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Cheng Y, Li Z, Cheng L, Yuan Y, Xie E, Cao X, Xin Z, Liu Y, Tang T, Hu X, Xu K, Manh Hung C, Jannat A, Li YX, Chen H, Ou JZ. Thickness-Dependent Room-Temperature Optoelectronic Gas Sensing Performances of 2D Nonlayered Indium Oxide Crystals from a Liquid Metal Printing Process. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 38015181 DOI: 10.1021/acsami.3c12787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Due to excellent gas sensing performances, such as high responsivity, good selectivity, and long-term stability, two-dimensional (2D) nonlayered metal oxide semiconductors have attracted wide attention. However, their thickness-dependent gas sensing behaviors are rarely investigated, which is critical in the development of practical 2D sensors. In this work, 2D In2O3 crystals with a range of thicknesses are realized by extracting the self-limited oxide layer from the liquid indium droplets in a controlled environment. A strong thickness-dependent optoelectronic NO2 sensing behavior at room temperature is observed. While full reversibility and excellent selectivity toward NO2 are shown despite the thicknesses of 2D In2O3, the 1.9 nm thick In2O3 exhibits a maximum response amplitude (ΔI/Ig = 1300) for 10 ppm of NO2 at room temperature with 365 nm light irradiation, which is about 18, 58, and 810 times larger than those of its 3.1 nm thick, 4.5 nm thick, and 6.2 nm thick counterparts, respectively. The shortest response and recovery times (i.e., 40 s/48 s) are demonstrated for the 1.88 nm thick In2O3 as well. We correlate such a phenomenon with the change in the In2O3 band structure, which is influenced by the thickness of 2D crystals. This work provides in-depth knowledge of the thickness-dependent gas-sensing performances of emerging 2D nonlayered metal oxide crystals, as well as the opportunities to develop next-generation high-performing room-temperature gas sensors.
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Affiliation(s)
- Yinfen Cheng
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Zhong Li
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
- Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing 211167, China
| | - Liang Cheng
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Yuxiao Yuan
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - En Xie
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Xiaolong Cao
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Zhenqing Xin
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Yaoyang Liu
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Tao Tang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Xinyi Hu
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Kai Xu
- School of Engineering, RMIT University, Melbourne 3000, Australia
| | - Chu Manh Hung
- International Training Institute for Materials Science, Hanoi University of Science and Technology, Hanoi 10000, Viet Nam
| | - Azmira Jannat
- School of Engineering, RMIT University, Melbourne 3000, Australia
| | - Yong Xiang Li
- School of Engineering, RMIT University, Melbourne 3000, Australia
| | - Hui Chen
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Jian Zhen Ou
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
- School of Engineering, RMIT University, Melbourne 3000, Australia
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Di Bernardo I, Ripoll-Sau J, Silva-Guillén JA, Calleja F, Ayani CG, Miranda R, Canadell E, Garnica M, Vázquez de Parga AL. Metastable Polymorphic Phases in Monolayer TaTe 2. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2300262. [PMID: 37029707 DOI: 10.1002/smll.202300262] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/09/2023] [Indexed: 06/19/2023]
Abstract
Polymorphic phases and collective phenomena-such as charge density waves (CDWs)-in transition metal dichalcogenides (TMDs) dictate the physical and electronic properties of the material. Most TMDs naturally occur in a single given phase, but the fine-tuning of growth conditions via methods such as molecular beam epitaxy (MBE) allows to unlock otherwise inaccessible polymorphic structures. Exploring and understanding the morphological and electronic properties of new phases of TMDs is an essential step to enable their exploitation in technological applications. Here, scanning tunneling microscopy (STM) is used to map MBE-grown monolayer (ML) TaTe2 . This work reports the first observation of the 1H polymorphic phase, coexisting with the 1T, and demonstrates that their relative coverage can be controlled by adjusting synthesis parameters. Several superperiodic structures, compatible with CDWs, are observed to coexist on the 1T phase. Finally, this work provides theoretical insight on the delicate balance between Te…Te and Ta-Ta interactions that dictates the stability of the different phases. The findings demonstrate that TaTe2 is an ideal platform to investigate competing interactions, and indicate that accurate tuning of growth conditions is key to accessing metastable states in TMDs.
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Affiliation(s)
- Iolanda Di Bernardo
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria, 3800, Australia
- School of Physics and Astronomy, Monash University, Victoria, 3800, Australia
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
| | - Joan Ripoll-Sau
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
| | - Jose Angel Silva-Guillén
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
| | - Fabian Calleja
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
| | - Cosme G Ayani
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
| | - Rodolfo Miranda
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
- Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Enric Canadell
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra, 08193, Spain
| | - Manuela Garnica
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
- Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Amadeo L Vázquez de Parga
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
- Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
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3
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Lu H, Liu W, Wang H, Liu X, Zhang Y, Yang D, Pi X. Molecular beam epitaxy growth and scanning tunneling microscopy study of 2D layered materials on epitaxial graphene/silicon carbide. NANOTECHNOLOGY 2023; 34:132001. [PMID: 36563353 DOI: 10.1088/1361-6528/acae28] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
Since the advent of atomically flat graphene, two-dimensional (2D) layered materials have gained extensive interest due to their unique properties. The 2D layered materials prepared on epitaxial graphene/silicon carbide (EG/SiC) surface by molecular beam epitaxy (MBE) have high quality, which can be directly applied without further transfer to other substrates. Scanning tunneling microscopy and spectroscopy (STM/STS) with high spatial resolution and high-energy resolution are often used to study the morphologies and electronic structures of 2D layered materials. In this review, recent progress in the preparation of various 2D layered materials that are either monoelemental or transition metal dichalcogenides on EG/SiC surface by MBE and their STM/STS investigations are introduced.
