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Toom SR, Sato T, Milne Z, Bernal RA, Jeng YR, Muratore C, Glavin NR, Carpick RW, Schall JD. Nanoscale Adhesion and Material Transfer at 2D MoS 2-MoS 2 Interfaces Elucidated by In Situ Transmission Electron Microscopy and Atomistic Simulations. ACS APPLIED MATERIALS & INTERFACES 2024; 16:30506-30520. [PMID: 38805354 DOI: 10.1021/acsami.4c03208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Low-dimensional materials, such as MoS2, hold promise for use in a host of emerging applications, including flexible, wearable sensors due to their unique electrical, thermal, optical, mechanical, and tribological properties. The implementation of such devices requires an understanding of adhesive phenomena at the interfaces between these materials. Here, we describe combined nanoscale in situ transmission electron microscopy (TEM)/atomic force microscopy (AFM) experiments and simulations measuring the work of adhesion (Wadh) between self-mated contacts of ultrathin nominally amorphous and nanocrystalline MoS2 films deposited on Si scanning probe tips. A customized TEM/AFM nanoindenter permitted high-resolution imaging and force measurements in situ. The Wadh values for nanocrystalline and nominally amorphous MoS2 were 604 ± 323 mJ/m2 and 932 ± 647 mJ/m2, respectively, significantly higher than previously reported values for mechanically exfoliated MoS2 single crystals. Closely matched molecular dynamics (MD) simulations show that these high values can be explained by bonding between the opposing surfaces at defects such as grain boundaries. Simulations show that as grain size decreases, the number of bonds formed, the Wadh and its variability all increase, further supporting that interfacial covalent bond formation causes high adhesion. In some cases, sliding between delaminated MoS2 flakes during separation is observed, which further increases the Wadh and the range of adhesive interaction. These results indicate that for low adhesion, the MoS2 grains should be large relative to the contact area to limit the opportunity for bonding, whereas small grains may be beneficial, where high adhesion is needed to prevent device delamination in flexible systems.
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Affiliation(s)
- Sathwik Reddy Toom
- Department of Mechanical Engineering, North Carolina A&T State University, Greensboro, North Carolina 27411, United States
| | - Takaaki Sato
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Zachary Milne
- Gatan, Inc., Pleasanton, California 94588, United States
| | - Rodrigo A Bernal
- Department of Mechanical Engineering, University of Texas, Dallas, Richardson, Texas 75080, United States
| | - Yeau-Ren Jeng
- Department of Biomedical Engineering, National Cheng Kung University in Tainan, Tainan 70101, Taiwan
| | - Christopher Muratore
- Department of Chemical and Materials Engineering, University of Dayton, Dayton, Ohio 45469, United States
| | - Nicholas R Glavin
- Materials and Manufacturing Directorate, US Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
| | - Robert W Carpick
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - J David Schall
- Department of Mechanical Engineering, North Carolina A&T State University, Greensboro, North Carolina 27411, United States
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Li Z, Bretscher H, Rao A. Chemical passivation of 2D transition metal dichalcogenides: strategies, mechanisms, and prospects for optoelectronic applications. NANOSCALE 2024; 16:9728-9741. [PMID: 38700268 DOI: 10.1039/d3nr06296a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
The interest in obtaining high-quality monolayer transition metal dichalcogenides (TMDs) for optoelectronic device applications has been growing dramatically. However, the prevalence of defects and unwanted doping in these materials remain challenges, as they both limit optical properties and device performance. Surface chemical treatments of monolayer TMDs have been effective in improving their photoluminescence yield and charge transport properties. In this scenario, a systematic understanding of the underlying mechanism of chemical treatments will lead to a rational design of passivation strategies in future research, ultimately taking a step toward practical optoelectronic applications. We will therefore describe in this mini-review the strategies, progress, mechanisms, and prospects of chemical treatments to passivate and improve the optoelectronic properties of TMDs.
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Affiliation(s)
- Zhaojun Li
- Solid State Physics, Department of Materials Science and Engineering, Uppsala University, 75103 Uppsala, Sweden.
| | - Hope Bretscher
- The Max Planck Institute for the Structure and Dynamics of Matter, 22761, Hamburg, Germany
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE, Cambridge, UK
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Katiyar AK, Hoang AT, Xu D, Hong J, Kim BJ, Ji S, Ahn JH. 2D Materials in Flexible Electronics: Recent Advances and Future Prospectives. Chem Rev 2024; 124:318-419. [PMID: 38055207 DOI: 10.1021/acs.chemrev.3c00302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Flexible electronics have recently gained considerable attention due to their potential to provide new and innovative solutions to a wide range of challenges in various electronic fields. These electronics require specific material properties and performance because they need to be integrated into a variety of surfaces or folded and rolled for newly formatted electronics. Two-dimensional (2D) materials have emerged as promising candidates for flexible electronics due to their unique mechanical, electrical, and optical properties, as well as their compatibility with other materials, enabling the creation of various flexible electronic devices. This article provides a comprehensive review of the progress made in developing flexible electronic devices using 2D materials. In addition, it highlights the key aspects of materials, scalable material production, and device fabrication processes for flexible applications, along with important examples of demonstrations that achieved breakthroughs in various flexible and wearable electronic applications. Finally, we discuss the opportunities, current challenges, potential solutions, and future investigative directions about this field.
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Affiliation(s)
- Ajit Kumar Katiyar
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Anh Tuan Hoang
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Duo Xu
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Juyeong Hong
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Beom Jin Kim
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Seunghyeon Ji
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Jong-Hyun Ahn
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
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Wang M, Luo R, Liu Y, Zhao X, Zhuang X, Xu WW, Chen M, Liu P. An unexpected interfacial Mo-rich phase in 2D molybdenum disulfide and 3D gold heterojunctions. NANOSCALE 2023; 15:14906-14911. [PMID: 37654188 DOI: 10.1039/d3nr01818k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
The interface engineering of two-dimensional transition metal dichalcogenides (2D-TMDs) and metals has been regarded as a promising strategy to modulate their outstanding electrical and optoelectronic properties. Chemical Vapour Deposition (CVD) is an effective strategy to regulate the contact interface between TMDs and metals via directly growing 2D TMDs on a 3D metal substrate. Nevertheless, the underlying mechanisms of interfacial phase formation and evolution during TMD growth on a metallic substrate are less known. In this work, we found a 2D non-van der Waals (vdW) Mo-rich phase (MoNSN+1) during thermal sulfidation of a Mo-Au surface alloy to molybdenum disulfide (MoS2) in a S-poor environment. Systematic atomic-scale observations reveal that the periodic Mo and S atomic layers are arranged separating from each other in the non-vdW Mo-rich phase, and the Mo-rich phase preferentially nucleates between outmost 2D MoS2 and a 3D nanostructured Au substrate which possesses copious surface steps and kinks. Theoretical calculations demonstrate that the appearance of the Mo-rich phase with a unique metallic nature causes an n-type contact interface with an ultralow transition energy barrier height. This study may help understand the formation mechanism of the interfacial second phase during the epitaxial growth of 2D-TMDs on 3D nanostructured metals, and provide a new approach to tune the Schottky barrier height by the design of the interfacial phase structure at the heterojunction.
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Affiliation(s)
- Mengjia Wang
- Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.
| | - Ruichun Luo
- School of Physical Sciences and CAS Key Laboratory of Vacuum Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuxin Liu
- Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
| | - Xiaoran Zhao
- Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.
| | - Xiaodong Zhuang
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Wen Wu Xu
- Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
| | - Mingwei Chen
- Department of Materials Science and Engineering, Johns Hopkin University, Baltimore, MD 21218, USA.
| | - Pan Liu
- Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.
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Mondal A, Biswas C, Park S, Cha W, Kang SH, Yoon M, Choi SH, Kim KK, Lee YH. Low Ohmic contact resistance and high on/off ratio in transition metal dichalcogenides field-effect transistors via residue-free transfer. NATURE NANOTECHNOLOGY 2023:10.1038/s41565-023-01497-x. [PMID: 37666942 DOI: 10.1038/s41565-023-01497-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 08/01/2023] [Indexed: 09/06/2023]
Abstract
Beyond-silicon technology demands ultrahigh performance field-effect transistors. Transition metal dichalcogenides provide an ideal material platform, but the device performances such as the contact resistance, on/off ratio and mobility are often limited by the presence of interfacial residues caused by transfer procedures. Here, we show an ideal residue-free transfer approach using polypropylene carbonate with a negligible residue coverage of ~0.08% for monolayer MoS2 at the centimetre scale. By incorporating a bismuth semimetal contact with an atomically clean monolayer MoS2 field-effect transistor on hexagonal boron nitride substrate, we obtain an ultralow Ohmic contact resistance of ~78 Ω µm, approaching the quantum limit, and a record-high on/off ratio of ~1011 at 15 K. Such an ultra-clean fabrication approach could be the ideal platform for high-performance electrical devices using large-area semiconducting transition metal dichalcogenides.
