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Dai C, Xiong H, He R, Zhu C, Li P, Guo M, Gou J, Mei M, Kong D, Li Q, Wee ATS, Fang X, Kong J, Liu Y, Wei D. Electro-Optical Multiclassification Platform for Minimizing Occasional Inaccuracy in Point-of-Care Biomarker Detection. Adv Mater 2024; 36:e2312540. [PMID: 38288781 DOI: 10.1002/adma.202312540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 01/13/2024] [Indexed: 02/06/2024]
Abstract
On-site diagnostic tests that accurately identify disease biomarkers lay the foundation for self-healthcare applications. However, these tests routinely rely on single-mode signals and suffer from insufficient accuracy, especially for multiplexed point-of-care tests (POCTs) within a few minutes. Here, this work develops a dual-mode multiclassification diagnostic platform that integrates an electrochemiluminescence sensor and a field-effect transistor sensor in a microfluidic chip. The microfluidic channel guides the testing samples to flow across electro-optical sensor units, which produce dual-mode readouts by detecting infectious biomarkers of tuberculosis (TB), human rhinovirus (HRV), and group B streptococcus (GBS). Then, machine-learning classifiers generate three-dimensional (3D) hyperplanes to diagnose different diseases. Dual-mode readouts derived from distinct mechanisms enhance the anti-interference ability physically, and machine-learning-aided diagnosis in high-dimensional space reduces the occasional inaccuracy mathematically. Clinical validation studies with 501 unprocessed samples indicate that the platform has an accuracy approaching 99%, higher than the 77%-93% accuracy of rapid point-of-care testing technologies at 100% statistical power (>150 clinical tests). Moreover, the diagnosis time is 5 min without a trade-off of accuracy. This work solves the occasional inaccuracy issue of rapid on-site diagnosis, endowing POCT systems with the same accuracy as laboratory tests and holding unique prospects for complicated scenes of personalized healthcare.
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Affiliation(s)
- Changhao Dai
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, China
| | - Huiwen Xiong
- Department of Chemistry, Fudan University, Shanghai, 200433, China
| | - Rui He
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 73000, China
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Chenxin Zhu
- Institute of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Pintao Li
- Department of Chemistry, Fudan University, Shanghai, 200433, China
| | - Mingquan Guo
- Department of Laboratory Medicine, Shanghai Public Health Clinical Center, Fudan University, Shanghai, 201508, China
| | - Jian Gou
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Miaomiao Mei
- Yizheng Hospital of Traditional Chinese Medicine, Yangzhou, 211400, China
| | - Derong Kong
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, China
| | - Qiang Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Xueen Fang
- Department of Chemistry, Fudan University, Shanghai, 200433, China
| | - Jilie Kong
- Department of Chemistry, Fudan University, Shanghai, 200433, China
| | - Yunqi Liu
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, China
| | - Dacheng Wei
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, China
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2
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Hu J, Han Y, Chi X, Omar GJ, Al Ezzi MME, Gou J, Yu X, Andrivo R, Watanabe K, Taniguchi T, Wee ATS, Qiao Z, Ariando A. Tunable Spin-Polarized States in Graphene on a Ferrimagnetic Oxide Insulator. Adv Mater 2024; 36:e2305763. [PMID: 37811809 DOI: 10.1002/adma.202305763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 10/01/2023] [Indexed: 10/10/2023]
Abstract
Spin-polarized two-dimensional (2D) materials with large and tunable spin-splitting energy promise the field of 2D spintronics. While graphene has been a canonical 2D material, its spin properties and tunability are limited. Here, this work demonstrates the emergence of robust spin-polarization in graphene with large and tunable spin-splitting energy of up to 132 meV at zero applied magnetic fields. The spin polarization is induced through a magnetic exchange interaction between graphene and the underlying ferrimagnetic oxide insulating layer, Tm3 Fe5 O12 , as confirmed by its X-ray magnetic circular dichroism (XMCD). The spin-splitting energies are directly measured and visualized by the shift in their Landau-fan diagram mapped by analyzing the measured Shubnikov-de-Haas (SdH) oscillations as a function of applied electric fields, showing consistent fit with the first-principles and machine learning calculations. Further, the observed spin-splitting energies can be tuned over a broad range between 98 and 166 meV by field cooling. The methods and results are applicable to other 2D (magnetic) materials and heterostructures, and offer great potential for developing next-generation spin logic and memory devices.
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Affiliation(s)
- Junxiong Hu
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Yulei Han
- International Center for Quantum Design of Functional Materials, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
- Department of Physics, Fuzhou University, Fuzhou, Fujian, 350108, China
| | - Xiao Chi
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Ganesh Ji Omar
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Mohammed Mohammed Esmail Al Ezzi
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Jian Gou
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Rusydi Andrivo
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Zhenhua Qiao
- International Center for Quantum Design of Functional Materials, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and 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
| | - A Ariando
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
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3
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Kong D, Zhang S, Guo M, Li S, Wang Q, Gou J, Wu Y, Chen Y, Yang Y, Dai C, Tian Z, Wee ATS, Liu Y, Wei D. Ultra-Fast Single-Nucleotide-Variation Detection Enabled by Argonaute-Mediated Transistor Platform. Adv Mater 2024; 36:e2307366. [PMID: 37805919 DOI: 10.1002/adma.202307366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 10/03/2023] [Indexed: 10/09/2023]
Abstract
"Test-and-go" single-nucleotide variation (SNV) detection within several minutes remains challenging, especially in low-abundance samples, since existing methods face a trade-off between sensitivity and testing speed. Sensitive detection usually relies on complex and time-consuming nucleic acid amplification or sequencing. Here, a graphene field-effect transistor (GFET) platform mediated by Argonaute protein that enables rapid, sensitive, and specific SNV detection is developed. The Argonaute protein provides a nanoscale binding channel to preorganize the DNA probe, accelerating target binding and rapidly recognizing SNVs with single-nucleotide resolution in unamplified tumor-associated microRNA, circulating tumor DNA, virus RNA, and reverse transcribed cDNA when a mismatch occurs in the seed region. An integrated microchip simultaneously detects multiple SNVs in agreement with sequencing results within 5 min, achieving the fastest SNV detection in a "test-and-go" manner without the requirement of nucleic acid extraction, reverse transcription, and amplification.
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Affiliation(s)
- Derong Kong
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, P. R. China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, P. R. China
| | - Shen Zhang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, P. R. China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, P. R. China
| | - Mingquan Guo
- Department of Laboratory Medicine, Shanghai Public Health Clinical Center, Fudan University, Shanghai, 200433, P. R. China
| | - Shenwei Li
- Shanghai International Travel Healthcare Center, Shanghai, 200335, P. R. China
| | - Qiang Wang
- Shanghai International Travel Healthcare Center, Shanghai, 200335, P. R. China
| | - Jian Gou
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Yungen Wu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, P. R. China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, P. R. China
| | - Yiheng Chen
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, P. R. China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, P. R. China
| | - Yuetong Yang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, P. R. China
| | - Changhao Dai
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, P. R. China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, P. R. China
| | - Zhengan Tian
- Shanghai International Travel Healthcare Center, Shanghai, 200335, P. R. China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Yunqi Liu
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, P. R. China
- Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Dacheng Wei
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, P. R. China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai, 200433, P. R. China
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4
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Gao W, Dou W, Zhou D, Song B, Niu T, Hua C, Wee ATS, Zhou M. Epitaxial Growth of 2D Binary Phosphides. Small Methods 2024:e2301512. [PMID: 38175841 DOI: 10.1002/smtd.202301512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Indexed: 01/06/2024]
Abstract
Combinations of phosphorus with main group III, IV, and V elements are theoretically predicted to generate 2D binary phosphides with extraordinary properties and promising applications. However, experimental synthesis is significantly lacking. Here, a general approach for preparing 2D binary phosphides is reported using single crystalline surfaces containing the constituent element of target 2D materials as the substrate. To validate this, SnP3 and BiP, representing typical 2D binary phosphides, are successfully synthesized on Cu2 Sn and bismuthene, respectively. Scanning tunneling microscopy imaging reveals a hexagonal pattern of SnP3 on Cu2 Sn, while α-BiP can be epitaxially grown on the α-bismuthene domain on Cu2 Sb. First-principles calculations reveal that the formation of SnP3 on Cu2 Sn is associated with strong interface bonding and significant charge transfer, while α-BiP interacts weakly with α-bismuthene so that its semiconducting property is preserved. The study demonstrates an attractive avenue for the atomic-scale growth of binary 2D materials via substrate phase engineering.
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Affiliation(s)
- Wenjin Gao
- Collaborative Center for Physics and Chemistry, Institute of International Innovation, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | - Wenzhen Dou
- Collaborative Center for Physics and Chemistry, Institute of International Innovation, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | - Dechun Zhou
- Collaborative Center for Physics and Chemistry, Institute of International Innovation, Beihang University, Hangzhou, 311115, China
- Department of Physics, National University of Singapore, Singapore, 117551, Singapore
| | - Biyu Song
- Collaborative Center for Physics and Chemistry, Institute of International Innovation, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | - Tianchao Niu
- Collaborative Center for Physics and Chemistry, Institute of International Innovation, Beihang University, Hangzhou, 311115, China
| | - Chenqiang Hua
- Collaborative Center for Physics and Chemistry, Institute of International Innovation, Beihang University, Hangzhou, 311115, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117551, Singapore
| | - Miao Zhou
- Collaborative Center for Physics and Chemistry, Institute of International Innovation, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
- Tianmushan Laboratory, Hangzhou, 310023, China
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5
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Whitcher TJ, Fauzi AD, Diao C, Chi X, Syahroni A, Asmara TC, Breese MBH, Castro Neto AH, Wee ATS, Majidi MA, Rusydi A. Reply to: Reassessing the existence of soft X-ray correlated plasmons. Nat Commun 2023; 14:6754. [PMID: 37875490 PMCID: PMC10597986 DOI: 10.1038/s41467-023-40652-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 08/01/2023] [Indexed: 10/26/2023] Open
Affiliation(s)
- T J Whitcher
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore.
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore.
- Centre for Advanced 2D Materials, National University of Singapore, 2 Science Drive 3, Singapore, 117546, Singapore.
| | - A D Fauzi
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - C Diao
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - X Chi
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - A Syahroni
- Department of Physics, University of Indonesia, Depok, 16424, Indonesia
| | - T C Asmara
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore
| | - M B H Breese
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - A H Castro Neto
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, Singapore, 117456, Singapore
| | - A T S Wee
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, Singapore, 117456, Singapore
| | - M A Majidi
- Department of Physics, University of Indonesia, Depok, 16424, Indonesia
| | - A Rusydi
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore.
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore.
- Centre for Advanced 2D Materials, National University of Singapore, 2 Science Drive 3, Singapore, 117546, Singapore.
- NUS Graduate School for Integrative Sciences and Engineering, Singapore, 117456, Singapore.
