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Nakamoto T, Matsuyama K, Sakai M, Chen CT, Cheuch YL, Mouri S, Yoshimura T, Fujimura N, Kiriya D. Selective Isolation of Mono- to Quadlayered 2D Materials via Sonication-Assisted Micromechanical Exfoliation. ACS NANO 2024; 18:2455-2463. [PMID: 38196098 DOI: 10.1021/acsnano.3c11099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
Mechanical exfoliation methods of two-dimensional materials have been an essential process for advanced devices and fundamental sciences. However, the exfoliation method usually generates various thick flakes, and a bunch of thick bulk flakes usually covers an entire substrate. Here, we developed a method to selectively isolate mono- to quadlayers of transition metal dichalcogenides (TMDCs) by sonication in organic solvents. The analysis reveals the importance of low interface energies between solvents and TMDCs, leading to the effective removal of bulk flakes under sonication. Importantly, a monolayer adjacent to bulk flakes shows cleavage at the interface, and the monolayer can be selectively isolated on the substrate. This approach can extend to preparing a monolayer device with crowded 17 electrode fingers surrounding the monolayer and for the measurement of electrostatic device performance.
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Affiliation(s)
- Tatsuya Nakamoto
- Department of Physics and Electronics, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Keigo Matsuyama
- Department of Physics and Electronics, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Masahiro Sakai
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Chieh-Ting Chen
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yu-Lun Cheuch
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Shinichiro Mouri
- College of Science and Engineering, Ritsumeikan University, Nojihigashi 1-1-1, Kusatsu, Shiga 525-8577, Japan
| | - Takeshi Yoshimura
- Department of Physics and Electronics, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
| | - Norifumi Fujimura
- Department of Physics and Electronics, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
| | - Daisuke Kiriya
- Department of Physics and Electronics, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
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Smyth CM, Cain JM, Boehm A, Ohlhausen JA, Lam MN, Yan X, Liu SE, Zeng TT, Sangwan VK, Hersam MC, Chou SS, Ohta T, Lu TM. Direct Characterization of Buried Interfaces in 2D/3D Heterostructures Enabled by GeO 2 Release Layer. ACS APPLIED MATERIALS & INTERFACES 2024; 16:2847-2860. [PMID: 38170963 DOI: 10.1021/acsami.3c12849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Inconsistent interface control in devices based on two-dimensional materials (2DMs) has limited technological maturation. Astounding variability of 2D/three-dimensional (2D/3D) interface properties has been reported, which has been exacerbated by the lack of direct investigations of buried interfaces commonly found in devices. Herein, we demonstrate a new process that enables the assembly and isolation of device-relevant heterostructures for buried interface characterization. This is achieved by implementing a water-soluble substrate (GeO2), which enables deposition of many materials onto the 2DM and subsequent heterostructure release by dissolving the GeO2 substrate. Here, we utilize this novel approach to compare how the chemistry, doping, and strain in monolayer MoS2 heterostructures fabricated by direct deposition vary from those fabricated by transfer techniques to show how interface properties differ with the heterostructure fabrication method. Direct deposition of thick Ni and Ti films is found to react with the monolayer MoS2. These interface reactions convert 50% of MoS2 into intermetallic species, which greatly exceeds the 10% conversion reported previously and 0% observed in transfer-fabricated heterostructures. We also measure notable differences in MoS2 carrier concentration depending on the heterostructure fabrication method. Direct deposition of thick Au, Ni, and Al2O3 films onto MoS2 increases the hole concentration by >1012 cm-2 compared to heterostructures fabricated by transferring MoS2 onto these materials. Thus, we demonstrate a universal method to fabricate 2D/3D heterostructures and expose buried interfaces for direct characterization.
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Affiliation(s)
| | - John M Cain
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Alex Boehm
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - James A Ohlhausen
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Mila Nhu Lam
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Xiaodong Yan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephanie E Liu
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Thomas T Zeng
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Stanley S Chou
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Taisuke Ohta
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Tzu-Ming Lu
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
- Center for Integrated Nanotechnologies (CINT), Sandia National Laboratories, Albuquerque, New Mexico 87123, United States
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3
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Lin WH, Li CS, Wu CI, Rossman GR, Atwater HA, Yeh NC. Dramatically Enhanced Valley-Polarized Emission by Alloying and Electrical Tuning of Monolayer WTe 2 x S 2(1- x ) Alloys at Room Temperature with 1T'-WTe 2 -Contact. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2304890. [PMID: 37974381 PMCID: PMC10787083 DOI: 10.1002/advs.202304890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 09/25/2023] [Indexed: 11/19/2023]
Abstract
Monolayer ternary tellurides based on alloying different transition metal dichalcogenides (TMDs) can result in new two-dimensional (2D) materials ranging from semiconductors to metals and superconductors with tunable optical and electrical properties. Semiconducting WTe2 x S2(1- x ) monolayer possesses two inequivalent valleys in the Brillouin zone, each valley coupling selectively with circularly polarized light (CPL). The degree of valley polarization (DVP) under the excitation of CPL represents the purity of valley polarized photoluminescence (PL), a critical parameter for opto-valleytronic applications. Here, new strategies to efficiently tailor the valley-polarized PL from semiconducting monolayer WTe2 x S2(1- x ) at room temperature (RT) through alloying and back-gating are presented. The DVP at RT is found to increase drastically from < 5% in WS2 to 40% in WTe0.12 S1.88 by Te-alloying to enhance the spin-orbit coupling. Further enhancement and control of the DVP from 40% up to 75% is demonstrated by electrostatically doping the monolayer WTe0.12 S1.88 via metallic 1T'-WTe2 electrodes, where the use of 1T'-WTe2 substantially lowers the Schottky barrier height (SBH) and weakens the Fermi-level pinning of the electrical contacts. The demonstration of drastically enhanced DVP and electrical tunability in the valley-polarized emission from 1T'-WTe2 /WTe0.12 S1.88 heterostructures paves new pathways towards harnessing valley excitons in ultrathin valleytronic devices for RT applications.
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Affiliation(s)
- Wei-Hsiang Lin
- Department of Applied Physics, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Chia-Shuo Li
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan, 106, P. R. China
| | - Chih-I Wu
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan, 106, P. R. China
| | - George R Rossman
- Department of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Harry A Atwater
- Department of Applied Physics, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Nai-Chang Yeh
- Department of Physics, California Institute of Technology, Pasadena, CA, 91125, USA
- Kavli Nanoscience Institute, California Institute of Technology, Pasadena, CA, 91125, USA
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Su ZC, Lin CF. Overcoming the Fermi-Level Pinning Effect in the Nanoscale Metal and Silicon Interface. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2193. [PMID: 37570511 PMCID: PMC10420943 DOI: 10.3390/nano13152193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 07/17/2023] [Accepted: 07/26/2023] [Indexed: 08/13/2023]
Abstract
Silicon-based photodetectors are attractive as low-cost and environmentally friendly optical sensors. Also, their compatibility with complementary metal-oxide-semiconductor (CMOS) technology is advantageous for the development of silicon photonics systems. However, extending optical responsivity of silicon-based photodetectors to the mid-infrared (mid-IR) wavelength range remains challenging. In developing mid-IR infrared Schottky detectors, nanoscale metals are critical. Nonetheless, one key factor is the Fermi-level pinning effect at the metal/silicon interface and the presence of metal-induced gap states (MIGS). Here, we demonstrate the utilization of the passivated surface layer on semiconductor materials as an insulating material in metal-insulator-semiconductor (MIS) contacts to mitigate the Fermi-level pinning effect. The removal of Fermi-level pinning effectively reduces the Schottky barrier height by 12.5% to 16%. The demonstrated devices exhibit a high responsivity of up to 234 μA/W at a wavelength of 2 μm, 48.2 μA/W at 3 μm, and 1.75 μA/W at 6 μm. The corresponding detectivities at 2 and 3 μm are 1.17 × 108 cm Hz1/2 W-1 and 2.41 × 107 cm Hz1/2 W-1, respectively. The expanded sensing wavelength range contributes to the application development of future silicon photonics integration platforms.
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Affiliation(s)
- Zih-Chun Su
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan;
| | - Ching-Fuh Lin
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan;
- Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan
- Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan
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5
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Choi D, Jeon J, Park TE, Ju BK, Lee KY. Schottky barrier height engineering on MoS 2 field-effect transistors using a polymer surface modifier on a contact electrode. DISCOVER NANO 2023; 18:80. [PMID: 37382714 DOI: 10.1186/s11671-023-03855-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 05/12/2023] [Indexed: 06/30/2023]
Abstract
Two-dimensional (2D) materials are highly sought after for their superior semiconducting properties, making them promising candidates for next-generation electronic and optoelectronic devices. Transition-metal dichalcogenides (TMDCs), such as molybdenum disulfide (MoS2) and tungsten diselenide (WSe2), are promising alternative 2D materials. However, the devices based on these materials experience performance deterioration due to the formation of a Schottky barrier between metal contacts and semiconducting TMDCs. Here, we performed experiments to reduce the Schottky barrier height of MoS2 field-effect transistors (FETs) by lowering the work function (Фm = Evacuum - EF,metal) of the contact metal. We chose polyethylenimine (PEI), a polymer containing simple aliphatic amine groups (-NH2), as a surface modifier of the Au (ФAu = 5.10 eV) contact metal. PEI is a well-known surface modifier that lowers the work function of various conductors such as metals and conducting polymers. Such surface modifiers have thus far been utilized in organic-based devices, including organic light-emitting diodes, organic solar cells, and organic thin-film transistors. In this study, we used the simple PEI coating to tune the work function of the contact electrodes of MoS2 FETs. The proposed method is rapid, easy to implement under ambient conditions, and effectively reduces the Schottky barrier height. We expect this simple and effective method to be widely used in large-area electronics and optoelectronics due to its numerous advantages.
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Affiliation(s)
- Dongwon Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
- Department of Electrical Engineering, Korea University, Seoul, 02841, South Korea
| | - Jeehoon Jeon
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Tae-Eon Park
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Byeong-Kwon Ju
- Department of Electrical Engineering, Korea University, Seoul, 02841, South Korea.
| | - Ki-Young Lee
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea.
