1
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Guo S, Wu K, Li C, Wang H, Sun Z, Xi D, Zhang S, Ding W, Zaghloul ME, Wang C, Castro FA, Yang D, Zhao Y. Integrated contact lens sensor system based on multifunctional ultrathin MoS 2 transistors. MATTER 2021; 4:969-985. [PMID: 33398259 PMCID: PMC7773002 DOI: 10.1016/j.matt.2020.12.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 10/28/2020] [Accepted: 12/03/2020] [Indexed: 05/19/2023]
Abstract
Smart contact lenses attract extensive interests due to their capability of directly monitoring physiological and ambient information. However, previous demonstrations usually lacked efficient sensor modalities, facile fabrication process, mechanical stability, or biocompatibility. Here, we demonstrate a flexible approach for fabrication of multifunctional smart contact lenses with an ultrathin MoS2 transistors-based serpentine mesh sensor system. The integrated sensor systems contain a photodetector for receiving optical information, a glucose sensor for monitoring glucose level directly from tear fluid, and a temperature sensor for diagnosing potential corneal disease. Unlike traditional sensors and circuit chips sandwiched in the lens substrate, this serpentine mesh sensor system can be directly mounted onto the lenses and maintain direct contact with tears, delivering high detection sensitivity, while being mechanically robust and not interfering with either blinking or vision. Furthermore, the in vitro cytotoxicity tests reveal good biocompatibility, thus holding promise as next-generation soft electronics for healthcare and medical applications.
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Affiliation(s)
- Shiqi Guo
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Kaijin Wu
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, CAS Center for Excellence in Complex System Mechanics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Chengpan Li
- Department of Electronic Science and Technology, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Hao Wang
- Athioula A. Martins Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Zheng Sun
- School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA
| | - Dawei Xi
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Sheng Zhang
- Ningbo Research Institute, Zhejiang University, Zhejiang, Ningbo 315100, China
| | - Weiping Ding
- Department of Electronic Science and Technology, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Mona E Zaghloul
- School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA
| | - Changning Wang
- Athioula A. Martins Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Fernando A Castro
- Advanced Technology Institute, University of Surrey, Guildford, Surrey GU2 7XH, UK
- National Physical Laboratory, Teddington, Middlesex TW11 0LW, UK
| | - Dong Yang
- Athioula A. Martins Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Yunlong Zhao
- Advanced Technology Institute, University of Surrey, Guildford, Surrey GU2 7XH, UK
- National Physical Laboratory, Teddington, Middlesex TW11 0LW, UK
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2
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Zhang X, Wang S, Lee CK, Cheng CM, Lan JC, Li X, Qiao J, Tao X. Unravelling the effect of sulfur vacancies on the electronic structure of the MoS 2 crystal. Phys Chem Chem Phys 2020; 22:21776-21783. [PMID: 32966363 DOI: 10.1039/c9cp07004d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molybdenum disulfide (MoS2) is one of the two-dimensional layered semiconductor transition metal dichalcogenides (TMDCs) with great potential in electronics, optoelectronics, and spintronic devices. Sulfur vacancies in MoS2 are the most prevalent defects. However, the effect of sulfur vacancies on the electronic structure of MoS2 is still in dispute. Here we experimentally and theoretically investigated the effect of sulfur vacancies in MoS2. The vacancies were intentionally introduced by thermal annealing of MoS2 crystals in a vacuum environment. Angle-resolved photoemission spectroscopy (ARPES) was used directly to observe the electronic structure of the MoS2 single crystals. The experimental result distinctly revealed the appearance of an occupied defect state just above the valence band maximum (VBM) and an upward shift of the VBM after creating sulfur vacancies. In addition, density functional theory (DFT) calculations also confirmed the existence of the occupied defect state close to the VBM as well as two deep unoccupied states induced by the sulfur vacancies. Our results provide evidence to contradict that sulfur vacancies indicate the origin of n-type behaviour in MoS2. This work provides a rational strategy for tuning the electronic structures of MoS2.