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6
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Wang X, Xia B, Hao Z, Kang H, Liu W, Chen Y, Jiang Q, Liu J, Gou J, Dong B, Wee ATS, Liu Y, Wei D. A closed-loop catalytic nanoreactor system on a transistor. Sci Adv 2023; 9:eadj0839. [PMID: 37729411 PMCID: PMC10511191 DOI: 10.1126/sciadv.adj0839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 08/17/2023] [Indexed: 09/22/2023]
Abstract
Precision chemistry demands miniaturized catalytic systems for sophisticated reactions with well-defined pathways. An ideal solution is to construct a nanoreactor system functioning as a chemistry laboratory to execute a full chemical process with molecular precision. However, existing nanoscale catalytic systems fail to in situ control reaction kinetics in a closed-loop manner, lacking the precision toward ultimate reaction efficiency. We find an inter-electrochemical gating effect when operating DNA framework-constructed enzyme cascade nanoreactors on a transistor, enabling in situ closed-loop reaction monitoring and modulation electrically. Therefore, a comprehensive system is developed, encapsulating nanoreactors, analyzers, and modulators, where the gate potential modulates enzyme activity and switches cascade reaction "ON" or "OFF." Such electric field-effect property enhances catalytic efficiency of enzyme by 343.4-fold and enables sensitive sarcosine assay for prostate cancer diagnoses, with a limit of detection five orders of magnitude lower than methodologies in clinical laboratory. By coupling with solid-state electronics, this work provides a perspective to construct intelligent nano-systems for precision chemistry.
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Affiliation(s)
- Xuejun Wang
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China
- Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai 200433, China
| | - Binbin Xia
- Institute of Molecular Medicine, Department of Urology, Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Zhuang Hao
- School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Hua Kang
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China
- Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai 200433, China
| | - Wentao Liu
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China
- Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai 200433, China
| | - Yiheng Chen
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China
- Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai 200433, China
| | - Qunfeng Jiang
- Department of Physics, Fudan University, Shanghai 200433, China
| | - Jingyuan Liu
- Global Clinical Operation, Johnson & Johnson, Shanghai 200233, China
| | - Jian Gou
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Baijun Dong
- Institute of Molecular Medicine, Department of Urology, Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Yunqi Liu
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai 200433, China
| | - Dacheng Wei
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China
- Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Laboratory of Molecular Materials and Devices, Fudan University, Shanghai 200433, China
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7
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Hu J, Tan J, Al Ezzi MM, Chattopadhyay U, Gou J, Zheng Y, Wang Z, Chen J, Thottathil R, Luo J, Watanabe K, Taniguchi T, Wee ATS, Adam S, Ariando A. Controlled alignment of supermoiré lattice in double-aligned graphene heterostructures. Nat Commun 2023; 14:4142. [PMID: 37438404 DOI: 10.1038/s41467-023-39893-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 06/30/2023] [Indexed: 07/14/2023] Open
Abstract
The supermoiré lattice, built by stacking two moiré patterns, provides a platform for creating flat mini-bands and studying electron correlations. An ultimate challenge in assembling a graphene supermoiré lattice is in the deterministic control of its rotational alignment, which is made highly aleatory due to the random nature of the edge chirality and crystal symmetry. Employing the so-called "golden rule of three", here we present an experimental strategy to overcome this challenge and realize the controlled alignment of double-aligned hBN/graphene/hBN supermoiré lattice, where the twist angles between graphene and top/bottom hBN are both close to zero. Remarkably, we find that the crystallographic edge of neighboring graphite can be used to better guide the stacking alignment, as demonstrated by the controlled production of 20 moiré samples with an accuracy better than ~ 0.2°. Finally, we extend our technique to low-angle twisted bilayer graphene and ABC-stacked trilayer graphene, providing a strategy for flat-band engineering in these moiré materials.
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Affiliation(s)
- Junxiong Hu
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Junyou Tan
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Mohammed M Al Ezzi
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Udvas Chattopadhyay
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Jian Gou
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Yuntian Zheng
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Zihao Wang
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
| | - Jiayu Chen
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Reshmi Thottathil
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Jiangbo Luo
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Shaffique Adam
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - A Ariando
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore.
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8
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Gou J, Bai H, Zhang X, Huang YL, Duan S, Ariando A, Yang SA, Chen L, Lu Y, Wee ATS. Two-dimensional ferroelectricity in a single-element bismuth monolayer. Nature 2023; 617:67-72. [PMID: 37020017 PMCID: PMC10156600 DOI: 10.1038/s41586-023-05848-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 02/15/2023] [Indexed: 04/07/2023]
Abstract
Ferroelectric materials are fascinating for their non-volatile switchable electric polarizations induced by the spontaneous inversion-symmetry breaking. However, in all of the conventional ferroelectric compounds, at least two constituent ions are required to support the polarization switching1,2. Here, we report the observation of a single-element ferroelectric state in a black phosphorus-like bismuth layer3, in which the ordered charge transfer and the regular atom distortion between sublattices happen simultaneously. Instead of a homogenous orbital configuration that ordinarily occurs in elementary substances, we found the Bi atoms in a black phosphorous-like Bi monolayer maintain a weak and anisotropic sp orbital hybridization, giving rise to the inversion-symmetry-broken buckled structure accompanied with charge redistribution in the unit cell. As a result, the in-plane electric polarization emerges in the Bi monolayer. Using the in-plane electric field produced by scanning probe microscopy, ferroelectric switching is further visualized experimentally. Owing to the conjugative locking between the charge transfer and atom displacement, we also observe the anomalous electric potential profile at the 180° tail-to-tail domain wall induced by competition between the electronic structure and electric polarization. This emergent single-element ferroelectricity broadens the mechanism of ferroelectrics and may enrich the applications of ferroelectronics in the future.
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Affiliation(s)
- Jian Gou
- Department of Physics, National University of Singapore, Singapore, Singapore.
| | - Hua Bai
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
- Department of Physics, Faculty of Science, Kunming University of Science and Technology, Kunming, China
| | - Xuanlin Zhang
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
| | - Yu Li Huang
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou, China
| | - Sisheng Duan
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - A Ariando
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, Singapore
| | - Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing, China.
- School of Physics, University of Chinese Academy of Sciences, Beijing, China.
| | - Yunhao Lu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China.
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, Singapore.
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, Singapore, Singapore.
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9
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Wang D, Wang Z, Liu W, Zhong S, Feng YP, Loh KP, Wee ATS. Real-Space Investigation of the Multiple Halogen Bonds by Ultrahigh-Resolution Scanning Probe Microscopy. Small 2022; 18:e2202368. [PMID: 35719029 DOI: 10.1002/smll.202202368] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Indexed: 06/15/2023]
Abstract
The chemical bond is of central interest in chemistry, and it is of significance to study the nature of intermolecular bonds in real-space. Herein, non-contact atomic force microscopy (nc-AFM) and low-temperature scanning tunneling microscopy (LT-STM) are employed to acquire real-space atomic information of molecular clusters, i.e., monomer, dimer, trimer, tetramer, formed on Au(111). The formation of the various molecular clusters is due to the diversity of halogen bonds. DFT calculation also suggests the formation of three distinct halogen bonds among the molecular clusters, which originates from the noncovalent interactions of Br-atoms with the positive potential H-atoms, neutral potential Br-atoms, and negative potential N-atoms, respectively. This work demonstrates the real-space investigation of the multiple halogen bonds by nc-AFM/LT-STM, indicating the potential use of this technique to study other intermolecular bonds and to understand complex supramolecular assemblies at the atomic/sub-molecular level.
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Affiliation(s)
- Dingguan Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Zishen Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Wei Liu
- School of Physics, Southeast University, 2 Southeast University Road, Nanjing, China
| | - Siying Zhong
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
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10
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Whitcher TJ, Fauzi AD, Caozheng D, Chi X, Syahroni A, Asmara TC, Breese MBH, Neto AHC, Wee ATS, Majidi MA, Rusydi A. Unravelling strong electronic interlayer and intralayer correlations in a transition metal dichalcogenide. Nat Commun 2021; 12:6980. [PMID: 34848717 PMCID: PMC8632915 DOI: 10.1038/s41467-021-27182-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 10/27/2021] [Indexed: 11/23/2022] Open
Abstract
Electronic correlations play important roles in driving exotic phenomena in condensed matter physics. They determine low-energy properties through high-energy bands well-beyond optics. Great effort has been made to understand low-energy excitations such as low-energy excitons in transition metal dichalcogenides (TMDCs), however their high-energy bands and interlayer correlation remain mysteries. Herewith, by measuring temperature- and polarization-dependent complex dielectric and loss functions of bulk molybdenum disulphide from near-infrared to soft X-ray, supported with theoretical calculations, we discover unconventional soft X-ray correlated-plasmons with low-loss, and electronic transitions that reduce dimensionality and increase correlations, accompanied with significantly modified low-energy excitons. At room temperature, interlayer electronic correlations, together with the intralayer correlations in the c-axis, are surprisingly strong, yielding a three-dimensional-like system. Upon cooling, wide-range spectral-weight transfer occurs across a few tens of eV and in-plane p-d hybridizations become enhanced, revealing strong Coulomb correlations and electronic anisotropy, yielding a two-dimensional-like system. Our result shows the importance of strong electronic, interlayer and intralayer correlations in determining electronic structure and opens up applications of utilizing TMDCs on plasmonic nanolithrography.
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Affiliation(s)
- T J Whitcher
- Advanced Research Initiative for Correlated-Electron Systems (ARiCES), Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore.
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore.
- Centre for Advanced 2D Materials, National University of Singapore, 2 Science Drive 3, Singapore, 117546, Singapore.
| | - Angga Dito Fauzi
- Advanced Research Initiative for Correlated-Electron Systems (ARiCES), Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - D Caozheng
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - X Chi
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 2 Science Drive 3, Singapore, 117546, Singapore
| | - A Syahroni
- Department of Physics, University of Indonesia, Depok, 16424, Indonesia
| | - T C Asmara
- Advanced Research Initiative for Correlated-Electron Systems (ARiCES), Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore
| | - M B H Breese
- Advanced Research Initiative for Correlated-Electron Systems (ARiCES), Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - A H Castro Neto
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - A T S Wee
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - M Aziz Majidi
- Department of Physics, University of Indonesia, Depok, 16424, Indonesia
| | - A Rusydi
- Advanced Research Initiative for Correlated-Electron Systems (ARiCES), Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117576, Singapore.
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore.
- Centre for Advanced 2D Materials, National University of Singapore, 2 Science Drive 3, Singapore, 117546, Singapore.
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore.
- NUS Graduate School for Integrative Sciences and Engineering, Singapore, 117456, Singapore.
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11
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Cao Y, Tan SL, Cheung EJH, Siew SY, Li C, Liu Y, Tang CS, Lal M, Chen G, Dogheche K, Yang P, Pennycook S, Wee ATS, Chua S, Dogheche E, Venkatesan T, Danner A. A Barium Titanate-on-Oxide Insulator Optoelectronics Platform. Adv Mater 2021; 33:e2101128. [PMID: 34323320 DOI: 10.1002/adma.202101128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/08/2021] [Indexed: 06/13/2023]
Abstract
Electro-optic modulators are among the most important building blocks in optical communication networks. Lithium niobate, for example, has traditionally been widely used to fabricate high-speed optical modulators due to its large Pockels effect. Another material, barium titanate, nominally has a 50 times stronger r-parameter and would ordinarily be a more attractive material choice for such modulators or other applications. In practice, barium titanate thin films for optical waveguide devices are usually grown on magnesium oxide due to its low refractive index, allowing vertical mode confinement. However, the crystal quality is normally degraded. Here, a group of scandate-based substrates with small lattice mismatch and low refractive index compared to that of barium titanate is identified, thus concurrently satisfying high crystal quality and vertical optical mode confinement. This work provides a platform for nonlinear on-chip optoelectronics and can be promising for waveguide-based optical devices such as Mach-Zehnder modulators, wavelength division multiplexing, and quantum optics-on-chip.