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Affiliation(s)
- Ashok Mondal
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Chandan Biswas
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon, Republic of Korea.
| | - Sehwan Park
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Wujoon Cha
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Seoung-Hun Kang
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Mina Yoon
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Soo Ho Choi
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Ki Kang Kim
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon, Republic of Korea.
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea.
- Department of Physics, Sungkyunkwan University, Suwon, Republic of Korea.
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Lee M, Kim TW, Park CY, Lee K, Taniguchi T, Watanabe K, Kim MG, Hwang DK, Lee YT. Graphene Bridge Heterostructure Devices for Negative Differential Transconductance Circuit Applications. NANO-MICRO LETTERS 2022; 15:22. [PMID: 36580180 PMCID: PMC9800667 DOI: 10.1007/s40820-022-01001-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/11/2022] [Indexed: 06/17/2023]
Abstract
Two-dimensional van der Waals (2D vdW) material-based heterostructure devices have been widely studied for high-end electronic applications owing to their heterojunction properties. In this study, we demonstrate graphene (Gr)-bridge heterostructure devices consisting of laterally series-connected ambipolar semiconductor/Gr-bridge/n-type molybdenum disulfide as a channel material for field-effect transistors (FET). Unlike conventional FET operation, our Gr-bridge devices exhibit non-classical transfer characteristics (humped transfer curve), thus possessing a negative differential transconductance. These phenomena are interpreted as the operating behavior in two series-connected FETs, and they result from the gate-tunable contact capacity of the Gr-bridge layer. Multi-value logic inverters and frequency tripler circuits are successfully demonstrated using ambipolar semiconductors with narrow- and wide-bandgap materials as more advanced circuit applications based on non-classical transfer characteristics. Thus, we believe that our innovative and straightforward device structure engineering will be a promising technique for future multi-functional circuit applications of 2D nanoelectronics.
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Affiliation(s)
- Minjong Lee
- Department of Electrical and Computer Engineering, Inha University, Incheon, 22212, Republic of Korea
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Tae Wook Kim
- Center for Opto-Electronic Materials and Devices, Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Chang Yong Park
- Department of Electrical and Computer Engineering, Inha University, Incheon, 22212, Republic of Korea
| | - Kimoon Lee
- Department of Physics, Kunsan National University, Gunsan, 54150, Republic of Korea
| | - Takashi Taniguchi
- Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - Kenji Watanabe
- Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - Min-Gu Kim
- Department of Electrical and Computer Engineering, Inha University, Incheon, 22212, Republic of Korea.
- Department of Information and Communication Engineering, Inha University, Incheon, 22212, Republic of Korea.
| | - Do Kyung Hwang
- Center for Opto-Electronic Materials and Devices, Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea.
- Division of Nanoscience and Technology, KIST School, University of Science and Technology (UST), Seoul, 02792, Republic of Korea.
| | - Young Tack Lee
- Department of Electrical and Computer Engineering, Inha University, Incheon, 22212, Republic of Korea.
- Department of Electronic Engineering, Inha University, Incheon, 22212, Republic of Korea.
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7
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Takeuchi H, Urakami N, Hashimoto Y. Oxidation of tantalum disulfide (TaS 2) films for gate dielectric and process design of two-dimensional field-effect device. NANOTECHNOLOGY 2022; 33:375204. [PMID: 35667365 DOI: 10.1088/1361-6528/ac75f9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/05/2022] [Indexed: 06/15/2023]
Abstract
Ta-based high-κdielectrics can be synthesized via the oxidation of TaS2films. In this study, we investigated the wet and dry oxidation of TaS2films via thermal annealing and plasma irradiation, respectively. The specific vibration observed via Raman spectroscopy, the bonding states observed via x-ray photoelectron spectroscopy, and capacitance measurements confirmed the oxidation of TaS2films with a dielectric constant of ∼14.9. Moreover, the electrical transport of the TaS2films along the in-plane direction indicated a change in conductivity before and after the oxidation. The thickness of the oxidized film was estimated. Accordingly, the layer-by-layer oxidation was limited to approximately 50 nm via plasma irradiation, whereas the TaS2films within 150 nm were fully oxidized via thermal annealing in ambient air. Therefore, a Ta-oxide/TaS2structure was fabricated as a stack material of insulator and metal when the thickness of the pristine film was greater than 50 nm. In addition, Ta-oxide films were integrated into bottom-gated two-dimensional (2D) field-effect transistors (FETs) using the dry transfer method. 2D FETs with multilayer MoTe2and MoS2films asp-type andn-type channels, respectively, were successfully fabricated. In particular, the Ta-oxide film synthesized via dry oxidation was used as a gate dielectric, and the device process could be simplified because the Ta-oxide/TaS2heterostructure can function as a stack material for gate insulators and gate electrodes. An anti-ambipolar transistor consisting of an MoTe2/MoS2heterojunction was also fabricated. For the transfer characteristics, a relatively sharp on-state bias range below 10 V and sufficiently high peak-to-valley ratio of 106atVDS = 3 V were obtained using the high-κ gate dielectric of Ta-oxide despite the presence of the multilayer channels (∼20 nm).
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Affiliation(s)
- Hayate Takeuchi
- Department of Electrical and Computer Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8533, Japan
| | - Noriyuki Urakami
- Department of Electrical and Computer Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8533, Japan
- Research Initiative for Supra-Materials, Shinshu University, 4-17-1 Wakasato, Nagano 380-8533, Japan
| | - Yoshio Hashimoto
- Department of Electrical and Computer Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8533, Japan
- Research Initiative for Supra-Materials, Shinshu University, 4-17-1 Wakasato, Nagano 380-8533, Japan
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Rigosi AF, Levy AL, Snure MR, Glavin NR. Turn of the decade: versatility of 2D hexagonal boron nitride. JPHYS MATERIALS 2021; 4:10.1088/2515-7639/abf1ab. [PMID: 34409257 PMCID: PMC8370033 DOI: 10.1088/2515-7639/abf1ab] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The era of two-dimensional (2D) materials, in its current form, truly began at the time that graphene was first isolated just over 15 years ago. Shortly thereafter, the use of 2D hexagonal boron nitride (h-BN) had expanded in popularity, with use of the thin isolator permeating a significant number of fields in condensed matter and beyond. Due to the impractical nature of cataloguing every use or research pursuit, this review will cover ground in the following three subtopics relevant to this versatile material: growth, electrical measurements, and applications in optics and photonics. Through understanding how the material has been utilized, one may anticipate some of the exciting directions made possible by the research conducted up through the turn of this decade.
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Affiliation(s)
- Albert F Rigosi
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, United States
| | - Antonio L Levy
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, United States
| | - Michael R Snure
- Sensors Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States
| | - Nicholas R Glavin
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States
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Kim J, Huong CTT, Long NV, Yoon M, Kim MJ, Jeong JK, Choi S, Kim DH, Lee CH, Lee SU, Sung MM. Complementary Hybrid Semiconducting Superlattices with Multiple Channels and Mutual Stabilization. NANO LETTERS 2020; 20:4864-4871. [PMID: 32551703 DOI: 10.1021/acs.nanolett.0c00859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
An organic-inorganic hybrid superlattice with near perfect synergistic integration of organic and inorganic constituents was developed to produce properties vastly superior to those of either moiety alone. The complementary hybrid superlattice is composed of multiple quantum wells of 4-mercaptophenol organic monolayers and amorphous ZnO nanolayers. Within the superlattice, multichannel formation was demonstrated at the organic-inorganic interfaces to produce an excellent-performance field effect transistor exhibiting outstanding field-effect mobility with band-like transport and steep subthreshold swing. Furthermore, mutual stabilizations between organic monolayers and ZnO effectively reduced the performance degradation notorious in exclusively organic and ZnO transistors.
