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Yin L, Cheng R, Ding J, Jiang J, Hou Y, Feng X, Wen Y, He J. Two-Dimensional Semiconductors and Transistors for Future Integrated Circuits. ACS NANO 2024; 18:7739-7768. [PMID: 38456396 DOI: 10.1021/acsnano.3c10900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
Silicon transistors are approaching their physical limit, calling for the emergence of a technological revolution. As the acknowledged ultimate version of transistor channels, 2D semiconductors are of interest for the development of post-Moore electronics due to their useful properties and all-in-one potentials. Here, the promise and current status of 2D semiconductors and transistors are reviewed, from materials and devices to integrated applications. First, we outline the evolution and challenges of silicon-based integrated circuits, followed by a detailed discussion on the properties and preparation strategies of 2D semiconductors and van der Waals heterostructures. Subsequently, the significant progress of 2D transistors, including device optimization, large-scale integration, and unconventional devices, are presented. We also examine 2D semiconductors for advanced heterogeneous and multifunctional integration beyond CMOS. Finally, the key technical challenges and potential strategies for 2D transistors and integrated circuits are also discussed. We envision that the field of 2D semiconductors and transistors could yield substantial progress in the upcoming years and hope this review will trigger the interest of scientists planning their next experiment.
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Affiliation(s)
- Lei Yin
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Ruiqing Cheng
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Jiahui Ding
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Jian Jiang
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Yutang Hou
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Xiaoqiang Feng
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Yao Wen
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Jun He
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
- Wuhan Institute of Quantum Technology, Wuhan 430206, People's Republic of China
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2
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Shanmugam A, Thekke Purayil MA, Dhurjati SA, Thalakulam M. Physical vapor deposition-free scalable high-efficiency electrical contacts to MoS 2. NANOTECHNOLOGY 2023; 35:115201. [PMID: 38055966 DOI: 10.1088/1361-6528/ad12e4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 12/05/2023] [Indexed: 12/08/2023]
Abstract
Fermi-level pinning caused by the kinetic damage during metallization has been recognized as one of the major reasons for the non-ideal behavior of electrical contacts, forbidding reaching the Schottky-Mott limit. In this manuscript, we present a scalable technique wherein Indium, a low-work-function metal, is diffused to contact a few-layered MoS2flake. The technique exploits a smooth outflow of Indium over gold electrodes to make edge contacts to pre-transferred MoS2flakes. We compare the performance of three pairs of contacts made onto the same MoS2flake, the bottom-gold, top-gold, and Indium contacts, and find that the Indium contacts are superior to other contacts. The Indium contacts maintain linearI-Vcharacteristics down to cryogenic temperatures with an extracted Schottky barrier height of ∼2.1 meV. First-principle calculations show the induced in-gap states close to the Fermi level, and the damage-free contact interface could be the reason for the nearly Ohmic behavior of the Indium/MoS2interface.
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Affiliation(s)
- Anusha Shanmugam
- Indian Institute of Science Education & Research Thiruvananthapuram, Kerala 695551, India
| | | | | | - Madhu Thalakulam
- Indian Institute of Science Education & Research Thiruvananthapuram, Kerala 695551, India
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3
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Oberoi A, Han Y, Stepanoff SP, Pannone A, Sun Y, Lin YC, Chen C, Shallenberger JR, Zhou D, Terrones M, Redwing JM, Robinson JA, Wolfe DE, Yang Y, Das S. Toward High-Performance p-Type Two-Dimensional Field Effect Transistors: Contact Engineering, Scaling, and Doping. ACS NANO 2023; 17:19709-19723. [PMID: 37812500 DOI: 10.1021/acsnano.3c03060] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
n-type field effect transistors (FETs) based on two-dimensional (2D) transition-metal dichalcogenides (TMDs) such as MoS2 and WS2 have come close to meeting the requirements set forth in the International Roadmap for Devices and Systems (IRDS). However, p-type 2D FETs are dramatically lagging behind in meeting performance standards. Here, we adopt a three-pronged approach that includes contact engineering, channel length (Lch) scaling, and monolayer doping to achieve high performance p-type FETs based on synthetic WSe2. Using electrical measurements backed by atomistic imaging and rigorous analysis, Pd was identified as the favorable contact metal for WSe2 owing to better epitaxy, larger grain size, and higher compressive strain, leading to a lower Schottky barrier height. While the ON-state performance of Pd-contacted WSe2 FETs was improved by ∼10× by aggressively scaling Lch from 1 μm down to ∼20 nm, ultrascaled FETs were found to be contact limited. To reduce the contact resistance, monolayer tungsten oxyselenide (WOxSey) obtained using self-limiting oxidation of bilayer WSe2 was used as a p-type dopant. This led to ∼5× improvement in the ON-state performance and ∼9× reduction in the contact resistance. We were able to achieve a median ON-state current as high as ∼10 μA/μm for ultrascaled and doped p-type WSe2 FETs with Pd contacts. We also show the applicability of our monolayer doping strategy to other 2D materials such as MoS2, MoTe2, and MoSe2.
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Affiliation(s)
- Aaryan Oberoi
- Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Ying Han
- Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Sergei P Stepanoff
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- Applied Research Laboratory, Penn State University, University Park, Pennsylvania 16802, United States
| | - Andrew Pannone
- Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Yongwen Sun
- Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Yu-Chuan Lin
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu City 300093, Taiwan
| | - Chen Chen
- 2D Crystal Consortium Materials Innovation Platform, Penn State University, University Park, Pennsylvania 16802, United States
| | - Jeffrey R Shallenberger
- Materials Characterization Laboratory, Penn State University, University Park, Pennsylvania 16802, United States
| | - Da Zhou
- Department of Physics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Mauricio Terrones
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Physics, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Joan M Redwing
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- 2D Crystal Consortium Materials Innovation Platform, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Electrical Engineering, Penn State University, University Park, Pennsylvania 16802, United States
| | - Joshua A Robinson
- Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- 2D Crystal Consortium Materials Innovation Platform, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Physics, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Douglas E Wolfe
- Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- Applied Research Laboratory, Penn State University, University Park, Pennsylvania 16802, United States
| | - Yang Yang
- Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Saptarshi Das
- Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Electrical Engineering, Penn State University, University Park, Pennsylvania 16802, United States
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4
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Mallik SK, Padhan R, Sahu MC, Roy S, Pradhan GK, Sahoo PK, Dash SP, Sahoo S. Thermally Driven Multilevel Non-Volatile Memory with Monolayer MoS 2 for Brain-Inspired Artificial Learning. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37467425 DOI: 10.1021/acsami.3c06336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
The demands of modern electronic components require advanced computing platforms for efficient information processing to realize in-memory operations with a high density of data storage capabilities toward developing alternatives to von Neumann architectures. Herein, we demonstrate the multifunctionality of monolayer MoS2 memtransistors, which can be used as a high-geared intrinsic transistor at room temperature; however, at a high temperature (>350 K), they exhibit synaptic multilevel memory operations. The temperature-dependent memory mechanism is governed by interfacial physics, which solely depends on the gate field modulated ion dynamics and charge transfer at the MoS2/dielectric interface. We have proposed a non-volatile memory application using a single Field Effect Transistor (FET) device where thermal energy can be ventured to aid the memory functions with multilevel (3-bit) storage capabilities. Furthermore, our devices exhibit linear and symmetry in conductance weight updates when subjected to electrical potentiation and depression. This feature has enabled us to attain a high classification accuracy while training and testing the Modified National Institute of Standards and Technology datasets through artificial neural network simulation. This work paves the way toward reliable data processing and storage using 2D semiconductors with high-packing density arrays for brain-inspired artificial learning.