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Affiliation(s)
- Hui Lu
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
- Institute of Advanced Semiconductors & Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, Zhejiang 311200, People's Republic of China
| | - Wenji Liu
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
| | - Haolin Wang
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
| | - Xiao Liu
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
- Institute of Advanced Semiconductors & Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, Zhejiang 311200, People's Republic of China
| | - Yiqiang Zhang
- School of Materials Science and Engineering & College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, People's Republic of China
| | - Deren Yang
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
- Institute of Advanced Semiconductors & Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, Zhejiang 311200, People's Republic of China
| | - Xiaodong Pi
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
- Institute of Advanced Semiconductors & Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, Zhejiang 311200, People's Republic of China
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4
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Catalytically Active Advanced Two-Dimensional Ultrathin Nanomaterials for Sustainable Energy. Catalysts 2022. [DOI: 10.3390/catal12101167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Advanced two-dimensional (2D) ultrathin nanomaterials’ unique structural and electronic properties and their applications in the photo-, photoelectro-, and electro-catalysis fields present timely topics related to the development of sustainable energy. This critical review briefly summarizes the state-of-the-art progress on 2D ultrathin nanomaterials. In this mini review, we started with the synthesis of 2D ultrathin nanomaterials. Then, various strategies for tailoring the electronic and configuration structures of these nanomaterials in the new energy catalysis field are surveyed, where the emphasis is mainly on structure-activity relationships. The advancements of versatile 2D ultrathin nanomaterials in the fields of hydrogen evolution, carbon dioxide conversion, and dinitrogen fixation for sustainable energy were also discussed. Finally, the existing challenges and future research directions in this promising field are presented.
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5
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Ripoll-Sau J, Calleja F, Casado Aguilar P, Ibarburu IM, Vázquez de Parga AL, Miranda R, Garnica M. Phase control and lateral heterostructures of MoTe 2 epitaxially grown on graphene/Ir(111). NANOSCALE 2022; 14:10880-10888. [PMID: 35848284 DOI: 10.1039/d2nr03074h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Engineering the growth of the different phases of two-dimensional transition metal dichalcogenides (2D-TMDs) is a promising way to exploit their potential since the phase determines their physical and chemical properties. Here, we report on the epitaxial growth of monolayer MoTe2 on graphene on an Ir(111) substrate. Scanning tunneling microscopy and spectroscopy provide insights into the structural and electronic properties of the different polymorphic phases, which remain decoupled from the substrate due to the weak interaction with graphene. In addition, we demonstrate a great control of the relative coverage of the relevant 1T' and 1H MoTe2 phases by varying the substrate temperature during the growth. In particular, we obtain large areas of the 1T' phase exclusively or the coexistence of both phases with different ratios.
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Affiliation(s)
- Joan Ripoll-Sau
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Fabian Calleja
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
| | - Pablo Casado Aguilar
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Iván M Ibarburu
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Amadeo L Vázquez de Parga
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Rodolfo Miranda
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Manuela Garnica
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, 28049 Madrid, Spain
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6
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Pan S, Hong M, Zhu L, Quan W, Zhang Z, Huan Y, Yang P, Cui F, Zhou F, Hu J, Zheng F, Zhang Y. On-Site Synthesis and Characterizations of Atomically-Thin Nickel Tellurides with Versatile Stoichiometric Phases through Self-Intercalation. ACS NANO 2022; 16:11444-11454. [PMID: 35786839 DOI: 10.1021/acsnano.2c05570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Self-intercalation of native metal atoms in two-dimensional (2D) transition metal dichalcogenides has received rapidly increasing interest, due to the generation of intriguing structures and exotic physical properties, however, only reported in limited materials systems. An emerging type-II Dirac semimetal, NiTe2, has inspired great attention at the 2D thickness region, but has been rarely achieved so far. Herein, we report the direct synthesis of mono- to few-layer Ni-tellurides including 1T-NiTe2 and Ni-rich stoichiometric phases on graphene/SiC(0001) substrates under ultra-high-vacuum conditions. Differing from previous chemical vapor deposition growth accompanied with transmission electron microscopy imaging, this work combines precisely tailored synthesis with on-site atomic-scale scanning tunneling microscopy observations, offering us visual information about the phase modulations of Ni-tellurides from 1T-phase NiTe2 to self-intercalated Ni3Te4 and Ni5Te6. The synthesis of Ni self-intercalated NixTey compounds is explained to be mediated by the high metal chemical potential under Ni-rich conditions, according to density functional theory calculations. More intriguingly, the emergence of superconductivity in bilayer NiTe2 intercalated with 50% Ni is also predicted, arising from the enhanced electron-phonon coupling strength after the self-intercalation. This work provides insight into the direct synthesis and stoichiometric phase modulation of 2D layered materials, enriching the family of self-intercalated materials and propelling their property explorations.