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Affiliation(s)
- Yu Cao
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Siew Li Tan
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Eric Jun Hao Cheung
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Shawn Yohanes Siew
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Changjian Li
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Yan Liu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Chi Sin Tang
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, University Hall, Tan Chin Tuan Wing, Singapore, 119077, Singapore
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Manohar Lal
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Guanyu Chen
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Karim Dogheche
- Institute of Electronics, Microelectronics, and Nanotechnology, IEMN DOAE, Université Polytechnique Hauts-de-France, Valenciennes, 59309, France
| | - Ping Yang
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Steven Pennycook
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Soojin Chua
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Elhadj Dogheche
- Institute of Electronics, Microelectronics, and Nanotechnology, IEMN DOAE, Université Polytechnique Hauts-de-France, Valenciennes, 59309, France
| | - Thirumalai Venkatesan
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Aaron Danner
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
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12
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Zhu R, Gao Z, Liang Q, Hu J, Wang JS, Qiu CW, Wee ATS. Observation of Anisotropic Magnetoresistance in Layered Nonmagnetic Semiconducting PdSe 2. ACS Appl Mater Interfaces 2021; 13:37527-37534. [PMID: 34333972 DOI: 10.1021/acsami.1c10500] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Anisotropy in crystals usually has remarkable consequences in two-dimensional (2D) materials, for example, black phosphorus, PdSe2, and SnS, arising from different lattice periodicities along different crystallographic directions. Electrical anisotropy has been successfully demonstrated in 2D materials, but anisotropic magnetoresistance in 2D materials is rarely studied. Herein, we report anisotropic magnetoresistance in layered nonmagnetic semiconducting PdSe2 flakes. Anisotropic magnetoresistance along the two crystalline axes under a perpendicular magnetic field is demonstrated, and the magnetoresistance along the a-axis is apparently different from the magnetoresistance along the b-axis. The magnetoresistance can also be flexibly tuned by applying a gate voltage, leveraging the semiconductor properties of PdSe2. The computed anisotropic electronic density of states and electronic mobility with ab initio density functional calculations support the anisotropic and measured magnetoresistance. Our findings advance the understanding of magnetoresistance in anisotropic transition-metal dichalcogenides and pave the way for potential applications in anisotropic spintronic devices.
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Affiliation(s)
- Rui Zhu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Zhibin Gao
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
| | - Qijie Liang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
- Songshan Lake Materials Laboratory, Songshan Lake Mat Lab, Dongguan 523808, China
| | - Junxiong Hu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Jian-Sheng Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
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13
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Gou J, Xia B, Wang X, Cheng P, Wee ATS, Duan W, Xu Y, Wu K, Chen L. Realizing quinary charge states of solitary defects in two-dimensional intermetallic semiconductor. Natl Sci Rev 2021; 9:nwab070. [PMID: 35233286 PMCID: PMC8881213 DOI: 10.1093/nsr/nwab070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/17/2021] [Accepted: 04/02/2021] [Indexed: 11/14/2022] Open
Abstract
Abstract
Creating and manipulating multiple charge states of solitary defects in semiconductors is of essential importance for solitary defect electronics, but is fundamentally limited by Coulomb's law. Achieving this objective is challenging, due to the conflicting requirements of the localization necessary for the sizable band gap and delocalization necessary for a low charging energy. Here, using scanning tunneling microscopy/spectroscopy experiments and first-principles calculations, we realized exotic quinary charge states of solitary defects in two-dimensional intermetallic semiconductor Sn2Bi. We also observed an ultralow defect charging energy that increases sublinearly with charge number rather than displaying the usual quadratic behavior. Our work suggests a promising route for constructing multiple defect-charge states by designing intermetallic semiconductors, and opens new opportunities for developing quantum devices with charge-based quantum states.
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Affiliation(s)
- Jian Gou
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
- Department of Physics, National University of Singapore, Singapore117542, Singapore
| | - Bingyu Xia
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xuguang Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Cheng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore117542, Singapore
| | - Wenhui Duan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Yong Xu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Kehui Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
| | - Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
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14
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Wong HF, Ng SM, Zhang W, Liu YK, Wong PKJ, Tang CS, Lam KK, Zhao XW, Meng ZG, Fei LF, Cheng WF, Nordheim DV, Wong WY, Wang ZR, Ploss B, Dai JY, Mak CL, Wee ATS, Leung CW. Modulating Magnetism in Ferroelectric Polymer-Gated Perovskite Manganite Films with Moderate Gate Pulse Chains. ACS Appl Mater Interfaces 2020; 12:56541-56548. [PMID: 33283518 DOI: 10.1021/acsami.0c14172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Most previous attempts on achieving electric-field manipulation of ferromagnetism in complex oxides, such as La0.66Sr0.33MnO3 (LSMO), are based on electrostatically induced charge carrier changes through high-k dielectrics or ferroelectrics. Here, the use of a ferroelectric copolymer, polyvinylidene fluoride with trifluoroethylene [P(VDF-TrFE)], as a gate dielectric to successfully modulate the ferromagnetism of the LSMO thin film in a field-effect device geometry is demonstrated. Specifically, through the application of low-voltage pulse chains inadequate to switch the electric dipoles of the copolymer, enhanced tunability of the oxide magnetic response is obtained, compared to that induced by ferroelectric polarization. Such observations have been attributed to electric field-induced oxygen vacancy accumulation/depletion in the LSMO layer upon the application of pulse chains, which is supported by surface-sensitive-characterization techniques, including X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism. These techniques not only unveil the electrochemical nature of the mechanism but also establish a direct correlation between the oxygen vacancies created and subsequent changes to the valence states of Mn ions in LSMO. These demonstrations based on the pulsing strategy can be a viable route equally applicable to other functional oxides for the construction of electric field-controlled magnetic devices.
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Affiliation(s)
- Hon Fai Wong
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Sheung Mei Ng
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Wen Zhang
- School of Electronics and Information and School of Microelectronics, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Yu Kuai Liu
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Ping Kwan Johnny Wong
- School of Electronics and Information and School of Microelectronics, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Chi Sin Tang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Ka Kin Lam
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Xu Wen Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Zhen Gong Meng
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Lin Feng Fei
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Wang Fai Cheng
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Danny von Nordheim
- Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany
| | - Wai Yeung Wong
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Zong Rong Wang
- State Key Lab of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Bernd Ploss
- Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany
| | - Ji-Yan Dai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
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15
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Hu J, Gou J, Yang M, Omar GJ, Tan J, Zeng S, Liu Y, Han K, Lim Z, Huang Z, Wee ATS, Ariando A. Room-Temperature Colossal Magnetoresistance in Terraced Single-Layer Graphene. Adv Mater 2020; 32:e2002201. [PMID: 32743844 DOI: 10.1002/adma.202002201] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/21/2020] [Indexed: 05/28/2023]
Abstract
Disorder-induced magnetoresistance (MR) effect is quadratic at low perpendicular magnetic fields and linear at high fields. This effect is technologically appealing, especially in 2D materials such as graphene, since it offers potential applications in magnetic sensors with nanoscale spatial resolution. However, it is a great challenge to realize a graphene magnetic sensor based on this effect because of the difficulty in controlling the spatial distribution of disorder and enhancing the MR sensitivity in the single-layer regime. Here, a room-temperature colossal MR of up to 5000% at 9 T is reported in terraced single-layer graphene. By laminating single-layer graphene on a terraced substrate, such as TiO2 -terminated SrTiO3 , a universal one order of magnitude enhancement in the MR compared to conventional single-layer graphene devices is demonstrated. Strikingly, a colossal MR of >1000% is also achieved in the terraced graphene even at a high carrier density of ≈1012 cm-2 . Systematic studies of the MR of single-layer graphene on various oxide- and non-oxide-based terraced surfaces demonstrate that the terraced structure is the dominant factor driving the MR enhancement. The results open a new route for tailoring the physical property of 2D materials by engineering the strain through a terraced substrate.
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Affiliation(s)
- Junxiong Hu
- NUSNNI, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Jian Gou
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Ming Yang
- Institute of Materials Research & Engineering, A*STAR (Agency for Science, Technology and Research), Singapore, 138634, Singapore
| | - Ganesh Ji Omar
- NUSNNI, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Junyou Tan
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Shengwei Zeng
- NUSNNI, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Yanpeng Liu
- State Key Laboratory of Mechanics and Control of Mechanical Structures, MOE Key Laboratory for Intelligent Nano Materials and Devices and Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China
| | - Kun Han
- NUSNNI, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Zhishiuh Lim
- NUSNNI, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Zhen Huang
- NUSNNI, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Ariando Ariando
- NUSNNI, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
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16
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Yi K, Jin Z, Bu S, Wang D, Liu D, Huang Y, Dong Y, Yuan Q, Liu Y, Wee ATS, Wei D. Catalyst-Free Growth of Two-Dimensional BC xN Materials on Dielectrics by Temperature-Dependent Plasma-Enhanced Chemical Vapor Deposition. ACS Appl Mater Interfaces 2020; 12:33113-33120. [PMID: 32574487 DOI: 10.1021/acsami.0c08555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Traditional methods to prepare two-dimensional (2D) B-C-N ternary materials (BCxN), such as chemical vapor deposition (CVD), require sophisticated experimental conditions such as high temperature, delicate control of precursors, and postgrowth transfer from catalytic substrates, and the products are generally thick or bulky films without the atomically mixed phase of B-C-N, hampering practical applications of these materials. Here, for the first time, we develop a temperature-dependent plasma-enhanced chemical vapor deposition (PECVD) method to grow 2D BCxN materials directly on noncatalytic dielectrics at low temperature with high controllability. The C, N, and B compositions can be tuned by simply changing the growth temperature. Thus, the properties of the as-made materials including band gap and conductivity are modulated, which is hardly achieved by other methods. A 2D hybridized BC2N film with a mixed BC2N phase is produced, for the first time, with a band gap of about 2.3 eV. The growth temperature is 580-620 °C, much lower than that of traditional catalytic CVD for growing BCxN. The product has a p-type conducting property and can be directly applied in field-effect transistors and sensors without postgrowth transfer, showing great promise for this method in future applications.