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Affiliation(s)
- Sameer Kumar Mallik
- Laboratory for Low Dimensional Materials, Institute of Physics, Bhubaneswar 751005, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Roshan Padhan
- Laboratory for Low Dimensional Materials, Institute of Physics, Bhubaneswar 751005, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Mousam Charan Sahu
- Laboratory for Low Dimensional Materials, Institute of Physics, Bhubaneswar 751005, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Suman Roy
- Laboratory for Low Dimensional Materials, Institute of Physics, Bhubaneswar 751005, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Gopal K Pradhan
- Department of Physics, School of Applied Sciences, KIIT Deemed to be University, Bhubaneswar 751024, Odisha, India
| | - Prasana Kumar Sahoo
- Materials Science Centre, Quantum Materials and Device Research Laboratory, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
| | - Saroj Prasad Dash
- Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg 41296, Sweden
| | - Satyaprakash Sahoo
- Laboratory for Low Dimensional Materials, Institute of Physics, Bhubaneswar 751005, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
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5
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Schranghamer TF, Sakib NU, Sadaf MUK, Subbulakshmi Radhakrishnan S, Pendurthi R, Agyapong AD, Stepanoff SP, Torsi R, Chen C, Redwing JM, Robinson JA, Wolfe DE, Mohney SE, Das S. Ultrascaled Contacts to Monolayer MoS 2 Field Effect Transistors. NANO LETTERS 2023; 23:3426-3434. [PMID: 37058411 DOI: 10.1021/acs.nanolett.3c00466] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Two-dimensional (2D) semiconductors possess promise for the development of field-effect transistors (FETs) at the ultimate scaling limit due to their strong gate electrostatics. However, proper FET scaling requires reduction of both channel length (LCH) and contact length (LC), the latter of which has remained a challenge due to increased current crowding at the nanoscale. Here, we investigate Au contacts to monolayer MoS2 FETs with LCH down to 100 nm and LC down to 20 nm to evaluate the impact of contact scaling on FET performance. Au contacts are found to display a ∼2.5× reduction in the ON-current, from 519 to 206 μA/μm, when LC is scaled from 300 to 20 nm. It is our belief that this study is warranted to ensure an accurate representation of contact effects at and beyond the technology nodes currently occupied by silicon.
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Affiliation(s)
- Thomas F Schranghamer
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Najam U Sakib
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Muhtasim Ul Karim Sadaf
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Shiva Subbulakshmi Radhakrishnan
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Rahul Pendurthi
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ama Duffie Agyapong
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sergei P Stepanoff
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Applied Research Laboratory, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Riccardo Torsi
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Chen Chen
- 2D Crystal Consortium Materials Innovation Platform, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joan M Redwing
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- 2D Crystal Consortium Materials Innovation Platform, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joshua A Robinson
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Douglas E Wolfe
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Applied Research Laboratory, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Suzanne E Mohney
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Saptarshi Das
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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6
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Tian J, Wang Q, Huang X, Tang J, Chu Y, Wang S, Shen C, Zhao Y, Li N, Liu J, Ji Y, Huang B, Peng Y, Yang R, Yang W, Watanabe K, Taniguchi T, Bai X, Shi D, Du L, Zhang G. Scaling of MoS 2 Transistors and Inverters to Sub-10 nm Channel Length with High Performance. NANO LETTERS 2023; 23:2764-2770. [PMID: 37010357 DOI: 10.1021/acs.nanolett.3c00031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Two-dimensional (2D) semiconductors such as monolayer molybdenum disulfide (MoS2) are promising building blocks for ultrascaled field effect transistors (FETs), benefiting from their atomic thickness, dangling-bond-free flat surface, and excellent gate controllability. However, despite great prospects, the fabrication of 2D ultrashort channel FETs with high performance and uniformity remains a challenge. Here, we report a self-encapsulated heterostructure undercut technique for the fabrication of sub-10 nm channel length MoS2 FETs. The fabricated 9 nm channel MoS2 FETs exhibit superior performances compared with sub-15 nm channel length including the competitive on-state current density of 734/433 μA/μm at VDS = 2/1 V, record-low DIBL of ∼50 mV/V, and superior on/off ratio of 3 × 107 and low subthreshold swing of ∼100 mV/dec. Furthermore, the ultrashort channel MoS2 FETs fabricated by this new technique show excellent homogeneity. Thanks to this, we scale the monolayer inverter down to sub-10 nm channel length.
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Affiliation(s)
- Jinpeng Tian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Qinqin Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Xudan Huang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Jian Tang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yanbang Chu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Shuopei Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
| | - Cheng Shen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yancong Zhao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Na Li
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
| | - Jieying Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yiru Ji
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Biying Huang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yalin Peng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Rong Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
| | - Wei Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
| | - Kenji Watanabe
- National Institute for Materials Science1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science1-1 Namiki, Tsukuba 305-0044, Japan
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Dongxia Shi
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Luojun Du
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Guangyu Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
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7
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Zhu Z, Kim JS, Moody MJ, Lauhon LJ. Edge and Interface Resistances Create Distinct Trade-Offs When Optimizing the Microstructure of Printed van der Waals Thin-Film Transistors. ACS NANO 2023; 17:575-586. [PMID: 36573755 DOI: 10.1021/acsnano.2c09527] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Inks based on two-dimensional (2D) materials could be used to tune the properties of printed electronics while maintaining compatibility with scalable manufacturing processes. However, a very wide range of performances have been reported in printed thin-film transistors in which the 2D channel material exhibits considerable variation in microstructure. The lack of quantitative physics-based relationships between film microstructure and transistor performance limits the codesign of exfoliation, sorting, and printing processes to inefficient empirical approaches. To rationally guide the development of 2D inks and related processing, we report a gate-dependent resistor network model that establishes distinct microstructure-performance relationships created by near-edge and intersheet resistances in printed van der Waals thin-film transistors. The model is calibrated by analyzing electrical output characteristics of model transistors consisting of overlapping 2D nanosheets with varied thicknesses that are mechanically exfoliated and transferred. Kelvin probe force microscopy analysis on the model transistors leads to the discovery that the nanosheet edges, not the intersheet resistance, limit transport due to their impact on charge carrier depletion and scattering. Our model suggests that when transport in a 2D material network is limited by the near-edge resistance, the optimum nanosheet thickness is dictated by a trade-off between charged impurity screening and gate screening, and the film mobilities are more sensitive to variations in printed nanosheet density. Removal of edge states can enable the realization of higher mobilities with thinner nanosheets due to reduced junction resistances and reduced gate screening. Our analysis of the influence of nanosheet edges on the effective film mobility not only examines the prospects of extant exfoliation methods to achieve the optimum microstructure but also provides important perspectives on processes that are essential to maximizing printed film performance.
