Strain engineering is a promising and fascinating approach to tailoring the electrical and optical properties of 2D materials, which is of great importance for fabricating excellent nano-devices. Although previous theoretical works have proved that the monolayer tellurene has desirable mechanical properties with the capability of withstanding large deformation and the tunable band gap and mobility conductance induced by in-plane strain, the effects of in-plane and out-of-plane strains on the properties of few-layer tellurene in different phases should be explored deeply. In this paper, calculations based on first-principles density functional theory were performed to predict the variation in crystal structures and electronic properties of few-layer tellurene, including the α and β phases. The analyses of mechanical properties show that few-layer α-Te can be more easily deformed in the armchair direction than β-Te owing to its lower Young's modulus and Poisson's ratio. The α-Te can be converted to β-Te by in-plane compressive strain. The variations in band structures indicate that the uniaxial strain can tune the band structures and even induce the semiconductor-to-metal transition in both few-layer α-Te and β-Te. Moreover, the compressive strain in the zigzag direction is the most feasible scheme due to the lower transition strain. In addition, few-layer β-Te is more easily converted to metal especially for the thicker flakes considering its smaller band gap. Hence, the strain-induced tunable electronic properties and semiconductor-to-metal transition of tellurene provide a theoretical foundation for fabricating metal-semiconductor junctions and corresponding nano-devices.
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Affiliation(s)
- Genwang Wang
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150001, China; (G.W.); (Y.D.); (Y.G.)
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Ye Ding
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150001, China; (G.W.); (Y.D.); (Y.G.)
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Yanchao Guan
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150001, China; (G.W.); (Y.D.); (Y.G.)
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Yang Wang
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150001, China; (G.W.); (Y.D.); (Y.G.)
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Lijun Yang
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150001, China; (G.W.); (Y.D.); (Y.G.)
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
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7
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Fan FR, Wang R, Zhang H, Wu W. Emerging beyond-graphene elemental 2D materials for energy and catalysis applications. Chem Soc Rev 2021; 50:10983-11031. [PMID: 34617521 DOI: 10.1039/c9cs00821g] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Elemental two-dimensional (2D) materials have emerged as promising candidates for energy and catalysis applications due to their unique physical, chemical, and electronic properties. These materials are advantageous in offering massive surface-to-volume ratios, favorable transport properties, intriguing physicochemical properties, and confinement effects resulting from the 2D ultrathin structure. In this review, we focus on the recent advances in emerging energy and catalysis applications based on beyond-graphene elemental 2D materials. First, we briefly introduce the general classification, structure, and properties of elemental 2D materials and the new advances in material preparation. We then discuss various applications in energy harvesting and storage, including solar cells, piezoelectric and triboelectric nanogenerators, thermoelectric devices, batteries, and supercapacitors. We further discuss the explorations of beyond-graphene elemental 2D materials for electrocatalysis, photocatalysis, and heterogeneous catalysis. Finally, the challenges and perspectives for the future development of elemental 2D materials in energy and catalysis are discussed.
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Affiliation(s)
- Feng Ru Fan
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, USA. .,Flex Laboratory, Purdue University, West Lafayette, Indiana 47907, USA
| | - Ruoxing Wang
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, USA. .,Flex Laboratory, Purdue University, West Lafayette, Indiana 47907, USA
| | - Hua Zhang
- Department of Chemistry, City University of Hong Kong, Hong Kong, China. .,Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, City University of Hong Kong, Shenzhen, 518057, China
| | - Wenzhuo Wu
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, USA. .,Flex Laboratory, Purdue University, West Lafayette, Indiana 47907, USA.,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
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8
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Liang Y, Shen S, Huang B, Dai Y, Ma Y. Intercorrelated ferroelectrics in 2D van der Waals materials. MATERIALS HORIZONS 2021; 8:1683-1689. [PMID: 34846498 DOI: 10.1039/d1mh00446h] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
2D intercorrelated ferroelectrics, exhibiting a coupled in-plane and out-of-plane ferroelectricity, is a fundamental phenomenon in the field of condensed-mater physics. The current research is based on the paradigm of bi-directional inversion asymmetry in single-layers, which restricts 2D intercorrelated ferroelectrics to extremely few systems. Herein, we propose a new scheme for achieving 2D intercorrelated ferroelectrics using van der Waals (vdW) interaction, and apply this scheme to a vast family of 2D vdW materials. Using first-principles, we demonstrate that 2D vdW multilayers, for example, BN, MoS2, InSe, CdS, PtSe2, TI2O, SnS2, Ti2CO2etc., can exhibit coupled in-plane and out-of-plane ferroelectricity, thus yielding 2D intercorrelated ferroelectric physics. We further predict that such intercorrelated ferroelectrics could demonstrate many distinct properties, for example, electrical full control of spin textures in trilayer PtSe2 and electrical permanent control of valley-contrasting physics in four-layer VS2. Our finding opens a new direction for 2D intercorrelated ferroelectric research.