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Affiliation(s)
- Kongyang Yi
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Institute of Molecular Materials and Devices, Fudan University, 200433 Shanghai, China
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200092, China
| | - Zhepeng Jin
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Institute of Molecular Materials and Devices, Fudan University, 200433 Shanghai, China
| | - Saiyu Bu
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200062, China
| | - Dingguan Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Donghua Liu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Institute of Molecular Materials and Devices, Fudan University, 200433 Shanghai, China
| | - Yamin Huang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200092, China
| | - Yemin Dong
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200092, China
| | - Qinghong Yuan
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200062, China
| | - Yunqi Liu
- Institute of Molecular Materials and Devices, Fudan University, 200433 Shanghai, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Dacheng Wei
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
- Institute of Molecular Materials and Devices, Fudan University, 200433 Shanghai, China
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17
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Gou J, Kong L, He X, Huang YL, Sun J, Meng S, Wu K, Chen L, Wee ATS. The effect of moiré superstructures on topological edge states in twisted bismuthene homojunctions. Sci Adv 2020; 6:eaba2773. [PMID: 32537502 PMCID: PMC7269654 DOI: 10.1126/sciadv.aba2773] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 04/08/2020] [Indexed: 06/11/2023]
Abstract
Creating and controlling the topological properties of two-dimensional topological insulators is essential for spintronic device applications. Here, we report the successful growth of bismuth homostructure consisting of monolayer bismuthene and single-layer black phosphorus-like Bi (BP-Bi) on the HOPG surface. Combining scanning tunneling microscopy/spectroscopy with noncontact atomic force microscopy, moiré superstructures with twist angles in the bismuth homostructure and the modulation of topological edge states of bismuthene were observed and studied. First-principles calculations reproduced the moiré superlattice and indicated that the structure fluctuation is ascribed to the stacking modes between bismuthene and BP-Bi, which induce spatially distributed interface interactions in the bismuth homostructure. The modulation of topological edge states is directly related to the variation of interlayer interactions. Our results suggest a promising pathway to tailor the topological states through interfacial interactions.
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Affiliation(s)
- Jian Gou
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Longjuan Kong
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoyue He
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Yu Li Huang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Jiatao Sun
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
- School of Information and Electronics, Key Laboratory for Low-dimensional Quantum Structure and Devices of Ministry of Industry and Information Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Sheng Meng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kehui Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, Singapore 117546, Singapore
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18
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Lee HG, Wang L, Si L, He X, Porter DG, Kim JR, Ko EK, Kim J, Park SM, Kim B, Wee ATS, Bombardi A, Zhong Z, Noh TW. Atomic-Scale Metal-Insulator Transition in SrRuO 3 Ultrathin Films Triggered by Surface Termination Conversion. Adv Mater 2020; 32:e1905815. [PMID: 31830343 DOI: 10.1002/adma.201905815] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/12/2019] [Indexed: 06/10/2023]
Abstract
The metal-insulator transition (MIT) in transition-metal-oxide is fertile ground for exploring intriguing physics and potential device applications. Here, an atomic-scale MIT triggered by surface termination conversion in SrRuO3 ultrathin films is reported. Uniform and effective termination engineering at the SrRuO3 (001) surface can be realized via a self-limiting water-leaching process. As the surface termination converts from SrO to RuO2 , a highly insulating and nonferromagnetic phase emerges within the topmost SrRuO3 monolayer. Such a spatially confined MIT is corroborated by systematic characterizations on electrical transport, magnetism, and scanning tunneling spectroscopy. Density functional theory calculations and X-ray linear dichroism further suggest that the surface termination conversion breaks the local octahedral symmetry of the crystal field. The resultant modulation in 4d orbital occupancy stabilizes a nonferromagnetic insulating surface state. This work introduces a new paradigm to stimulate and tune exotic functionalities of oxide heterostructures with atomic precision.
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Affiliation(s)
- Han Gyeol Lee
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Lingfei Wang
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Liang Si
- Key Laboratory of Magnetic Materials and Devices & Zhejiang Province, Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Institut für Festkörperphysik, Vienna, 1040, Austria
| | - Xiaoyue He
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Songshan Lake Materials Laboratory, Dongguan, 523808, P. R. China
| | - Daniel G Porter
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Eun Kyo Ko
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jinkwon Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sung Min Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Bongju Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Alessandro Bombardi
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Zhicheng Zhong
- Key Laboratory of Magnetic Materials and Devices & Zhejiang Province, Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- China Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
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19
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Xie A, Yin X, Tang CS, Fauzi AD, Chi X, Diao C, Sahdan MF, Birowosuto MD, Dang C, Rusydi A, Wee ATS. Electronic Modulation in Site-Selective Occupation of Quasi-2D Triangular-Lattice Cs 2CuCl 4-xBr x Perovskite Probed by Surface-Sensitive Characterization. ACS Appl Mater Interfaces 2020; 12:4114-4122. [PMID: 31927903 DOI: 10.1021/acsami.9b19517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A controllable electronic manipulation in a frustrated magnetic system such as solution-based two-dimensional (2D) all-inorganic perovskites offers a possible route for their integrations with electronic and magnetic devices for their advanced applications. Here, we perform element-specific investigations of an emergent class of quasi-2D all-inorganic perovskites Cs2CuCl4-xBrx with (0 ≤ x ≤ 4) using a combination of synchrotron-radiation photoelectron techniques. Surface- and element-sensitive X-ray absorption spectroscopy spectra of Cu L2,3 edges indicate strong electronic transition that is largely influenced by their halogen content at room temperature. This implies that site-selective occupation largely dominates the electronic transition across the unoccupied states of these series since chlorine atoms possess a stronger electronegative character than bromine atoms. Moreover, the implication of halogen site is reflected in the valence band of Cl-rich copper perovskite in which the valence band edge is closer to Fermi energy (EF) than that of the Br-rich compound. Furthermore, X-ray magnetic circular dichroism spectra of mixed ratio and Br-rich compounds exhibit antiferromagnetism at room temperature. These site-specific magnetic-spectroscopic results are corroborated by density functional theory calculations. The strong electronic modulation and the local magnetic spectroscopy results in these solution-based and low-temperature-growth materials will pave the way toward energy- and cost-efficient perovskite devices.
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Affiliation(s)
- Aozhen Xie
- CINTRA UMI CNRS/NTU/THALES , Singapore 637553 , Singapore
- School of Electrical and Electronic Engineering , Nanyang Technological University , Singapore 639798 , Singapore
- Energy Research Institute@NTU (ERI@N) , Nanyang Technological University , Singapore 637553 , Singapore
| | - Xinmao Yin
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
| | - Chi Sin Tang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
- NUS Graduate School for Integrative Sciences and Engineering , National University of Singapore , Singapore 117456 , Singapore
| | - Angga Dito Fauzi
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
| | - Xiao Chi
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
| | - Caozheng Diao
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
| | - Muhammad Fauzi Sahdan
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
| | - Muhammad Danang Birowosuto
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Energy Research Institute@NTU (ERI@N) , Nanyang Technological University , Singapore 637553 , Singapore
| | - Cuong Dang
- CINTRA UMI CNRS/NTU/THALES , Singapore 637553 , Singapore
- School of Electrical and Electronic Engineering , Nanyang Technological University , Singapore 639798 , Singapore
- Energy Research Institute@NTU (ERI@N) , Nanyang Technological University , Singapore 637553 , Singapore
| | - Andrivo Rusydi
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 5 Research Link , Singapore 117603 , Singapore
- NUS Graduate School for Integrative Sciences and Engineering , National University of Singapore , Singapore 117456 , Singapore
- NUSNNI-NanoCore , National University of Singapore , Singapore 117411 , Singapore
| | - Andrew Thye Shen Wee
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
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20
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Hong X, Hu G, Zhao W, Wang K, Sun S, Zhu R, Wu J, Liu W, Loh KP, Wee ATS, Wang B, Alù A, Qiu CW, Lu P. Structuring Nonlinear Wavefront Emitted from Monolayer Transition-Metal Dichalcogenides. Research (Wash D C) 2020; 2020:9085782. [PMID: 32328579 PMCID: PMC7163797 DOI: 10.34133/2020/9085782] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 03/02/2020] [Indexed: 04/29/2023]
Abstract
The growing demand for tailored nonlinearity calls for a structure with unusual phase discontinuity that allows the realization of nonlinear optical chirality, holographic imaging, and nonlinear wavefront control. Transition-metal dichalcogenide (TMDC) monolayers offer giant optical nonlinearity within a few-angstrom thickness, but limitations in optical absorption and domain size impose restriction on wavefront control of nonlinear emissions using classical light sources. In contrast, noble metal-based plasmonic nanosieves support giant field enhancements and precise nonlinear phase control, with hundred-nanometer pixel-level resolution; however, they suffer from intrinsically weak nonlinear susceptibility. Here, we report a multifunctional nonlinear interface by integrating TMDC monolayers with plasmonic nanosieves, yielding drastically different nonlinear functionalities that cannot be accessed by either constituent. Such a hybrid nonlinear interface allows second-harmonic (SH) orbital angular momentum (OAM) generation, beam steering, versatile polarization control, and holograms, with an effective SH nonlinearity χ (2) of ~25 nm/V. This designer platform synergizes the TMDC monolayer and plasmonic nanosieves to empower tunable geometric phases and large field enhancement, paving the way toward multifunctional and ultracompact nonlinear optical devices.
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Affiliation(s)
- Xuanmiao Hong
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Guangwei Hu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583
- Advanced Science Research Center, City University of New York, New York 10031, USA
| | - Wenchao Zhao
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Kai Wang
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Shang Sun
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583
| | - Rui Zhu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Jing Wu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634
| | - Weiwei Liu
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 17543
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, Block S14, 6 Science Drive 2, Singapore 117546
| | - Bing Wang
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Andrea Alù
- Advanced Science Research Center, City University of New York, New York 10031, USA
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583
| | - Peixiang Lu
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Optical Information and Pattern Recognition, Wuhan Institute of Technology, Wuhan 430205, China
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21
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Liu S, Yang K, Liu W, Zhang E, Li Z, Zhang X, Liao Z, Zhang W, Sun J, Yang Y, Gao H, Huang C, Ai L, Wong PKJ, Wee ATS, N’Diaye AT, Morton SA, Kou X, Zou J, Xu Y, Wu H, Xiu F. Two-dimensional ferromagnetic superlattices. Natl Sci Rev 2019; 7:745-754. [PMID: 34692093 PMCID: PMC8289050 DOI: 10.1093/nsr/nwz205] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/02/2019] [Accepted: 12/13/2019] [Indexed: 11/14/2022] Open
Abstract
Mechanically exfoliated two-dimensional ferromagnetic materials (2D FMs) possess long-range ferromagnetic order and topologically nontrivial skyrmions in few layers. However, because of the dimensionality effect, such few-layer systems usually exhibit much lower Curie temperature (TC) compared to their bulk counterparts. It is therefore of great interest to explore effective approaches to enhance their TC, particularly in wafer-scale for practical applications. Here, we report an interfacial proximity-induced high-TC 2D FM Fe3GeTe2 (FGT) via A-type antiferromagnetic material CrSb (CS) which strongly couples to FGT. A superlattice structure of (FGT/CS)n, where n stands for the period of FGT/CS heterostructure, has been successfully produced with sharp interfaces by molecular-beam epitaxy on 2-inch wafers. By performing elemental specific X-ray magnetic circular dichroism (XMCD) measurements, we have unequivocally discovered that TC of 4-layer Fe3GeTe2 can be significantly enhanced from 140 K to 230 K because of the interfacial ferromagnetic coupling. Meanwhile, an inverse proximity effect occurs in the FGT/CS interface, driving the interfacial antiferromagnetic CrSb into a ferrimagnetic state as evidenced by double-switching behavior in hysteresis loops and the XMCD spectra. Density functional theory calculations show that the Fe-Te/Cr-Sb interface is strongly FM coupled and doping of the spin-polarized electrons by the interfacial Cr layer gives rise to the TC enhancement of the Fe3GeTe2 films, in accordance with our XMCD measurements. Strikingly, by introducing rich Fe in a 4-layer FGT/CS superlattice, TC can be further enhanced to near room temperature. Our results provide a feasible approach for enhancing the magnetic order of few-layer 2D FMs in wafer-scale and render opportunities for realizing realistic ultra-thin spintronic devices.