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Samy O, Belmoubarik M, Otsuji T, El Moutaouakil A. A Voltage-Tuned Terahertz Absorber Based on MoS 2/Graphene Nanoribbon Structure. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13111716. [PMID: 37299619 DOI: 10.3390/nano13111716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/07/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023]
Abstract
Terahertz frequency has promising applications in communication, security scanning, medical imaging, and industry. THz absorbers are one of the required components for future THz applications. However, nowadays, obtaining a high absorption, simple structure, and ultrathin absorber is a challenge. In this work, we present a thin THz absorber that can be easily tuned through the whole THz range (0.1-10 THz) by applying a low gate voltage (<1 V). The structure is based on cheap and abundant materials (MoS2/graphene). Nanoribbons of MoS2/graphene heterostructure are laid over a SiO2 substrate with an applied vertical gate voltage. The computational model shows that we can achieve an absorptance of approximately 50% of the incident light. The absorptance frequency can be tuned through varying the structure and the substrate dimensions, where the nanoribbon width can be varied approximately from 90 nm to 300 nm, while still covering the whole THz range. The structure performance is not affected by high temperatures (500 K and above), so it is thermally stable. The proposed structure represents a low-voltage, easily tunable, low-cost, and small-size THz absorber that can be used in imaging and detection. It is an alternative to expensive THz metamaterial-based absorbers.
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Affiliation(s)
- Omnia Samy
- College of Engineering, United Arab University, Al Ain P.O. Box 15551, United Arab Emirates
| | - Mohamed Belmoubarik
- International Iberian Nanotechnology Laboratory, INL, Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal
| | - Taiichi Otsuji
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Amine El Moutaouakil
- College of Engineering, United Arab University, Al Ain P.O. Box 15551, United Arab Emirates
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7
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Yakubovsky DI, Grudinin DV, Ermolaev GA, Vyshnevyy AA, Mironov MS, Novikov SM, Arsenin AV, Volkov VS. Scanning Near-Field Optical Microscopy of Ultrathin Gold Films. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:1376. [PMID: 37110961 PMCID: PMC10146867 DOI: 10.3390/nano13081376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 04/13/2023] [Accepted: 04/13/2023] [Indexed: 06/19/2023]
Abstract
Ultrathin metal films are an essential platform for two-dimensional (2D) material compatible and flexible optoelectronics. Characterization of thin and ultrathin film-based devices requires a thorough consideration of the crystalline structure and local optical and electrical properties of the metal-2D material interface since they could be dramatically different from the bulk material. Recently, it was demonstrated that the growth of gold on the chemical vapor deposited monolayer MoS2 leads to a continuous metal film that preserves plasmonic optical response and conductivity even at thicknesses below 10 nm. Here, we examined the optical response and morphology of ultrathin gold films deposited on exfoliated MoS2 crystal flakes on the SiO2/Si substrate via scattering-type scanning near-field optical microscopy (s-SNOM). We demonstrate a direct relationship between the ability of thin film to support guided surface plasmon polaritons (SPP) and the s-SNOM signal intensity with a very high spatial resolution. Using this relationship, we observed the evolution of the structure of gold films grown on SiO2 and MoS2 with an increase in thickness. The continuous morphology and superior ability with respect to supporting SPPs of the ultrathin (≤10 nm) gold on MoS2 is further confirmed with scanning electron microscopy and direct observation of SPP fringes via s-SNOM. Our results establish s-SNOM as a tool for testing plasmonic films and motivate further theoretical research on the impact of the interplay between the guided modes and the local optical properties on the s-SNOM signal.
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Affiliation(s)
- Dmitry I. Yakubovsky
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia; (D.I.Y.); (D.V.G.); (G.A.E.); (A.A.V.); (M.S.M.); (S.M.N.); (A.V.A.)
| | - Dmitry V. Grudinin
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia; (D.I.Y.); (D.V.G.); (G.A.E.); (A.A.V.); (M.S.M.); (S.M.N.); (A.V.A.)
| | - Georgy A. Ermolaev
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia; (D.I.Y.); (D.V.G.); (G.A.E.); (A.A.V.); (M.S.M.); (S.M.N.); (A.V.A.)
| | - Andrey A. Vyshnevyy
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia; (D.I.Y.); (D.V.G.); (G.A.E.); (A.A.V.); (M.S.M.); (S.M.N.); (A.V.A.)
| | - Mikhail S. Mironov
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia; (D.I.Y.); (D.V.G.); (G.A.E.); (A.A.V.); (M.S.M.); (S.M.N.); (A.V.A.)
| | - Sergey M. Novikov
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia; (D.I.Y.); (D.V.G.); (G.A.E.); (A.A.V.); (M.S.M.); (S.M.N.); (A.V.A.)
| | - Aleksey V. Arsenin
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia; (D.I.Y.); (D.V.G.); (G.A.E.); (A.A.V.); (M.S.M.); (S.M.N.); (A.V.A.)
- Laboratory of Advanced Functional Materials, Yerevan State University, Yerevan 0025, Armenia
| | - Valentyn S. Volkov
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia; (D.I.Y.); (D.V.G.); (G.A.E.); (A.A.V.); (M.S.M.); (S.M.N.); (A.V.A.)
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8
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Li Z, Zheng Y, Li G, Wang H, Zhu W, Wang H, Chen Z, Yuan Y, Zeng XC, Wu Y. Resolving Interface Barrier Deviation from the Schottky-Mott Rule: A Mitigation Strategy via Engineering MoS 2-Metal van der Waals Contact. J Phys Chem Lett 2023; 14:2940-2949. [PMID: 36930804 DOI: 10.1021/acs.jpclett.3c00056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The Schottky barrier (SB) in the ultraclean van der Waals contact between two-dimensional (2D) MoS2 and three-dimensional (3D) indium (In) strikingly deviates from the Schottky-Mott limit (SML). Herein, on the basis of first-principles calculation, the origin of the SB deviation is brought to bear, as well as a strategy for mitigating the SB deviation. In light of the good agreement between the SB and the corrected SB by interface potential difference (ΔV) and Fermi -level shift (ΔEF) based on the SML, the SB deviation is attributed to the combined effects of ΔV and ΔEF. Furthermore, when a Au, Sc, or Ti thin film is coated on the back side of In, the SB deviation and the sum of ΔV and ΔEF decrease similarly. Importantly, in the Ti coating situation, the SB is reduced to 0.12 eV, notably smaller than the value of 0.30 eV in the Au coating case. This interface engineering can be generalized to regulate the SB between a 2D semiconductor and a 3D alloy.
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Affiliation(s)
- Zhongjun Li
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Shanxi University, Taiyuan 030006, China
| | - Yahui Zheng
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Guojun Li
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Hanxi Wang
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Weiduo Zhu
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Haidi Wang
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Zhao Chen
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Yupeng Yuan
- School of Materials Science and Engineering, Anhui University, Hefei 2300601, Anhui, China
| | - Xiao Cheng Zeng
- Department of Materials Science & Engineering, City University of Hong Kong, Kowloon 999077, Hong Kong, China
- Department of Chemistry, University of Nebraska─Lincoln, Lincoln, Nebraska 68588, United States
| | - Yucheng Wu
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
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9
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Thoutam LR, Mathew R, Ajayan J, Tayal S, Nair SV. A critical review of fabrication challenges and reliability issues in top/bottom gated MoS 2field-effect transistors. NANOTECHNOLOGY 2023; 34:232001. [PMID: 36731113 DOI: 10.1088/1361-6528/acb826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/02/2023] [Indexed: 06/18/2023]
Abstract
The voyage of semiconductor industry to decrease the size of transistors to achieve superior device performance seems to near its physical dimensional limitations. The quest is on to explore emerging material systems that offer dimensional scaling to match the silicon- based technologies. The discovery of atomic flat two-dimensional materials has opened up a completely new avenue to fabricate transistors at sub-10 nanometer level which has the potential to compete with modern silicon-based semiconductor devices. Molybdenum disulfide (MoS2) is a two-dimensional layered material with novel semiconducting properties at atomic level seems like a promising candidate that can possibly meet the expectation of Moore's law. This review discusses the various 'fabrication challenges' in making MoS2based electronic devices from start to finish. The review outlines the intricate challenges of substrate selection and various synthesis methods of mono layer and few-layer MoS2. The review focuses on the various techniques and methods to minimize interface defect density at substrate/MoS2interface for optimum MoS2-based device performance. The tunable band-gap of MoS2with varying thickness presents a unique opportunity for contact engineering to mitigate the contact resistance issue using different elemental metals. In this work, we present a comprehensive overview of different types of contact materials with myriad geometries that show a profound impact on device performance. The choice of different insulating/dielectric gate oxides on MoS2in co-planar and vertical geometry is critically reviewed and the physical feasibility of the same is discussed. The experimental constraints of different encapsulation techniques on MoS2and its effect on structural and electronic properties are extensively discussed.
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Affiliation(s)
- Laxman Raju Thoutam
- Amrita School of Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Ponekkara, Kochi 682041, India
| | - Ribu Mathew
- School of Electrical & Electronics Engineering, VIT Bhopal University, Bhopal, 466114, India
| | - J Ajayan
- Department of Electronics and Communication Engineering, SR University, Warangal, 506371, India
| | - Shubham Tayal
- Department of Electronics and Communication Engineering, SR University, Warangal, 506371, India
| | - Shantikumar V Nair
- Amrita School of Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Ponekkara, Kochi 682041, India
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10
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Hwa Y, Chee SS. Improvement of Visible Photodetection of Chemical Vapor Deposition-Grown MoS 2 Devices via Graphene/Au Contacts. SENSORS (BASEL, SWITZERLAND) 2022; 22:9687. [PMID: 36560055 PMCID: PMC9783588 DOI: 10.3390/s22249687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/07/2022] [Accepted: 12/08/2022] [Indexed: 06/17/2023]
Abstract
Two-dimensional (2D) molybdenum disulfide (MoS2) is a promising material for constructing high-performance visible photosensor arrays because of its high mobility and scale-up process. These distinct properties enable the construction of practical optoelectrical sensor arrays. However, contact engineering for MoS2 films is not still optimized. In this work, we inserted a graphene interlayer between the MoS2 films and Au contacts (graphene/Au) via the wet-transfer method to boost the device performance. Using graphene/Au contacts, outstanding electrical properties, namely field-effect mobility of 12.06 cm2/V∙s, on/off current ratio of 1.0 × 107, and responsivity of 610 A/W under illumination at 640 nm, were achieved. These favorable results were from the Fermi-level depinning effect induced by the graphene interlayer. Our results may help to construct large-area photonic sensor arrays based on 2D materials.