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Affiliation(s)
- Jongchan Kim
- Department of Chemistry, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 04763, Republic of Korea
| | - Chu Thi Thu Huong
- Department of Chemistry, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 04763, Republic of Korea
| | - Nguyen Van Long
- Department of Chemistry, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 04763, Republic of Korea
| | - Minho Yoon
- Department of Chemistry, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 04763, Republic of Korea
| | - Min Jae Kim
- Department of Electronic Engineering, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 04763, Republic of Korea
| | - Jae Kyeong Jeong
- Department of Electronic Engineering, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 04763, Republic of Korea
| | - Sungju Choi
- C-ICT Research Center (ERC), School of Electrical Engineering, Kookmin University, 77 Jeongneung-Ro, Seongbuk-Gu, Seoul 02707, Republic of Korea
| | - Dae Hwan Kim
- C-ICT Research Center (ERC), School of Electrical Engineering, Kookmin University, 77 Jeongneung-Ro, Seongbuk-Gu, Seoul 02707, Republic of Korea
| | - Chi Ho Lee
- Department of Applied Chemistry, Hanyang University, 55 Hanyangdeahak-Ro, Sangnok-Gu, Ansan 15588, Republic of Korea
| | - Sang Uck Lee
- Department of Applied Chemistry, Hanyang University, 55 Hanyangdeahak-Ro, Sangnok-Gu, Ansan 15588, Republic of Korea
| | - Myung Mo Sung
- Department of Chemistry, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 04763, Republic of Korea
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Mahmood A, Rahman G. Structural and electronic properties of two-dimensional hydrogenated Xenes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:205501. [PMID: 31945759 DOI: 10.1088/1361-648x/ab6cbd] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Structural and electronic properties of pristine two-dimensional group IV Xenes (X = C, Si, Ge, Sn, Pb) and hydrogenated Xenes are studied, using density functional theory (DFT) calculations with and without spin-orbit coupling (SOC). The pristine hexagonal monolayer Xenes show buckled structure upon relaxation except graphene. The buckling [Formula: see text] increases linearly from graphene to plumbene. The band structures without SOC of group-IV Xenes are semi-metallic. However, inclusion of SOC mainly opens the bandgap at the Dirac point. Semi hydrogenation leads to enhanced buckling in all Xenes which indicate a tendency towards more sp 3 like structures. The electronic structures of semi hydrogenated Xenes do not show Dirac cones. Spin polarized band structures show magnetism with magnetic moment of 1.0 [Formula: see text] and all SH Xenes are magnetic semiconductor except SH plumbene. Full hydrogenation vanishes buckling upon relaxation and the structure becomes planar implying sp 2-like hybridization. The band structures for fully hydrogenated Xenes turns out to be semiconducting and the Dirac cones also disappear. The bandgap changes from indirect to direct at FH stanene, while FH plumbene turns out to be semi-metallic. SOC gives rise to bandgap of 0.47 eV in FH plumbene, which is otherwise a semi-metal.
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Affiliation(s)
- Asad Mahmood
- Department of Physics, Quaid-i-Azam University, Islamabad 45320, Pakistan
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11
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Liao W, Zhao S, Li F, Wang C, Ge Y, Wang H, Wang S, Zhang H. Interface engineering of two-dimensional transition metal dichalcogenides towards next-generation electronic devices: recent advances and challenges. NANOSCALE HORIZONS 2020; 5:787-807. [PMID: 32129353 DOI: 10.1039/c9nh00743a] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Over the past decade, two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted tremendous research interest for future electronics owing to their atomically thin thickness, compelling properties and various potential applications. However, interface engineering including contact optimization and channel modulations for 2D TMDCs represents fundamental challenges in ultimate performance of ultrathin electronics. This article provides a comprehensive overview of the basic understanding of contacts and channel engineering of 2D TMDCs and emerging electronics benefiting from these varying approaches. In particular, we elucidate multifarious contact engineering approaches such as edge contact, phase engineering and metal transfer to suppress the Fermi level pinning effect at the metal/TMDC interface, various channel treatment avenues such as van der Waals heterostructures, surface charge transfer doping to modulate the device properties, and as well the novel electronics constructed by interface engineering such as diodes, circuits and memories. Finally, we conclude this review by addressing the current challenges facing 2D TMDCs towards next-generation electronics and offering our insights into future directions of this field.
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Affiliation(s)
- Wugang Liao
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
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12
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Matsoso BJ, Vuillet-a-Ciles V, Bois L, Toury B, Journet C. Improving Formation Conditions and Properties of hBN Nanosheets Through BaF 2-assisted Polymer Derived Ceramics (PDCs) Technique. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E443. [PMID: 32121460 PMCID: PMC7152994 DOI: 10.3390/nano10030443] [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: 01/17/2020] [Revised: 02/20/2020] [Accepted: 02/26/2020] [Indexed: 05/31/2023]
Abstract
Hexagonal boron nitrite (hBN) is an attractive material for many applications such as in electronics as a complement to graphene, in anti-oxidation coatings, light emitters, etc. However, the synthesis of high-quality hBN at cost-effective conditions is still a great challenge. Thus, this work reports on the synthesis of large-area and crystalline hBN nanosheets via the modified polymer derived ceramics (PDCs) process. The addition of both the BaF2 and Li3N, as melting-point reduction and crystallization agents, respectively, led to the production of hBN powders with excellent physicochemical properties at relatively low temperatures and atmospheric pressure conditions. For instance, XRD, Raman, and XPS data revealed improved crystallinity and quality at a decreased formation temperature of 1200 °C upon the addition of 5 wt% of BaF2. Moreover, morphological determination illustrated the formation of multi-layered nanocrystalline and well-defined shaped hBN powders with crystal sizes of 2.74-8.41 ± 0.71 µm in diameter. Despite the compromised thermal stability, as shown by the ease of oxidation at high temperatures, this work paves way for the production of large-scale and high-quality hBN crystals at a relatively low temperature and atmospheric pressure conditions.
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Affiliation(s)
| | | | | | | | - Catherine Journet
- Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Univ Lyon, Université Claude Bernard Lyon 1, F-69622 Villeurbanne CEDEX, France; (B.J.M.); (L.B.); (B.T.)
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13
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Pradhan NR, Garcia C, Lucking MC, Pakhira S, Martinez J, Rosenmann D, Divan R, Sumant AV, Terrones H, Mendoza-Cortes JL, McGill SA, Zhigadlo ND, Balicas L. Raman and electrical transport properties of few-layered arsenic-doped black phosphorus. NANOSCALE 2019; 11:18449-18463. [PMID: 31576874 DOI: 10.1039/c9nr04598h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Black phosphorus (b-P) is an allotrope of phosphorus whose properties have attracted great attention. In contrast to other 2D compounds, or pristine b-P, the properties of b-P alloys have yet to be explored. In this report, we present a detailed study on the Raman spectra and on the temperature dependence of the electrical transport properties of As-doped black phosphorus (b-AsP) for an As fraction x = 0.25. The observed complex Raman spectra were interpreted with the support of Density Functional Theory (DFT) calculations since each original mode splits in three due to P-P, P-As, and As-As bonds. Field-effect transistors (FET) fabricated from few-layered b-AsP exfoliated onto Si/SiO2 substrates exhibit hole-doped like conduction with a room temperature ON/OFF current ratio of ∼103 and an intrinsic field-effect mobility approaching ∼300 cm2 V-1 s-1 at 300 K which increases up to 600 cm2 V-1 s-1 at 100 K when measured via a 4-terminal method. Remarkably, these values are comparable to, or higher, than those initially reported for pristine b-P, indicating that this level of As doping is not detrimental to its transport properties. The ON to OFF current ratio is observed to increase up to 105 at 4 K. At high gate voltages b-AsP displays metallic behavior with the resistivity decreasing with decreasing temperature and saturating below T ∼100 K, indicating a gate-induced insulator to metal transition. Similarly to pristine b-P, its transport properties reveal a high anisotropy between armchair (AC) and zig-zag (ZZ) directions. Electronic band structure computed through periodic dispersion-corrected hybrid Density Functional Theory (DFT) indicate close proximity between the Fermi level and the top of the valence band(s) thus explaining its hole doped character. Our study shows that b-AsP has potential for optoelectronics applications that benefit from its anisotropic character and the ability to tune its band gap as a function of the number of layers and As content.
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Affiliation(s)
- Nihar R Pradhan
- Department of Chemistry, Physics and Atmospheric Sciences, Jackson State University, Jackson, MS 39217, USA.
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14
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Paul Inbaraj CR, Gudelli VK, Mathew RJ, Ulaganathan RK, Sankar R, Lin HY, Lin HI, Liao YM, Cheng HY, Lin KH, Chou FC, Chen YT, Lee CH, Guo GY, Chen YF. Sn-Doping Enhanced Ultrahigh Mobility In 1-xSn xSe Phototransistor. ACS APPLIED MATERIALS & INTERFACES 2019; 11:24269-24278. [PMID: 31250634 DOI: 10.1021/acsami.9b06433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Two-dimensional ternary materials are attracting widespread interest because of the additional degree of freedom available to tailor the material property for a specific application. An In1-xSnxSe phototransistor possessing tunable ultrahigh mobility by Sn-doping engineering is demonstrated in this study. A striking feature of In1-xSnxSe flakes is the reduction in the oxide phase compared to undoped InSe, which is validated by spectroscopic analyses. Moreover, first-principles density functional calculations performed for the In1-xSnxSe crystal system reveal the same effective mass when doped with Sn atoms. Hence, because of an increased lifetime owing to the enhanced crystal quality, the carriers in In1-xSnxSe have higher mobility than in InSe. The internally boosted electrical properties of In1-xSnxSe exhibit ultrahigh mobility of 2560 ± 240 cm2 V-1 s-1 by suppressing the interfacial traps with substrate modification and channel encapsulation. As a phototransistor, the ultrathin In1-xSnxSe flakes are highly sensitive with a detectivity of 1014 Jones. It possesses a large photoresponsivity and photogain (Vg = 40 V) as high as 3 × 105 A W-1 and 0.5 × 106, respectively. The obtained results outperform all previously reported performances of InSe-based devices. Thus, the doping-engineered In1-xSnxSe-layered semiconductor finds a potential application in optoelectronics and meets the demand for faster electronic technology.