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Affiliation(s)
- Zhehao Zhu
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Joon-Seok Kim
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Michael J Moody
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
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8
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Wang S, Liu X, Zhou P. The Road for 2D Semiconductors in the Silicon Age. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2106886. [PMID: 34741478 DOI: 10.1002/adma.202106886] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/21/2021] [Indexed: 06/13/2023]
Abstract
Continued reduction in transistor size can improve the performance of silicon integrated circuits (ICs). However, as Moore's law approaches physical limits, high-performance growth in silicon ICs becomes unsustainable, due to challenges of scaling, energy efficiency, and memory limitations. The ultrathin layers, diverse band structures, unique electronic properties, and silicon-compatible processes of 2D materials create the potential to consistently drive advanced performance in ICs. Here, the potential of fusing 2D materials with silicon ICs to minimize the challenges in silicon ICs, and to create technologies beyond the von Neumann architecture, is presented, and the killer applications for 2D materials in logic and memory devices to ease scaling, energy efficiency bottlenecks, and memory dilemmas encountered in silicon ICs are discussed. The fusion of 2D materials allows the creation of all-in-one perception, memory, and computation technologies beyond the von Neumann architecture to enhance system efficiency and remove computing power bottlenecks. Progress on the 2D ICs demonstration is summarized, as well as the technical hurdles it faces in terms of wafer-scale heterostructure growth, transfer, and compatible integration with silicon ICs. Finally, the promising pathways and obstacles to the technological advances in ICs due to the integration of 2D materials with silicon are presented.
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Affiliation(s)
- Shuiyuan Wang
- ASIC & System State Key Lab, School of Microelectronics, Fudan University, Shanghai, 200433, China
| | - Xiaoxian Liu
- ASIC & System State Key Lab, School of Microelectronics, Fudan University, Shanghai, 200433, China
| | - Peng Zhou
- ASIC & System State Key Lab, School of Microelectronics, Fudan University, Shanghai, 200433, China
- Frontier Institute of Chip and System, Shanghai Frontier Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai, 200433, China
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9
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Xiong H, Xu L, Gao C, Zhang Q, Deng M, Wang Q, Zhang J, Fuchs D, Li W, Cui A, Shang L, Jiang K, Hu Z, Chu J. Optically Modulated HfS 2-Based Synapses for Artificial Vision Systems. ACS APPLIED MATERIALS & INTERFACES 2021; 13:50132-50140. [PMID: 34662123 DOI: 10.1021/acsami.1c14332] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The simulation of human brain neurons by synaptic devices could be an effective strategy to break through the notorious "von Neumann Bottleneck" and "Memory Wall". Herein, opto-electronic synapses based on layered hafnium disulfide (HfS2) transistors have been investigated. The basic functions of biological synapses are realized and optimized by modifying pulsed light conditions. Furthermore, 2 × 2 pixel imaging chips have also been developed. Two-pixel visual information is illuminated on diagonal pixels of the imaging array by applying light pulses (λ = 405 nm) with different pulse frequencies, mimicking short-term memory and long-term memory characteristics of the human vision system. In addition, an optically/electrically driven neuromorphic computation is demonstrated by machine learning to classify hand-written numbers with an accuracy of about 88.5%. This work will be an important step toward an artificial neural network comprising neuromorphic vision sensing and training functions.
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Affiliation(s)
- Hao Xiong
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Liping Xu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
- Center for Advanced Electronic Materials and Devices, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Caifang Gao
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Qing Zhang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Menghan Deng
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Qiangfei Wang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Jinzhong Zhang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
- Chongqing Key Laboratory of Precision Optics, Chongqing Institute of East China Normal University, Chongqing 401123, China
| | - Dirk Fuchs
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, Karlsruhe 75021, Germany
| | - Wenwu Li
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Anyang Cui
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Liyan Shang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Kai Jiang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Zhigao Hu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
| | - Junhao Chu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
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10
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Tang A, Kumar A, Jaikissoon M, Saraswat K, Wong HSP, Pop E. Toward Low-Temperature Solid-Source Synthesis of Monolayer MoS 2. ACS APPLIED MATERIALS & INTERFACES 2021; 13:41866-41874. [PMID: 34427445 DOI: 10.1021/acsami.1c06812] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional (2D) semiconductors have been proposed for heterogeneous integration with existing silicon technology; however, their chemical vapor deposition (CVD) growth temperatures are often too high. Here, we demonstrate direct CVD solid-source precursor synthesis of continuous monolayer (1L) MoS2 films at 560 °C in 50 min, within the 450-to-600 °C, 2 h thermal budget window required for back-end-of-the-line compatibility with modern silicon technology. Transistor measurements reveal on-state current up to ∼140 μA/μm at 1 V drain-to-source voltage for 100 nm channel lengths, the highest reported to date for 1L MoS2 grown below 600 °C using solid-source precursors. The effective mobility from transfer length method test structures is 29 ± 5 cm2 V-1 s-1 at 6.1 × 1012 cm-2 electron density, which is comparable to mobilities reported from films grown at higher temperatures. The results of this work provide a path toward the realization of high-quality, thermal-budget-compatible 2D semiconductors for heterogeneous integration with silicon manufacturing.