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Affiliation(s)
- Yeongsik Hwa
- Nano Convergence Materials Center, Korea Institute of Ceramic Engineering and Technology (KICET), Jinju 52851, Republic of Korea
- School of Materials Science and Engineering, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Sang-Soo Chee
- Nano Convergence Materials Center, Korea Institute of Ceramic Engineering and Technology (KICET), Jinju 52851, Republic of Korea
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11
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Shen Y, Dong Z, Sun Y, Guo H, Wu F, Li X, Tang J, Liu J, Wu X, Tian H, Ren TL. The Trend of 2D Transistors toward Integrated Circuits: Scaling Down and New Mechanisms. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2201916. [PMID: 35535757 DOI: 10.1002/adma.202201916] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/12/2022] [Indexed: 06/14/2023]
Abstract
2D transition metal chalcogenide (TMDC) materials, such as MoS2 , have recently attracted considerable research interest in the context of their use in ultrascaled devices owing to their excellent electronic properties. Microprocessors and neural network circuits based on MoS2 have been developed at a large scale but still do not have an advantage over silicon in terms of their integrated density. In this study, the current structures, contact engineering, and doping methods for 2D TMDC materials for the scaling-down process and performance optimization are reviewed. Devices are introduced according to a new mechanism to provide the comprehensive prospects for the use of MoS2 beyond the traditional complementary-metal-oxide semiconductor in order to summarize obstacles to the goal of developing high-density and low-power integrated circuits (ICs). Finally, prospects for the use of MoS2 in large-scale ICs from the perspectives of the material, system performance, and application to nonlogic functionalities such as sensor circuits and analogous circuits, are briefly analyzed. The latter issue is along the direction of "more than Moore" research.
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Affiliation(s)
- Yang Shen
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100084, China
| | - Zuoyuan Dong
- Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic Engineering, East China Normal University, Shanghai, 200241, China
| | - Yabin Sun
- Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic Engineering, East China Normal University, Shanghai, 200241, China
| | - Hao Guo
- Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement, School of Instrument and Electronics, North University of China, Taiyuan, Shanxi, 030051, China
| | - Fan Wu
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100084, China
| | - Xianglong Li
- Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic Engineering, East China Normal University, Shanghai, 200241, China
| | - Jun Tang
- Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement, School of Instrument and Electronics, North University of China, Taiyuan, Shanxi, 030051, China
| | - Jun Liu
- Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement, School of Instrument and Electronics, North University of China, Taiyuan, Shanxi, 030051, China
| | - Xing Wu
- Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic Engineering, East China Normal University, Shanghai, 200241, China
| | - He Tian
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100084, China
| | - Tian-Ling Ren
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100084, China
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12
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Fu X, Li T, Li Q, Hao C, Zhang L, Fu D, Wang J, Xu H, Gu Y, Zhong F, He T, Zhang K, Panin GN, Lu W, Miao J, Hu W. Geometry-asymmetric photodetectors from metal-semiconductor-metal van der Waals heterostructures. MATERIALS HORIZONS 2022; 9:3095-3101. [PMID: 36268699 DOI: 10.1039/d2mh00872f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The functional diversities of two-dimensional (2D) material devices with simple architectures are ultimately limited by immature doping techniques. An alternative strategy is to use geometry-asymmetric metal-semiconductor-metal (GA-MSM) structures, which enable the basic functions of semiconductor junctions such as rectification and photovoltaics. Here, the mixed-dimensional van der Waals heterostructures (MDvdWHs) based on the separation and self-assembly of p-type SnS layered nanosheets (NSs) and n-type SnS2 nanoparticles (NPs) are obtained using an aqueous phase exfoliation (APE) method. Due to the surface charge transfer doping, the carrier transport mechanism of devices based on MDvdWHs turns from thermionic field emission (TFE) to thermionic emission (TE), with the rectification factor (Iforward/Ireverse) changing from 0.7 to 3. To further illustrate the experimental results, the generic current transport models of GA-MSM devices have been established based on the TE and TFE mechanisms in which the TE and TFE mechanisms lead to opposite rectification phenomena in good agreement with the experimental results. The GA-MSM devices show a photovoltaic effect with a high responsivity of 35 A W-1 and detectivity of 3.4 × 1011 cm Hz1/2 W-1. This study not only provides a novel strategy to design photovoltaic devices with MDvdWHs, but more importantly, we have established fundamental models for the rectification behavior of GA-MSM devices.
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Affiliation(s)
- Xiao Fu
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tangxin Li
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qing Li
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chunhui Hao
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Zhang
- Ministry of Education Key Laboratory for Green Preparation and Application of Functional Materials, Hubei Provincial Key Laboratory of Polymers, School of Materials Science and Engineering, Hubei University, Wuhan 430062, P. R. China
| | - Dejun Fu
- Innovation Center of Research Institute of Tsinghua University in Zhuhai, Zhuhai 519000, China
| | - Jinjin Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hangyu Xu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yue Gu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fang Zhong
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ting He
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kun Zhang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Gennady N Panin
- Institute of Microelectronics Technology and High-Purity Materials Russian Academy of Sciences, Chernogolovka, Moscow 142432, Russia
| | - Wei Lu
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinshui Miao
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weida Hu
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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13
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Song Y, Wang Y, Shao J, Ye K, Wang Q, Wang G. Boosting CO 2 Electroreduction via Construction of a Stable ZnS/ZnO Interface. ACS APPLIED MATERIALS & INTERFACES 2022; 14:20368-20374. [PMID: 34636530 DOI: 10.1021/acsami.1c15669] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Carbon dioxide (CO2) electroreduction can offer a way of relieving environmental and energy issues. Gold and silver catalysts show considerable electrochemical performance for CO production; however, the electrochemical CO2 conversion to CO is still restricted by the Faradaic efficiency, current density, and stability over the catalysts. Non-noble metal (zinc) is considered as a promising catalyst for CO2 electroreduction because of its low cost. However, because of the electron-rich property of zinc, it has a weak adsorption capacity of intermediates, resulting in a poor CO2 electroreduction performance. In this work, ZnS nanoparticles are embedded onto the ZnO surface to construct a stable ZnS/ZnO interface structure. The ZnS/ZnO interface reaches a maximum current density of 327.2 ± 10.6 mA cm-2 with a CO Faradaic efficiency of 91.9 ± 0.6% at -0.73 V vs a reversible hydrogen electrode (RHE) and remains stable for 40 h at a current density of 115.7 ± 7.0 mA cm-2 with a CO Faradaic efficiency of 93.8 ± 3.7% at -0.56 V vs RHE.
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Affiliation(s)
- Yanpeng Song
- Key Laboratory of Superlight Materials and Surface Technology of Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yi Wang
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- College of Energy, University of Chinese Academy of Sciences, Beijing 100039, China
| | - Jiaqi Shao
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- College of Energy, University of Chinese Academy of Sciences, Beijing 100039, China
| | - Ke Ye
- Key Laboratory of Superlight Materials and Surface Technology of Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China
| | - Qi Wang
- Liaoning Key Materials Laboratory for Railway, School of Materials and Engineering, Dalian Jiaotong University, Dalian 116028, China
| | - Guoxiong Wang
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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14
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Li YD, Zhen WL, Weng SR, Hu HJ, Niu R, Yue ZL, Xu F, Zhu WK, Zhang CJ. Interface effects of Schottky devices built from MoS 2and high work function metals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:165001. [PMID: 35105834 DOI: 10.1088/1361-648x/ac50db] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
Schottky junctions, formed by high work function metals and semiconductors, are important devices in electronics and optoelectronics. The metal deposition in traditional Schottky interfaces usually damages the semiconductor surface and causes defect states, which reduces the Schottky barrier height and device performance. This can be avoided in the atomically smooth interface formed by two-dimensional (2D) metals and semiconductors. For better interface tailoring engineering, it is particularly important to understand various interface effects in such 2D Schottky devices under critical or boundary conditions. Here we report the fabrication and testing of three types of MoS2devices, i.e., using PtTe2, Cr and Au as contact materials. While the Cr/MoS2contact is an ohmic contact, the other two are Schottky contacts. The van-der-Waals interface of PtTe2-MoS2results in a well-defined OFF state and a significant rectification ratio of 104. This parameter, together with an ideality factor 2.1, outperforms the device based on evaporated Au. Moreover, a device in the intermediate condition is also presented. An abrupt increase in the reverse current is observed and understood based on the enhanced tunneling current. Our work manifests the essential role of doping concentration and provides another example for 2D Schottky interface design.
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Affiliation(s)
- Y D Li
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
- University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - W L Zhen
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - S R Weng
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - H J Hu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - R Niu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Z L Yue
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - F Xu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - W K Zhu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - C J Zhang
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
- Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
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15
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Sun Y, Niu G, Ren W, Meng X, Zhao J, Luo W, Ye ZG, Xie YH. Hybrid System Combining Two-Dimensional Materials and Ferroelectrics and Its Application in Photodetection. ACS NANO 2021; 15:10982-11013. [PMID: 34184877 DOI: 10.1021/acsnano.1c01735] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Photodetectors are one of the most important components for a future "Internet-of-Things" information society. Compared to the mainstream semiconductor-based photodetectors, emerging devices based on two-dimensional (2D) materials and ferroelectrics as well as their hybrid systems have been extensively studied in recent decades due to their outstanding performances and related interesting physical, electrical, and optoelectronic phenomena. In this paper, we review the photodetection based on 2D materials and ferroelectric hybrid systems. The fundamentals of 2D and ferroelectric materials as well as the interaction in the hybrid system will be introduced. Ferroelectricity modulated optoelectronic properties in the hybrid system will be discussed in detail. After the basics and figures of merit of photodetectors are summarized, the 2D-ferroelectrics devices with different structures including p-n diodes, Schottky diodes, and field-effect transistors will be reviewed and compared. The polarization of ferroelectrics offers the possibility of the modulation and enhancement of the photodetection in the hybrid detectors, which will be discussed in depth. Finally, the challenges and perspectives of the photodetectors based on 2D ferroelectrics will be proposed. This Review outlines the important aspects of the recent development of the hybrid system of 2D and ferroelectric materials, which could interact with each other and thus lead to photodetectors with higher performances. Such a Review will be helpful for the research of emerging physical phenomena and for the design of multifunctional nanoscale electronic and optoelectronic devices.