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Affiliation(s)
| | - Vijay Kumar Gudelli
- Physics Division , National Center for Theoretical Sciences , Hsinchu 30013 , Taiwan
| | - Roshan Jesus Mathew
- Department of Engineering and System Science , National Tsing Hua University , Hsinchu 30013 , Taiwan
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
| | | | | | | | | | | | | | | | | | - Yit-Tsong Chen
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
| | - Chih-Hao Lee
- Department of Engineering and System Science , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Guang-Yu Guo
- Physics Division , National Center for Theoretical Sciences , Hsinchu 30013 , Taiwan
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15
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Liu T, Liu S, Tu KH, Schmidt H, Chu L, Xiang D, Martin J, Eda G, Ross CA, Garaj S. Crested two-dimensional transistors. NATURE NANOTECHNOLOGY 2019; 14:223-226. [PMID: 30718834 DOI: 10.1038/s41565-019-0361-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 01/02/2019] [Indexed: 05/23/2023]
Abstract
Two-dimensional transition metal dichalcogenide (TMD) materials, albeit promising candidates for applications in electronics and optoelectronics1-3, are still limited by their low electrical mobility under ambient conditions. Efforts to improve device performance through a variety of routes, such as modification of contact metals4 and gate dielectrics5-9 or encapsulation in hexagonal boron nitride10, have yielded limited success at room temperature. Here, we report a large increase in the performance of TMD field-effect transistors operating under ambient conditions, achieved by engineering the substrate's surface morphology. For MoS2 transistors fabricated on crested substrates, we observed an almost two orders of magnitude increase in carrier mobility compared to standard devices, as well as very high saturation currents. The mechanical strain in TMDs has been predicted to boost carrier mobility11, and has been shown to influence the local bandgap12,13 and quantum emission properties14 of TMDs. With comprehensive investigation of different dielectric environments and morphologies, we demonstrate that the substrate's increased corrugation, with its resulting strain field, is the dominant factor driving performance enhancement. This strategy is universally valid for other semiconducting TMD materials, either p-doped or n-doped, opening them up for applications in heterogeneous integrated electronics.
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Affiliation(s)
- Tao Liu
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Song Liu
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Institute of Chemical Biology and Nanomedicine, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China
| | - Kun-Hua Tu
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Hennrik Schmidt
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
| | - Leiqiang Chu
- Department of Physics, National University of Singapore, Singapore, Singapore
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Du Xiang
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Jens Martin
- Department of Physics, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
| | - Goki Eda
- Department of Physics, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Caroline A Ross
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Slaven Garaj
- Department of Physics, National University of Singapore, Singapore, Singapore.
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, Singapore.
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
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16
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Joo MK, Yun Y, Ji H, Suh D. Coulomb scattering mechanism transition in 2D layered MoTe 2: effect of high-κ passivation and Schottky barrier height. NANOTECHNOLOGY 2019; 30:035206. [PMID: 30444730 DOI: 10.1088/1361-6528/aae99c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Clean interface and low contact resistance are crucial requirements in two-dimensional (2D) materials to preserve their intrinsic carrier mobility. However, atomically thin 2D materials are sensitive to undesired Coulomb scatterers such as surface/interface adsorbates, metal-to-semiconductor Schottky barrier (SB), and ionic charges in the gate oxides, which often limits the understanding of the charge scattering mechanism in 2D electronic systems. Here, we present the effects of hafnium dioxide (HfO2) high-κ passivation and SB height on the low-frequency (LF) noise characteristics of multilayer molybdenum ditelluride (MoTe2) transistors. The passivated HfO2 passivation layer significantly suppresses the surface reaction and enhances dielectric screening effect, resulting in an excess electron n-doping, zero hysteresis, and substantial improvement in carrier mobility. After the high-κ HfO2 passivation, the obtained LF noise data appropriately demonstrates the transition of the Coulomb scattering mechanism from the SB contact to the channel, revealing the significant SB noise contribution to the 1/f noise. The substantial excess LF noise in the subthreshold regime is mainly attributed to the excess metal-to-MoTe2 SB noise and is fully eliminated at the high drain bias regime. This study provides a clear insight into the origin of electronic signal perturbation in 2D electronic systems.
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Affiliation(s)
- Min-Kyu Joo
- Department of Applied Physics, Sookmyung Women's University, Seoul 04310, Republic of Korea
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17
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Shim J, Bae SH, Kong W, Lee D, Qiao K, Nezich D, Park YJ, Zhao R, Sundaram S, Li X, Yeon H, Choi C, Kum H, Yue R, Zhou G, Ou Y, Lee K, Moodera J, Zhao X, Ahn JH, Hinkle C, Ougazzaden A, Kim J. Controlled crack propagation for atomic precision handling of wafer-scale two-dimensional materials. Science 2018; 362:665-670. [DOI: 10.1126/science.aat8126] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 08/11/2018] [Accepted: 09/21/2018] [Indexed: 01/18/2023]
Abstract
Although flakes of two-dimensional (2D) heterostructures at the micrometer scale can be formed with adhesive-tape exfoliation methods, isolation of 2D flakes into monolayers is extremely time consuming because it is a trial-and-error process. Controlling the number of 2D layers through direct growth also presents difficulty because of the high nucleation barrier on 2D materials. We demonstrate a layer-resolved 2D material splitting technique that permits high-throughput production of multiple monolayers of wafer-scale (5-centimeter diameter) 2D materials by splitting single stacks of thick 2D materials grown on a single wafer. Wafer-scale uniformity of hexagonal boron nitride, tungsten disulfide, tungsten diselenide, molybdenum disulfide, and molybdenum diselenide monolayers was verified by photoluminescence response and by substantial retention of electronic conductivity. We fabricated wafer-scale van der Waals heterostructures, including field-effect transistors, with single-atom thickness resolution.
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Affiliation(s)
- Jaewoo Shim
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sang-Hoon Bae
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Wei Kong
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Doyoon Lee
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kuan Qiao
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Daniel Nezich
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA, USA
| | - Yong Ju Park
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Ruike Zhao
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH, USA
| | - Suresh Sundaram
- School of Electrical and Computer Engineering, Georgia Institute of Technology, UMI 2958 GT-CNRS, GT-Lorraine, Metz, France
| | - Xin Li
- School of Electrical and Computer Engineering, Georgia Institute of Technology, UMI 2958 GT-CNRS, GT-Lorraine, Metz, France
| | - Hanwool Yeon
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Chanyeol Choi
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Hyun Kum
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ruoyu Yue
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, USA
| | - Guanyu Zhou
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, USA
| | - Yunbo Ou
- Department of Physics, and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kyusang Lee
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Departments of Electrical and Computer Engineering and Materials Science Engineering, University of Virginia, Charlottesville, VA, USA
| | - Jagadeesh Moodera
- Department of Physics, and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Xuanhe Zhao
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jong-Hyun Ahn
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Christopher Hinkle
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, USA
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Abdallah Ougazzaden
- School of Electrical and Computer Engineering, Georgia Institute of Technology, UMI 2958 GT-CNRS, GT-Lorraine, Metz, France
| | - Jeehwan Kim
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Microsystem Technology Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
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18
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Duong NT, Bang S, Lee SM, Dang DX, Kuem DH, Lee J, Jeong MS, Lim SC. Parameter control for enhanced peak-to-valley current ratio in a MoS 2/MoTe 2 van der Waals heterostructure. NANOSCALE 2018; 10:12322-12329. [PMID: 29946582 DOI: 10.1039/c8nr01711e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The Ids-Vds properties of a van der Waals cross-junction of few layered MoS2/MoTe2 were investigated, and the physical device parameters were altered in order to transform the conduction mechanism from thermionic emission to interband tunneling. The pristine heterostructure demonstrated rectification behavior of typical p-n junction diodes, because of the p-type and n-type nature of MoTe2 and MoS2, respectively. Lowering the contact resistance between the metal and channel materials, by changing the electrode metals from Au to Pd and Ti, alone did not give rise to carrier conduction through the hetero-interband tunneling between MoTe2 and MoS2. In addition to the reduction in contact resistance, the chemical doping of MoS2 using Benzyl Viologen (BV) achieves hetero-interband tunneling between MoTe2 and MoS2, which probably narrows the depletion layer by degenerating MoS2. The peak-to-valley ratio of the tunneling current of the BV-doped heterostructure of MoS2/MoTe2 is about 4.8, which is comparable to that of the commercially available Si tunneling diode.
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Affiliation(s)
- Ngoc Thanh Duong
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea.