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Affiliation(s)
- Alvin Tang
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - Aravindh Kumar
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - Marc Jaikissoon
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - Krishna Saraswat
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Precourt Institute for Energy, Stanford University, Stanford, California 94305, United States
| | - H-S Philip Wong
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
- Precourt Institute for Energy, Stanford University, Stanford, California 94305, United States
| | - Eric Pop
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Precourt Institute for Energy, Stanford University, Stanford, California 94305, United States
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11
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Pang CS, Zhou R, Liu X, Wu P, Hung TYT, Guo S, Zaghloul ME, Krylyuk S, Davydov AV, Appenzeller J, Chen Z. Mobility Extraction in 2D Transition Metal Dichalcogenide Devices-Avoiding Contact Resistance Implicated Overestimation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2100940. [PMID: 34110675 PMCID: PMC9703574 DOI: 10.1002/smll.202100940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/25/2021] [Indexed: 06/01/2023]
Abstract
Schottky barrier (SB) transistors operate distinctly different from conventional metal-oxide semiconductor field-effect transistors, in a unique way that the gate impacts the carrier injection from the metal source/drain contacts into the channel region. While it has been long recognized that this can have severe implications for device characteristics in the subthreshold region, impacts of contact gating of SB in the on-state of the devices, which affects evaluation of intrinsic channel properties, have been yet comprehensively studied. Due to the fact that contact resistance (RC ) is always gate-dependent in a typical back-gated device structure, the traditional approach of deriving field-effect mobility from the maximum transconductance (gm ) is in principle not correct and can even overestimate the mobility. In addition, an exhibition of two different threshold voltages for the channel and the contact region leads to another layer of complexity in determining the true carrier concentration calculated from Q = COX * (VG -VTH ). Through a detailed experimental analysis, the effect of different effective oxide thicknesses, distinct SB heights, and doping-induced reductions in the SB width are carefully evaluated to gain a better understanding of their impact on important device metrics.
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Affiliation(s)
- Chin-Sheng Pang
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Ruiping Zhou
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Xiangkai Liu
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Peng Wu
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Terry Y T Hung
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Shiqi Guo
- School of Engineering and Applied Science, The George Washington University, Washington, DC, 20052, USA
| | - Mona E Zaghloul
- School of Engineering and Applied Science, The George Washington University, Washington, DC, 20052, USA
| | - Sergiy Krylyuk
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD, 20899, USA
| | - Albert V Davydov
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD, 20899, USA
| | - Joerg Appenzeller
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Zhihong Chen
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
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12
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Yi J, Sun X, Zhu C, Li S, Liu Y, Zhu X, You W, Liang D, Shuai Q, Wu Y, Li D, Pan A. Double-Gate MoS 2 Field-Effect Transistors with Full-Range Tunable Threshold Voltage for Multifunctional Logic Circuits. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101036. [PMID: 34057257 DOI: 10.1002/adma.202101036] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 04/07/2021] [Indexed: 05/07/2023]
Abstract
Multifunctional reconfigurable devices, with higher information capacity, smaller size, and more functions, are urgently needed and draw most attention in frontiers in information technology. 2D semiconductors, ascribing to ultrathin body and easy electrostatic control, show great potential in developing reconfigurable functional units. This work proposes a novel double-gate field-effect transistor architecture with equal top and bottom gate (TG and BG) and realizes flexible optimization of the subthreshold swing (SS) and threshold voltage (VTH ). While the TG and BG are used simultaneously, as a single gate to drive the transistor, ultralow average SS value of 65.5 mV dec-1 can be obtained in a large current range over 104 , enabling the application in high gain inverter. While one gate is used to initialize the channel doping, full logic swing inverter circuit with high noise margin (over 90%) is demonstrated. Such device prototype is further extended for designing reconfigurable logic applications and can be dynamically switched and well maintained between binary and ternary logics. This study provides important concept and device prototype for future multifunctional logic applications.
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Affiliation(s)
- Jiali Yi
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Xingxia Sun
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Chenguang Zhu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Shengman Li
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Yong Liu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Xiaoli Zhu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Wenxia You
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Delang Liang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Qin Shuai
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Yanqing Wu
- Wuhan National High Magnetic Field Center and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Dong Li
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Anlian Pan
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China
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13
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Stanley LJ, Chuang HJ, Zhou Z, Koehler MR, Yan J, Mandrus DG, Popović D. Low-Temperature 2D/2D Ohmic Contacts in WSe 2 Field-Effect Transistors as a Platform for the 2D Metal-Insulator Transition. ACS APPLIED MATERIALS & INTERFACES 2021; 13:10594-10602. [PMID: 33617715 DOI: 10.1021/acsami.0c21440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report the fabrication of hexagonal-boron-nitride (hBN) encapsulated multiterminal WSe2 Hall bars with 2D/2D low-temperature Ohmic contacts as a platform for investigating the two-dimensional (2D) metal-insulator transition. We demonstrate that the WSe2 devices exhibit Ohmic behavior down to 0.25 K and at low enough excitation voltages to avoid current-heating effects. Additionally, the high-quality hBN-encapsulated WSe2 devices in ideal Hall-bar geometry enable us to accurately determine the carrier density. Measurements of the temperature (T) and density (ns) dependence of the conductivity σ(T, ns) demonstrate scaling behavior consistent with a metal-insulator quantum phase transition driven by electron-electron interactions but where disorder-induced local magnetic moments are also present. Our findings pave the way for further studies of the fundamental quantum mechanical properties of 2D transition metal dichalcogenides using the same contact engineering.
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Affiliation(s)
- Lily J Stanley
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
- Department of Physics, Florida State University, Tallahassee, Florida 32306, United States
| | - Hsun-Jen Chuang
- Physics and Astronomy Department, Wayne State University, Detroit, Michigan 48202, United States
| | - Zhixian Zhou
- Physics and Astronomy Department, Wayne State University, Detroit, Michigan 48202, United States
| | - Michael R Koehler
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jiaqiang Yan
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
- Oak Ridge National Lab, Oak Ridge, Tennessee 37830, United States
| | - David G Mandrus
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
- Oak Ridge National Lab, Oak Ridge, Tennessee 37830, United States
| | - Dragana Popović
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
- Department of Physics, Florida State University, Tallahassee, Florida 32306, United States
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14
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Promises and prospects of two-dimensional transistors. Nature 2021; 591:43-53. [PMID: 33658691 DOI: 10.1038/s41586-021-03339-z] [Citation(s) in RCA: 315] [Impact Index Per Article: 105.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 12/14/2020] [Indexed: 01/31/2023]
Abstract
Two-dimensional (2D) semiconductors have attracted tremendous interest as atomically thin channels that could facilitate continued transistor scaling. However, despite many proof-of-concept demonstrations, the full potential of 2D transistors has yet to be determined. To this end, the fundamental merits and technological limits of 2D transistors need a critical assessment and objective projection. Here we review the promise and current status of 2D transistors, and emphasize that widely used device parameters (such as carrier mobility and contact resistance) could be frequently misestimated or misinterpreted, and may not be the most reliable performance metrics for benchmarking 2D transistors. We suggest that the saturation or on-state current density, especially in the short-channel limit, could provide a more reliable measure for assessing the potential of diverse 2D semiconductors, and should be applied for cross-checking different studies, especially when milestone performance metrics are claimed. We also summarize the key technical challenges in optimizing the channels, contacts, dielectrics and substrates and outline potential pathways to push the performance limit of 2D transistors. We conclude with an overview of the critical technical targets, the key technological obstacles to the 'lab-to-fab' transition and the potential opportunities arising from the use of these atomically thin semiconductors.