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Affiliation(s)
- Yanxiao Sun
- Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, Shaanxi, P. R. China
| | - Gang Niu
- Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, Shaanxi, P. R. China
| | - Wei Ren
- Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, Shaanxi, P. R. China
| | - Xiangjian Meng
- National Laboratory for Infrared Physics Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, P. R. China
| | - Jinyan Zhao
- Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, Shaanxi, P. R. China
| | - Wenbo Luo
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, P. R. China
| | - Zuo-Guang Ye
- Department of Chemistry and 4D Laboratories, Simon Fraser University, Burnaby V5A 1S6, British Columbia, Canada
| | - Ya-Hong Xie
- Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles 90024, California, United States
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16
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Fabrication of Large-Area Molybdenum Disulfide Device Arrays Using Graphene/Ti Contacts. Molecules 2021; 26:molecules26154394. [PMID: 34361548 PMCID: PMC8348625 DOI: 10.3390/molecules26154394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/17/2021] [Accepted: 07/19/2021] [Indexed: 11/16/2022] Open
Abstract
Two-dimensional (2D) molybdenum disulfide (MoS2) is the most mature material in 2D material fields owing to its relatively high mobility and scalability. Such noticeable properties enable it to realize practical electronic and optoelectronic applications. However, contact engineering for large-area MoS2 films has not yet been established, although contact property is directly associated to the device performance. Herein, we introduce graphene-interlayered Ti contacts (graphene/Ti) into large-area MoS2 device arrays using a wet-transfer method. We achieve MoS2 devices with superior electrical and photoelectrical properties using graphene/Ti contacts, with a field-effect mobility of 18.3 cm2/V∙s, on/off current ratio of 3 × 107, responsivity of 850 A/W, and detectivity of 2 × 1012 Jones. This outstanding performance is attributable to a reduction in the Schottky barrier height of the resultant devices, which arises from the decreased work function of graphene induced by the charge transfer from Ti. Our research offers a direction toward large-scale electronic and optoelectronic applications based on 2D materials.
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17
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Tumino F, Grazianetti C, Martella C, Ruggeri M, Russo V, Li Bassi A, Molle A, Casari CS. Hydrophilic Character of Single-Layer MoS 2 Grown on Ag(111). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:9479-9485. [PMID: 34055127 PMCID: PMC8154856 DOI: 10.1021/acs.jpcc.1c01768] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/12/2021] [Indexed: 05/12/2023]
Abstract
The study of MoS2/metal interfaces is crucial for engineering efficient semiconductor-metal contacts in 2D MoS2-based devices. Here we investigate a MoS2/Ag heterostructure fabricated by growing a single MoS2 layer on Ag(111) by pulsed laser deposition under ultrahigh vacuum (UHV) conditions. The surface structure is observed in situ by scanning tunneling microscopy, revealing the hexagonal moiré pattern characteristic of the clean MoS2/Ag(111) interface. Ex situ Raman spectroscopy reveals an anomalous behavior of vibrational modes, induced by the strong MoS2-Ag interaction. After few-hours exposure to ambient conditions the Raman response significantly changes and the formation of molybdenum oxysulfides is revealed by X-ray photoelectron spectroscopy. These effects are due to the interplay with water vapor and can be reversed by a moderate UHV annealing. A polymeric (PMMA) capping is demonstrated to hinder water-induced modifications, preserving the original interface quality for months.
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Affiliation(s)
- Francesco Tumino
- Department
of Energy, Politecnico di Milano, via G. Ponzio 34/3, Milano, I-20133, Italy
| | - Carlo Grazianetti
- CNR-IMM
Unit of Agrate Brianza, via C. Olivetti 2, Agrate Brianza, I-20864, Italy
| | - Christian Martella
- CNR-IMM
Unit of Agrate Brianza, via C. Olivetti 2, Agrate Brianza, I-20864, Italy
| | - Marina Ruggeri
- Department
of Energy, Politecnico di Milano, via G. Ponzio 34/3, Milano, I-20133, Italy
| | - Valeria Russo
- Department
of Energy, Politecnico di Milano, via G. Ponzio 34/3, Milano, I-20133, Italy
| | - Andrea Li Bassi
- Department
of Energy, Politecnico di Milano, via G. Ponzio 34/3, Milano, I-20133, Italy
| | - Alessandro Molle
- CNR-IMM
Unit of Agrate Brianza, via C. Olivetti 2, Agrate Brianza, I-20864, Italy
| | - Carlo S. Casari
- Department
of Energy, Politecnico di Milano, via G. Ponzio 34/3, Milano, I-20133, Italy
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18
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Reconfigurable electronics by disassembling and reassembling van der Waals heterostructures. Nat Commun 2021; 12:1825. [PMID: 33758200 PMCID: PMC7988143 DOI: 10.1038/s41467-021-22118-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 03/03/2021] [Indexed: 01/12/2023] Open
Abstract
Van der Waals heterostructures (vdWHs) have attracted tremendous interest owing to the ability to assemble diverse building blocks without the constraints of lattice matching and processing compatibility. However, once assembled, the fabricated vdWHs can hardly be separated into individual building blocks for further manipulation, mainly due to technical difficulties in the disassembling process. Here, we show a method to disassemble the as-fabricated vdWHs into individual building blocks, which can be further reassembled into new vdWHs with different device functionalities. With this technique, we demonstrate reconfigurable transistors from n-type to p-type and back-gate to dual-gate structures through re-stacking. Furthermore, reconfigurable device behaviors from floating gate memory to Schottky diode and reconfigurable anisotropic Raman behaviors have been obtained through layer re-sequencing and re-twisting, respectively. Our results could lead to a reverse engineering concept of disassembled vdWHs electronics in parallel with state-of-the-art vdWHs electronics, offering a general method for multi-functional pluggable electronics and optoelectronics with limited material building blocks. Here, the authors report a method to fabricate reconfigurable electronic devices based on 2D materials by using polyvinyl alcohol as substrate. This technique enables repeatable disassembling and reassembling of van der Waals heterostructures with different functionalities.
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19
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Li M, Lan F, Yang W, Ji Z, Zhang Y, Xi N, Xin X, Jin X, Li G. Influence of MoS 2-metal interface on charge injection: a comparison between various metal contacts. NANOTECHNOLOGY 2020; 31:395713. [PMID: 32662448 DOI: 10.1088/1361-6528/ab9cf6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Achieving good contacts is vital for harnessing the fascinating properties of two-dimensional (2D) materials. However, unsatisfactory 2D material-metal interfaces remain a problem that hinders the successful application of 2D materials for fabricating nanodevices. In this study, Kelvin probe force microscopy (KPFM) and other high-resolution microscopy techniques are utilized to characterize the surface morphology and contact interface between MoS2 and common metals including Au, Ti, Pd, and Ni. Surface potential information, including the contact potential difference ([Formula: see text]) and surface potential difference ([Formula: see text]) of each MoS2-metal contact, is obtained. By comparing the surface potential distribution mappings with and without illumination, non-zero surface photovoltage (SPV) values and evident shift with amplitudes of 32 mV and 44 mV are observed for MoS2-Au and Ti, but not for MoS2-Pd and Ni. The Schottky barrier heights of MoS2-Au, Ti, Pd, and Ni are roughly evaluated from their I-V curves. Raman spectroscopy is also carried out to ensure more convincing results. All the results suggest that a smoother MoS2-metal interface results in better charge transport behaviors. Our analysis of the underlying mechanism and experimental findings offer a new perspective to better understand MoS2-metal contacts and underscore the fundamental importance of interface morphology for MoS2-based devices.
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Affiliation(s)
- Meng Li
- College of Information Science and Engineering, Shenyang University of Technology, Shenyang, People's Republic of China. State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, People's Republic of China
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20
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Lu J, Zheng Z, Yao J, Gao W, Xiao Y, Zhang M, Li J. An asymmetric contact-induced self-powered 2D In 2S 3 photodetector towards high-sensitivity and fast-response. NANOSCALE 2020; 12:7196-7205. [PMID: 32195529 DOI: 10.1039/d0nr00517g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Self-powered photodetectors have triggered extensive attention in recent years due to the advantages of high sensitivity, fast response, low power consumption, high level of integration and wireless operation. To date, most self-powered photodetectors are implemented through the construction of either heterostructures or asymmetric electrode material contact, which are complex to process and costly to produce. Herein, for the first time, we achieved a self-powered operation by adopting a geometrical asymmetry in the device architecture, where a triangular non-layered 2D In2S3 flake with an asymmetric contact is combined with the traditional photogating effect. Importantly, the device achieves excellent photoresponsivity (740 mA W-1), high detectivity (1.56 × 1010 Jones), and fast response time (9/10 ms) under zero bias. Furthermore, the asymmetric In2S3/Si photodetector manifests long-term stability. Even after 1000 cycles of operation, the asymmetric In2S3/Si device displays negligible performance degradation. In sum, the above results highlight a novel route towards self-powered photodetectors with high performance, simple processing and structure in the future.
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Affiliation(s)
- Jianting Lu
- School of Materials and Energy, Guangdong University of Technology, Guangzhou, 510006, Guangdong, P. R. China.
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21
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Contacts for Molybdenum Disulfide: Interface Chemistry and Thermal Stability. MATERIALS 2020; 13:ma13030693. [PMID: 32033092 PMCID: PMC7040825 DOI: 10.3390/ma13030693] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 01/25/2020] [Accepted: 01/31/2020] [Indexed: 12/01/2022]
Abstract
In this review on contacts with MoS2, we consider reports on both interface chemistry and device characteristics. We show that there is considerable disagreement between reported properties, at least some of which may be explained by variability in the properties of geological MoS2. Furthermore, we highlight that while early experiments using photoemission to study the interface behavior of metal-MoS2 showed a lack of Fermi-level pinning, device measurements repeatedly confirm that the interface is indeed pinned. Here we suggest that a parallel conduction mechanism enabled by metallic defects in the MoS2 materials may explain both results. We note that processing conditions during metal depositions on MoS2 can play a critical role in the interface chemistry, with differences between high vacuum and ultra-high vacuum being particularly important for low work function metals. This can be used to engineer the interfaces by using thin metal-oxide interlayers to protect the MoS2 from reactions with the metals. We also report on the changes in the interfaces that can occur at high temperature which include enhanced reactions between Ti or Cr and MoS2, diffusion of Ag into MoS2, and delamination of Fe. What is clear is that there is a dearth of experimental work that investigates both the interface chemistry and device properties in parallel.