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19
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Ji L, Shi J, Zhang ZY, Wang J, Zhang J, Tao C, Cao H. Theoretical prediction of high electron mobility in multilayer MoS2 heterostructured with MoSe2. J Chem Phys 2018; 148:014704. [DOI: 10.1063/1.4998672] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Liping Ji
- Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, Lanzhou 730000, China
- National & Local Joint Engineering Laboratory for Optical Conversion Materials and Technology, Lanzhou University, Lanzhou 730000, China
| | - Juan Shi
- Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, Lanzhou 730000, China
- National & Local Joint Engineering Laboratory for Optical Conversion Materials and Technology, Lanzhou University, Lanzhou 730000, China
| | - Z. Y. Zhang
- Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, Lanzhou 730000, China
- National & Local Joint Engineering Laboratory for Optical Conversion Materials and Technology, Lanzhou University, Lanzhou 730000, China
- Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, China
| | - Jun Wang
- Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, Lanzhou 730000, China
- National & Local Joint Engineering Laboratory for Optical Conversion Materials and Technology, Lanzhou University, Lanzhou 730000, China
| | - Jiachi Zhang
- Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, Lanzhou 730000, China
- National & Local Joint Engineering Laboratory for Optical Conversion Materials and Technology, Lanzhou University, Lanzhou 730000, China
| | - Chunlan Tao
- Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, China
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Haining Cao
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
- Center for Computational Science, Korea Institute of Science and Technology, Seoul 136791, South Korea
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20
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Yoon M, Ko KR, Min SW, Im S. Polymer/oxide bilayer dielectric for hysteresis-minimized 1 V operating 2D TMD transistors. RSC Adv 2018; 8:2837-2843. [PMID: 35541189 PMCID: PMC9077681 DOI: 10.1039/c7ra12641g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/08/2018] [Indexed: 11/21/2022] Open
Abstract
By inserting hydroxyl-group free organic dielectric between hydrophilic oxide dielectric and 2D TMD channel, highly stable 2D FETs are achieved. This concept was successfully extended to a practical device application such as stable 1 V operation of 2D MoTe2 FET.
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Affiliation(s)
- Minho Yoon
- Institute of Physics and Applied Physics
- Yonsei University
- Seoul 120-749
- Korea
| | - Kyeong Rok Ko
- Institute of Physics and Applied Physics
- Yonsei University
- Seoul 120-749
- Korea
| | - Sung-Wook Min
- Institute of Physics and Applied Physics
- Yonsei University
- Seoul 120-749
- Korea
| | - Seongil Im
- Institute of Physics and Applied Physics
- Yonsei University
- Seoul 120-749
- Korea
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21
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Kim HJ, Kim D, Jung S, Bae MH, Yi SN, Watanabe K, Taniguchi T, Chang SK, Ha DH. Homogeneity and tolerance to heat of monolayer MoS2 on SiO2 and h-BN. RSC Adv 2018; 8:12900-12906. [PMID: 35541259 PMCID: PMC9079624 DOI: 10.1039/c8ra01849a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 03/26/2018] [Indexed: 11/22/2022] Open
Abstract
We investigated the homogeneity and tolerance to heat of monolayer MoS2 using photoluminescence (PL) spectroscopy. For MoS2 on SiO2, the PL spectra of the basal plane differ from those of the edge, but MoS2 on hexagonal boron nitride (h-BN) was electron-depleted with a homogeneous PL spectra over the entire area. Annealing at 450 °C rendered MoS2 on SiO2 homogeneously electron-depleted over the entire area by creating numerous defects; moreover, annealing at 550 °C and subsequent laser irradiation on the MoS2 monolayer caused a loss of its inherent crystal structure. On the other hand, monolayer MoS2 on h-BN was preserved up to 550 °C with its PL spectra not much changed compared with MoS2 on SiO2. We performed an experiment to qualitatively compare the binding energies between various layers, and discuss the tolerance of monolayer MoS2 to heat on the basis of interlayer/interfacial binding energy. We investigated the homogeneity and tolerance to heat of monolayer MoS2 using photoluminescence (PL) spectroscopy.![]()
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Affiliation(s)
- Ho-Jong Kim
- Quantum Technology Institute
- Korea Research Institute of Standards and Science
- Daejeon 34113
- Republic of Korea
- Department of Physics
| | - Daehee Kim
- Quantum Technology Institute
- Korea Research Institute of Standards and Science
- Daejeon 34113
- Republic of Korea
| | - Suyong Jung
- Quantum Technology Institute
- Korea Research Institute of Standards and Science
- Daejeon 34113
- Republic of Korea
| | - Myung-Ho Bae
- Quantum Technology Institute
- Korea Research Institute of Standards and Science
- Daejeon 34113
- Republic of Korea
| | - Sam Nyung Yi
- Department of Electronic Material Engineering
- Korea Maritime and Ocean University
- Busan 49112
- Republic of Korea
| | - Kenji Watanabe
- National Institute for Materials Science
- Tsukuba 305-0044
- Japan
| | | | - Soo Kyung Chang
- Department of Physics
- Yonsei University
- Seoul 03722
- Republic of Korea
| | - Dong Han Ha
- Quantum Technology Institute
- Korea Research Institute of Standards and Science
- Daejeon 34113
- Republic of Korea
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22
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Schulman DS, Sebastian A, Buzzell D, Huang YT, Arnold AJ, Das S. Facile Electrochemical Synthesis of 2D Monolayers for High-Performance Thin-Film Transistors. ACS APPLIED MATERIALS & INTERFACES 2017; 9:44617-44624. [PMID: 29210272 DOI: 10.1021/acsami.7b14711] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper, we report high-performance monolayer thin-film transistors (TFTs) based on a variety of two-dimensional layered semiconductors such as MoS2, WS2, and MoSe2 which were obtained from their corresponding bulk counterparts via an anomalous but high-yield and low-cost electrochemical corrosion process, also referred to as electro-ablation (EA), at room temperature. These monolayer TFTs demonstrated current ON-OFF ratios in excess of 107 along with ON currents of 120 μA/μm for MoS2, 40 μA/μm for WS2, and 40 μA/μm for MoSe2 which clearly outperform the existing TFT technologies. We found that these monolayers have larger Schottky barriers for electron injection compared to their multilayer counterparts, which is partially compensated by their superior electrostatics and ultra-thin tunnel barriers. We observed an Anderson type semiconductor-to-metal transition in these monolayers and also discussed possible scattering mechanisms that manifest in the temperature dependence of the electron mobility. Finally, our study suggests superior chemical stability and electronic integrity of monolayers even after being exposed to extreme electro-oxidation and corrosion processes which is promising for the implementation of such TFTs in harsh environment sensing. Overall, the EA process proves to be a facile synthesis route offering higher monolayer yields than mechanical exfoliation and lower cost and complexity than chemical vapor deposition methods.
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Affiliation(s)
| | | | | | - Yu-Ting Huang
- Department of Mechanical Engineering, University of Hong Kong , Pokfulam, Hong Kong
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23
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Ji H, Joo MK, Yi H, Choi H, Gul HZ, Ghimire MK, Lim SC. Tunable Mobility in Double-Gated MoTe 2 Field-Effect Transistor: Effect of Coulomb Screening and Trap Sites. ACS APPLIED MATERIALS & INTERFACES 2017; 9:29185-29192. [PMID: 28786660 DOI: 10.1021/acsami.7b05865] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
There is a general consensus that the carrier mobility in a field-effect transistor (FET) made of semiconducting transition-metal dichalcogenides (s-TMDs) is severely degraded by the trapping/detrapping and Coulomb scattering of carriers by ionic charges in the gate oxides. Using a double-gated (DG) MoTe2 FET, we modulated and enhanced the carrier mobility by adjusting the top- and bottom-gate biases. The relevant mechanism for mobility tuning in this device was explored using static DC and low-frequency (LF) noise characterizations. In the investigations, LF-noise analysis revealed that for a strong back-gate bias the Coulomb scattering of carriers by ionized traps in the gate dielectrics is strongly screened by accumulation charges. This significantly reduces the electrostatic scattering of channel carriers by the interface trap sites, resulting in increased mobility. The reduction of the number of effective trap sites also depends on the gate bias, implying that owing to the gate bias, the carriers are shifted inside the channel. Thus, the number of active trap sites decreases as the carriers are repelled from the interface by the gate bias. The gate-controlled Coulomb-scattering parameter and the trap-site density provide new handles for improving the carrier mobility in TMDs, in a fundamentally different way from dielectric screening observed in previous studies.