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Affiliation(s)
- Shuangyuan Pan
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Min Hong
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Lijie Zhu
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Wenzhi Quan
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
| | - Zehui Zhang
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Yahuan Huan
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Pengfei Yang
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
| | - Fangfang Cui
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Fan Zhou
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
| | - Jingyi Hu
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
| | - Feipeng Zheng
- Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics, Jinan University, Guangzhou 510632, People's Republic of China
| | - Yanfeng Zhang
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
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7
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Li JW, Ke SS, Deng HX, Sun X, Guo Y, Lü HF. Defect modulated electronic structure and magnetism in the 1T′ phase of Janus MoSSe. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2021.111440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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8
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Li Y, Wang M, Yi Y, Lu C, Dou S, Sun J. Metallic Transition Metal Dichalcogenides of Group VIB: Preparation, Stabilization, and Energy Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2005573. [PMID: 33734605 DOI: 10.1002/smll.202005573] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/21/2020] [Indexed: 06/12/2023]
Abstract
Layered transition metal dichalcogenides (TMDs) of group VIB have been widely used in the realms of energy storage and conversions. Along with the existence of semiconducting states, their metallic phases have recently attracted numerous attentions owing to their fascinating physical and chemical properties. Many efforts have been devoted to obtain metallic TMDs with high purity and yield. Nevertheless, such metallic phase is thermodynamically metastable and tends to convert into semiconducting phase, which necessitates the exploration over effective strategies to ensure the stability. In this review, typical fabrication routes are introduced and those critical factors during preparation are elaborately discussed. Moreover, the stabilized strategies are summarized with concrete examples highlighting the key mechanisms toward efficient stabilization. Finally, emerging energy applications are overviewed. This review presents comprehensive research status of metallic group VIB TMDs, aiming to facilitate further scientific investigations and promote future practical applications in the fields of energy storage and conversion.
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Affiliation(s)
- Yihui Li
- College of Energy, Soochow Institute for Energy and Materials InnovationS (SIEMIS), Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, 688 Moye Road, Suzhou, 215006, P. R. China
| | - Menglei Wang
- College of Energy, Soochow Institute for Energy and Materials InnovationS (SIEMIS), Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, 688 Moye Road, Suzhou, 215006, P. R. China
| | - Yuyang Yi
- College of Energy, Soochow Institute for Energy and Materials InnovationS (SIEMIS), Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, 688 Moye Road, Suzhou, 215006, P. R. China
| | - Chen Lu
- College of Energy, Soochow Institute for Energy and Materials InnovationS (SIEMIS), Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, 688 Moye Road, Suzhou, 215006, P. R. China
- Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Shixue Dou
- Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Jingyu Sun
- College of Energy, Soochow Institute for Energy and Materials InnovationS (SIEMIS), Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, 688 Moye Road, Suzhou, 215006, P. R. China
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9
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Han B, Yang C, Xu X, Li Y, Shi R, Liu K, Wang H, Ye Y, Lu J, Yu D, Gao P. Correlating the electronic structures of metallic/semiconducting MoTe 2 interface to its atomic structures. Natl Sci Rev 2021; 8:nwaa087. [PMID: 34691565 PMCID: PMC8288393 DOI: 10.1093/nsr/nwaa087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/03/2020] [Accepted: 04/15/2020] [Indexed: 11/13/2022] Open
Abstract
Contact interface properties are important in determining the performances of devices that are based on atomically thin two-dimensional (2D) materials, especially for those with short channels. Understanding the contact interface is therefore important to design better devices. Herein, we use scanning transmission electron microscopy, electron energy loss spectroscopy, and first-principles calculations to reveal the electronic structures within the metallic (1T')-semiconducting (2H) MoTe2 coplanar phase boundary across a wide spectral range and correlate its properties to atomic structures. We find that the 2H-MoTe2 excitonic peaks cross the phase boundary into the 1T' phase within a range of approximately 150 nm. The 1T'-MoTe2 crystal field can penetrate the boundary and extend into the 2H phase by approximately two unit-cells. The plasmonic oscillations exhibit strong angle dependence, that is a red-shift of π+σ (approximately 0.3-1.2 eV) occurs within 4 nm at 1T'/2H-MoTe2 boundaries with large tilt angles, but there is no shift at zero-tilted boundaries. These atomic-scale measurements reveal the structure-property relationships of the 1T'/2H-MoTe2 boundary, providing useful information for phase boundary engineering and device development based on 2D materials.