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15
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Sebastian A, Pendurthi R, Choudhury TH, Redwing JM, Das S. Benchmarking monolayer MoS 2 and WS 2 field-effect transistors. Nat Commun 2021; 12:693. [PMID: 33514710 PMCID: PMC7846590 DOI: 10.1038/s41467-020-20732-w] [Citation(s) in RCA: 137] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 12/17/2020] [Indexed: 11/09/2022] Open
Abstract
Here we benchmark device-to-device variation in field-effect transistors (FETs) based on monolayer MoS2 and WS2 films grown using metal-organic chemical vapor deposition process. Our study involves 230 MoS2 FETs and 160 WS2 FETs with channel lengths ranging from 5 μm down to 100 nm. We use statistical measures to evaluate key FET performance indicators for benchmarking these two-dimensional (2D) transition metal dichalcogenide (TMD) monolayers against existing literature as well as ultra-thin body Si FETs. Our results show consistent performance of 2D FETs across 1 × 1 cm2 chips owing to high quality and uniform growth of these TMDs followed by clean transfer onto device substrates. We are able to demonstrate record high carrier mobility of 33 cm2 V-1 s-1 in WS2 FETs, which is a 1.5X improvement compared to the best reported in the literature. Our experimental demonstrations confirm the technological viability of 2D FETs in future integrated circuits.
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Affiliation(s)
- Amritanand Sebastian
- Department of Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA
| | - Rahul Pendurthi
- Department of Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA
| | - Tanushree H Choudhury
- 2D Crystal Consortium-Materials Innovation Platform (2DCC-MIP), Penn State University, University Park, PA, 16802, USA
| | - Joan M Redwing
- 2D Crystal Consortium-Materials Innovation Platform (2DCC-MIP), Penn State University, University Park, PA, 16802, USA.,Department of Materials Science and Engineering, Penn State University, University Park, PA, 16802, USA.,Materials Research Institute, Penn State University, University Park, PA, 16802, USA
| | - Saptarshi Das
- Department of Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA. .,Department of Materials Science and Engineering, Penn State University, University Park, PA, 16802, USA. .,Materials Research Institute, Penn State University, University Park, PA, 16802, USA.
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16
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Jelver L, Stradi D, Stokbro K, Jacobsen KW. Schottky barrier lowering due to interface states in 2D heterophase devices. NANOSCALE ADVANCES 2021; 3:567-574. [PMID: 36131736 PMCID: PMC9418679 DOI: 10.1039/d0na00795a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/05/2020] [Indexed: 05/03/2023]
Abstract
The Schottky barrier of a metal-semiconductor junction is one of the key quantities affecting the charge transport in a transistor. The Schottky barrier height depends on several factors, such as work function difference, local atomic configuration in the interface, and impurity doping. We show that also the presence of interface states at 2D metal-semiconductor junctions can give rise to a large renormalization of the effective Schottky barrier determined from the temperature dependence of the current. We investigate the charge transport in n- and p-doped monolayer MoTe2 1T'-1H junctions using ab initio quantum transport calculations. The Schottky barriers are extracted both from the projected density of states and the transmission spectrum, and by simulating the IT-characteristic and applying the thermionic emission model. We find interface states originating from the metallic 1T' phase rather than the semiconducting 1H phase in contrast to the phenomenon of Fermi level pinning. Furthermore, we find that these interface states mediate large tunneling currents which dominates the charge transport and can lower the effective barrier to a value of only 55 meV.
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Affiliation(s)
- Line Jelver
- CAMD, Dept. of Physics, Technical University of Denmark Bldg. 309 DK-2800 Kongens Lyngby Denmark
- Synopsys QuantumATK Fruebjergvej 3, PostBox 4 DK-2100 Copenhagen Denmark
| | - Daniele Stradi
- Synopsys QuantumATK Fruebjergvej 3, PostBox 4 DK-2100 Copenhagen Denmark
| | - Kurt Stokbro
- Synopsys QuantumATK Fruebjergvej 3, PostBox 4 DK-2100 Copenhagen Denmark
| | - Karsten Wedel Jacobsen
- CAMD, Dept. of Physics, Technical University of Denmark Bldg. 309 DK-2800 Kongens Lyngby Denmark
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17
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Sun X, Zhu C, Liu H, Zheng B, Liu Y, Yi J, Fang L, Liu Y, Wang X, Zubair M, Zhu X, Wang X, Li D, Pan A. Contact and injection engineering for low SS reconfigurable FETs and high gain complementary inverters. Sci Bull (Beijing) 2020; 65:2007-2013. [PMID: 36659059 DOI: 10.1016/j.scib.2020.06.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 05/09/2020] [Accepted: 06/15/2020] [Indexed: 01/21/2023]
Abstract
The newly emerged two-dimensional (2D) semiconducting materials, owning to the atomic thick nature and excellent optical and electrical properties, are considered as potential candidates to solve the bottlenecks of traditional semiconductors. However, the realization of high performance 2D semiconductor-based field-effect transistors (FETs) has been a longstanding challenge in 2D electronics, which is mainly ascribing to the presence of significant Schottky barrier (SB) at metal-semiconductor interfaces. Here, an additional contact gate is induced in 2D ambipolar FET to realize near ideal reconfigurable FET (RFET) devices without restrictions of SB. Benefitting from the consistently high doping of contact region, the effective SB height can be maintained at ultra-small value during all operation conditions, resulting in the near ideal subthreshold swing (SS) values (132 mV/decade for MoTe2 RFET and 67 mV/decade for WSe2 RFET) and the relatively high mobility (28.6 cm2/(V s) for MoTe2 RFET and 89.8 cm2/(V s) for WSe2 RFET). Moreover, the flexible control on the doping polarity of contact region enables the remodeling and switching of the achieved unipolar FETs between p-type mode and n-type mode. Based on such reconfigurable behaviors, high gain complementary MoTe2 inverters are further realized. The findings in this work push forward the development of high-performance 2D semiconductor integrated devices and circuits.
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Affiliation(s)
- Xingxia Sun
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Chenguang Zhu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Huawei Liu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Biyuan Zheng
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Yong Liu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Jiali Yi
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Lizhen Fang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Ying Liu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Xingwang Wang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Muhammad Zubair
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Xiaoli Zhu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Xiao Wang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Dong Li
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China.
| | - Anlian Pan
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China.