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Affiliation(s)
- Hyunjin Ji
- Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 16419, Republic of Korea
| | - Min-Kyu Joo
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Hojoon Yi
- Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Homin Choi
- Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Hamza Zad Gul
- Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Mohan Kumar Ghimire
- Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Seong Chu Lim
- Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
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24
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Liu Y, Ang KW. Monolithically Integrated Flexible Black Phosphorus Complementary Inverter Circuits. ACS NANO 2017; 11:7416-7423. [PMID: 28654244 DOI: 10.1021/acsnano.7b03703] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Two-dimensional (2D) inverters are a fundamental building block for flexible logic circuits which have previously been realized by heterogeneously wiring transistors with two discrete channel materials. Here, we demonstrate a monolithically integrated complementary inverter made using a homogeneous black phosphorus (BP) nanosheet on flexible substrates. The digital logic inverter circuit is demonstrated via effective threshold voltage tuning within a single BP material, which offers both electron and hole dominated conducting channels with nearly symmetric pinch-off and current saturation. Controllable electron concentration is achieved by accurately modulating the aluminum (Al) donor doping, which realizes BP n-FET with a room-temperature on/off ratio >103. Simultaneously, work function engineering is employed to obtain a low Schottky barrier contact electrode that facilities hole injection, thus enhancing the current density of the BP p-FET by 9.4 times. The flexible inverter circuit shows a clear digital logic voltage inversion operation along with a larger-than-unity direct current voltage gain, while exhibits alternating current dynamic signal switching at a record high frequency up to 100 kHz and remarkable electrical stability upon mechanical bending with a radii as small as 4 mm. Our study demonstrates a practical monolithic integration strategy for achieving functional logic circuits on one material platform, paving the way for future high-density flexible electronic applications.
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Affiliation(s)
- Yuanda Liu
- Department of Electrical and Computer Engineering National University of Singapore 4 Engineering Drive 3, 117583, Singapore
- Centre for Advanced 2D Materials National University of Singapore 6 Science Drive 2, 117546, Singapore
| | - Kah-Wee Ang
- Department of Electrical and Computer Engineering National University of Singapore 4 Engineering Drive 3, 117583, Singapore
- Centre for Advanced 2D Materials National University of Singapore 6 Science Drive 2, 117546, Singapore
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Schulman DS, Arnold AJ, Razavieh A, Nasr J, Das S. The Prospect of Two-Dimensional Heterostructures: A Review of Recent Breakthroughs. IEEE NANOTECHNOLOGY MAGAZINE 2017. [DOI: 10.1109/mnano.2017.2679240] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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26
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Moon BH, Han GH, Kim H, Choi H, Bae JJ, Kim J, Jin Y, Jeong HY, Joo MK, Lee YH, Lim SC. Junction-Structure-Dependent Schottky Barrier Inhomogeneity and Device Ideality of Monolayer MoS 2 Field-Effect Transistors. ACS APPLIED MATERIALS & INTERFACES 2017; 9:11240-11246. [PMID: 28266221 DOI: 10.1021/acsami.6b16692] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Although monolayer transition metal dichalcogenides (TMDs) exhibit superior optical and electrical characteristics, their use in digital switching devices is limited by incomplete understanding of the metal contact. Comparative studies of Au top and edge contacts with monolayer MoS2 reveal a temperature-dependent ideality factor and Schottky barrier height (SBH). The latter originates from inhomogeneities in MoS2 caused by defects, charge puddles, and grain boundaries, which cause local variation in the work function at Au-MoS2 junctions and thus different activation temperatures for thermionic emission. However, the effect of inhomogeneities due to impurities on the SBH varies with the junction structure. The weak Au-MoS2 interaction in the top contact, which yields a higher SBH and ideality factor, is more affected by inhomogeneities than the strong interaction in the edge contact. Observed differences in the SBH and ideality factor in different junction structures clarify how the SBH and inhomogeneities can be controlled in devices containing TMD materials.
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Affiliation(s)
- Byoung Hee Moon
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Gang Hee Han
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Hyun Kim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Homin Choi
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Jung Jun Bae
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Jaesu Kim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Youngjo Jin
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Hye Yun Jeong
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Min-Kyu Joo
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Seong Chu Lim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
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27
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Liu Y, Ong ZY, Wu J, Zhao Y, Watanabe K, Taniguchi T, Chi D, Zhang G, Thong JTL, Qiu CW, Hippalgaonkar K. Thermal Conductance of the 2D MoS 2/h-BN and graphene/h-BN Interfaces. Sci Rep 2017; 7:43886. [PMID: 28262778 PMCID: PMC5338337 DOI: 10.1038/srep43886] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 02/02/2017] [Indexed: 11/16/2022] Open
Abstract
Two-dimensional (2D) materials and their corresponding van der Waals heterostructures have drawn tremendous interest due to their extraordinary electrical and optoelectronic properties. Insulating 2D hexagonal boron nitride (h-BN) with an atomically smooth surface has been widely used as a passivation layer to improve carrier transport for other 2D materials, especially for Transition Metal Dichalcogenides (TMDCs). However, heat flow at the interface between TMDCs and h-BN, which will play an important role in thermal management of various electronic and optoelectronic devices, is not yet understood. In this paper, for the first time, the interface thermal conductance (G) at the MoS2/h-BN interface is measured by Raman spectroscopy, and the room-temperature value is (17.0 ± 0.4) MW · m−2K−1. For comparison, G between graphene and h-BN is also measured, with a value of (52.2 ± 2.1) MW · m−2K−1. Non-equilibrium Green’s function (NEGF) calculations, from which the phonon transmission spectrum can be obtained, show that the lower G at the MoS2/h-BN interface is due to the weaker cross-plane transmission of phonon modes compared to graphene/h-BN. This study demonstrates that the MoS2/h-BN interface limits cross-plane heat dissipation, and thereby could impact the design and applications of 2D devices while considering critical thermal management.
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Affiliation(s)
- Yi Liu
- Department of Electrical and Computer Engineering, National University of Singapore, Engineering Drive 3, 117583, Singapore
| | - Zhun-Yong Ong
- Institute of High Performance Computing, #16-16, 1 Fusionopolis Way, Agency for Science, Technology and Research, 138632, Singapore
| | - Jing Wu
- Institute of Materials Research and Engineering, #08-03, 2 Fusionopolis Way, Agency for Science, Technology and Research, 138634, Singapore
| | - Yunshan Zhao
- Department of Electrical and Computer Engineering, National University of Singapore, Engineering Drive 3, 117583, Singapore
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - Dongzhi Chi
- Institute of Materials Research and Engineering, #08-03, 2 Fusionopolis Way, Agency for Science, Technology and Research, 138634, Singapore
| | - Gang Zhang
- Institute of High Performance Computing, #16-16, 1 Fusionopolis Way, Agency for Science, Technology and Research, 138632, Singapore
| | - John T L Thong
- Department of Electrical and Computer Engineering, National University of Singapore, Engineering Drive 3, 117583, Singapore
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Engineering Drive 3, 117583, Singapore.,Optical Science and Engineering Center, Department of Electrical and Computer Engineering, National University of Singapore, 117583, Singapore
| | - Kedar Hippalgaonkar
- Institute of Materials Research and Engineering, #08-03, 2 Fusionopolis Way, Agency for Science, Technology and Research, 138634, Singapore
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Joo MK, Moon BH, Ji H, Han GH, Kim H, Lee G, Lim SC, Suh D, Lee YH. Understanding Coulomb Scattering Mechanism in Monolayer MoS 2 Channel in the Presence of h-BN Buffer Layer. ACS APPLIED MATERIALS & INTERFACES 2017; 9:5006-5013. [PMID: 28093916 DOI: 10.1021/acsami.6b15072] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
As the thickness becomes thinner, the importance of Coulomb scattering in two-dimensional layered materials increases because of the close proximity between channel and interfacial layer and the reduced screening effects. The Coulomb scattering in the channel is usually obscured mainly by the Schottky barrier at the contact in the noise measurements. Here, we report low-temperature (T) noise measurements to understand the Coulomb scattering mechanism in the MoS2 channel in the presence of h-BN buffer layer on the silicon dioxide (SiO2) insulating layer. One essential measure in the noise analysis is the Coulomb scattering parameter (αSC) which is different for channel materials and electron excess doping concentrations. This was extracted exclusively from a 4-probe method by eliminating the Schottky contact effect. We found that the presence of h-BN on SiO2 provides the suppression of αSC twice, the reduction of interfacial traps density by 100 times, and the lowered Schottky barrier noise by 50 times compared to those on SiO2 at T = 25 K. These improvements enable us to successfully identify the main noise source in the channel, which is the trapping-detrapping process at gate dielectrics rather than the charged impurities localized at the channel, as confirmed by fitting the noise features to the carrier number and correlated mobility fluctuation model. Further, the reduction in contact noise at low temperature in our system is attributed to inhomogeneous distributed Schottky barrier height distribution in the metal-MoS2 contact region.
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Affiliation(s)
- Min-Kyu Joo
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Byoung Hee Moon
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Hyunjin Ji
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Gang Hee Han
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
| | - Hyun Kim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Gwanmu Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Seong Chu Lim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Dongseok Suh
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 16419, Republic of Korea
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29
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Jang SK, Youn J, Song YJ, Lee S. Synthesis and Characterization of Hexagonal Boron Nitride as a Gate Dielectric. Sci Rep 2016; 6:30449. [PMID: 27458024 PMCID: PMC4960585 DOI: 10.1038/srep30449] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 07/01/2016] [Indexed: 11/09/2022] Open
Abstract
Two different growth modes of large-area hexagonal boron nitride (h-BN) film, a conventional chemical vapor deposition (CVD) growth mode and a high-pressure CVD growth mode, were compared as a function of the precursor partial pressure. Conventional self-limited CVD growth was obtained below a critical partial pressure of the borazine precursor, whereas a thick h-BN layer (thicker than a critical thickness of 10 nm) was grown beyond a critical partial pressure. An interesting coincidence of a critical thickness of 10 nm was identified in both the CVD growth behavior and in the breakdown electric field strength and leakage current mechanism, indicating that the electrical properties of the CVD h-BN film depended significantly on the film growth mode and the resultant film quality.