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Affiliation(s)
- Bo Han
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Department of Material Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Chen Yang
- State Key Laboratory for Artificial Microstructure & Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Xiaolong Xu
- State Key Laboratory for Artificial Microstructure & Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Yuehui Li
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Ruochen Shi
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Kaihui Liu
- State Key Laboratory for Artificial Microstructure & Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Haicheng Wang
- State Key Laboratory of Advanced Materials for Smart Sensing, GRINM Group Co. Ltd., Beijing, and GRIMAT Engineering Institute Co. Ltd., Beijing 101402, China
| | - Yu Ye
- State Key Laboratory for Artificial Microstructure & Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Jing Lu
- State Key Laboratory for Artificial Microstructure & Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Dapeng Yu
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - Peng Gao
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
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10
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Ogorzałek Z, Seredyński B, Kret S, Kwiatkowski A, Korona KP, Grzeszczyk M, Mierzejewski J, Wasik D, Pacuski W, Sadowski J, Gryglas-Borysiewicz M. Charge transport in MBE-grown 2H-MoTe 2 bilayers with enhanced stability provided by an AlO x capping layer. NANOSCALE 2020; 12:16535-16542. [PMID: 32790820 DOI: 10.1039/d0nr03148h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Thin layers of transition metal dichalcogenides have been intensively studied over the last few years due to their novel physical phenomena and potential applications. One of the biggest problems in laboratory handling and moving on to application-ready devices lies in the high sensitivity of their physicochemical properties to ambient conditions. We demonstrate that novel, in situ capping with an ultra-thin, aluminum film efficiently protects thin MoTe2 layers stabilizing their electronic transport properties after exposure to ambient conditions. The experiments have been performed on bilayers of 2H-MoTe2 grown by molecular beam epitaxy on large area GaAs(111)B substrates. The crystal structure, surface morphology and thickness of the deposited MoTe2 layers have been precisely controlled in situ with a reflection high energy electron diffraction system. As evidenced by high resolution transmission electron microscopy, MoTe2 films exhibit perfect arrangement in the 2H phase and the epitaxial relation to the GaAs(111)B substrates. After the growth, the samples were in situ capped with a thin (3 nm) film of aluminum, which oxidizes after exposure to ambient conditions. This oxide serves as a protective layer to the underlying MoTe2. Resistivity measurements of the MoTe2 layers with and without the cap, exposed to low vacuum, nitrogen and air, revealed a huge difference in their stability. The significant rise of resistance is observed for the unprotected sample while the resistance of the protected one is constant. Wide range temperature resistivity studies showed that charge transport in MoTe2 is realized by hopping with an anomalous hopping exponent of x ≃ 0.66, reported also previously for ultra-thin, metallic layers.
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Affiliation(s)
- Zuzanna Ogorzałek
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland.
| | | | - Sławomir Kret
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668, Warsaw, Poland
| | - Adam Kwiatkowski
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland.
| | - Krzysztof P Korona
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland.
| | | | - Janusz Mierzejewski
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland.
| | - Dariusz Wasik
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland.
| | - Wojciech Pacuski
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland.
| | - Janusz Sadowski
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland. and Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668, Warsaw, Poland and Department of Physics and Electrical Engineering, Linnaeus University, SE-391 82, Kalmar, Sweden
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11
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Li Z, Song Y, Tang S. Quantum spin Hall state in monolayer 1T '-TMDCs. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:333001. [PMID: 32244235 DOI: 10.1088/1361-648x/ab8660] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 04/03/2020] [Indexed: 06/11/2023]
Abstract
Although the 1T'phase is rare in the transition metal dichalcogenides (TMDCs) family, it has attracted rapid growing research interest due to the coexistence of superconductivity, unsaturated magneto-resistance, topological phases etc. Among them, the quantum spin Hall (QSH) state in monolayer 1T'-TMDCs is especially interesting because of its unique van der Waals crystal structure, bringing advantages in the fundamental research and application. For example, the van der Waals two-dimensional (2D) layer is vital in building novel functional vertical heterostructure. The monolayer 1T'-TMDCs has become one of the widely studied QSH insulator. In this review, we review the recent progress in fabrications of monolayer 1T'-TMDCs and evidence that establishes it as QSH insulator.
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Affiliation(s)
- Zhuojun Li
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, People's Republic of China
| | - Yekai Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, People's Republic of China
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, People's Republic of China
| | - Shujie Tang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, People's Republic of China
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12
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Castelino R, Pham TT, Felten A, Sporken R. Substrate temperature dependence of the crystalline quality for the synthesis of pure-phase MoTe 2 on graphene/6H-SiC(0001) by molecular beam epitaxy. NANOTECHNOLOGY 2020; 31:115702. [PMID: 31770732 DOI: 10.1088/1361-6528/ab5be9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
MoTe2 has two stable solid phases. 2H-MoTe2 is semiconducting while 1T' is semimetallic. The selective synthesis of pure-phase thin films is still challenging. In this study, we have investigated the growth temperature dependence of MoTe2 synthesized by molecular beam epitaxy and have identified the optimum temperature for growing the stoichiometric films. It is confirmed that the crystalline quality of MoTe2 strongly depends on the substrate temperature. Post-growth annealing of grown layers at 400 °C stabilizes the semiconducting phase. The structural properties and the phase change in our materials are analyzed in details by reflection high energy electron diffraction, low energy electron diffraction, auger electron spectroscopy, x-ray photoemission spectroscopy, and scanning tunneling microscopy.