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Chee SS, Lee JH, Lee K, Ham MH. Defect-Assisted Contact Property Enhancement in a Molybdenum Disulfide Monolayer. ACS APPLIED MATERIALS & INTERFACES 2020; 12:4129-4134. [PMID: 31880145 DOI: 10.1021/acsami.9b19681] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Contact engineering for two-dimensional (2D) transition metal dichalcogenides (TMDCs) is crucial for realizing high-performance 2D TMDC devices, and most studies on contact properties of 2D TMDCs have mainly focused on Fermi level unpinning. Here, we investigated electrical and photoelectrical properties of chemical vapor deposition (CVD)-grown molybdenum disulfide (MoS2) monolayer devices depending on metal contacts, Ti/Pt, Ti/Au, Ti, and Ag, and particularly demonstrated the essential role of defects in MoS2 in contact properties. Remarkably, MoS2 devices with Ag contacts show a field-effect mobility of 12.2 cm2 V-1 s-1, an on/off current ratio of 7 × 107, and a photoresponsivity of 1020 A W-1, which are outstanding compared to similar devices with other metal contacts. These improvements are attributed to a reduced Schottky barrier height, thanks to the small work function of Ag and Ag-MoS2 orbital hybridization at the interface, which facilitates efficient charge transfer between MoS2 and Ag. Interestingly, X-ray photoelectron spectroscopic analysis reveals that Ag2S was formed in our defect-containing CVD-grown MoS2 monolayer, but such orbital hybridization is not observed in a nearly defect-free exfoliated MoS2. This distinction shows that defects existing in MoS2 enable Ag to effectively couple to MoS2 and correspondingly enhance multiple electrical and photoelectrical properties.
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Affiliation(s)
- Sang-Soo Chee
- School of Materials Science and Engineering , Gwangju Institute of Science & Technology (GIST) , 123 Cheomdangwagi-ro , Buk-gu, Gwangju 61005 , Republic of Korea
| | - Joo-Hyoung Lee
- School of Materials Science and Engineering , Gwangju Institute of Science & Technology (GIST) , 123 Cheomdangwagi-ro , Buk-gu, Gwangju 61005 , Republic of Korea
| | - Kayoung Lee
- School of Materials Science and Engineering , Gwangju Institute of Science & Technology (GIST) , 123 Cheomdangwagi-ro , Buk-gu, Gwangju 61005 , Republic of Korea
| | - Moon-Ho Ham
- School of Materials Science and Engineering , Gwangju Institute of Science & Technology (GIST) , 123 Cheomdangwagi-ro , Buk-gu, Gwangju 61005 , Republic of Korea
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Sun Y, Moe YA, Xu Y, Sun Y, Wang X, Li F, Liu K, Wang R. Evolution of local strain in Ag-deposited monolayer MoS 2 modulated by interface interactions. NANOSCALE 2019; 11:22432-22439. [PMID: 31742287 DOI: 10.1039/c9nr07599b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Strain is usually unavoidable in the fabrication of devices based on two-dimensional (2D) transition metal chalcogenides (TMDCs). When metals are deposited onto monolayer TMDCs, strain can be induced at metal-TMDC interfaces and evolves with elapsed time. However, the effect of the substrate on the strain evolution at the metal-TMDC interfaces is still unclear, which hinders the development of reliable 2D TMDC-based devices with perfect contacts. In this work, we investigated the evolution of metal-induced local strains for Ag-deposited monolayer MoS2 on three kinds of substrates with different interface interactions, i.e., sapphire, SiO2/Si, and mica. The interface interaction between MoS2 and sapphire is the strongest, while that between MoS2 and mica is the weakest. With the splitting of MoS2 Raman peaks as an indicator of local strain, the evolution behavior of the local strain at the Ag-MoS2 interfaces is found to greatly depend on the interface interactions from the underlying substrates. With elapsed time, the local strain is best preserved on sapphire but relaxed most easily on mica. Density-functional theory calculations show that the adsorption energies at the interfaces are different for MoS2 on different substrates, suggesting that the interface interaction between monolayer MoS2 and the substrates is crucial for the strain evolution. Our work is of benefit for the study of stability and reliability of devices based on TMDCs, particularly for flexible electronic devices.
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Affiliation(s)
- Yinghui Sun
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China.
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Sotthewes K, van Bremen R, Dollekamp E, Boulogne T, Nowakowski K, Kas D, Zandvliet HJW, Bampoulis P. Universal Fermi-Level Pinning in Transition-Metal Dichalcogenides. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:5411-5420. [PMID: 30873255 PMCID: PMC6410613 DOI: 10.1021/acs.jpcc.8b10971] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/13/2019] [Indexed: 05/26/2023]
Abstract
Understanding the electron transport through transition-metal dichalcogenide (TMDC)-based semiconductor/metal junctions is vital for the realization of future TMDC-based (opto-)electronic devices. Despite the bonding in TMDCs being largely constrained within the layers, strong Fermi-level pinning (FLP) was observed in TMDC-based devices, reducing the tunability of the Schottky barrier height. We present evidence that metal-induced gap states (MIGS) are the origin for the large FLP similar to conventional semiconductors. A variety of TMDCs (MoSe2, WSe2, WS2, and MoTe2) were investigated using high-spatial-resolution surface characterization techniques, permitting us to distinguish between defected and pristine regions. The Schottky barrier heights on the pristine regions can be explained by MIGS, inducing partial FLP. The FLP strength is further enhanced by disorder-induced gap states induced by transition-metal vacancies or substitutionals at the defected regions. Our findings emphasize the importance of defects on the electron transport properties in TMDC-based devices and confirm the origin of FLP in TMDC-based metal/semiconductor junctions.
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Affiliation(s)
- Kai Sotthewes
- Physics
of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
- II.
Institute of Physics B and JARA-FIT, RWTH-Aachen
University, 52056 Aachen, Germany
| | - Rik van Bremen
- Physics
of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Edwin Dollekamp
- Physics
of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Tim Boulogne
- Physics
of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Krystian Nowakowski
- Physics
of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Daan Kas
- Physics
of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Harold J. W. Zandvliet
- Physics
of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Pantelis Bampoulis
- Physics
of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands
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Wang XF, Tian H, Liu Y, Shen S, Yan Z, Deng N, Yang Y, Ren TL. Two-Mode MoS 2 Filament Transistor with Extremely Low Subthreshold Swing and Record High On/Off Ratio. ACS NANO 2019; 13:2205-2212. [PMID: 30694651 DOI: 10.1021/acsnano.8b08876] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
With rapid development of integrated circuits, urgent requirements for a transistor with lower subthreshold swing (SS) and better contact properties are needed. To optimize the SS and contact issues, we propose a concept of molybdenum disulfide (MoS2) filament transistor with two modes. We successfully fabricated the proposed devices in a wafer-scale. Mode I can enable the device with extremely low SS down to 2.26 mV/dec by switching the contact filament between on and off while mode II can realize a record high on/off ratio of 2.6 × 109 by using filament as quasi-zero dimensional (quasi-0D) contact. Compared to conventional three-dimensional (3D) contact, quasi-0D contact using conductive filament improves the current density nearly 50 times. We also built a spice model to simulate the electrical behaviors, and the simulation results show an extremely low SS in mode I (using abrupt filament formation/rupture) and excellent quasi-0D contact in mode II. The two-mode MoS2 filament transistor can significantly improve the SS and contact comparing to those of the state-of-the-art transistors, which has the great potential to boost the development of the next generation mainstream transistors.
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Affiliation(s)
- Xue-Feng Wang
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) , Tsinghua University , Beijing 100084 , China
| | - He Tian
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) , Tsinghua University , Beijing 100084 , China
| | - Yanming Liu
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) , Tsinghua University , Beijing 100084 , China
| | - Shuhong Shen
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) , Tsinghua University , Beijing 100084 , China
| | - Zhaoyi Yan
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) , Tsinghua University , Beijing 100084 , China
| | - Ningqin Deng
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) , Tsinghua University , Beijing 100084 , China
| | - Yi Yang
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) , Tsinghua University , Beijing 100084 , China
| | - Tian-Ling Ren
- Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) , Tsinghua University , Beijing 100084 , China
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Chee SS, Seo D, Kim H, Jang H, Lee S, Moon SP, Lee KH, Kim SW, Choi H, Ham MH. Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High-Mobility MoS 2 Field-Effect Transistors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1804422. [PMID: 30411825 DOI: 10.1002/adma.201804422] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 10/05/2018] [Indexed: 06/08/2023]
Abstract
2D transition metal dichalcogenides (TMDCs) have emerged as promising candidates for post-silicon nanoelectronics owing to their unique and outstanding semiconducting properties. However, contact engineering for these materials to create high-performance devices while adapting for large-area fabrication is still in its nascent stages. In this study, graphene/Ag contacts are introduced into MoS2 devices, for which a graphene film synthesized by chemical vapor deposition (CVD) is inserted between a CVD-grown MoS2 film and a Ag electrode as an interfacial layer. The MoS2 field-effect transistors with graphene/Ag contacts show improved electrical and photoelectrical properties, achieving a field-effect mobility of 35 cm2 V-1 s-1 , an on/off current ratio of 4 × 108 , and a photoresponsivity of 2160 A W-1 , compared to those of devices with conventional Ti/Au contacts. These improvements are attributed to the low work function of Ag and the tunability of graphene Fermi level; the n-doping of Ag in graphene decreases its Fermi level, thereby reducing the Schottky barrier height and contact resistance between the MoS2 and electrodes. This demonstration of contact interface engineering with CVD-grown MoS2 and graphene is a key step toward the practical application of atomically thin TMDC-based devices with low-resistance contacts for high-performance large-area electronics and optoelectronics.