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Affiliation(s)
- Sung Kyu Jang
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 440-746, South Korea
| | - Jiyoun Youn
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 440-746, South Korea
| | - Young Jae Song
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 440-746, South Korea.,Department of Physics, Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 440-746, South Korea.,Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419 Republic of Korea
| | - Sungjoo Lee
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 440-746, South Korea.,College of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 440-746, South Korea.,Center for Human Interface Nanotechnology (HINT), Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 440-746, South Korea
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30
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Schmidt H, Giustiniano F, Eda G. Electronic transport properties of transition metal dichalcogenide field-effect devices: surface and interface effects. Chem Soc Rev 2016; 44:7715-36. [PMID: 26088725 DOI: 10.1039/c5cs00275c] [Citation(s) in RCA: 153] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recent explosion of interest in two-dimensional (2D) materials research has led to extensive exploration of physical and chemical phenomena unique to this new class of materials and their technological potential. Atomically thin layers of group 6 transition metal dichalcogenides (TMDs) such as MoS2 and WSe2 are remarkably stable semiconductors that allow highly efficient electrostatic control due to their 2D nature. Field effect transistors (FETs) based on 2D TMDs are basic building blocks for novel electronic and chemical sensing applications. Here, we review the state-of-the-art of TMD-based FETs and summarize the current understanding of interface and surface effects that play a major role in these systems. We discuss how controlled doping is key to tailoring the electrical response of these materials and realizing high performance devices. The first part of this review focuses on some fundamental features of gate-modulated charge transport in 2D TMDs. We critically evaluate the role of surfaces and interfaces based on the data reported in the literature and explain the observed discrepancies between the experimental and theoretical values of carrier mobility. The second part introduces various non-covalent strategies for achieving desired doping in these systems. Gas sensors based on charge transfer doping and electrostatic stabilization are introduced to highlight progress in this direction. We conclude the review with an outlook on the realization of tailored TMD-based field-effect devices through surface and interface chemistry.
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Affiliation(s)
- Hennrik Schmidt
- Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546 and Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Francesco Giustiniano
- Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546 and Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Goki Eda
- Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546 and Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
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31
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Li SL, Tsukagoshi K, Orgiu E, Samorì P. Charge transport and mobility engineering in two-dimensional transition metal chalcogenide semiconductors. Chem Soc Rev 2016; 45:118-51. [DOI: 10.1039/c5cs00517e] [Citation(s) in RCA: 341] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This review presents recent progress on charge transport properties, carrier scattering mechanisms, and carrier mobility engineering of two-dimensional transition metal chalcogenides.
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Affiliation(s)
- Song-Lin Li
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS) and International Center for Frontier Research in Chemistry (icFRC)
- Université de Strasbourg and Centre National de la Recherche Scientifique (CNRS)
- Strasbourg 67083
- France
| | - Kazuhito Tsukagoshi
- World Premier International Center for Materials Nanoarchitechtonics (WPI-MANA)
- National Institute for Materials Science (NIMS)
- Tsukuba
- Japan
| | - Emanuele Orgiu
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS) and International Center for Frontier Research in Chemistry (icFRC)
- Université de Strasbourg and Centre National de la Recherche Scientifique (CNRS)
- Strasbourg 67083
- France
| | - Paolo Samorì
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS) and International Center for Frontier Research in Chemistry (icFRC)
- Université de Strasbourg and Centre National de la Recherche Scientifique (CNRS)
- Strasbourg 67083
- France
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32
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Huang W, Gan L, Li H, Ma Y, Zhai T. 2D layered group IIIA metal chalcogenides: synthesis, properties and applications in electronics and optoelectronics. CrystEngComm 2016. [DOI: 10.1039/c5ce01986a] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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33
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Qiu D, Lee DU, Park CS, Lee KS, Kim EK. Transport properties of unrestricted carriers in bridge-channel MoS2 field-effect transistors. NANOSCALE 2015; 7:17556-17562. [PMID: 26446693 DOI: 10.1039/c5nr04397b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Unsuppressed carrier scattering from the underlying substrate in a layered two-dimensional material system is extensively observed, which degrades significantly the performance of devices. Beyond the material itself, understanding the intrinsic interfacial and surficial properties is an important issue for the analysis of a high-κ/MoS2 heterostructure. Here, we report on the electronic transport properties of bridge-channel MoS2 field-effect transistors fabricated by a contamination-free transfer method. After neglecting all the surrounding perturbations, it is possible to reveal the significant improvement of room-temperature mobility and subthreshold slope. A systematic study on variable-temperature transport measurements has quantified the trap density of states both in free-standing and SiO2-supported MoS2 systems. Compared to the bridge-channel MoS2 devices with an ideal interface, the unsuspended devices have a large amount of band tail states, and then the impact of their electronic states on the device performance is also discussed.
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Affiliation(s)
- Dongri Qiu
- Quantum-Function Research Laboratory and Department of Physics, Hanyang University, Seoul 133-791, South Korea.
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34
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Jin K, Liu D, Tian Y. Enhancing the interlayer adhesive force in twisted multilayer MoS₂ by thermal annealing treatment. NANOTECHNOLOGY 2015; 26:405708. [PMID: 26376935 DOI: 10.1088/0957-4484/26/40/405708] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Few-layer MoS2 has recently gained great attention owing to its remarkable mechanical and photoelectric properties, which are strongly influenced by the interactions and relative orientations between layers. Here, we report on Raman scattering measurements of twisted MoS2 flakes prepared by exfoliation and nondestructive transfer. Thermal annealing treatment can effectively enhance the interlayer coupling of twisted MoS2 and lead to a van der Waals (vdW) interaction between two stacked layers. We have roughly calculated the interlayer coupling force by a diatomic chain model (DCM) and found that the interlayer adhesive force increased by ∼20% compared with no-treatment samples. We additionally found that the non-Bernal stacking structure of MoS2 induces a weakening in the interlayer coupling. This study could promote the development of novel semiconductors, optoelectronic devices, and superlubricity materials.
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Affiliation(s)
- Ke Jin
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, People's Republic of China
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35
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Qiu D, Kim EK. Electrically Tunable and Negative Schottky Barriers in Multi-layered Graphene/MoS2 Heterostructured Transistors. Sci Rep 2015; 5:13743. [PMID: 26333680 PMCID: PMC4558713 DOI: 10.1038/srep13743] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 08/04/2015] [Indexed: 11/09/2022] Open
Abstract
We fabricated multi-layered graphene/MoS2 heterostructured devices by positioning mechanically exfoliated bulk graphite and single-crystalline 2H-MoS2 onto Au metal pads on a SiO2/Si substrate via a contamination-free dry transfer technique. We also studied the electrical transport properties of Au/MoS2 junction devices for systematic comparison. A previous work has demonstrated the existence of a positive Schottky barrier height (SBH) in the metal/MoS2 system. However, analysis of the SBH indicates that the contacts of the multi-layered graphene/MoS2 have tunable negative barriers in the range of 300 to -46 meV as a function of gate voltage. It is hypothesized that this tunable SBH is responsible for the modulation of the work function of the thick graphene in these devices. Despite the large number of graphene layers, it is possible to form ohmic contacts, which will provide new opportunities for the engineering of highly efficient contacts in flexible electronics and photonics.
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Affiliation(s)
- Dongri Qiu
- Quantum-Function Research Laboratory and Department of Physics, Hanyang University, Seoul 133-791, South Korea
| | - Eun Kyu Kim
- Quantum-Function Research Laboratory and Department of Physics, Hanyang University, Seoul 133-791, South Korea
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36
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Li L, Lee I, Lim D, Kang M, Kim GH, Aoki N, Ochiai Y, Watanabe K, Taniguchi T. Raman shift and electrical properties of MoS2 bilayer on boron nitride substrate. NANOTECHNOLOGY 2015; 26:295702. [PMID: 26136152 DOI: 10.1088/0957-4484/26/29/295702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have fabricated a bilayer molybdenum disulphide (MoS2) transistor on boron nitride (BN) substrate and performed Raman spectroscopy and electrical measurements with this device. The characteristic Raman peaks show an upshift about 2.5 cm(-1) with the layer lying on BN, and a narrower line width in comparison with those on a SiO2 substrate. The device has a maximum drain current larger than 1 μA and a high current on/off ratio of greater than 10(8). In the temperature range of 100 K-293 K, the two terminal gate effect mobility and the carrier density do not change significantly with temperature. Results of the Raman and electrical measurements reveal that BN is a suitable substrate for atomic layer electrical devices.