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Affiliation(s)
- Roshan Castelino
- Namur Institute of Structured Matter (NISM), Department of Physics, University of Namur, 61 Rue de Bruxelles, B-5000 Namur, Belgium
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13
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He Q, Li P, Wu Z, Yuan B, Luo Z, Yang W, Liu J, Cao G, Zhang W, Shen Y, Zhang P, Liu S, Shao G, Yao Z. Molecular Beam Epitaxy Scalable Growth of Wafer-Scale Continuous Semiconducting Monolayer MoTe 2 on Inert Amorphous Dielectrics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1901578. [PMID: 31199026 DOI: 10.1002/adma.201901578] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/08/2019] [Indexed: 06/09/2023]
Abstract
Monolayer MoTe2 , with the narrowest direct bandgap of ≈1.1 eV among Mo- and W-based transition metal dichalcogenides, has attracted increasing attention as a promising candidate for applications in novel near-infrared electronics and optoelectronics. Realizing 2D lateral growth is an essential prerequisite for uniform thickness and property control over the large scale, while it is not successful yet. Here, layer-by-layer growth of 2 in. wafer-scale continuous monolayer 2H-MoTe2 films on inert SiO2 dielectrics by molecular beam epitaxy is reported. A single-step Mo-flux controlled nucleation and growth process is developed to suppress island growth. Atomically flat 2H-MoTe2 with 100% monolayer coverage is successfully grown on inert 2 in. SiO2 /Si wafer, which exhibits highly uniform in-plane structural continuity and excellent phonon-limited carrier transport behavior. The dynamics-controlled growth recipe is also extended to fabricate continuous monolayer 2H-MoTe2 on atomic-layer-deposited Al2 O3 dielectric. With the breakthrough in growth of wafer-scale continuous 2H-MoTe2 monolayers on device compatible dielectrics, batch fabrication of high-mobility monolayer 2H-MoTe2 field-effect transistors and the three-level integration of vertically stacked monolayer 2H-MoTe2 transistor arrays for 3D circuitry are successfully demonstrated. This work provides novel insights into the scalable synthesis of monolayer 2H-MoTe2 films on universal substrates and paves the way for the ultimate miniaturization of electronics.
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Affiliation(s)
- Qingyuan He
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Pengji Li
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Zhiheng Wu
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Bin Yuan
- Process Research R&D Array Technology Department, Visionox Technology Co., Ltd., Gu'an New Industry Park, Langfang, 065500, P. R. China
| | - Zhongtao Luo
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Wenlong Yang
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Jie Liu
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Guoqin Cao
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
- Institutes for Renewable Energy and Environmental Technologies, University of Bolton, Bolton, BL3 5AB, UK
| | - Wenfeng Zhang
- Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Yonglong Shen
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Peng Zhang
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Suilin Liu
- Analytical & Testing Center, Sichuan University, Chengdu, 610064, P. R. China
| | - Guosheng Shao
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Zhiqiang Yao
- State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
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14
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Yuan S, Luo X, Chan HL, Xiao C, Dai Y, Xie M, Hao J. Room-temperature ferroelectricity in MoTe 2 down to the atomic monolayer limit. Nat Commun 2019; 10:1775. [PMID: 30992431 PMCID: PMC6467908 DOI: 10.1038/s41467-019-09669-x] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/17/2019] [Indexed: 12/02/2022] Open
Abstract
Ferroelectrics allow for a wide range of intriguing applications. However, maintaining ferroelectricity has been hampered by intrinsic depolarization effects. Here, by combining first-principles calculations and experimental studies, we report on the discovery of robust room-temperature out-of-plane ferroelectricity which is realized in the thinnest monolayer MoTe2 with unexploited distorted 1T (d1T) phase. The origin of the ferroelectricity in d1T-MoTe2 results from the spontaneous symmetry breaking due to the relative atomic displacements of Mo atoms and Te atoms. Furthermore, a large ON/OFF resistance ratio is achieved in ferroelectric devices composed of MoTe2-based van der Waals heterostructure. Our work demonstrates that ferroelectricity can exist in two-dimensional layered material down to the atomic monolayer limit, which can result in new functionalities and achieve unexpected applications in atomic-scale electronic devices. It is difficult to maintain ferroelectricity in the two dimensional limit. Here, the authors report robust room-temperature ferroelectricity in the thinnest monolayer MoTe2 due to relative atomic displacements of Mo and Te atoms.
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Affiliation(s)
- Shuoguo Yuan
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, PR China
| | - Xin Luo
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, PR China.,School of Physics, Sun Yat-sen University, Guangzhou, 510275, PR China
| | - Hung Lit Chan
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, PR China
| | - Chengcheng Xiao
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, PR China
| | - Yawei Dai
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China
| | - Maohai Xie
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China
| | - Jianhua Hao
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, PR China.