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Affiliation(s)
- Sang-Soo Chee
- School of Materials Science and Engineering, Gwangju Institute of Science & Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Dongpyo Seo
- School of Materials Science and Engineering, Gwangju Institute of Science & Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Hanggyu Kim
- School of Materials Science and Engineering, Gwangju Institute of Science & Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Hanbyeol Jang
- School of Materials Science and Engineering, Gwangju Institute of Science & Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Seungmin Lee
- School of Electrical and Electronic Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Seung Pil Moon
- KEPCO Research Institute, Korea Electric Power Corporation, Naju, 58214, Republic of Korea
| | - Kyu Hyoung Lee
- Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Sung Wng Kim
- Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Hyunyong Choi
- School of Electrical and Electronic Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Moon-Ho Ham
- School of Materials Science and Engineering, Gwangju Institute of Science & Technology (GIST), Gwangju, 61005, Republic of Korea
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Moe YA, Sun Y, Ye H, Liu K, Wang R. Probing Evolution of Local Strain at MoS 2-Metal Boundaries by Surface-Enhanced Raman Scattering. ACS APPLIED MATERIALS & INTERFACES 2018; 10:40246-40254. [PMID: 30360611 DOI: 10.1021/acsami.8b13241] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Strain usually exists in two-dimensional (2D) materials and devices, and its presence drastically modulates their properties. When 2D materials interface with noble metals, local strain and surface plasmon can couple at the metal-2D material boundaries, delivering a lot of intriguing phenomena. Current studies are mostly focused on the explanations of these strain-related phenomena based on a static point of view. Although strain can typically be relaxed in many environments, the time evolution of strain at metal-2D material interfaces remains largely unknown. In this work, we investigate the evolution of local strain at Ag-MoS2 boundaries by surface-enhanced Raman scattering. With the split of MoS2 Raman peaks as an indicator of local strain, it is found that the originally localized strain at Ag-MoS2 boundaries evolves and relaxes with time into a delocalized strain in MoS2 plane. The time to start the strain relaxation depends on the number of layers of MoS2 flakes, suggesting that the relaxation may result from the mechanical instability of the interface between the topmost MoS2 layer and the underlying materials. The relaxation occurs in a certain period of time, i.e., ∼70 days for 1L and ∼30 days for 3L. Accompanying the strain relaxation, surface sulfurization of Ag also occurs, a process that reduces the strength of locally enhanced electric field. Our results not only provide a deep understanding of strain evolution at metal-MoS2 interfaces but also shed light on the optimization of MoS2-based device fabrications.
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Affiliation(s)
- Yan Aung Moe
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China
| | - Yinghui Sun
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China
| | - Huanyu Ye
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China
| | - Kai Liu
- State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering , Tsinghua University , Beijing 100084 , People's Republic of China
| | - Rongming Wang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China
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28
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Progress in Contact, Doping and Mobility Engineering of MoS2: An Atomically Thin 2D Semiconductor. CRYSTALS 2018. [DOI: 10.3390/cryst8080316] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Atomically thin molybdenum disulfide (MoS2), a member of the transition metal dichalcogenide (TMDC) family, has emerged as the prototypical two-dimensional (2D) semiconductor with a multitude of interesting properties and promising device applications spanning all realms of electronics and optoelectronics. While possessing inherent advantages over conventional bulk semiconducting materials (such as Si, Ge and III-Vs) in terms of enabling ultra-short channel and, thus, energy efficient field-effect transistors (FETs), the mechanically flexible and transparent nature of MoS2 makes it even more attractive for use in ubiquitous flexible and transparent electronic systems. However, before the fascinating properties of MoS2 can be effectively harnessed and put to good use in practical and commercial applications, several important technological roadblocks pertaining to its contact, doping and mobility (µ) engineering must be overcome. This paper reviews the important technologically relevant properties of semiconducting 2D TMDCs followed by a discussion of the performance projections of, and the major engineering challenges that confront, 2D MoS2-based devices. Finally, this review provides a comprehensive overview of the various engineering solutions employed, thus far, to address the all-important issues of contact resistance (RC), controllable and area-selective doping, and charge carrier mobility enhancement in these devices. Several key experimental and theoretical results are cited to supplement the discussions and provide further insight.
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29
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Yu S, Zhu H, Eshun K, Shi C, Zeng M, Jiang K, Li Q. Dirac fermions induced in strained zigzag phosphorus nanotubes and their applications in field effect transistors. Phys Chem Chem Phys 2018; 18:32521-32527. [PMID: 27874108 DOI: 10.1039/c6cp05810h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, Dirac fermions have been obtained and engineered in one-dimensional (1D) zigzag phosphorus nanotubes (ZPNTs). We have performed a comprehensive first-principles computational study of the electronic properties of ZPNTs with various diameters. The results indicate that as the lattice parameter (Lc) along the axial direction increases, ZPNTs undergo transitions from metal to semimetal and semimetal to semiconductor, whereas Dirac fermions appear at Lc ranging from 3.90 Å to 4.10 Å. In particular, a field effect transistor (FET) based on 12-ZPNT (with 12 unit cells in the transverse direction) exhibits semiconductor behaviors with efficient gate-effect modulation at Lc = 4.60 Å. However, only weak gate modulation is demonstrated when the nanotube becomes a semimetal at Lc = 4.10 Å. This study indicates that ZPNTs are profoundly appealing for applications in strain sensors. Our findings pave the way for the development of high-performance strain-engineered electronics based on Dirac fermions in 1D materials.
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Affiliation(s)
- Sheng Yu
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA.
| | - Hao Zhu
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA. and State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China
| | - Kwesi Eshun
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA.
| | - Chen Shi
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA.
| | - Min Zeng
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA. and Institute for Advanced Materials, South China Normal University, Guangzhou 510006, China
| | - Kai Jiang
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA.
| | - Qiliang Li
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA.
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Hajzus JR, Biacchi AJ, Le ST, Richter CA, Hight Walker AR, Porter LM. Contacts to solution-synthesized SnS nanoribbons: dependence of barrier height on metal work function. NANOSCALE 2017; 10:319-327. [PMID: 29214263 PMCID: PMC5826728 DOI: 10.1039/c7nr07403d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Tin(ii) monosulfide (SnS) is a layered, anisotropic material that is of interest as a two-dimensional semiconductor for opto-electronic, thermoelectric, and piezoelectric applications. In this study, the effect of work function on contact behavior was investigated. Ni/Au, Pd/Au, Cr/Au, and Ti/Au contacts were fabricated onto individual, solution-synthesized, p-type SnS nanoribbons. The lower work function metals (Cr and Ti) formed Schottky contacts, whereas the higher work function metals (Ni and Pd) formed ohmic or semi-ohmic contacts. Of the ohmic contacts, Ni was found to have a lower contact resistance (∼10-4 Ω cm2 or lower) than Pd (∼10-3 Ω cm2 or lower). Both the calculated Schottky barriers (0.39 and 0.50 eV) for Cr and Ti, respectively, and the ohmic behavior for Ni and Pd agree with behavior predicted by Schottky-Mott theory. The results indicate that high work function metals should be considered to form low resistance contacts to SnS multilayers.
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Affiliation(s)
- Jenifer R Hajzus
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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31
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Burman D, Ghosh R, Santra S, Kumar Ray S, Kumar Guha P. Role of vacancy sites and UV-ozone treatment on few layered MoS 2 nanoflakes for toxic gas detection. NANOTECHNOLOGY 2017; 28:435502. [PMID: 28832016 DOI: 10.1088/1361-6528/aa87cd] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Various issues like global warming and environmental pollutions have led to the research of toxic gas detection worldwide. In this work, we have tried to develop a molybdenum disulfide (MoS2) based gas sensor to detect toxic gases like ammonia and NO. MoS2, an inorganic analog of graphene, has attracted lots of attention for many different applications recently. This paper reports the use of liquid exfoliated MoS2 nanoflakes as the sensing layer in a handheld, resistive toxic gas sensor. The nanoflakes were exfoliated from MoS2 bulk powder using a sonication based exfoliation technique at room temperature. The successful exfoliation of the nanoflakes was characterized using different techniques e.g., optical microscopy, atomic force microscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy, x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy and ultraviolet-visible spectrophotometry. The characterization results showed that few-layered nanoflakes have successfully been exfoliated. The MoS2 nanoflakes showed reasonable sensing towards ammonia and NO. In order to explore the effect of particle size on ammonia sensing, the MoS2 flakes were also exfoliated using different sonication times. We also observed that various factors like presence of vacancy sites, ambient oxygen, humidity, different contact electrodes have significant effect on the sensing characteristics. In fact, the response of the sensing layer against 400 ppm of ammonia increased from 54.1% to ∼80% when it was UV-ozone treated. This work holds promises to developing cost-effective, reliable and highly sensitive MoS2 based ammonia sensors.
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Affiliation(s)
- Debasree Burman
- Department of Electronics & Electrical Communication Engineering, IIT Kharagpur, 721302, India
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32
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Kondekar NP, Boebinger MG, Woods EV, McDowell MT. In Situ XPS Investigation of Transformations at Crystallographically Oriented MoS 2 Interfaces. ACS APPLIED MATERIALS & INTERFACES 2017; 9:32394-32404. [PMID: 28846377 DOI: 10.1021/acsami.7b10230] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nanoscale transition-metal dichalcogenide (TMDC) materials, such as MoS2, exhibit promising behavior in next-generation electronics and energy-storage devices. TMDCs have a highly anisotropic crystal structure, with edge sites and basal planes exhibiting different structural, chemical, and electronic properties. In virtually all applications, two-dimensional or bulk TMDCs must be interfaced with other materials (such as electrical contacts in a transistor). The presence of edge sites vs basal planes (i.e., the crystallographic orientation of the TMDC) could influence the chemical and electronic properties of these solid-state interfaces, but such effects are not well understood. Here, we use in situ X-ray photoelectron spectroscopy (XPS) to investigate how the crystallography and structure of MoS2 influence chemical transformations at solid-state interfaces with various other materials. MoS2 materials with controllably aligned crystal structures (horizontal vs vertical orientation of basal planes) were fabricated, and in situ XPS was carried out by sputter-depositing three different materials (Li, Ge, and Ag) onto MoS2 within an XPS instrument while periodically collecting photoelectron spectra; these deposited materials are of interest due to their application in electronic devices or energy storage. The results showed that Li reacts readily with both crystallographic orientations of MoS2 to form metallic Mo and Li2S, while Ag showed very little chemical or electronic interaction with either type of MoS2. In contrast, Ge showed significant chemical interactions with MoS2 basal planes, but only minor chemical changes were observed when Ge contacted MoS2 edge sites. These findings have implications for electronic transport and band alignment at these interfaces, which is of significant interest for a variety of applications.