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18
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Kozhakhmetov A, Schuler B, Tan AMZ, Cochrane KA, Nasr JR, El-Sherif H, Bansal A, Vera A, Bojan V, Redwing JM, Bassim N, Das S, Hennig RG, Weber-Bargioni A, Robinson JA. Scalable Substitutional Re-Doping and its Impact on the Optical and Electronic Properties of Tungsten Diselenide. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2005159. [PMID: 33169451 DOI: 10.1002/adma.202005159] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Reliable, controlled doping of 2D transition metal dichalcogenides will enable the realization of next-generation electronic, logic-memory, and magnetic devices based on these materials. However, to date, accurate control over dopant concentration and scalability of the process remains a challenge. Here, a systematic study of scalable in situ doping of fully coalesced 2D WSe2 films with Re atoms via metal-organic chemical vapor deposition is reported. Dopant concentrations are uniformly distributed over the substrate surface, with precisely controlled concentrations down to <0.001% Re achieved by tuning the precursor partial pressure. Moreover, the impact of doping on morphological, chemical, optical, and electronic properties of WSe2 is elucidated with detailed experimental and theoretical examinations, confirming that the substitutional doping of Re at the W site leads to n-type behavior of WSe2 . Transport characteristics of fabricated back-gated field-effect-transistors are directly correlated to the dopant concentration, with degrading device performances for doping concentrations exceeding 1% of Re. The study demonstrates a viable approach to introducing true dopant-level impurities with high precision, which can be scaled up to batch production for applications beyond digital electronics.
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Affiliation(s)
- Azimkhan Kozhakhmetov
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, 8600, Switzerland
| | - Anne Marie Z Tan
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Katherine A Cochrane
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Joseph R Nasr
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hesham El-Sherif
- Department of Materials Science and Engineering, McMaster University, Hamilton, ON, L8S 4L8, Canada
| | - Anushka Bansal
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Alex Vera
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Vincent Bojan
- Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Joan M Redwing
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
- Two-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Nabil Bassim
- Department of Materials Science and Engineering, McMaster University, Hamilton, ON, L8S 4L8, Canada
| | - Saptarshi Das
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, 16802, USA
- Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Richard G Hennig
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | | | - Joshua A Robinson
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
- Two-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
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19
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Trung N, Hossain MI, Alam MI, Ando A, Kitakami O, Kikuchi N, Takaoka T, Sainoo Y, Arafune R, Komeda T. In Situ Study of Molecular Doping of Chlorine on MoS 2 Field Effect Transistor Device in Ultrahigh Vacuum Conditions. ACS OMEGA 2020; 5:28108-28115. [PMID: 33163793 PMCID: PMC7643195 DOI: 10.1021/acsomega.0c03741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/08/2020] [Indexed: 06/11/2023]
Abstract
We report a precise measurement of the sensor behavior of the field effect transistor (FET) formed with the MoS2 channel when the channel part is exposed to Cl2 gas. The gas exposure and the electrical measurement of the MoS2 FET were executed with in situ ultrahigh-vacuum (UHV) conditions in which the surface analysis techniques were equipped. This makes it possible to detect how much sensitivity the MoS2 FET can provide and understand the surface properties. With the Cl2 gas exposure to the channel, the plot of the drain current versus the gate voltage (I d-V g curve) shifts monotonically toward the positive direction of V g, suggesting that the adsorbate acts as an electron acceptor. The I d-V g shifts are numerically estimated by measuring the onset of I d (threshold voltage, V th) and the mobility as a function of the dosing amounts of the Cl2 gas. The behaviors of both the V th shift and the mobility with the Cl2 dosing amount can be fitted with the Langmuir adsorption kinetics, which is typically seen in the uptake curve of molecule adsorption onto well-defined surfaces. This can be accounted for by a model where an impinging molecule occupies an empty site with a certain probability, and each adsorbate receives a certain amount of negative charge from the MoS2 surface up to the monolayer coverage. The charge transfer makes the V th shifts. In addition, the mobility is reduced by the enhancement of the Coulomb scattering for the electron flow in the MoS2 channel by the accumulated charge. From the thermal desorption spectroscopy (TDS) measurement and density functional theory (DFT) calculations, we concluded that the adsorbate that is responsible for the change of the FET property is the Cl atom that is dissociated from the Cl2 molecule. The monotonic shift of V th with the coverage suggests that the MoS2 device sensor has a good sensitivity to detect 10-3 monolayers (ML) of adsorption corresponding to the ppb level sensor with an activation time of 1 s.
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Affiliation(s)
- Nguyen
Tat Trung
- Department
of Chemistry, Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 980-8578, Japan
| | - Mohammad Ikram Hossain
- Department
of Chemistry, Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 980-8578, Japan
| | - Md Iftekharul Alam
- Department
of Chemistry, Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 980-8578, Japan
| | - Atsushi Ando
- Nanoelectronics
Research Institute, National Institute of
Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Osamu Kitakami
- Institute
of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, 2-1-1, Katahira, Aoba-Ku, Sendai 980-0877, Japan
- Center
for Spintronics Research Network, Tohoku
University, Sendai 980-0877, Japan
| | - Nobuaki Kikuchi
- Institute
of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, 2-1-1, Katahira, Aoba-Ku, Sendai 980-0877, Japan
- Center
for Spintronics Research Network, Tohoku
University, Sendai 980-0877, Japan
| | - Tsuyoshi Takaoka
- Institute
of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, 2-1-1, Katahira, Aoba-Ku, Sendai 980-0877, Japan
| | - Yasuyuki Sainoo
- Institute
of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, 2-1-1, Katahira, Aoba-Ku, Sendai 980-0877, Japan
| | - Ryuichi Arafune
- International
Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 304-0044, Japan
| | - Tadahiro Komeda
- Institute
of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, 2-1-1, Katahira, Aoba-Ku, Sendai 980-0877, Japan
- Center
for Spintronics Research Network, Tohoku
University, Sendai 980-0877, Japan
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20
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Abstract
In this article, we adopt a radical approach for next generation ultra-low-power sensor design by embracing the evolutionary success of animals with extraordinary sensory information processing capabilities that allow them to survive in extreme and resource constrained environments. Stochastic resonance (SR) is one of those astounding phenomena, where noise, which is considered detrimental for electronic circuits and communication systems, plays a constructive role in the detection of weak signals. Here, we show SR in a photodetector based on monolayer MoS2 for detecting ultra-low-intensity subthreshold optical signals from a distant light emitting diode (LED). We demonstrate that weak periodic LED signals, which are otherwise undetectable, can be detected by a MoS2 photodetector in the presence of a finite and optimum amount of white Gaussian noise at a frugal energy expenditure of few tens of nano-Joules. The concept of SR is generic in nature and can be extended beyond photodetector to any other sensors. Here, the authors take advantage of stochastic resonance in a photodetector based on monolayer MoS2 for measuring otherwise undetectable, ultra-low-intensity, subthreshold optical signals from a distant light emitting diode in the presence of a finite and optimum amount of white Gaussian noise.