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15
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Cheng F, Hu Z, Xu H, Shao Y, Su J, Chen Z, Ji W, Loh KP. Interface Engineering of Au(111) for the Growth of 1T'-MoSe 2. ACS NANO 2019; 13:2316-2323. [PMID: 30632743 DOI: 10.1021/acsnano.8b09054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Phase-controlled synthesis of two-dimensional transition-metal dichalcogenides (TMDCs) is of great interest due to the distinct properties of the different phases. However, it is challenging to prepare metallic phase of group-VI TMDCs due to their metastability. At the monolayer level, interface engineering can be used to stabilize the metastable phase. Here, we demonstrate the selective growth of either single-layer 1H- or 1T'-MoSe2 on Au(111) by molecular-beam epitaxy; the two phases can be unambiguously distinguished using scanning tunnelling microscopy and spectroscopy. While the growth of 1H-MoSe2 is favorable on pristine Au(111), the growth of 1T'-MoSe2 is promoted by the predeposition of Se on Au(111). The selective growth of the 1T'-MoSe2 on Se-pretreated Au(111) is attributed to the Mo intercalation induced stabilization of the 1T' phase, which is supported by density functional theory calculations. In addition, 1T' twin boundaries and 1H-1T' heterojunctions were observed and found to exhibit enhanced tunnelling conductivity. The substrate pretreatment approach for phase-controlled epitaxy could be applicable to other group-VI TMDCs grown on Au (111).
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Affiliation(s)
- Fang Cheng
- Department of Chemistry , National University of Singapore , 117543 Singapore
| | - Zhixin Hu
- Center for Joint Quantum Studies and Department of Physics, Institute of Science , Tianjin University , Tianjin 300350 , China
| | - Hai Xu
- Department of Chemistry , National University of Singapore , 117543 Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore 117546 , Singapore
| | - Yan Shao
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , China
| | - Jie Su
- Department of Chemistry , National University of Singapore , 117543 Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore 117546 , Singapore
| | - Zhi Chen
- Department of Chemistry , National University of Singapore , 117543 Singapore
| | - Wei Ji
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices , Renmin University of China , Beijing 100872 , China
| | - Kian Ping Loh
- Department of Chemistry , National University of Singapore , 117543 Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore 117546 , Singapore
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16
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Tang Q. Enhanced 1T′-Phase Stabilization and Chemical Reactivity in a MoTe2
Monolayer through Contact with a 2D Ca2
N Electride. Chemphyschem 2019; 20:595-601. [DOI: 10.1002/cphc.201801047] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/18/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Qing Tang
- School of Chemistry and Chemical Engineering; Chongqing University; Chongqing 401331 China
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17
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Batzill M. Mirror twin grain boundaries in molybdenum dichalcogenides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:493001. [PMID: 30457114 DOI: 10.1088/1361-648x/aae9cf] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Mirror twin grain boundaries (MTBs) exist at the interface between two grains of 60° rotated hexagonal transition metal dichalcogenides (TMDC). These grain boundaries form a regular atomic structure that extends in one dimension and thus may be described as a one-dimensional (1D) lattice embedded in the 2D TMDC. In this review, the different atomic structures and compositions of these MTBs are discussed. The obvious formation of MTBs is by coalescence of two twinned grains. In addition, however, in MoSe2 and MoTe2 a different formation mechanism has been revealed for the formation of Mo-rich MTBs. It has been shown that excess Mo can be incorporated into the TMDC lattices. These excess Mo atoms can then reorganize into closed, triangular MTB-loops that can grow in size by adding more Mo atoms to them. This mechanism allows the formation of dense MTB networks in MoSe2 and MoTe2. Such MTB networks have been observed in samples grown by molecular beam epitaxy (MBE) and consequently their presence needs to be considered in understanding the properties of MBE grown MoSe2 and MoTe2. Density functional theory as well as photoemission spectroscopy of MTB networks have shown that MTBs exhibit dispersing 1D-bands that intersect the Fermi-level, thus suggesting that these are 1D electron systems. Consequently, experimental data have been interpreted to reveal a charge density wave (or Peierls) instability, as well as a Tomonaga-Luttinger liquid behavior for electrons confined in 1D. We discuss these observations and the controversies that remain in the interpretation of some data. The metallic properties of the MTBs and their formation in dense networks also sparked the potential use of such crystal modifications for making metallic contacts to MoTe2 or MoSe2. Moreover, these crystal modifications may also boost the catalytic properties of these materials.