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Affiliation(s)
- Shanshan Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Ke Yang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai 200433, China
| | - Wenqing Liu
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Enze Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Zihan Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Xiaoqian Zhang
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Zhiming Liao
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
| | - Wen Zhang
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Jiabao Sun
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Yunkun Yang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Han Gao
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
| | - Ce Huang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Linfeng Ai
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
| | - Alpha T N’Diaye
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Simon A Morton
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Xufeng Kou
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jin Zou
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane QLD 4072, Australia
| | - Yongbing Xu
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Hua Wu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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22
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He X, Zhang L, Chua R, Wong PKJ, Arramel A, Feng YP, Wang SJ, Chi D, Yang M, Huang YL, Wee ATS. Selective self-assembly of 2,3-diaminophenazine molecules on MoSe 2 mirror twin boundaries. Nat Commun 2019; 10:2847. [PMID: 31253803 PMCID: PMC6599086 DOI: 10.1038/s41467-019-10801-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 06/03/2019] [Indexed: 11/25/2022] Open
Abstract
The control of the density and type of line defects on two-dimensional (2D) materials enable the development of new methods to tailor their physical and chemical properties. In particular, mirror twin boundaries (MTBs) on transition metal dichacogenides have attracted much interest due to their metallic state with charge density wave transition and spin-charge separation property. In this work, we demonstrate the self-assembly of 2,3-diaminophenazine (DAP) molecule porous structure with alternate L-type and T-type aggregated configurations on the MoSe2 hexagonal wagon-wheel pattern surface. This site-specific molecular self-assembly is attributed to the more chemically reactive metallic MTBs compared to the pristine semiconducting MoSe2 domains. First-principles calculations reveal that the active MTBs couple with amino groups in the DAP molecules facilitating the DAP assembly. Our results demonstrate the site-dependent electronic and chemical properties of MoSe2 monolayers, which can be exploited as a natural template to create ordered nanostructures.
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Affiliation(s)
- Xiaoyue He
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Lei Zhang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Rebekah Chua
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- NUS Graduate School for Integrative Sciences & Engineering (NGS), National University of Singapore, 28 Medical Drive, Singapore, 117456, Singapore
| | - Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, Singapore, 117546, Singapore
| | - Arramel Arramel
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Shi Jie Wang
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore
| | - Dongzhi Chi
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore
| | - Ming Yang
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore.
| | - Yu Li Huang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore.
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, Singapore, 117546, Singapore.
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23
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Liang Q, Wang Q, Zhang Q, Wei J, Lim SX, Zhu R, Hu J, Wei W, Lee C, Sow C, Zhang W, Wee ATS. High-Performance, Room Temperature, Ultra-Broadband Photodetectors Based on Air-Stable PdSe 2. Adv Mater 2019; 31:e1807609. [PMID: 31025440 DOI: 10.1002/adma.201807609] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 03/31/2019] [Indexed: 05/12/2023]
Abstract
Photodetection over a broad spectral range is crucial for optoelectronic applications such as sensing, imaging, and communication. Herein, a high-performance ultra-broadband photodetector based on PdSe2 with unique pentagonal atomic structure is reported. The photodetector responds from visible to mid-infrared range (up to ≈4.05 µm), and operates stably in ambient and at room temperature. It promises improved applications compared to conventional mid-infrared photodetectors. The highest responsivity and external quantum efficiency achieved are 708 A W-1 and 82 700%, respectively, at the wavelength of 1064 nm. Efficient optical absorption beyond 8 µm is observed, indicating that the photodetection range can extend to longer than 4.05 µm. Owing to the low crystalline symmetry of layered PdSe2 , anisotropic properties of the photodetectors are observed. This emerging material shows potential for future infrared optoelectronics and novel devices in which anisotropic properties are desirable.
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Affiliation(s)
- Qijie Liang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Qixing Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Qian Zhang
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117574, Singapore
| | - Jingxuan Wei
- Department of Electrical and Computer Engineering, National University of, Singapore, 117583, Singapore
| | - Sharon Xiaodai Lim
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Rui Zhu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Junxiong Hu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Wei Wei
- Department of Electrical and Computer Engineering, National University of, Singapore, 117583, Singapore
| | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of, Singapore, 117583, Singapore
| | - ChorngHaur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, Block S14, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Wenjing Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, Block S14, 6 Science Drive 2, Singapore, 117546, Singapore
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24
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Wong PKJ, Zhang W, Bussolotti F, Yin X, Herng TS, Zhang L, Huang YL, Vinai G, Krishnamurthi S, Bukhvalov DW, Zheng YJ, Chua R, N'Diaye AT, Morton SA, Yang CY, Ou Yang KH, Torelli P, Chen W, Goh KEJ, Ding J, Lin MT, Brocks G, de Jong MP, Castro Neto AH, Wee ATS. Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet. Adv Mater 2019; 31:e1901185. [PMID: 30997712 DOI: 10.1002/adma.201901185] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 03/30/2019] [Indexed: 06/09/2023]
Abstract
Monolayer VSe2 , featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic 2D transition-metal dichalcogenides (2D-TMDs). Herein, by means of in situ microscopy and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X-ray and angle-resolved photoemission, and X-ray absorption, direct spectroscopic signatures are established, that identify the metallic 1T-phase and vanadium 3d1 electronic configuration in monolayer VSe2 grown on graphite by molecular-beam epitaxy. Element-specific X-ray magnetic circular dichroism, complemented with magnetic susceptibility measurements, further reveals monolayer VSe2 as a frustrated magnet, with its spins exhibiting subtle correlations, albeit in the absence of a long-range magnetic order down to 2 K and up to a 7 T magnetic field. This observation is attributed to the relative stability of the ferromagnetic and antiferromagnetic ground states, arising from its atomic-scale structural features, such as rotational disorders and edges. The results of this study extend the current understanding of metallic 2D-TMDs in the search for exotic low-dimensional quantum phenomena, and stimulate further theoretical and experimental studies on van der Waals monolayer magnets.
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Affiliation(s)
- Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Wen Zhang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Fabio Bussolotti
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*Star), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore
| | - Xinmao Yin
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Tun Seng Herng
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Lei Zhang
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Yu Li Huang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Giovanni Vinai
- Instituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. Km 163.5, Trieste, I-34149, Italy
| | - Sridevi Krishnamurthi
- Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Danil W Bukhvalov
- College of Science, Institute of Materials Physics and Chemistry, Nanjing Forestry University, Nanjing, 210037, P. R. China
- Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002, Yekaterinburg, Russia
| | - Yu Jie Zheng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Rebekah Chua
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Alpha T N'Diaye
- Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Simon A Morton
- Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Chao-Yao Yang
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Kui-Hon Ou Yang
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Piero Torelli
- Instituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. Km 163.5, Trieste, I-34149, Italy
| | - Wei Chen
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Department of Chemistry, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Kuan Eng Johnson Goh
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*Star), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore
| | - Jun Ding
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Minn-Tsong Lin
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Geert Brocks
- Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Michel P de Jong
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Antonio H Castro Neto
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Andrew Thye Shen Wee
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
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25
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Liu D, Chen X, Yan Y, Zhang Z, Jin Z, Yi K, Zhang C, Zheng Y, Wang Y, Yang J, Xu X, Chen J, Lu Y, Wei D, Wee ATS, Wei D. Conformal hexagonal-boron nitride dielectric interface for tungsten diselenide devices with improved mobility and thermal dissipation. Nat Commun 2019; 10:1188. [PMID: 30867418 PMCID: PMC6416324 DOI: 10.1038/s41467-019-09016-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 02/05/2019] [Indexed: 11/29/2022] Open
Abstract
Relatively low mobility and thermal conductance create challenges for application of tungsten diselenide (WSe2) in high performance devices. Dielectric interface is of extremely importance for improving carrier transport and heat spreading in a semiconductor device. Here, by near-equilibrium plasma-enhanced chemical vapour deposition, we realize catalyst-free growth of poly-crystalline two-dimensional hexagonal-boron nitride (2D-BN) with domains around 20~ 200 nm directly on SiO2/Si, quartz, sapphire, silicon or SiO2/Si with three-dimensional patterns at 300 °C. Owing to the atomically-clean van-der-Walls conformal interface and the fact that 2D-BN can better bridge the vibrational spectrum across the interface and protect interfacial heat conduction against substrate roughness, both improved performance and thermal dissipation of WSe2 field-effect transistor are realized with mobility around 56~ 121 cm2 V−1 s−1 and saturated power intensity up to 4.23 × 103 W cm−2. Owing to its simplicity, conformal growth on three-dimensional surface, compatibility with microelectronic process, it has potential for application in future two-dimensional electronics. Plasma-enhanced chemical vapour deposition (PECVD) is an industrially compatible microelectronics technology. Here, the authors use PECVD to obtain low-temperature, catalyst-free growth of poly-crystalline two-dimensional hexagonal-boron nitride, thus enabling superior thermal dissipation in WSe2 field-effect transistors with mobility up to 121 cm2 V−1 s−1.
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Affiliation(s)
- Donghua Liu
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, 200433, China.,Department of Macromolecular Science, Fudan University, Shanghai, 200433, China
| | - Xiaosong Chen
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, 200433, China.,Department of Macromolecular Science, Fudan University, Shanghai, 200433, China
| | - Yaping Yan
- Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai, 200092, China.,China-EU Joint Lab for Nanophononics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Zhongwei Zhang
- Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai, 200092, China.,China-EU Joint Lab for Nanophononics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Zhepeng Jin
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, 200433, China.,Department of Macromolecular Science, Fudan University, Shanghai, 200433, China
| | - Kongyang Yi
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, 200433, China.,Department of Macromolecular Science, Fudan University, Shanghai, 200433, China
| | - Cong Zhang
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, 200433, China.,Department of Macromolecular Science, Fudan University, Shanghai, 200433, China
| | - Yujie Zheng
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Yao Wang
- International Center for New-Structured Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Jun Yang
- Key Laboratory of Multi-scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China
| | - Xiangfan Xu
- Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai, 200092, China. .,China-EU Joint Lab for Nanophononics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China.
| | - Jie Chen
- Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai, 200092, China.,China-EU Joint Lab for Nanophononics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Yunhao Lu
- International Center for New-Structured Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Dapeng Wei
- Key Laboratory of Multi-scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China.