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Affiliation(s)
- Xixia Zhang
- State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
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3
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Konar R, Rosy, Perelshtein I, Teblum E, Telkhozhayeva M, Tkachev M, Richter JJ, Cattaruzza E, Pietropolli Charmet A, Stoppa P, Noked M, Nessim GD. Scalable Synthesis of Few-Layered 2D Tungsten Diselenide (2H-WSe 2) Nanosheets Directly Grown on Tungsten (W) Foil Using Ambient-Pressure Chemical Vapor Deposition for Reversible Li-Ion Storage. ACS OMEGA 2020; 5:19409-19421. [PMID: 32803034 PMCID: PMC7424584 DOI: 10.1021/acsomega.0c01155] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 07/13/2020] [Indexed: 09/14/2024]
Abstract
We report a facile two-furnace APCVD synthesis of 2H-WSe2. A systematic study of the process parameters is performed to show the formation of the phase-pure material. Extensive characterization of the bulk and exfoliated material confirm that 2H-WSe2 is layered (i.e., 2D). X-ray diffraction (XRD) confirms the phase, while high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM) clarify the morphology of the material. Focused ion beam scanning electron microscopy (FIB-SEM) estimates the depth of the 2H-WSe2 formed on W foil to be around 5-8 μm, and Raman/UV-vis measurements prove the quality of the exfoliated 2H-WSe2. Studies on the redox processes of lithium-ion batteries (LiBs) show an increase in capacity up to 500 cycles. On prolonged cycling, the discharge capacity up to the 50th cycle at 250 mA/g of the material shows a stable value of 550 mAh/g. These observations indicate that exfoliated 2H-WSe2 has promising applications as an LiB electrode material.
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Affiliation(s)
- Rajashree Konar
- Chemistry,
Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
| | - Rosy
- Chemistry,
Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
| | - Ilana Perelshtein
- Institute
of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
| | - Eti Teblum
- Institute
of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
| | - Madina Telkhozhayeva
- Chemistry,
Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
| | - Maria Tkachev
- Institute
of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
| | - Jonathan J. Richter
- Chemistry,
Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
| | - Elti Cattaruzza
- Department
of Molecular Sciences and Nanosystems, Ca’Foscari
University of Venice, Via Torino, 155, Venezia-Mestre 30172, Italy
| | - Andrea Pietropolli Charmet
- Department
of Molecular Sciences and Nanosystems, Ca’Foscari
University of Venice, Via Torino, 155, Venezia-Mestre 30172, Italy
| | - Paolo Stoppa
- Department
of Molecular Sciences and Nanosystems, Ca’Foscari
University of Venice, Via Torino, 155, Venezia-Mestre 30172, Italy
| | - Malachi Noked
- Chemistry,
Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
| | - Gilbert Daniel Nessim
- Chemistry,
Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat
Gan 52900, Israel
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4
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Ahmed T, Bellare P, Debnath R, Roy A, Ravishankar N, Ghosh A. Thermal History-Dependent Current Relaxation in hBN/MoS 2 van der Waals Dimers. ACS NANO 2020; 14:5909-5916. [PMID: 32310636 DOI: 10.1021/acsnano.0c01079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Combining atomically thin layers of van der Waals (vdW) materials in a chosen vertical sequence is an emerging route to create devices with desired functionalities. While this method aims to exploit the individual properties of partnering layers, strong interlayer coupling can significantly alter their electronic and optical properties. Here we explored the impact of the vdW epitaxy on electrical transport in atomically thin molybdenum disulfide (MoS2) when it forms a vdW dimer with crystalline films of hexagonal boron nitride (hBN). We observe a thermal history-dependent long-term (over ∼40 h) current relaxation in the overlap region of MoS2/hBN heterostructures, which is absent in bare MoS2 layers (or homoepitaxial MoS2/MoS2 dimers) on the same substrate. Concurrent relaxation in the low-frequency Raman modes in MoS2 in the heterostructure region suggests a slow structural relaxation between trigonal and octahedral polymorphs of MoS2 as a likely driving mechanism that also results in inhomogeneous charge distribution in the MoS2 layer. Our experiment yields an aspect of vdW heteroepitaxy that can be generic to electrical devices with atomically thin transition-metal dichalcogenides.
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Affiliation(s)
- Tanweer Ahmed
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Pavithra Bellare
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Rahul Debnath
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Ahin Roy
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | | | - Arindam Ghosh
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
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5
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Yang D, Wang H, Luo S, Wang C, Zhang S, Guo S. Paper-Cut Flexible Multifunctional Electronics Using MoS 2 Nanosheet. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E922. [PMID: 31248055 PMCID: PMC6669538 DOI: 10.3390/nano9070922] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/18/2019] [Accepted: 06/21/2019] [Indexed: 11/18/2022]
Abstract
Art and science represent human creativity and rational thinking, respectively. When the two seemingly opposite fields are intertwined, there is always a life-changing spark. In particular, the integration of ancient traditional Chinese art into the latest electronic devices is always been an unexcavated topic. Fabricating two-dimensional material with a tensile strain less than 3% with an ultimate global stretch has been an important problem that plagues the current flexible electronics field. The current research is limited to material in small scale, and it is always necessary to develop and extend large-sized flexible electronic systems. Here, inspired by the traditional Chinese paper-cut structure, we present a highly deformable multifunctional electronic system based on the MoS2 nanosheet. In this work, we first demonstrate how the traditional paper-cut structure can open the view of flexible electronics. In order to obtain a large area of MoS2 with excellent performance, we use a metal-assisted exfoliation method to transfer MoS2, followed by fabricating a field effect transistor to characterize its excellent electrical properties. Two photodetectors and a temperature sensor are produced with good performance. The mechanical simulation proves that the structure has more advantages in stretchability than other typical paper-cut structures. From the experimental and mechanical point of view, it is proved that the device can work stably under high deformation. We finally show that the device has broad application prospects in highly deformed organs, tissues, and joints. These findings set a good example of traditional Chinese culture to guide innovation in the field of electronic devices.