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Affiliation(s)
- Matthias Batzill
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
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18
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Ugeda MM, Pulkin A, Tang S, Ryu H, Wu Q, Zhang Y, Wong D, Pedramrazi Z, Martín-Recio A, Chen Y, Wang F, Shen ZX, Mo SK, Yazyev OV, Crommie MF. Observation of topologically protected states at crystalline phase boundaries in single-layer WSe 2. Nat Commun 2018; 9:3401. [PMID: 30143617 PMCID: PMC6109167 DOI: 10.1038/s41467-018-05672-w] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 07/15/2018] [Indexed: 11/20/2022] Open
Abstract
Transition metal dichalcogenide materials are unique in the wide variety of structural and electronic phases they exhibit in the two-dimensional limit. Here we show how such polymorphic flexibility can be used to achieve topological states at highly ordered phase boundaries in a new quantum spin Hall insulator (QSHI), 1T'-WSe2. We observe edge states at the crystallographically aligned interface between a quantum spin Hall insulating domain of 1T'-WSe2 and a semiconducting domain of 1H-WSe2 in contiguous single layers. The QSHI nature of single-layer 1T'-WSe2 is verified using angle-resolved photoemission spectroscopy to determine band inversion around a 120 meV energy gap, as well as scanning tunneling spectroscopy to directly image edge-state formation. Using this edge-state geometry we confirm the predicted penetration depth of one-dimensional interface states into the two-dimensional bulk of a QSHI for a well-specified crystallographic direction. These interfaces create opportunities for testing predictions of the microscopic behavior of topologically protected boundary states.
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Affiliation(s)
- Miguel M Ugeda
- Donostia International Physics Center (DIPC), Manuel Lardizábal 4, 20018, San Sebastián, Spain.
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel Lardizábal 5, 20018, San Sebastián, Spain.
- Ikerbasque, Basque Foundation for Science, 48013, Bilbao, Spain.
| | - Artem Pulkin
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Shujie Tang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Quansheng Wu
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Yi Zhang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Dillon Wong
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Zahra Pedramrazi
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Ana Martín-Recio
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049, Madrid, Spain
| | - Yi Chen
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Feng Wang
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Kavli Energy NanoScience Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Zhi-Xun Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Oleg V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Michael F Crommie
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Kavli Energy NanoScience Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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19
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Zhang H, Bao C, Jiang Z, Zhang K, Li H, Chen C, Avila J, Wu Y, Duan W, Asensio MC, Zhou S. Resolving Deep Quantum-Well States in Atomically Thin 2H-MoTe 2 Flakes by Nanospot Angle-Resolved Photoemission Spectroscopy. NANO LETTERS 2018; 18:4664-4668. [PMID: 29991260 DOI: 10.1021/acs.nanolett.8b00589] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Transition-metal dichalcogenides exhibit strong quantum confinement effects, and their electronic structure is strongly dependent on the number of layers. Resolving the thickness-dependent electronic structure is important. While the electronic structure of atomically thin 2H-MoSe2 or 2H-MoS2 have been explored, information on the experimental electronic structure of 2H-MoTe2 is still missing. Here, by using nanospot angle-resolved photoemission spectroscopy (nanoARPES), we reveal the experimental electronic structure of exfoliated 2H-MoTe2 thin flakes with different thickness (three, five, and seven monolayers). Well-separated quantum-well states are clearly observed in thin 2H-MoTe2 flakes at deep valence bands at energies between -3 to -5 eV, while those at the top of the valence band between -1 and -2 eV are much more closely spaced compared with those from 2H-MoSe2 and 2H-MoS2. First-principles calculation shows that the main difference is attributed to the weaker hybridization and smaller energy difference between Mo 4d z2 and Te 5p z orbitals as compared with Se 4p z and S 3p z orbitals. Our work demonstrates the power of nanoARPES in resolving the electronic structure of atomically thin exfoliated flakes.
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Affiliation(s)
| | | | | | | | | | - Chaoyu Chen
- Synchrotron SOLEIL , L'Orme des Merisiers, Saint Aubin-BP 48 , 91192 Gif sur Yvette Cedex , France
| | - José Avila
- Synchrotron SOLEIL , L'Orme des Merisiers, Saint Aubin-BP 48 , 91192 Gif sur Yvette Cedex , France
| | | | - Wenhui Duan
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , PR China
| | - Maria C Asensio
- Synchrotron SOLEIL , L'Orme des Merisiers, Saint Aubin-BP 48 , 91192 Gif sur Yvette Cedex , France
| | - Shuyun Zhou
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , PR China
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20
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Han GH, Duong DL, Keum DH, Yun SJ, Lee YH. van der Waals Metallic Transition Metal Dichalcogenides. Chem Rev 2018; 118:6297-6336. [PMID: 29957928 DOI: 10.1021/acs.chemrev.7b00618] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Transition metal dichalcogenides are layered materials which are composed of transition metals and chalcogens of the group VIA in a 1:2 ratio. These layered materials have been extensively investigated over synthesis and optical and electrical properties for several decades. It can be insulators, semiconductors, or metals revealing all types of condensed matter properties from a magnetic lattice distorted to superconducting characteristics. Some of these also feature the topological manner. Instead of covering the semiconducting properties of transition metal dichalcogenides, which have been extensively revisited and reviewed elsewhere, here we present the structures of metallic transition metal dichalcogenides and their synthetic approaches for not only high-quality wafer-scale samples using conventional methods (e.g., chemical vapor transport, chemical vapor deposition) but also local small areas by a modification of the materials using Li intercalation, electron beam irradiation, light illumination, pressures, and strains. Some representative band structures of metallic transition metal dichalcogenides and their strong layer-dependence are reviewed and updated, both in theoretical calculations and experiments. In addition, we discuss the physical properties of metallic transition metal dichalcogenides such as periodic lattice distortion, magnetoresistance, superconductivity, topological insulator, and Weyl semimetal. Approaches to overcome current challenges related to these materials are also proposed.