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Affiliation(s)
- Lijun Li
- School of Electronic and Electrical Engineering and Sungkyunkwan University Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, Korea
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37
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Zheng C, Xu ZQ, Zhang Q, Edmonds MT, Watanabe K, Taniguchi T, Bao Q, Fuhrer MS. Profound Effect of Substrate Hydroxylation and Hydration on Electronic and Optical Properties of Monolayer MoS2. NANO LETTERS 2015; 15:3096-102. [PMID: 25897823 DOI: 10.1021/acs.nanolett.5b00098] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Atomic force microscopy, Kelvin probe force microscopy, and scanning photoluminescence spectroscopy image the progressive postgrowth hydroxylation and hydration of atomically flat Al2O3(0001) under monolayer MoS2, manifested in large work function shifts (100 mV) due to charge transfer (>10(13) cm(-2)) from the substrate and changes in PL intensity, energy, and peak width. In contrast, trapped water between exfoliated graphene and Al2O3(0001) causes surface potential and doping changes one and two orders of magnitude smaller, respectively, and MoS2 grown on hydrophobic hexagonal boron nitride is unaffected by water exposure.
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Affiliation(s)
| | | | | | | | - Kenji Watanabe
- ∥National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- ∥National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Qiaoliang Bao
- ⊥Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, People's Republic of China
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38
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Transport properties of pristine few-layer black phosphorus by van der Waals passivation in an inert atmosphere. Nat Commun 2015; 6:6647. [PMID: 25858614 DOI: 10.1038/ncomms7647] [Citation(s) in RCA: 239] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 02/16/2015] [Indexed: 12/23/2022] Open
Abstract
Ultrathin black phosphorus is a two-dimensional semiconductor with a sizeable band gap. Its excellent electronic properties make it attractive for applications in transistor, logic and optoelectronic devices. However, it is also the first widely investigated two-dimensional material to undergo degradation upon exposure to ambient air. Therefore a passivation method is required to study the intrinsic material properties, understand how oxidation affects the physical properties and enable applications of phosphorene. Here we demonstrate that atomically thin graphene and hexagonal boron nitride can be used for passivation of ultrathin black phosphorus. We report that few-layer pristine black phosphorus channels passivated in an inert gas environment, without any prior exposure to air, exhibit greatly improved n-type charge transport resulting in symmetric electron and hole transconductance characteristics.
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39
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Yuan H, Cheng G, You L, Li H, Zhu H, Li W, Kopanski JJ, Obeng YS, Hight Walker AR, Gundlach DJ, Richter CA, Ioannou DE, Li Q. Influence of metal-MoS2 interface on MoS2 transistor performance: comparison of Ag and Ti contacts. ACS APPLIED MATERIALS & INTERFACES 2015; 7:1180-7. [PMID: 25514512 DOI: 10.1021/am506921y] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In this work, we compare the electrical characteristics of MoS2 field-effect transistors (FETs) with Ag source/drain contacts with those with Ti and demonstrate that the metal-MoS2 interface is crucial to the device performance. MoS2 FETs with Ag contacts show more than 60 times higher ON-state current than those with Ti contacts. In order to better understand the mechanism of the better performance with Ag contacts, 5 nm Au/5 nm Ag (contact layer) or 5 nm Au/5 nm Ti film was deposited onto MoS2 monolayers and few layers, and the topography of metal films was characterized using scanning electron microscopy and atomic force microscopy. The surface morphology shows that, while there exist pinholes in Au/Ti film on MoS2, Au/Ag forms a smoother and denser film. Raman spectroscopy was carried out to investigate the metal-MoS2 interface. The Raman spectra from MoS2 covered with Au/Ag or Au/Ti film reveal that Ag or Ti is in direct contact with MoS2. Our findings show that the smoother and denser Au/Ag contacts lead to higher carrier transport efficiency.
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Affiliation(s)
- Hui Yuan
- Semiconductor and Dimensional Metrology Division, National Institute of Standards and Technology , Gaithersburg, Maryland 20878, United States
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40
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Na J, Lee YT, Lim JA, Hwang DK, Kim GT, Choi WK, Song YW. Few-layer black phosphorus field-effect transistors with reduced current fluctuation. ACS NANO 2014; 8:11753-62. [PMID: 25369559 DOI: 10.1021/nn5052376] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We investigated the reduction of current fluctuations in few-layer black phosphorus (BP) field-effect transistors resulting from Al2O3 passivation. In order to verify the effect of Al2O3 passivation on device characteristics, measurements and analyses were conducted on thermally annealed devices before and after the passivation. More specifically, static and low-frequency noise analyses were used in monitoring the charge transport characteristics in the devices. The carrier number fluctuation (CNF) model, which is related to the charge trapping/detrapping process near the interface between the channel and gate dielectric, was employed to describe the current fluctuation phenomena. Noise reduction due to the Al2O3 passivation was expressed in terms of the reduced interface trap density values D(it) and N(it), extracted from the subthreshold slope (SS) and the CNF model, respectively. The deviations between the interface trap density values extracted using the SS value and CNF model are elucidated in terms of the role of the Schottky barrier between the few-layer BP and metal contact. Furthermore, the preservation of the Al2O3-passivated few-layer BP flakes in ambient air for two months was confirmed by identical Raman spectra.
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Affiliation(s)
- Junhong Na
- Interface Control Research Center, Future Convergence Research Division, Korea Institute of Science and Technology , Seoul 136-791, South Korea
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41
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Towards intrinsic charge transport in monolayer molybdenum disulfide by defect and interface engineering. Nat Commun 2014; 5:5290. [DOI: 10.1038/ncomms6290] [Citation(s) in RCA: 463] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 09/17/2014] [Indexed: 01/12/2023] Open
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Li H, Wu J, Huang X, Yin Z, Liu J, Zhang H. A universal, rapid method for clean transfer of nanostructures onto various substrates. ACS NANO 2014; 8:6563-70. [PMID: 24954078 DOI: 10.1021/nn501779y] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Transfer and integration of nanostructures onto target substrates is the prerequisite for their fundamental studies and practical applications. Conventional transfer techniques that involve stamping, lift-off, and/or striping suffer from the process-specific drawbacks, such as the requirement for chemical etchant or high-temperature annealing and the introduction of surface discontinuities and/or contaminations that can greatly hinder the properties and functions of the transferred materials. Herein, we report a universal and rapid transfer method implementable at mild conditions. Nanostructures with various dimensionalities (i.e., nanoparticles, nanowires, and nanosheets) and surface properties (i.e., hydrophilic and hydrophobic) can be easily transferred to diverse substrates including hydrophilic, hydrophobic, and flexible surfaces with good fidelity. Importantly, our method ensures the rapid and clean transfer of two-dimensional materials and allows for the facile fabrication of vertical heterostructures with various compositions used for electronic devices. We believe that our method can facilitate the development of nanoelectronics by accelerating the clean transfer and integration of low-dimensional materials into multidimensional structures.
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Affiliation(s)
- Hai Li
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, 639798 Singapore
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43
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Ganatra R, Zhang Q. Few-layer MoS2: a promising layered semiconductor. ACS NANO 2014; 8:4074-99. [PMID: 24660756 DOI: 10.1021/nn405938z] [Citation(s) in RCA: 453] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Due to the recent expanding interest in two-dimensional layered materials, molybdenum disulfide (MoS2) has been receiving much research attention. Having an ultrathin layered structure and an appreciable direct band gap of 1.9 eV in the monolayer regime, few-layer MoS2 has good potential applications in nanoelectronics, optoelectronics, and flexible devices. In addition, the capability of controlling spin and valley degrees of freedom makes it a promising material for spintronic and valleytronic devices. In this review, we attempt to provide an overview of the research relevant to the structural and physical properties, fabrication methods, and electronic devices of few-layer MoS2. Recent developments and advances in studying the material are highlighted.
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Affiliation(s)
- Rudren Ganatra
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University , 639798 Singapore
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Jariwala D, Sangwan VK, Lauhon LJ, Marks TJ, Hersam MC. Emerging device applications for semiconducting two-dimensional transition metal dichalcogenides. ACS NANO 2014; 8:1102-20. [PMID: 24476095 DOI: 10.1021/nn500064s] [Citation(s) in RCA: 977] [Impact Index Per Article: 97.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
With advances in exfoliation and synthetic techniques, atomically thin films of semiconducting transition metal dichalcogenides have recently been isolated and characterized. Their two-dimensional structure, coupled with a direct band gap in the visible portion of the electromagnetic spectrum, suggests suitability for digital electronics and optoelectronics. Toward that end, several classes of high-performance devices have been reported along with significant progress in understanding their physical properties. Here, we present a review of the architecture, operating principles, and physics of electronic and optoelectronic devices based on ultrathin transition metal dichalcogenide semiconductors. By critically assessing and comparing the performance of these devices with competing technologies, the merits and shortcomings of this emerging class of electronic materials are identified, thereby providing a roadmap for future development.
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Affiliation(s)
- Deep Jariwala
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
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