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21
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Yang H, Xiang D, Mao H, Liu T, Wang Y, Guo R, Zheng Y, Ye X, Gao J, Ge Q, Deng C, Cai W, Zhang X, Qin S, Chen W. Native Oxide Seeded Spontaneous Integration of Dielectrics on Exfoliated Black Phosphorus. ACS APPLIED MATERIALS & INTERFACES 2020; 12:24411-24418. [PMID: 32352282 DOI: 10.1021/acsami.0c01161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional (2D) semiconductors have been a central focus for next-generation electronics and optoelectronics owing to their great potential to extend the scaling limits in a silicon transistor. However, due to the lack of surface dangling bonds in most 2D semiconductors, such as graphene and transition metal dichalcogenides (TMDs), the direct growth of the high-κ film on these 2D materials via an atomic layer deposition (ALD) technique often produces dielectrics with poor quality, which hinders their integration in the modern semiconductor industry. Here, we comprehensively investigate the ALD growth of the Al2O3 layer on 2D exfoliated black phosphorus (BP). Intriguingly, we found that the 2D BP with "silicon-like" characteristics possesses a native surface oxide layer PxOy after air exposure. The PxOy-induced surface dangling bonds enable the spontaneous integration of the high-quality Al2O3 layer on the BP flake without any pretreatments to functionalize the surface. Additionally, the Al2O3 layer could effectively passivate BP to prevent its degradation in ambient conditions, which addresses the most serious problem of the BP material. Moreover, the Al2O3-encapsulated BP field-effect transistor (FET) exhibits good electrical transport performance, with a high hole mobility of ∼420 cm2 V-1 s-1 and electron mobility of ∼80 cm2 V-1 s-1. Moreover, the high-quality Al2O3 layer can also be integrated into the top-gated BP transistor and inverter. Our findings reveal the silicon-like characteristics of BP for the high-κ ALD dielectric growth technology, which promises the seamless integration of 2D BP in the modern semiconductor industry.
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Affiliation(s)
- Hang Yang
- College of Arts and Science, National University of Defense Technology, Changsha 410073, China
- Department of Physics, National University of Singapore, Singapore 117543, Singapore
| | - Du Xiang
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Hongying Mao
- Department of Physics, Hangzhou Normal University, Hangzhou 311121, China
| | - Tao Liu
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Yanan Wang
- Department of Physics, National University of Singapore, Singapore 117543, Singapore
| | - Rui Guo
- Department of Physics, National University of Singapore, Singapore 117543, Singapore
| | - Yue Zheng
- Department of Physics, National University of Singapore, Singapore 117543, Singapore
| | - Xin Ye
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Jing Gao
- Department of Physics, National University of Singapore, Singapore 117543, Singapore
| | - Qi Ge
- Chongqing 2D Materials Institute, Liangjiang New Area, Chongqing 400714, China
| | - Chuyun Deng
- College of Arts and Science, National University of Defense Technology, Changsha 410073, China
| | - Weiwei Cai
- College of Physical Science and Technology, Xiamen University, Xiamen 361005, China
| | - Xueao Zhang
- Chongqing 2D Materials Institute, Liangjiang New Area, Chongqing 400714, China
- College of Physical Science and Technology, Xiamen University, Xiamen 361005, China
| | - Shiqiao Qin
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
| | - Wei Chen
- Department of Physics, National University of Singapore, Singapore 117543, Singapore
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
- National University of Singapore (Suzhou) Research Institute, 377 Lin Quan Street, Suzhou Industrial Park, Suzhou 215123, Jiangsu, China
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22
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Pyeon JJ, Baek IH, Lee WC, Lee H, Won SO, Lee GY, Chung TM, Han JH, Baek SH, Kim JS, Choi JW, Kang CY, Kim SK. Wafer-Scale, Conformal, and Low-Temperature Synthesis of Layered Tin Disulfides for Emerging Nonplanar and Flexible Electronics. ACS APPLIED MATERIALS & INTERFACES 2020; 12:2679-2686. [PMID: 31849212 DOI: 10.1021/acsami.9b19471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Two-dimensional (2D) metal dichalcogenides have drawn considerable interest because they offer possibilities for the implementation of emerging electronics. The emerging electronics are moving toward two major directions: vertical expansion of device space and flexibility. However, the development of a synthesis method for 2D metal dichalcogenides that meets all the requirements remains a significant challenge. Here, we propose a promising method for wafer-scale, conformal, and low-temperature (≤240 °C) synthesis of single-phase SnS2 via the atomic layer deposition technique. There is a trade-off relationship between the crystallinity and orientation preference of SnS2, which is efficiently eliminated by the two-step growth occurring at different temperatures. Consequently, the van der Waals layers of the highly crystalline SnS2 are parallel to the substrate. Thin-film transistors (TFTs) comprising the SnS2 layer show reasonable electrical performances (field-effect mobility: ∼0.8 cm2 V-1 s-1 and on/off ratio: ∼106), which are comparable to that of a single-crystal SnS2 flake. Moreover, we demonstrate nonplanar and flexible TFTs to identify the feasibility of the implementation of future electronics. Both the diagonal-structured TFT and flexible TFT fabricated without a transfer process show electrical performances comparable to those of rigid and planar TFTs. Particularly, the flexible TFT does not exhibit substantial degradation even after 2000 bending cycles. Our work would provide decisive opportunities for the implementation of future electronic devices utilizing 2D metal chalcogenides.