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Dacheng Wei
- State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, 200433, China. .,Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
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26
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Zhang Z, Liu E, Zhang W, Wong PKJ, Xu Z, Hu F, Li X, Tang J, Wee ATS, Xu F. Mechanical Strain Manipulation of Exchange Bias Field and Spin Dynamics in FeCo/IrMn Multilayers Grown on Flexible Substrates. ACS Appl Mater Interfaces 2019; 11:8258-8265. [PMID: 30697995 DOI: 10.1021/acsami.8b21421] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
As a key effect in spintronic devices, exchange bias has attracted tremendous attention. Various approaches have been attempted for optimizing this effect, among which the application of strain in flexible exchange-biased systems is promising, but little significant improvement has been reported. Here, we demonstrate encouraging progress in this field. With a pure mechanical compressive strain of -6.26‰ applied to the flexible polyimide (PI) substrate, distinct enhancement of ∼900% in the bias field (from 20 to 200 Oe) is achieved for the exchange-biased (FeCo/IrMn)3/Ta multilayers grown on top of a flexible PI substrate, accompanied by a notable decrease in the Gilbert damping parameter from 0.02 to 0.008, signifying an improved exchange bias effect as well as a potentially reduced switching current density. The underlying mechanism is investigated by a systematic ferromagnetic resonance study, suggesting that the angle between the unidirectional and uniaxial magnetic easy axes plays an important role, which may be controlled by adjusting the layer number. This work offers an efficient strategy for tuning the exchange bias effect via applying appropriate mechanical strain on a multiperiodic exchange bias multilayered system, opening up an avenue for tailoring the magnetic properties of flexible spintronic devices.
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Affiliation(s)
- Zhi Zhang
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Er Liu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Wen Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
| | - Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
| | - Zhan Xu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Fang Hu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Xia Li
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Jiaxuan Tang
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Andrew Thye Shen Wee
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
| | - Feng Xu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
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27
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Zeng SW, Yin XM, Herng TS, Han K, Huang Z, Zhang LC, Li CJ, Zhou WX, Wan DY, Yang P, Ding J, Wee ATS, Coey JMD, Venkatesan T, Rusydi A, Ariando A. Oxygen Electromigration and Energy Band Reconstruction Induced by Electrolyte Field Effect at Oxide Interfaces. Phys Rev Lett 2018; 121:146802. [PMID: 30339445 DOI: 10.1103/physrevlett.121.146802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Indexed: 06/08/2023]
Abstract
Electrolyte gating is a powerful means for tuning the carrier density and exploring the resultant modulation of novel properties on solid surfaces. However, the mechanism, especially its effect on the oxygen migration and electrostatic charging at the oxide heterostructures, is still unclear. Here we explore the electrolyte gating on oxygen-deficient interfaces between SrTiO_{3} (STO) crystals and LaAlO_{3} (LAO) overlayer through the measurements of electrical transport, x-ray absorption spectroscopy, and photoluminescence spectra. We found that oxygen vacancies (O_{vac}) were filled selectively and irreversibly after gating due to oxygen electromigration at the amorphous LAO/STO interface, resulting in a reconstruction of its interfacial band structure. Because of the filling of O_{vac}, the amorphous interface also showed an enhanced electron mobility and quantum oscillation of the conductance. Further, the filling effect could be controlled by the degree of the crystallinity of the LAO overlayer by varying the growth temperatures. Our results reveal the different effects induced by electrolyte gating, providing further clues to understand the mechanism of electrolyte gating on buried interfaces and also opening a new avenue for constructing high-mobility oxide interfaces.
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Affiliation(s)
- S W Zeng
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - X M Yin
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore 117603, Singapore
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - T S Herng
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
| | - K Han
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Z Huang
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - L C Zhang
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - C J Li
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
| | - W X Zhou
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - D Y Wan
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - P Yang
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore 117603, Singapore
| | - J Ding
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
| | - A T S Wee
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research, National University of Singapore, Singapore 117546, Singapore
| | - J M D Coey
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- School of Physics and CRANN, Trinity College, Dublin 2, Ireland
| | - T Venkatesan
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore
| | - A Rusydi
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore 117603, Singapore
| | - A Ariando
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore
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28
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Li S, Lin YC, Zhao W, Wu J, Wang Z, Hu Z, Shen Y, Tang DM, Wang J, Zhang Q, Zhu H, Chu L, Zhao W, Liu C, Sun Z, Taniguchi T, Osada M, Chen W, Xu QH, Wee ATS, Suenaga K, Ding F, Eda G. Vapour-liquid-solid growth of monolayer MoS 2 nanoribbons. Nat Mater 2018; 17:535-542. [PMID: 29686277 DOI: 10.1038/s41563-018-0055-z] [Citation(s) in RCA: 141] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 03/13/2018] [Indexed: 05/23/2023]
Abstract
Chemical vapour deposition of two-dimensional materials typically involves the conversion of vapour precursors to solid products in a vapour-solid-solid mode. Here, we report the vapour-liquid-solid growth of monolayer MoS2, yielding highly crystalline ribbons with a width of few tens to thousands of nanometres. This vapour-liquid-solid growth is triggered by the reaction between MoO3 and NaCl, which results in the formation of molten Na-Mo-O droplets. These droplets mediate the growth of MoS2 ribbons in the 'crawling mode' when saturated with sulfur. The locally well-defined orientations of the ribbons reveal the regular horizontal motion of the droplets during growth. Using atomic-resolution scanning transmission electron microscopy and second harmonic generation microscopy, we show that the ribbons are grown homoepitaxially on monolayer MoS2 with predominantly 2H- or 3R-type stacking. Our findings highlight the prospects for the controlled growth of atomically thin nanostructure arrays for nanoelectronic devices and the development of unique mixed-dimensional structures.
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Affiliation(s)
- Shisheng Li
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore.
- Department of Physics, National University of Singapore, Singapore, Singapore.
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan.
| | - Yung-Chang Lin
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Wen Zhao
- Center for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan, Republic of Korea
| | - Jing Wu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore, Singapore
| | - Zhuo Wang
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Zehua Hu
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Youde Shen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Dai-Ming Tang
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan
| | - Junyong Wang
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Qi Zhang
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Hai Zhu
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Leiqiang Chu
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Weijie Zhao
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Chang Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
| | - Zhipei Sun
- Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
- QTF Centre of Excellence, Department of Applied Physics, Aalto University, Aalto, Finland
| | - Takaaki Taniguchi
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan
| | - Minoru Osada
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan
- Institute of Materials and Systems for Sustainability (iMaSS), Nagoya University, Nagoya, Japan
| | - Wei Chen
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Qing-Hua Xu
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Andrew Thye Shen Wee
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Kazu Suenaga
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, Japan
| | - Feng Ding
- Center for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan, Republic of Korea
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Goki Eda
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore.
- Department of Physics, National University of Singapore, Singapore, Singapore.
- Department of Chemistry, National University of Singapore, Singapore, Singapore.
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29
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Abstract
Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for applications in two-dimensional nanoelectronics devices. Although many methods to synthesize SnSe nanocrystals have been developed, a simple way to fabricate large-sized single-layer SnSe flakes remains a great challenge. Herein, we show the experimental method to directly grow large-sized single-layer rectangular SnSe flakes on commonly used SiO2/Si insulating substrates using a straightforward two-step fabrication method in an atmospheric pressure quartz tube furnace system. The single-layer rectangular SnSe flakes with an average thickness of ~6.8 Å and lateral dimensions of about 30 µm × 50 µm were fabricated by a combination of vapor transport deposition technique and nitrogen etching route. We characterized the morphology, microstructure, and electrical properties of the rectangular SnSe flakes and obtained excellent crystallinity and good electronic properties. This article about the two-step fabrication method can help researchers grow other similar two-dimensional, large-sized, single-layer materials using an atmospheric pressure system.
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Affiliation(s)
- Jizhou Jiang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University; Department of Physics, National University of Singapore;
| | - Calvin Pei Yu Wong
- Department of Physics, National University of Singapore; NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences
| | - Wenjing Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University;
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore; Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore;
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30
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Song Z, Schultz T, Ding Z, Lei B, Han C, Amsalem P, Lin T, Chi D, Wong SL, Zheng YJ, Li MY, Li LJ, Chen W, Koch N, Huang YL, Wee ATS. Electronic Properties of a 1D Intrinsic/p-Doped Heterojunction in a 2D Transition Metal Dichalcogenide Semiconductor. ACS Nano 2017; 11:9128-9135. [PMID: 28753270 DOI: 10.1021/acsnano.7b03953] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Two-dimensional (2D) semiconductors offer a convenient platform to study 2D physics, for example, to understand doping in an atomically thin semiconductor. Here, we demonstrate the fabrication and unravel the electronic properties of a lateral doped/intrinsic heterojunction in a single-layer (SL) tungsten diselenide (WSe2), a prototype semiconducting transition metal dichalcogenide (TMD), partially covered with a molecular acceptor layer, on a graphite substrate. With combined experiments and theoretical modeling, we reveal the fundamental acceptor-induced p-doping mechanism for SL-WSe2. At the 1D border between the doped and undoped SL-WSe2 regions, we observe band bending and explain it by Thomas-Fermi screening. Using atomically resolved scanning tunneling microscopy and spectroscopy, the screening length is determined to be in the few nanometer range, and we assess the carrier density of intrinsic SL-WSe2. These findings are of fundamental and technological importance for understanding and employing surface doping, for example, in designing lateral organic TMD heterostructures for future devices.
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Affiliation(s)
- Zhibo Song
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634
| | - Thorsten Schultz
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin , Brook-Taylor Straße 6, 12489 Berlin, Germany
| | - Zijing Ding
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University , Shenzhen 518060, China
| | - Bo Lei
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Cheng Han
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University , Shenzhen 518060, China
- Department of Chemistry, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Patrick Amsalem
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin , Brook-Taylor Straße 6, 12489 Berlin, Germany
| | - Tingting Lin
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634
| | - Dongzhi Chi
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634
| | - Swee Liang Wong
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634
| | - Yu Jie Zheng
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Ming-Yang Li
- Research Center for Applied Sciences, Academia Sinica , Taipei 10617, Taiwan
- Physical Sciences and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Lain-Jong Li
- Physical Sciences and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Wei Chen
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Department of Chemistry, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin , Brook-Taylor Straße 6, 12489 Berlin, Germany
| | - Yu Li Huang
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546
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31
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Li M, Liu D, Wei D, Song X, Wei D, Wee ATS. Controllable Synthesis of Graphene by Plasma-Enhanced Chemical Vapor Deposition and Its Related Applications. Adv Sci (Weinh) 2016; 3:1600003. [PMID: 27980983 PMCID: PMC5102669 DOI: 10.1002/advs.201600003] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 03/09/2016] [Indexed: 05/07/2023]
Abstract
Graphene and its derivatives hold a great promise for widespread applications such as field-effect transistors, photovoltaic devices, supercapacitors, and sensors due to excellent properties as well as its atomically thin, transparent, and flexible structure. In order to realize the practical applications, graphene needs to be synthesized in a low-cost, scalable, and controllable manner. Plasma-enhanced chemical vapor deposition (PECVD) is a low-temperature, controllable, and catalyst-free synthesis method suitable for graphene growth and has recently received more attentions. This review summarizes recent advances in the PECVD growth of graphene on different substrates, discusses the growth mechanism and its related applications. Furthermore, the challenges and future development in this field are also discussed.