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Affiliation(s)
- Neha P Kondekar
- School of Materials Science and Engineering, Georgia Institute of Technology , 771 Ferst Drive, Atlanta, Georgia 30332, United States
| | - Matthew G Boebinger
- School of Materials Science and Engineering, Georgia Institute of Technology , 771 Ferst Drive, Atlanta, Georgia 30332, United States
| | - Eric V Woods
- Materials Characterization Facility, Institute for Electronics and Nanotechnology, Georgia Institute of Technology , 345 Ferst Drive, Atlanta, Georgia 30332, United States
| | - Matthew T McDowell
- School of Materials Science and Engineering, Georgia Institute of Technology , 771 Ferst Drive, Atlanta, Georgia 30332, United States
- G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology , 801 Ferst Drive, Atlanta, Georgia 30332, United States
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33
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Nie XR, Sun BQ, Zhu H, Zhang M, Zhao DH, Chen L, Sun QQ, Zhang DW. Impact of Metal Contacts on the Performance of Multilayer HfS 2 Field-Effect Transistors. ACS APPLIED MATERIALS & INTERFACES 2017; 9:26996-27003. [PMID: 28730801 DOI: 10.1021/acsami.7b06160] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
HfS2 is one of the emerging transition metal dichalcogenides and is very promising for low-power nanoelectronics and high-sensitivity optoelectronic device applications. We studied the band structures of 1T-HfS2 with different thicknesses by first principles simulation, and the impact of different metal contacts to the HfS2 device performance has been experimentally studied. Back-gate and top-gate HfS2 field-effect transistors (FETs) were fabricated, and better electrical characteristics have been achieved with the FETs with the Ti/Au contact as compared with the Pt-contacted FETs. Thin layers of Pt and Ti/Au films were deposited on HfS2 flakes to investigate the metal/HfS2 interface by using scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. A smoother Ti/Au film was formed on HfS2, resulting in higher carrier injection and transport efficiency. The phonon behavior being dominated by the interface chemical bonding at the Ti/Au contact region has been confirmed with the more sensitive A1g phonon mode from the bilayer HfS2.
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Affiliation(s)
- Xin-Ran Nie
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China
| | - Bing-Qi Sun
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China
| | - Hao Zhu
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China
| | - Min Zhang
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China
| | - Dong-Hui Zhao
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China
| | - Lin Chen
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China
| | - Qing-Qing Sun
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China
| | - David Wei Zhang
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China
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Xu J, Chen L, Dai YW, Cao Q, Sun QQ, Ding SJ, Zhu H, Zhang DW. A two-dimensional semiconductor transistor with boosted gate control and sensing ability. SCIENCE ADVANCES 2017; 3:e1602246. [PMID: 28560330 PMCID: PMC5438220 DOI: 10.1126/sciadv.1602246] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 03/16/2017] [Indexed: 05/23/2023]
Abstract
Transistors with exfoliated two-dimensional (2D) materials on a SiO2/Si substrate have been applied and have been proven effective in a wide range of applications, such as circuits, memory, photodetectors, gas sensors, optical modulators, valleytronics, and spintronics. However, these devices usually suffer from limited gate control because of the thick SiO2 gate dielectric and the lack of reliable transfer method. We introduce a new back-gate transistor scheme fabricated on a novel Al2O3/ITO (indium tin oxide)/SiO2/Si "stack" substrate, which was engineered with distinguishable optical identification of exfoliated 2D materials. High-quality exfoliated 2D materials could be easily obtained and recognized on this stack. Two typical 2D materials, MoS2 and ReS2, were implemented to demonstrate the enhancement of gate controllability. Both transistors show excellent electrical characteristics, including steep subthreshold swing (62 mV dec-1 for MoS2 and 83 mV dec-1 for ReS2), high mobility (61.79 cm2 V-1 s-1 for MoS2 and 7.32 cm2 V-1 s-1 for ReS2), large on/off ratio (~107), and reasonable working gate bias (below 3 V). Moreover, MoS2 and ReS2 photodetectors fabricated on the basis of the scheme have impressively leading photoresponsivities of 4000 and 760 A W-1 in the depletion area, respectively, and both have exceeded 106 A W-1 in the accumulation area, which is the best ever obtained. This opens up a suite of applications of this novel platform in 2D materials research with increasing needs of enhanced gate control.
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Li M, Liu N, Li P, Shi J, Li G, Xi N, Wang Y, Liu L. Performance Investigation of Multilayer MoS 2 Thin-Film Transistors Fabricated via Mask-free Optically Induced Electrodeposition. ACS APPLIED MATERIALS & INTERFACES 2017; 9:8361-8370. [PMID: 28240858 DOI: 10.1021/acsami.6b15419] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Transition metal dichalcogenides, particularly MoS2, have recently received enormous interest in explorations of the physics and technology of nanodevice applications because of their excellent optical and electronic properties. Although monolayer MoS2 has been extensively investigated for various possible applications, its difficulty of fabrication renders it less appealing than multilayer MoS2. Moreover, multilayer MoS2, with its inherent high electronic/photonic state densities, has higher output driving capabilities and can better satisfy the ever-increasing demand for versatile devices. Here, we present multilayer MoS2 back-gate thin-film transistors (TFTs) that can achieve a relatively low subthreshold swing of 0.75 V/decade and a high mobility of 41 cm2·V-1·s-1, which exceeds the typical mobility value of state-of-the-art amorphous silicon-based TFTs by a factor of 80. Ag and Au electrode-based MoS2 TFTs were fabricated by a convenient and rapid process. Then we performed a detailed analysis of the impacts of metal contacts and MoS2 film thickness on electronic performance. Our findings show that smoother metal contacts exhibit better electronic characteristics and that MoS2 film thickness should be controlled within a reasonable range of 30-40 nm to obtain the best mobility values, thereby providing valuable insights regarding performance enhancement for MoS2 TFTs. Additionally, to overcome the limitations of the conventional fabrication method, we employed a novel approach known as optically induced electrodeposition (OIE), which allows the flexible and precise patterning of metal films and enables rapid and mask-free device fabrication, for TFT fabrication.
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Affiliation(s)
- Meng Li
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences , Shenyang 110016, China
- University of the Chinese Academy of Sciences , Beijing 100049, China
| | - Na Liu
- School of Mechatronics Engineering and Automation, Shanghai University , Shanghai 200072, China
| | - Pan Li
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences , Shenyang 110016, China
- University of the Chinese Academy of Sciences , Beijing 100049, China
| | - Jialin Shi
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences , Shenyang 110016, China
- University of the Chinese Academy of Sciences , Beijing 100049, China
| | - Guangyong Li
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences , Shenyang 110016, China
- University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Ning Xi
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences , Shenyang 110016, China
- Emerging Technologies Institute, Department of Industrial & Manufacturing Systems Engineering, University of Hong Kong , Pokfulam, Hong Kong, China
| | - Yuechao Wang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences , Shenyang 110016, China
| | - Lianqing Liu
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences , Shenyang 110016, China
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Zhou X, Zhang Q, Gan L, Li H, Xiong J, Zhai T. Booming Development of Group IV-VI Semiconductors: Fresh Blood of 2D Family. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2016; 3:1600177. [PMID: 27981008 PMCID: PMC5157174 DOI: 10.1002/advs.201600177] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Indexed: 05/19/2023]
Abstract
As an important component of 2D layered materials (2DLMs), the 2D group IV metal chalcogenides (GIVMCs) have drawn much attention recently due to their earth-abundant, low-cost, and environmentally friendly characteristics, thus catering well to the sustainable electronics and optoelectronics applications. In this instructive review, the booming research advancements of 2D GIVMCs in the last few years have been presented. First, the unique crystal and electronic structures are introduced, suggesting novel physical properties. Then the various methods adopted for synthesis of 2D GIVMCs are summarized such as mechanical exfoliation, solvothermal method, and vapor deposition. Furthermore, the review focuses on the applications in field effect transistors and photodetectors based on 2D GIVMCs, and extends to flexible devices. Additionally, the 2D GIVMCs based ternary alloys and heterostructures have also been presented, as well as the applications in electronics and optoelectronics. Finally, the conclusion and outlook have also been presented in the end of the review.
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Affiliation(s)
- Xing Zhou
- State Key Laboratory of Material Processing and Die & Mould TechnologySchool of Materials Science and EngineeringHuazhong University of Science and Technology (HUST)Wuhan430074P. R. China
| | - Qi Zhang
- State Key Laboratory of Material Processing and Die & Mould TechnologySchool of Materials Science and EngineeringHuazhong University of Science and Technology (HUST)Wuhan430074P. R. China
| | - Lin Gan
- State Key Laboratory of Material Processing and Die & Mould TechnologySchool of Materials Science and EngineeringHuazhong University of Science and Technology (HUST)Wuhan430074P. R. China
| | - Huiqiao Li
- State Key Laboratory of Material Processing and Die & Mould TechnologySchool of Materials Science and EngineeringHuazhong University of Science and Technology (HUST)Wuhan430074P. R. China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Films and Integrated DevicesUniversity of Electronic Science and Technology of ChinaChengdu611731P. R. China
| | - Tianyou Zhai
- State Key Laboratory of Material Processing and Die & Mould TechnologySchool of Materials Science and EngineeringHuazhong University of Science and Technology (HUST)Wuhan430074P. R. China
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Zhou P, Song X, Yan X, Liu C, Chen L, Sun Q, Zhang DW. Controlling the work function of molybdenum disulfide by in situ metal deposition. NANOTECHNOLOGY 2016; 27:344002. [PMID: 27419644 DOI: 10.1088/0957-4484/27/34/344002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Control of the work function of molybdenum disulfide (MoS2) under ultrathin metal was investigated using in situ metal deposition and direct ultraviolet photoelectron spectroscopy measurement in an ultra-high vacuum system. When the metal thickness turned from two dimensional into bulk, the work function was also raised up at the nickel-MoS2 interface, barely changed at the titanium-MoS2 interface and lowered at the hafnium-MoS2 interface. Meanwhile, the mechanisms of charge transfer and band alignment with metal deposition were also discussed. The Schottky barrier at metal-MoS2 interfaces could be tailored by both types and thicknesses of deposited metal. The low work function metal was a good indicator for MoS2 contact electrodes. It paved the way towards future high performance MoS2 device applications.
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Affiliation(s)
- Peng Zhou
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
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Uncovering edge states and electrical inhomogeneity in MoS2 field-effect transistors. Proc Natl Acad Sci U S A 2016; 113:8583-8. [PMID: 27444021 DOI: 10.1073/pnas.1605982113] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The understanding of various types of disorders in atomically thin transition metal dichalcogenides (TMDs), including dangling bonds at the edges, chalcogen deficiencies in the bulk, and charges in the substrate, is of fundamental importance for TMD applications in electronics and photonics. Because of the imperfections, electrons moving on these 2D crystals experience a spatially nonuniform Coulomb environment, whose effect on the charge transport has not been microscopically studied. Here, we report the mesoscopic conductance mapping in monolayer and few-layer MoS2 field-effect transistors by microwave impedance microscopy (MIM). The spatial evolution of the insulator-to-metal transition is clearly resolved. Interestingly, as the transistors are gradually turned on, electrical conduction emerges initially at the edges before appearing in the bulk of MoS2 flakes, which can be explained by our first-principles calculations. The results unambiguously confirm that the contribution of edge states to the channel conductance is significant under the threshold voltage but negligible once the bulk of the TMD device becomes conductive. Strong conductance inhomogeneity, which is associated with the fluctuations of disorder potential in the 2D sheets, is also observed in the MIM images, providing a guideline for future improvement of the device performance.