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Affiliation(s)
- Jung Joon Pyeon
- KU-KIST Graduate School of Converging Science and Technology , Korea University , Seoul 02841 , Korea
- Center for Electronic Materials , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - In-Hwan Baek
- Center for Electronic Materials , Korea Institute of Science and Technology , Seoul 02792 , Korea
- Department of Materials Science and Engineering , Seoul National University , Seoul 08826 , Korea
| | - Woo Chul Lee
- Center for Electronic Materials , Korea Institute of Science and Technology , Seoul 02792 , Korea
- Department of Materials Science and Engineering , Seoul National University , Seoul 08826 , Korea
| | - Hansol Lee
- Advanced Analysis Center , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Sung Ok Won
- Advanced Analysis Center , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Ga-Yeon Lee
- Division of Advanced Materials , Korea Research Institute of Chemical Technology , Daejeon 34114 , Korea
| | - Taek-Mo Chung
- Division of Advanced Materials , Korea Research Institute of Chemical Technology , Daejeon 34114 , Korea
| | - Jeong Hwan Han
- Department of Materials Science and Engineering , Seoul National University of Science and Technology , Seoul 01811 , Korea
| | - Seung-Hyub Baek
- Center for Electronic Materials , Korea Institute of Science and Technology , Seoul 02792 , Korea
- Department of Materials Science and Engineering , Yonsei University , Seoul 03722 , Korea
- Yonsei-KIST Convergence Research Institute , Seoul 02792 , Korea
| | - Jin-Sang Kim
- Center for Electronic Materials , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Ji-Won Choi
- Center for Electronic Materials , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Chong-Yun Kang
- KU-KIST Graduate School of Converging Science and Technology , Korea University , Seoul 02841 , Korea
- Center for Electronic Materials , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Seong Keun Kim
- Center for Electronic Materials , Korea Institute of Science and Technology , Seoul 02792 , Korea
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23
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Sebastian A, Pannone A, Subbulakshmi Radhakrishnan S, Das S. Gaussian synapses for probabilistic neural networks. Nat Commun 2019; 10:4199. [PMID: 31519885 PMCID: PMC6744503 DOI: 10.1038/s41467-019-12035-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 08/13/2019] [Indexed: 11/09/2022] Open
Abstract
The recent decline in energy, size and complexity scaling of traditional von Neumann architecture has resurrected considerable interest in brain-inspired computing. Artificial neural networks (ANNs) based on emerging devices, such as memristors, achieve brain-like computing but lack energy-efficiency. Furthermore, slow learning, incremental adaptation, and false convergence are unresolved challenges for ANNs. In this article we, therefore, introduce Gaussian synapses based on heterostructures of atomically thin two-dimensional (2D) layered materials, namely molybdenum disulfide and black phosphorus field effect transistors (FETs), as a class of analog and probabilistic computational primitives for hardware implementation of statistical neural networks. We also demonstrate complete tunability of amplitude, mean and standard deviation of the Gaussian synapse via threshold engineering in dual gated molybdenum disulfide and black phosphorus FETs. Finally, we show simulation results for classification of brainwaves using Gaussian synapse based probabilistic neural networks.
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Affiliation(s)
- Amritanand Sebastian
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, 16802, USA
| | - Andrew Pannone
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, 16802, USA
| | - Shiva Subbulakshmi Radhakrishnan
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, 16802, USA
- Electrical and Electronics Engineering, Amrita Vishwa Vidyapeetham, Ettimadai, Coimbatore, Tamil Nadu, 641112, India
| | - Saptarshi Das
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Materials Research Institute, Pennsylvania State University, University Park, PA, 16802, USA.
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24
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Cheng Z, Yu Y, Singh S, Price K, Noyce SG, Lin YC, Cao L, Franklin AD. Immunity to Contact Scaling in MoS 2 Transistors Using in Situ Edge Contacts. NANO LETTERS 2019; 19:5077-5085. [PMID: 31283241 DOI: 10.1021/acs.nanolett.9b01355] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Atomically thin two-dimensional (2D) materials are promising candidates for sub-10 nm transistor channels due to their ultrathin body thickness, which results in strong electrostatic gate control. Properly scaling a transistor technology requires reducing both the channel length (distance from source to drain) and the contact length (distance that source and drain interface with semiconducting channel). Contact length scaling remains an unresolved epidemic for transistor scaling, affecting devices from all semiconductors-silicon to 2D materials. Here, we show that clean edge contacts to 2D MoS2 can provide immunity to the contact-scaling problem, with performance that is independent of contact length down to the 20 nm regime. Using a directional ion beam, in situ edge contacts of various metal-MoS2 interfaces are studied. Characterization of the intricate edge interface using cross-sectional electron microscopy reveals distinct morphological effects on the MoS2 depending on its thickness-from monolayer to few-layer films. The in situ edge contacts also exhibit an order of magnitude higher performance compared to the best-reported ex situ metal edge contacts. Our work provides experimental evidence for a solution to contact scaling in transistors, using 2D materials with clean edge contact interfaces, opening a new way of designing devices with 2D materials.
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Affiliation(s)
- Zhihui Cheng
- Department of Electrical and Computer Engineering , Duke University , Durham , North Carolina 27708 , United States
| | - Yifei Yu
- Department of Materials Science and Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Shreya Singh
- Department of Electrical and Computer Engineering , Duke University , Durham , North Carolina 27708 , United States
| | - Katherine Price
- Department of Electrical and Computer Engineering , Duke University , Durham , North Carolina 27708 , United States
| | - Steven G Noyce
- Department of Electrical and Computer Engineering , Duke University , Durham , North Carolina 27708 , United States
| | - Yuh-Chen Lin
- Department of Electrical and Computer Engineering , Duke University , Durham , North Carolina 27708 , United States
| | - Linyou Cao
- Department of Materials Science and Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Aaron D Franklin
- Department of Electrical and Computer Engineering , Duke University , Durham , North Carolina 27708 , United States
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
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25
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Zhang X, Zhang F, Wang Y, Schulman DS, Zhang T, Bansal A, Alem N, Das S, Crespi VH, Terrones M, Redwing JM. Defect-Controlled Nucleation and Orientation of WSe 2 on hBN: A Route to Single-Crystal Epitaxial Monolayers. ACS NANO 2019; 13:3341-3352. [PMID: 30758945 DOI: 10.1021/acsnano.8b09230] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A defect-controlled approach for the nucleation and epitaxial growth of WSe2 on hBN is demonstrated. The WSe2 domains exhibit a preferred orientation of over 95%, leading to a reduced density of inversion domain boundaries (IDBs) upon coalescence. First-principles calculations and experimental studies as a function of growth conditions and substrate pretreatment confirm that WSe2 nucleation density and orientation are controlled by the hBN surface defect density rather than thermodynamic factors. Detailed transmission electron microscopy analysis provides support for the role of single-atom vacancies on the hBN surface that trap W atoms and break surface symmetry leading to a reduced formation energy for one orientation of WSe2 domains. Through careful control of nucleation and extended lateral growth time, fully coalesced WSe2 monolayer films on hBN were achieved. Low-temperature photoluminescence (PL) measurements and transport measurements of back-gated field-effect transistor devices fabricated on WSe2/hBN films show improved optical and electrical properties compared to films grown on sapphire under similar conditions. Our results reveal an important nucleation mechanism for the epitaxial growth of van der Waals heterostructures and demonstrate hBN as a superior substrate for single-crystal transition-metal dichalcogenide (TMD) films, resulting in a reduced density of IDBs and improved properties. The results motivate further efforts focused on the development of single crystal hBN substrates and epilayers for synthesis of wafer-scale single crystal TMD films.
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