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Affiliation(s)
- Yan Liang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Str. 27, Jinan 250100, People's Republic of China.
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9
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Sachdeva PK, Gupta S, Bera C. Large piezoelectric and thermal expansion coefficients with negative Poisson's ratio in strain-modulated tellurene. NANOSCALE ADVANCES 2021; 3:3279-3287. [PMID: 36133659 PMCID: PMC9418014 DOI: 10.1039/d0na00930j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 04/06/2021] [Indexed: 05/17/2023]
Abstract
Two dimensional (2D) chalcogenide monolayers have diversified applications in optoelectronics, piezotronics, sensors and energy harvesting. The group-IV tellurene monolayer is one such emerging material in the 2D family owing to its piezoelectric, thermoelectric and optoelectronic properties. In this paper, the mechanical and piezoelectric properties of 2D tellurene in centrosymmetric β and non-centrosymmetric β' phases are investigated using density functional theory. β'-Te has shown a negative Poisson's ratio of -0.024 along the zigzag direction. Giant in-plane piezoelectric coefficients of -83.89 × 10-10 C m-1 and -42.58 × 10-10 C m-1 are observed for β'-Te under biaxial and uniaxial strains, respectively. The predicted values are remarkably higher, that is 23 and 12 times the piezoelectric coefficient of a MoS2 monolayer with biaxial and uniaxial strain in the zigzag direction, respectively. A large thermal expansion coefficient of tellurene is also estimated using quasi harmonic approximation. High piezoelectricity combined with exotic mechanical and thermal properties makes tellurene a very promising candidate in nanoelectronics.
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Affiliation(s)
- Parrydeep Kaur Sachdeva
- Institute of Nano Science and Technology Knowledge City, Sector-81, S. A. S Nagar Mohali Punjab 140306 India
- University Institute of Engineering and Technology, Panjab University Sector-25 Chandigarh 160014 India
- Department of Physics, Panjab University Sector-14 Chandigarh 160014 India
| | - Shuchi Gupta
- University Institute of Engineering and Technology, Panjab University Sector-25 Chandigarh 160014 India
| | - Chandan Bera
- Institute of Nano Science and Technology Knowledge City, Sector-81, S. A. S Nagar Mohali Punjab 140306 India
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10
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Cai X, Ma Y, Ma J, Xu D, Luo X. Structure and electronic bandgap tunability of m-plane GaN multilayers. Phys Chem Chem Phys 2021; 23:5431-5437. [PMID: 33646234 DOI: 10.1039/d0cp06093c] [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
Two-dimensional (2D) gallium nitride (GaN) has attracted a lot of attention due to its promising applications in photoelectric nano-devices. Most previous research studies have focused on polar c-plane 2D structures. Here, by employing first principles calculations, we systematically investigate the structural and electronic properties of non-polar m-plane GaN with different numbers of atomic layers. The results show a layer-dependent structure transition and electronic band variation for m-plane GaN. It is found that the monolayer keeps a planar hexagonal structure due to sp2 hybridization, whereas the multilayers are formed by stacking of buckled hexagonal monolayers with unsaturated coordination number at the surface sublayer and bulk-like inner layers. These discrepancies in the structure further induce an indirect to direct transition of the band gap type when the layer number reaches twelve. By carefully examining the relationship between the structure and electronic bandgap, we find that the indirect bandgap comes from the unsaturated surface with a planar like structure. On surface modification, saturation of the surface dangling bonds results in an indirect to direct band gap transition.
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Affiliation(s)
- Xueru Cai
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
| | - Yiming Ma
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
| | - Jinlong Ma
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
| | - Dongwei Xu
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
| | - Xiaobing Luo
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
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