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Affiliation(s)
- Menglin Li
- State Key Laboratory of Molecular Engineering of PolymersDepartment of Macromolecular ScienceFudan UniversityShanghai200433P. R. China
| | - Donghua Liu
- State Key Laboratory of Molecular Engineering of PolymersDepartment of Macromolecular ScienceFudan UniversityShanghai200433P. R. China
| | - Dacheng Wei
- State Key Laboratory of Molecular Engineering of PolymersDepartment of Macromolecular ScienceFudan UniversityShanghai200433P. R. China
| | - Xuefen Song
- Key Laboratory of Multi‐scale Manufacturing TechnologyChongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing400714P. R. China
| | - Dapeng Wei
- Key Laboratory of Multi‐scale Manufacturing TechnologyChongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing400714P. R. China
| | - Andrew Thye Shen Wee
- Physics DepartmentNational University of Singapore2 Science Drive 3Singapore117542Singapore
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32
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Jiang J, Zou J, Wee ATS, Zhang W. Use of Single-Layer g-C 3N 4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS). Sci Rep 2016; 6:34599. [PMID: 27687573 PMCID: PMC5043347 DOI: 10.1038/srep34599] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/15/2016] [Indexed: 01/30/2023] Open
Abstract
Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.
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Affiliation(s)
- Jizhou Jiang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore
| | - Jing Zou
- School of Chemistry and Environmental Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Wuhan Institute of Technology, Wuhan 430073, P.R. China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore
| | - Wenjing Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
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33
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Schenk AK, Tadich A, Sear MJ, Qi D, Wee ATS, Stacey A, Pakes CI. The surface electronic structure of silicon terminated (100) diamond. Nanotechnology 2016; 27:275201. [PMID: 27211214 DOI: 10.1088/0957-4484/27/27/275201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A combination of synchrotron-based x-ray spectroscopy and contact potential difference measurements have been used to examine the electronic structure of the (3 × 1) silicon terminated (100) diamond surface under ultra high vacuum conditions. An occupied surface state which sits 1.75 eV below the valence band maximum has been identified, and indications of mid-gap unoccupied surface states have been found. Additionally, the pristine silicon terminated surface is shown to possess a negative electron affinity of -0.86 ± 0.1 eV.
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Affiliation(s)
- A K Schenk
- Department of Chemistry and Physics, La Trobe Institute for Molecular Sciences, La Trobe University, Victoria 3086, Australia
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Huang H, Tan Z, He Y, Liu J, Sun J, Zhao K, Zhou Z, Tian G, Wong SL, Wee ATS. Competition between Hexagonal and Tetragonal Hexabromobenzene Packing on Au(111). ACS Nano 2016; 10:3198-3205. [PMID: 26905460 DOI: 10.1021/acsnano.5b04970] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Low-temperature scanning tunneling microscope investigations reveal that hexabromobenzene (HBB) molecules arrange in either hexagonally closely packed (hcp) [Formula: see text] or tetragonal [Formula: see text] structure on Au(111) dependent on a small substrate temperature difference around 300 K. The underlying mechanism is investigated by density functional theory calculations, which reveal that substrate-mediated intermolecular noncovalent C-Br···Br-C attractions induce hcp HBB islands, keeping the well-known Au(111)-22×√3 reconstruction intact. Upon deposition at 330 K, HBB molecules trap freely diffusing Au adatoms to form tetragonal islands. This enhances the attraction between HBB and Au(111) but partially reduces the intermolecular C-Br···Br-C attractions, altering the Au(111)-22×√3 reconstruction. In both cases, the HBB molecule adsorbs on a bridge site, forming a ∼15° angle between the C-Br direction and [112̅]Au, indicating the site-specific molecule-substrate interactions. We show that the competition between intermolecular and molecule-substrate interactions determines molecule packing at the subnanometer scale, which will be helpful for crystal engineering, functional materials, and organic electronics.
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Affiliation(s)
- Han Huang
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
| | | | | | - Jian Liu
- Institute of Physics, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
| | - Jiatao Sun
- Institute of Physics, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
| | | | | | | | - Swee Liang Wong
- Institute of Materials Research and Engineering, Agency for Science Technology and Research , 3, Research Link, Singapore 117602, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
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35
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Zheng YJ, Huang YL, Chen Y, Zhao W, Eda G, Spataru CD, Zhang W, Chang YH, Li LJ, Chi D, Quek SY, Wee ATS. Heterointerface Screening Effects between Organic Monolayers and Monolayer Transition Metal Dichalcogenides. ACS Nano 2016; 10:2476-2484. [PMID: 26792247 DOI: 10.1021/acsnano.5b07314] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The nature and extent of electronic screening at heterointerfaces and their consequences on energy level alignment are of profound importance in numerous applications, such as solar cells, electronics etc. The increasing availability of two-dimensional (2D) transition metal dichalcogenides (TMDs) brings additional opportunities for them to be used as interlayers in "van der Waals (vdW) heterostructures" and organic/inorganic flexible devices. These innovations raise the question of the extent to which the 2D TMDs participate actively in dielectric screening at the interface. Here we study perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) monolayers adsorbed on single-layer tungsten diselenide (WSe2), bare graphite, and Au(111) surfaces, revealing a strong dependence of the PTCDA HOMO-LUMO gap on the electronic screening effects from the substrate. The monolayer WSe2 interlayer provides substantial, but not complete, screening at the organic/inorganic interface. Our results lay a foundation for the exploitation of the complex interfacial properties of hybrid systems based on TMD materials.
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Affiliation(s)
- Yu Jie Zheng
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
| | - Yu Li Huang
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634, Singapore
| | - Yifeng Chen
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
| | - Weijie Zhao
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
| | - Goki Eda
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore
| | - Catalin D Spataru
- Sandia National Laboratories , Livermore, California 94551, United States
| | - Wenjing Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University , Shenzhen 518060, China
| | - Yung-Huang Chang
- Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan
| | - Lain-Jong Li
- Physical Sciences and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Dongzhi Chi
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634, Singapore
| | - Su Ying Quek
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
- Institute of High Performance Computing, Agency for Science Technology and Research , 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
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36
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Cheng CM, Xie LF, Pachoud A, Moser HO, Chen W, Wee ATS, Castro Neto AH, Tsuei KD, Özyilmaz B. Anomalous spectral features of a neutral bilayer graphene. Sci Rep 2015; 5:10025. [PMID: 25985064 PMCID: PMC4434949 DOI: 10.1038/srep10025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 02/23/2015] [Indexed: 11/11/2022] Open
Abstract
Graphene and its bilayer are two-dimensional systems predicted to show exciting many-body effects near the neutrality point. The ideal tool to investigate spectrum reconstruction effects is angle-resolved photoemission spectroscopy (ARPES) as it probes directly the band structure with information about both energy and momentum. Here we reveal, by studying undoped exfoliated bilayer graphene with ARPES, two essential aspects of its many-body physics: the electron-phonon scattering rate has an anisotropic k-dependence and the type of electronic liquid is non-Fermi liquid. The latter behavior is evident from an observed electron-electron scattering rate that scales linearly with energy from 100 meV to 600 meV and that is associated with the proximity of bilayer graphene to a two-dimensional quantum critical point of competing orders.
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Affiliation(s)
- C-M Cheng
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu, 30076, Taiwan
| | - L F Xie
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.,NanoCore, 4 Engineering Drive 3, National University of Singapore 117576, Singapore
| | - A Pachoud
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.,Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, 28 Medical Drive, 117456, Singapore.,Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore
| | - H O Moser
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.,Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link 117603, Singapore.,Karlsruhe Institute of Technology (KIT), Network of Excellent Retired Scientists (NES) and Institute of Microstructure Technology (IMT), Postfach 3640, 76021 Karlsruhe, Germany
| | - W Chen
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.,Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore
| | - A T S Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.,Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore
| | - A H Castro Neto
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.,Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore
| | - K-D Tsuei
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu, 30076, Taiwan.,Department of Physics, National Tsing Hua University, 101 Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
| | - B Özyilmaz
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.,NanoCore, 4 Engineering Drive 3, National University of Singapore 117576, Singapore.,Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore
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37
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Zhang JL, Zhong S, Zhong JQ, Niu TC, Hu WP, Wee ATS, Chen W. Rational design of two-dimensional molecular donor-acceptor nanostructure arrays. Nanoscale 2015; 7:4306-24. [PMID: 25684203 DOI: 10.1039/c4nr06741j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The construction of long-range ordered organic donor-acceptor nanostructure arrays over microscopic areas supported on solid substrates is one of the most challenging tasks towards the realization of molecular nanodevices. They can also be used as ideal model systems to understand light induced charge transfer, charge separation and energy conversion processes and mechanisms at the nanometer scale. The aim of this paper is to highlight recent advances and progress in this topic. Special attention is given to two different strategies for the construction of organic donor-acceptor nanostructure arrays, namely (i) molecular self-assembly on artificially patterned or pre-defined molecular surface nanotemplates and (ii) molecular nanostructure formation steered via directional and selective intermolecular interactions. The interfacial charge transfer and the energy level alignment of these donor-acceptor nanostructures are also discussed.
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Affiliation(s)
- Jia Lin Zhang
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore
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38
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Wang D, Liu L, Chen W, Chen X, Huang H, He J, Feng YP, Wee ATS, Shen DZ. Optimized growth of graphene on SiC: from the dynamic flip mechanism. Nanoscale 2015; 7:4522-4528. [PMID: 25682710 DOI: 10.1039/c4nr07197b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Thermal decomposition of single-crystal SiC is one of the popular methods for growing graphene. However, the mechanism of graphene formation on the SiC surface is poorly understood, and the application of this method is also hampered by its high growth temperature. In this study, based on the ab initio calculations, we propose a vacancy assisted Si-C bond flipping model for the dynamic process of graphene growth on SiC. The fact that the critical stages during growth take place at different energy costs allows us to propose an energetic-beam controlled growth method that not only significantly lowers the growth temperature but also makes it possible to grow high-quality graphene with the desired size and patterns directly on the SiC substrate.
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Affiliation(s)
- Dandan Wang
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, No. 3888 Dongnanhu Road, Changchun, 130033, People's Republic of China.
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39
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Shen Q, He JH, Zhang JL, Wu K, Xu GQ, Wee ATS, Chen W. Self-assembled two-dimensional nanoporous molecular arrays and photoinduced polymerization of 4-bromo-4′-hydroxybiphenyl on Ag(111). J Chem Phys 2015; 142:101902. [DOI: 10.1063/1.4906116] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Qian Shen
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602, Singapore
| | - Jing Hui He
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602, Singapore
| | - Jia Lin Zhang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
| | - Kai Wu
- Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602, Singapore
- BNLMS, SKLSCUSS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People’s Republic of China
| | - Guo Qin Xu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602, Singapore
- National University of Singapore (Suzhou) Research Institute, Suzhou, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Wei Chen
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, 1 CREATE Way, #15-01, CREATE Tower, Singapore 138602, Singapore
- National University of Singapore (Suzhou) Research Institute, Suzhou, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
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40
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Wei D, Peng L, Li M, Mao H, Niu T, Han C, Chen W, Wee ATS. Low temperature critical growth of high quality nitrogen doped graphene on dielectrics by plasma-enhanced chemical vapor deposition. ACS Nano 2015; 9:164-171. [PMID: 25581685 DOI: 10.1021/nn505214f] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nitrogen doping is one of the most promising routes to modulate the electronic characteristic of graphene. Plasma-enhanced chemical vapor deposition (PECVD) enables low-temperature graphene growth. However, PECVD growth of nitrogen doped graphene (NG) usually requires metal-catalysts, and to the best of our knowledge, only amorphous carbon-nitrogen films have been produced on dielectric surfaces by metal-free PECVD. Here, a critical factor for metal-free PECVD growth of NG is reported, which allows high quality NG crystals to be grown directly on dielectrics like SiO2/Si, Al2O3, h-BN, mica at 435 °C without a catalyst. Thus, the processes needed for loading the samples on dielectrics and n-type doping are realized in a simple PECVD, which would be of significance for future graphene electronics due to its compatibility with the current microelectronic processes.