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Kwon HJ, Jang J, Grigoropoulos CP. Laser Direct Writing Process for Making Electrodes and High-k Sol-Gel ZrO2 for Boosting Performances of MoS2 Transistors. ACS APPLIED MATERIALS & INTERFACES 2016; 8:9314-9318. [PMID: 27011225 DOI: 10.1021/acsami.5b11357] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A series of two-dimensional (2D) transition metal dichalcogenides (TMDCs), including molybdenum disulfide (MoS2), can be attractive materials for photonic and electronic applications due to their exceptional properties. Among these unique properties, high mobility of 2D TMDCs enables realization of high-performance nanoelectronics based on a thin film transistor (TFT) platform. In this contribution, we report highly enhanced field effect mobility (μ(eff) = 50.1 cm(2)/(V s), ∼2.5 times) of MoS2 TFTs through the sol-gel processed high-k ZrO2 (∼22.0) insulator, compared to those of typical MoS2/SiO2/Si structures (μ(eff) = 19.4 cm(2)/(V s)) because a high-k dielectric layer can suppress Coulomb electron scattering and reduce interface trap concentration. Additionally, in order to avoid costly conventional mask based photolithography and define the patterns, we employ a simple laser direct writing (LDW) process. This process allows precise and flexible control with reasonable resolution (up to ∼10 nm), depending on the system, and enables fabrication of arbitrarily patterned devices. Taking advantage of continuing developments in laser technology offers a substantial cost decrease, and LDW may emerge as a promising technology.
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Affiliation(s)
- Hyuk-Jun Kwon
- Department of Mechanical Engineering, University of California, Berkeley , Berkeley, California 94720-1740, United States
| | - Jaewon Jang
- School of Electronics Engineering, Kyungpook National University , Daegu 702-701, Korea
| | - Costas P Grigoropoulos
- Department of Mechanical Engineering, University of California, Berkeley , Berkeley, California 94720-1740, United States
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40
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Liu Y, Stradins P, Wei SH. Van der Waals metal-semiconductor junction: Weak Fermi level pinning enables effective tuning of Schottky barrier. SCIENCE ADVANCES 2016; 2:e1600069. [PMID: 27152360 PMCID: PMC4846439 DOI: 10.1126/sciadv.1600069] [Citation(s) in RCA: 221] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 03/24/2016] [Indexed: 05/19/2023]
Abstract
Two-dimensional (2D) semiconductors have shown great potential for electronic and optoelectronic applications. However, their development is limited by a large Schottky barrier (SB) at the metal-semiconductor junction (MSJ), which is difficult to tune by using conventional metals because of the effect of strong Fermi level pinning (FLP). We show that this problem can be overcome by using 2D metals, which are bounded with 2D semiconductors through van der Waals (vdW) interactions. This success relies on a weak FLP at the vdW MSJ, which is attributed to the suppression of metal-induced gap states. Consequently, the SB becomes tunable and can vanish with proper 2D metals (for example, H-NbS2). This work not only offers new insights into the fundamental properties of heterojunctions but also uncovers the great potential of 2D metals for device applications.
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Affiliation(s)
- Yuanyue Liu
- National Renewable Energy Laboratory, Golden, CO 80401, USA
- Corresponding author. E-mail: (Y.L.); (S.-H.W.)
| | - Paul Stradins
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Su-Huai Wei
- National Renewable Energy Laboratory, Golden, CO 80401, USA
- Beijing Computational Science Research Center, Beijing 100094, China
- Corresponding author. E-mail: (Y.L.); (S.-H.W.)
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Lampeka YD, Tsymbal LV. Nanocomposites of Two-Dimensional Molybdenum and Tungsten Dichalcogenides with Metal Particles: Preparation and Prospects for Application. THEOR EXP CHEM+ 2015. [DOI: 10.1007/s11237-015-9410-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Sanne A, Ghosh R, Rai A, Yogeesh MN, Shin SH, Sharma A, Jarvis K, Mathew L, Rao R, Akinwande D, Banerjee S. Radio Frequency Transistors and Circuits Based on CVD MoS2. NANO LETTERS 2015; 15:5039-45. [PMID: 26134588 DOI: 10.1021/acs.nanolett.5b01080] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We report on the gigahertz radio frequency (RF) performance of chemical vapor deposited (CVD) monolayer MoS2 field-effect transistors (FETs). Initial DC characterizations of fabricated MoS2 FETs yielded current densities exceeding 200 μA/μm and maximum transconductance of 38 μS/μm. A contact resistance corrected low-field mobility of 55 cm(2)/(V s) was achieved. Radio frequency FETs were fabricated in the ground-signal-ground (GSG) layout, and standard de-embedding techniques were applied. Operating at the peak transconductance, we obtain short-circuit current-gain intrinsic cutoff frequency, fT, of 6.7 GHz and maximum intrinsic oscillation frequency, fmax, of 5.3 GHz for a device with a gate length of 250 nm. The MoS2 device afforded an extrinsic voltage gain Av of 6 dB at 100 MHz with voltage amplification until 3 GHz. With the as-measured frequency performance of CVD MoS2, we provide the first demonstration of a common-source (CS) amplifier with voltage gain of 14 dB and an active frequency mixer with conversion gain of -15 dB. Our results of gigahertz frequency performance as well as analog circuit operation show that large area CVD MoS2 may be suitable for industrial-scale electronic applications.
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Affiliation(s)
- Atresh Sanne
- †Microelectronics Research Center and ‡Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
| | - Rudresh Ghosh
- †Microelectronics Research Center and ‡Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
| | - Amritesh Rai
- †Microelectronics Research Center and ‡Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
| | - Maruthi Nagavalli Yogeesh
- †Microelectronics Research Center and ‡Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
| | - Seung Heon Shin
- †Microelectronics Research Center and ‡Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
| | - Ankit Sharma
- †Microelectronics Research Center and ‡Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
| | | | - Leo Mathew
- §Applied Novel Devices Inc., Austin, Texas 78717, United States
| | - Rajesh Rao
- §Applied Novel Devices Inc., Austin, Texas 78717, United States
| | - Deji Akinwande
- †Microelectronics Research Center and ‡Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
| | - Sanjay Banerjee
- †Microelectronics Research Center and ‡Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
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He G, Ghosh K, Singisetti U, Ramamoorthy H, Somphonsane R, Bohra G, Matsunaga M, Higuchi A, Aoki N, Najmaei S, Gong Y, Zhang X, Vajtai R, Ajayan PM, Bird JP. Conduction Mechanisms in CVD-Grown Monolayer MoS2 Transistors: From Variable-Range Hopping to Velocity Saturation. NANO LETTERS 2015; 15:5052-8. [PMID: 26121164 DOI: 10.1021/acs.nanolett.5b01159] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We fabricate transistors from chemical vapor deposition-grown monolayer MoS2 crystals and demonstrate excellent current saturation at large drain voltages (Vd). The low-field characteristics of these devices indicate that the electron mobility is likely limited by scattering from charged impurities. The current-voltage characteristics exhibit variable range hopping at low Vd and evidence of velocity saturation at higher Vd. This work confirms the excellent potential of MoS2 as a possible channel-replacement material and highlights the role of multiple transport phenomena in governing its transistor action.
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Affiliation(s)
- G He
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - K Ghosh
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - U Singisetti
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - H Ramamoorthy
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - R Somphonsane
- ‡Department of Physics, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
| | - G Bohra
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - M Matsunaga
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - A Higuchi
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - N Aoki
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - S Najmaei
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Y Gong
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - X Zhang
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - R Vajtai
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - P M Ajayan
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - J P Bird
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
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Ioannou D, Kandukuri L, Simpson JL, Tempest HG. Chromosome territory repositioning induced by PHA-activation of lymphocytes: A 2D and 3D appraisal. Mol Cytogenet 2015; 8:47. [PMID: 26146516 PMCID: PMC4490598 DOI: 10.1186/s13039-015-0146-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 05/14/2015] [Indexed: 11/26/2022] Open
Abstract
Background Genomes and by extension chromosome territories (CTs) in a variety of organisms exhibit nonrandom organization within interphase nuclei. CTs are susceptible to movement upon induction by a variety of stimuli, including: cell differentiation, growth factors, genotoxic agents, proliferating status, and stimulants that induce novel transcription profiles. These findings suggest nuclear architecture can undergo reorganization, providing support for a functional significance of CT organization. The effect of the initiation of transcription on global scale chromatin architecture has been underexplored. This study investigates the organization of all 24 human chromosomes in lymphocytes from two individuals in resting and phytohaemagglutinin activated lymphocytes using 2D and 3D approaches. Results The radial organization of CTs in lymphocytes in both resting and activated lymphocytes follows a gene-density pattern. However, CT organization in activated nuclei appears less constrained exhibiting a more random organization. We report differences in the spatial relationship between homologous and heterologous CTs in activated nuclei. In addition, a reproducible radial hierarchy of CTs was identified and evidence of a CT repositioning was observed in activated nuclei using both 2D and 3D approaches. Conclusions Alterations between resting and activated lymphocytes could be adaptation of CTs to the new transcription profile and possibly the formation of new neighborhoods of interest or interaction of CTs with nuclear landmarks. The increased distances between homologous and heterologous CTs in activated lymphocytes could be a reflection of a defensive mechanism to reduce potential interaction to prevent any structural chromosome abnormalities (e.g. translocations) as a result of DNA damage that increases during lymphocyte activation.
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Affiliation(s)
- Dimitrios Ioannou
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199 USA
| | - Lakshmi Kandukuri
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199 USA ; Present address Centre for Cellular and Molecular Biology (CCMB), Council of Scientific and Industrial Research (CSIR) Uppal Road, Hyderabad, 500 007 India
| | - Joe Leigh Simpson
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199 USA
| | - Helen Ghislaine Tempest
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199 USA ; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199 USA
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