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Affiliation(s)
- Dong Yang
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
- Athioula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Hao Wang
- Athioula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Shenglin Luo
- Athioula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Changning Wang
- Athioula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Sheng Zhang
- Micro/Nano Technology Center, Tokai University, 4-1-1 Kitakaname, Hiratsuka-city, Kanagawa 259-1292, Japan.
| | - Shiqi Guo
- School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA.
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
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6
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Moon BH, Bae JJ, Han GH, Kim H, Choi H, Lee YH. Anomalous Conductance near Percolative Metal-Insulator Transition in Monolayer MoS 2 at Low Voltage Regime. ACS NANO 2019; 13:6631-6637. [PMID: 31122017 DOI: 10.1021/acsnano.9b00755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Conductivity of the insulating phase increases generally at an elevated drain-source voltage due to the field-enhanced hopping or heating effect. Meanwhile, a transport mechanism governed by percolation in a low compensated semiconductor gives rise to the reduced conductivity at a low-field regime. Here, in addition to this behavior, we report the anomalous conductivity behavior to transform from a percolative metallic to an insulating phase at the low voltage regime in monolayer molybdenum disulfide (MoS2). Percolation transport at low source-drain voltage is governed by inhomogeneously distributed potential in strongly interacting monolayer MoS2 with a substrate, distinct from the quantum phase transition in multilayer MoS2. At a high source-drain voltage regime, the insulating phase is transformed further to a metallic phase, exhibiting multiphases of metallic-insulating-metallic transitions in monolayer MoS2. These behaviors highlight MoS2 as a model system to study various classical and quantum transports as well as metal-insulator transition in two-dimensional systems.
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Affiliation(s)
- Byoung Hee Moon
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Jung Jun Bae
- WIT Co., Ltd. , 89, Seoho-ro, Gwonseon-gu , Suwon 16614 , Republic of Korea
| | - Gang Hee Han
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
| | - Hyun Kim
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Homin Choi
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
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7
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Yang M, Kim TY, Lee T, Hong S. Nanoscale enhancement of photoconductivity by localized charge traps in the grain structures of monolayer MoS 2. Sci Rep 2018; 8:15822. [PMID: 30361562 PMCID: PMC6202400 DOI: 10.1038/s41598-018-34209-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 10/12/2018] [Indexed: 12/03/2022] Open
Abstract
We report a method for mapping the nanoscale anomalous enhancement of photoconductivity by localized charge traps in the grain structures of a molybdenum disulfide (MoS2) monolayer. In this work, a monolayer MoS2 film was laterally scanned by a nanoscale conducting probe that was used to make direct contact with the MoS2 surface. Electrical currents and noise maps were measured through the probe. By analyzing the data, we obtained maps for the sheet resistance and charge trap density for the MoS2 grain structures. The maps clearly show grains for which sheet resistance and charge trap density were lower than those of the grain boundaries. Interestingly, we found an unusual inverse proportionality between the sheet resistance and charge trap density in the grains, which originated from the unique role of sulfur vacancies acting as both charge hopping sites and traps in monolayer MoS2. In addition, under light illumination, the larger the trap density of a region was, the larger the photocurrent of the region was, indicating anomalous enhancement of the photocurrent by traps. Since our method provides valuable insights to understand the nanoscale effects of traps on photoconductive charge transport, it can be a powerful tool for noise studies and the practical application of two-dimensional materials.
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Affiliation(s)
- Myungjae Yang
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Tae-Young Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Takhee Lee
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Seunghun Hong
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea.