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Affiliation(s)
- Dacheng Wei
- Department of Macromolecular Science, Fudan University , Shanghai 200433, China
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41
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Chang YH, Zhang W, Zhu Y, Han Y, Pu J, Chang JK, Hsu WT, Huang JK, Hsu CL, Chiu MH, Takenobu T, Li H, Wu CI, Chang WH, Wee ATS, Li LJ. Monolayer MoSe2 grown by chemical vapor deposition for fast photodetection. ACS Nano 2014; 8:8582-8590. [PMID: 25094022 DOI: 10.1021/nn503287m] [Citation(s) in RCA: 216] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Monolayer molybdenum disulfide (MoS2) has become a promising building block in optoelectronics for its high photosensitivity. However, sulfur vacancies and other defects significantly affect the electrical and optoelectronic properties of monolayer MoS2 devices. Here, highly crystalline molybdenum diselenide (MoSe2) monolayers have been successfully synthesized by the chemical vapor deposition (CVD) method. Low-temperature photoluminescence comparison for MoS2 and MoSe2 monolayers reveals that the MoSe2 monolayer shows a much weaker bound exciton peak; hence, the phototransistor based on MoSe2 presents a much faster response time (<25 ms) than the corresponding 30 s for the CVD MoS2 monolayer at room temperature in ambient conditions. The images obtained from transmission electron microscopy indicate that the MoSe exhibits fewer defects than MoS2. This work provides the fundamental understanding for the differences in optoelectronic behaviors between MoSe2 and MoS2 and is useful for guiding future designs in 2D material-based optoelectronic devices.
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Affiliation(s)
- Yung-Huang Chang
- Institute of Atomic and Molecular Sciences, Academia Sinica , Taipei 11529, Taiwan
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42
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Zhang W, Chiu MH, Chen CH, Chen W, Li LJ, Wee ATS. Role of metal contacts in high-performance phototransistors based on WSe2 monolayers. ACS Nano 2014; 8:8653-61. [PMID: 25106792 DOI: 10.1021/nn503521c] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Phototransistors based on monolayer transition metal dichalcogenides (TMD) have high photosensitivity due to their direct band gap transition. However, there is a lack of understanding of the effect of metal contacts on the performance of atomically thin TMD phototransistors. Here, we fabricate phototransistors based on large-area chemical vapor deposition (CVD) tungsten diselenide (WSe2) monolayers contacted with the metals of different work function values. We found that the low Schottky-contact WSe2 phototransistors exhibit a very high photo gain (10(5)) and specific detectivity (10(14)Jones), values higher than commercial Si- and InGaAs-based photodetectors; however, the response speed is longer than 5 s in ambient air. In contrast, the high Schottky-contact phototransistors display a fast response time shorter than 23 ms, but the photo gain and specific detectivity decrease by several orders of magnitude. Moreover, the fast response speed of the high Schottky-contact devices is maintained for a few months in ambient air. This study demonstrates that the contact plays an important role in TMD phototransistors, and barrier height tuning is critical for optimizing the photoresponse and photoresponsivity.
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Song B, Sun Q, Li H, Ge B, Pan JS, Wee ATS, Zhang Y, Huang S, Zhou R, Gao X, Huang F, Fang H. Frontispiece: Irreversible Denaturation of Proteins through Aluminum‐Induced Formation of Backbone Ring Structures. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/anie.201482571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Bo Song
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Qian Sun
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Haikuo Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Baosheng Ge
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Ji Sheng Pan
- Institute of Materials Research and Engineering, Singapore 117602 (Republic of Singapore)
| | - Andrew Thye Shen Wee
- Physics Department, National University of Singapore, Singapore 117542 (Republic of Singapore)
| | - Yong Zhang
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)
| | - Shaohua Huang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China)
| | - Ruhong Zhou
- IBM Thomas J. Watson Research Center, New York, NY 10598 (USA)
| | - Xingyu Gao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Fang Huang
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Haiping Fang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
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Song B, Sun Q, Li H, Ge B, Pan JS, Wee ATS, Zhang Y, Huang S, Zhou R, Gao X, Huang F, Fang H. Frontispiz: Irreversible Denaturation of Proteins through Aluminum‐Induced Formation of Backbone Ring Structures. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201482571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Bo Song
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Qian Sun
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Haikuo Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Baosheng Ge
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Ji Sheng Pan
- Institute of Materials Research and Engineering, Singapore 117602 (Republic of Singapore)
| | - Andrew Thye Shen Wee
- Physics Department, National University of Singapore, Singapore 117542 (Republic of Singapore)
| | - Yong Zhang
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)
| | - Shaohua Huang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China)
| | - Ruhong Zhou
- IBM Thomas J. Watson Research Center, New York, NY 10598 (USA)
| | - Xingyu Gao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Fang Huang
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Haiping Fang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
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Lin JD, Han C, Wang F, Wang R, Xiang D, Qin S, Zhang XA, Wang L, Zhang H, Wee ATS, Chen W. Electron-doping-enhanced trion formation in monolayer molybdenum disulfide functionalized with cesium carbonate. ACS Nano 2014; 8:5323-9. [PMID: 24785254 DOI: 10.1021/nn501580c] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report effective and stable electron doping of monolayer molybdenum disulfide (MoS2) by cesium carbonate (Cs2CO3) surface functionalization. The electron charge carrier concentration in exfoliated monolayer MoS2 can be increased by about 9 times after Cs2CO3 functionalization. The n-type doping effect was evaluated by in situ transport measurements of MoS2 field-effect transistors (FETs) and further corroborated by in situ ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and Raman scattering measurements. The electron doping enhances the formation of negative trions (i.e., a quasiparticle comprising two electrons and one hole) in monolayer MoS2 under light irradiation and significantly reduces the charge recombination of photoexcited electron-hole pairs. This results in large photoluminescence suppression and an obvious photocurrent enhancement in monolayer MoS2 FETs.
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Affiliation(s)
- Jia Dan Lin
- College of Science, National University of Defense Technology , Changsha 410073, China
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Song B, Sun Q, Li H, Ge B, Pan JS, Wee ATS, Zhang Y, Huang S, Zhou R, Gao X, Huang F, Fang H. Irreversible Denaturation of Proteins through Aluminum‐Induced Formation of Backbone Ring Structures. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201307955] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Bo Song
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Qian Sun
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Haikuo Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Baosheng Ge
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Ji Sheng Pan
- Institute of Materials Research and Engineering, Singapore 117602 (Republic of Singapore)
| | - Andrew Thye Shen Wee
- Physics Department, National University of Singapore, Singapore 117542 (Republic of Singapore)
| | - Yong Zhang
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)
| | - Shaohua Huang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China)
| | - Ruhong Zhou
- IBM Thomas J. Watson Research Center, New York, NY 10598 (USA)
| | - Xingyu Gao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Fang Huang
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Haiping Fang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
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Song B, Sun Q, Li H, Ge B, Pan JS, Wee ATS, Zhang Y, Huang S, Zhou R, Gao X, Huang F, Fang H. Irreversible Denaturation of Proteins through Aluminum‐Induced Formation of Backbone Ring Structures. Angew Chem Int Ed Engl 2014; 53:6358-63. [PMID: 24777568 DOI: 10.1002/anie.201307955] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 03/24/2014] [Indexed: 12/16/2022]
Affiliation(s)
- Bo Song
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Qian Sun
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Haikuo Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Baosheng Ge
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Ji Sheng Pan
- Institute of Materials Research and Engineering, Singapore 117602 (Republic of Singapore)
| | - Andrew Thye Shen Wee
- Physics Department, National University of Singapore, Singapore 117542 (Republic of Singapore)
| | - Yong Zhang
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)
| | - Shaohua Huang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China)
| | - Ruhong Zhou
- IBM Thomas J. Watson Research Center, New York, NY 10598 (USA)
| | - Xingyu Gao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
| | - Fang Huang
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Changjiang West Road 66, Qingdao 266580 (China)
| | - Haiping Fang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box 800‐204, Shanghai 201800 (China)
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Zhong JQ, Qin X, Zhang JL, Kera S, Ueno N, Wee ATS, Yang J, Chen W. Energy level realignment in weakly interacting donor-acceptor binary molecular networks. ACS Nano 2014; 8:1699-707. [PMID: 24433044 DOI: 10.1021/nn406050e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Understanding the effect of intermolecular and molecule-substrate interactions on molecular electronic states is key to revealing the energy level alignment mechanism at organic-organic heterojunctions or organic-inorganic interfaces. In this paper, we investigate the energy level alignment mechanism in weakly interacting donor-acceptor binary molecular superstructures, comprising copper hexadecafluorophthalocyanine (F16CuPc) intermixed with copper phthalocyanine (CuPc), or manganese phthalocynine (MnPc) on graphite. The molecular electronic structures have been systematically studied by in situ ultraviolet photoelectron spectroscopy (UPS) and low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/STS) experiments and corroborated by density functional theory (DFT) calculations. As demonstrated by the UPS and LT-STM/STS measurements, the observed unusual energy level realignment (i.e., a large downward shift in donor HOMO level and a corresponding small upward shift in acceptor HOMO level) in the CuPc-F16CuPc binary superstructures originates from the balance between intermolecular and molecule-substrate interactions. The enhanced intermolecular interactions through the hydrogen bonding between neighboring CuPc and F16CuPc can stabilize the binary superstructures and modify the local molecular electronic states. The obvious molecular energy level shift was explained by gap-state-mediated interfacial charge transfer.
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Affiliation(s)
- Jian-Qiang Zhong
- Department of Physics, National University of Singapore , 2 Science Drive 3, 117542, Singapore
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Wan W, Li H, Huang H, Wong SL, Lv L, Gao Y, Wee ATS. Incorporating isolated molybdenum (Mo) atoms into bilayer epitaxial graphene on 4H-SiC(0001). ACS Nano 2014; 8:970-976. [PMID: 24354296 DOI: 10.1021/nn4057929] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The atomic structures and electronic properties of isolated Mo atoms in bilayer epitaxial graphene (BLEG) on 4H-SiC(0001) are investigated by low temperature scanning tunneling microscopy (LT-STM). LT-STM results reveal that isolated Mo dopants prefer to substitute C atoms at α-sites and preferentially locate between the graphene bilayers. First-principles calculations confirm that the embedding of single Mo dopants within BLEG is energetically favorable as compared to monolayer graphene. The calculated band structures show that Mo-incorporated BLEG is n-doped, and each Mo atom introduces a local magnetic moment of 1.81 μB into BLEG. Our findings demonstrate a simple and stable method to incorporate single transition metal dopants into the graphene lattice to tune its electronic and magnetic properties for possible use in graphene spin devices.
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Affiliation(s)
- Wen Wan
- Institute of Super-microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, The Central South University , Changsha, Hunan 410083, PR China
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Wei D, Lu Y, Han C, Niu T, Chen W, Wee ATS. Critical Crystal Growth of Graphene on Dielectric Substrates at Low Temperature for Electronic Devices. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201306086] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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