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Affiliation(s)
- Gang Hee Han
- Center for Integrated Nanostructure Physics (CINAP) , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea.,Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Dinh Loc Duong
- Center for Integrated Nanostructure Physics (CINAP) , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea.,Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Dong Hoon Keum
- Center for Integrated Nanostructure Physics (CINAP) , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea.,Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Seok Joon Yun
- Center for Integrated Nanostructure Physics (CINAP) , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea.,Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics (CINAP) , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea.,Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea.,Department of Physics , Sungkyunkwan University , Suwon 16419 , Republic of Korea
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21
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Yu Y, Wang G, Tan Y, Wu N, Zhang XA, Qin S. Phase-Controlled Growth of One-Dimensional Mo 6Te 6 Nanowires and Two-Dimensional MoTe 2 Ultrathin Films Heterostructures. NANO LETTERS 2018; 18:675-681. [PMID: 29262252 DOI: 10.1021/acs.nanolett.7b03058] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Controllable synthesizing of one-dimensional-two-dimensional (1D-2D) heterostructures and tuning their atomic and electronic structures is nowadays of particular interest due to the extraordinary properties and potential applications. Here, we demonstrate the temperature-induced phase-controlled growth of 1D Mo6Te6-2D MoTe2 heterostructures via molecular beam epitaxy. In situ scanning tunneling microscopy study shows 2D ultrathin films are synthesized at low temperature range, while 1D nanowires gradually arise and dominate as temperature increasing. X-ray photoelectron spectroscopy confirms the good stoichiometry and scanning tunneling spectroscopy reveals the semimetallic property of grown Mo6Te6 nanowires. Through in situ annealing, a phase transition from 2D MoTe2 to 1D Mo6Te6 is induced, thus forming a semimetal-semiconductor junction in atomic level. An upward band bending of 2H-MoTe2 is caused by lateral hole injection from Mo6Te6. The work suggests a new route to synthesize 1D semimetallic transition metal chalcogenide nanowires, which could serve as ultrasmall conducting building blocks and enable band engineering in future 1D-2D heterostructure devices.
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Affiliation(s)
- Yayun Yu
- College of Science, National University of Defense Technology , Changsha 410073, China
- State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University , Beijing 100084, China
| | - Guang Wang
- College of Science, National University of Defense Technology , Changsha 410073, China
- State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University , Beijing 100084, China
- State Key Laboratory of High Performance Computing, National University of Defense Technology , Changsha 410073, China
| | - Yuan Tan
- College of Science, National University of Defense Technology , Changsha 410073, China
| | - Nannan Wu
- College of Science, National University of Defense Technology , Changsha 410073, China
| | - Xue-Ao Zhang
- College of Science, National University of Defense Technology , Changsha 410073, China
- State Key Laboratory of High Performance Computing, National University of Defense Technology , Changsha 410073, China
| | - Shiqiao Qin
- College of Science, National University of Defense Technology , Changsha 410073, China
- State Key Laboratory of High Performance Computing, National University of Defense Technology , Changsha 410073, China
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Peng L, Yuan Y, Li G, Yang X, Xian JJ, Yi CJ, Shi YG, Fu YS. Observation of topological states residing at step edges of WTe 2. Nat Commun 2017; 8:659. [PMID: 28939864 PMCID: PMC5610310 DOI: 10.1038/s41467-017-00745-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/25/2017] [Indexed: 12/03/2022] Open
Abstract
Topological states emerge at the boundary of solids as a consequence of the nontrivial topology of the bulk. Recently, theory predicts a topological edge state on single layer transition metal dichalcogenides with 1T' structure. However, its existence still lacks experimental proof. Here, we report the direct observations of the topological states at the step edge of WTe2 by spectroscopic-imaging scanning tunneling microscopy. A one-dimensional electronic state residing at the step edge of WTe2 is observed, which exhibits remarkable robustness against edge imperfections. First principles calculations rigorously verify the edge state has a topological origin, and its topological nature is unaffected by the presence of the substrate. Our study supports the existence of topological edge states in 1T'-WTe2, which may envision in-depth study of its topological physics and device applications.Two-dimensional topological insulators support edge conduction electrons but its realization in real materials is rare. Here, Peng et al. report the direct observation of topological states at the step edge of WTe2.
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Affiliation(s)
- Lang Peng
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yuan Yuan
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Gang Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 200031, China.
- Institute of Solid State Physics, Vienna University of Technology, A-1040, Vienna, Austria.
| | - Xing Yang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jing-Jing Xian
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Chang-Jiang Yi
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100084, China
| | - You-Guo Shi
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100084, China
| | - Ying-Shuang Fu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China.
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