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8
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Ji H, Yi H, Seok J, Kim H, Lee YH, Lim SC. Gas adsorbates are Coulomb scatterers, rather than neutral ones, in a monolayer MoS 2 field effect transistor. NANOSCALE 2018; 10:10856-10862. [PMID: 29873382 DOI: 10.1039/c8nr03570a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Direct current (DC) and low-frequency (LF) noise analyses of a chemical vapor deposition (CVD)-grown monolayer MoS2 field effect transistor (FET) indicate that time-varying carrier perturbations originate from gas adsorbates. The LF noise analysis supports that the natural desorption of physisorbed gas molecules, water and oxygen, largely reduces the interface trap density (NST) under vacuum conditions (∼10-8 Torr) for 2 weeks. After a longer period of 8 months under vacuum, the carrier scattering mechanism alters, in particular for the low carrier density (Nacc) region. A decrease of both NST and the scattering parameter αSC with desorption of surface adsorbates from MoS2, explains the enhanced carrier mobility and the early turn-on of the device. The stabilized carrier behavior is verified with γ = 0.5 in the formula αSC ∝ Nacc-γ, as in Si-MOSFETs. Our results support that the gas adsorbates work as charged impurities, rather than neutral ones.
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Affiliation(s)
- Hyunjin Ji
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon 16419, Korea.
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9
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Kim TY, Ha J, Cho K, Pak J, Seo J, Park J, Kim JK, Chung S, Hong Y, Lee T. Transparent Large-Area MoS 2 Phototransistors with Inkjet-Printed Components on Flexible Platforms. ACS NANO 2017; 11:10273-10280. [PMID: 28841294 DOI: 10.1021/acsnano.7b04893] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have gained considerable attention as an emerging semiconductor due to their promising atomically thin film characteristics with good field-effect mobility and a tunable band gap energy. However, their electronic applications have been generally realized with conventional inorganic electrodes and dielectrics implemented using conventional photolithography or transferring processes that are not compatible with large-area and flexible device applications. To facilitate the advantages of 2D TMDCs in practical applications, strategies for realizing flexible and transparent 2D electronics using low-temperature, large-area, and low-cost processes should be developed. Motivated by this challenge, we report fully printed transparent chemical vapor deposition (CVD)-synthesized monolayer molybdenum disulfide (MoS2) phototransistor arrays on flexible polymer substrates. All the electronic components, including dielectric and electrodes, were directly deposited with mechanically tolerable organic materials by inkjet-printing technology onto transferred monolayer MoS2, and their annealing temperature of <180 °C allows the direct fabrication on commercial flexible substrates without additional assisted-structures. By integrating the soft organic components with ultrathin MoS2, the fully printed MoS2 phototransistors exhibit excellent transparency and mechanically stable operation.
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Affiliation(s)
- Tae-Young Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Jewook Ha
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Kyungjune Cho
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Jinsu Pak
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Jiseok Seo
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Jongjang Park
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Jae-Keun Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Seungjun Chung
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Yongtaek Hong
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
| | - Takhee Lee
- Department of Physics and Astronomy, and Institute of Applied Physics, and ‡Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University , Seoul, 08826, Korea
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10
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Hsieh K, Kochat V, Zhang X, Gong Y, Tiwary CS, Ajayan PM, Ghosh A. Effect of Carrier Localization on Electrical Transport and Noise at Individual Grain Boundaries in Monolayer MoS 2. NANO LETTERS 2017; 17:5452-5457. [PMID: 28786685 DOI: 10.1021/acs.nanolett.7b02099] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Despite its importance in the large-scale synthesis of transition metal dichalcogenides (TMDC) molecular layers, the generic quantum effects on electrical transport across individual grain boundaries (GBs) in TMDC monolayers remain unclear. Here we demonstrate that strong carrier localization due to the increased density of defects determines both temperature dependence of electrical transport and low-frequency noise at the GBs of chemical vapor deposition (CVD)-grown MoS2 layers. Using field effect devices designed to explore transport across individual GBs, we show that the localization length of electrons in the GB region is ∼30-70% lower than that within the grain, even though the room temperature conductance across the GB, oriented perpendicular to the overall flow of current, may be lower or higher than the intragrain region. Remarkably, we find that the stronger localization is accompanied by nearly 5 orders of magnitude enhancement in the low-frequency noise at the GB region, which increases exponentially when the temperature is reduced. The microscopic framework of electrical transport and noise developed in this paper may be readily extended to other strongly localized two-dimensional systems, including other members of the TMDC family.
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Affiliation(s)
- Kimberly Hsieh
- Department of Physics, Indian Institute of Science , Bangalore 560012, India
| | - Vidya Kochat
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - Xiang Zhang
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - Yongji Gong
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - Chandra Sekhar Tiwary
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - Pulickel M Ajayan
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - Arindam Ghosh
- Department of Physics, Indian Institute of Science , Bangalore 560012, India
- Centre for Nano Science and Engineering, Indian Institute of Science , Bangalore 560012, India
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