1
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Liu H, Zhang T, Wu P, Lee HW, Liu Z, Tang TW, Tang SY, Kang T, Park JH, Wang J, Zhang K, Zheng X, Peng YR, Chueh YL, Liu Y, Palacios T, Kong J, Luo Z. Boosting Monolayer Transition Metal Dichalcogenides Growth by Hydrogen-Free Ramping during Chemical Vapor Deposition. NANO LETTERS 2024; 24:8277-8286. [PMID: 38949123 DOI: 10.1021/acs.nanolett.4c01314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
The controlled vapor-phase synthesis of two-dimensional (2D) transition metal dichalcogenides (TMDs) is essential for functional applications. While chemical vapor deposition (CVD) techniques have been successful for transition metal sulfides, extending these methods to selenides and tellurides often faces challenges due to uncertain roles of hydrogen (H2) in their synthesis. Using CVD growth of MoSe2 as an example, this study illustrates the role of a H2-free environment during temperature ramping in suppressing the reduction of MoO3, which promotes effective vaporization and selenization of the Mo precursor to form MoSe2 monolayers with excellent crystal quality. As-synthesized MoSe2 monolayer-based field-effect transistors show excellent carrier mobility of up to 20.9 cm2/(V·s) with an on-off ratio of 7 × 107. This approach can be extended to other TMDs, such as WSe2, MoTe2, and MoSe2/WSe2 in-plane heterostructures. Our work provides a rational and facile approach to reproducibly synthesize high-quality TMD monolayers, facilitating their translation from laboratory to manufacturing.
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Affiliation(s)
- Hongwei Liu
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, P. R. China
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Tianyi Zhang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Peng Wu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Hae Won Lee
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Zhenjing Liu
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, P. R. China
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Tsz Wing Tang
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, P. R. China
| | - Shin-Yi Tang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 30013, Taiwan
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Ting Kang
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, P. R. China
- Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha 410082, P. R. China
| | - Ji-Hoon Park
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jun Wang
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, P. R. China
| | - Kenan Zhang
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, P. R. China
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Xudong Zheng
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yu-Ren Peng
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 30013, Taiwan
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Yu-Lun Chueh
- Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 30013, Taiwan
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Yuan Liu
- Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha 410082, P. R. China
| | - Tomás Palacios
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jing Kong
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Zhengtang Luo
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, P. R. China
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2
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Luo X, Jiao Y, Li H, Liu Q, Liu J, Wang M, Liu Y. Impact of Carrier Gas Flow Rate on the Synthesis of Monolayer WSe 2 via Hydrogen-Assisted Chemical Vapor Deposition. MATERIALS (BASEL, SWITZERLAND) 2024; 17:2190. [PMID: 38793257 PMCID: PMC11123087 DOI: 10.3390/ma17102190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/16/2024] [Accepted: 04/18/2024] [Indexed: 05/26/2024]
Abstract
Transition metal dichalcogenides (TMDs), particularly monolayer TMDs with direct bandgap properties, are key to advancing optoelectronic device technology. WSe2 stands out due to its adjustable carrier transport, making it a prime candidate for optoelectronic applications. This study explores monolayer WSe2 synthesis via H2-assisted CVD, focusing on how carrier gas flow rate affects WSe2 quality. A comprehensive characterization of monolayer WSe2 was conducted using OM (optical microscope), Raman spectroscopy, PL spectroscopy, AFM, SEM, XPS, HRTEM, and XRD. It was found that H2 incorporation and flow rate critically influence WSe2's growth and structural integrity, with low flow rates favoring precursor concentration for product formation and high rates causing disintegration of existing structures. This research accentuates the significance of fine-tuning the carrier gas flow rate for optimizing monolayer WSe2 synthesis, offering insights for fabricating monolayer TMDs like WS2, MoSe2, and MoS2, and facilitating their broader integration into optoelectronic devices.
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Affiliation(s)
| | | | | | | | | | | | - Yong Liu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, International School of Materials Science and Engineering (ISMSE), State Wuhan University of Technology, Wuhan 430070, China; (X.L.); (Y.J.); (H.L.); (Q.L.); (J.L.); (M.W.)
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3
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Köster J, Kretschmer S, Storm A, Rasper F, Kinyanjui MK, Krasheninnikov AV, Kaiser U. Phase transformations in single-layer MoTe 2stimulated by electron irradiation and annealing. NANOTECHNOLOGY 2024; 35:145301. [PMID: 38096582 DOI: 10.1088/1361-6528/ad15bb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 12/14/2023] [Indexed: 01/16/2024]
Abstract
Among two-dimensional (2D) transition metal dichalcogenides (TMDs), MoTe2is predestined for phase-engineering applications due to the small difference in free energy between the semiconducting H-phase and metallic 1T'-phase. At the same time, the complete picture of the phase evolution originating from point defects in single-layer of semiconducting H-MoTe2via Mo6Te6nanowires to cubic molybdenum has not yet been reported so far, and it is the topic of the present study. The occurring phase transformations in single-layer H-MoTe2were initiated by 40-80 kV electrons in the spherical and chromatic aberration-corrected high-resolution transmission electron microscope and/or when subjected to high temperatures. We analyse the damage cross-section at voltages between 40 kV and 80 kV and relate the results to previously published values for other TMDs. Then we demonstrate that electron beam irradiation offers a route to locally transform freestanding single-layer H-MoTe2into one-dimensional (1D) Mo6Te6nanowires. Combining the experimental data with the results of first-principles calculations, we explain the transformations in MoTe2single-layers and Mo6Te6nanowires by an interplay of electron-beam-induced energy transfer, atom ejection, and oxygen absorption. Further, the effects emerging from electron irradiation are compared with those produced byin situannealing in a vacuum until pure molybdenum crystals are obtained at temperatures of about 1000 °C. A detailed understanding of high-temperature solid-to-solid phase transformation in the 2D limit can provide insights into the applicability of this material for future device fabrication.
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Affiliation(s)
- Janis Köster
- Electron Microscopy Group of Materials Science, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Silvan Kretschmer
- Institut of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
| | - Alexander Storm
- Electron Microscopy Group of Materials Science, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Fabian Rasper
- Electron Microscopy Group of Materials Science, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Michael K Kinyanjui
- Electron Microscopy Group of Materials Science, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Arkady V Krasheninnikov
- Institut of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
- Department of Applied Physics, Aalto University, PO Box 14100, FI-00076 Aalto, Finland
| | - Ute Kaiser
- Electron Microscopy Group of Materials Science, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
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4
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Kumar A, Sanger A, Kang SB, Chandra R. Interface Engineering-Driven Room-Temperature Ultralow Gas Sensors with Elucidating Sensing Performance of Heterostructure Transition Metal Dichalcogenide Thin Films. ACS Sens 2023; 8:3824-3835. [PMID: 37769211 DOI: 10.1021/acssensors.3c01290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
In this report, we investigate the room-temperature gas sensing performance of heterostructure transition metal dichalcogenide (MoSe2/MoS2, WS2/MoS2, and WSe2/MoS2) thin films grown over a silicon substrate using a pulse laser deposition technique. The sensing response of the aforementioned sensors to a low concentration range of NO2, NH3, H2, CO, and H2S gases in air has been assessed at room temperature. The obtained results reveal that the heterojunctions of metal dichalcogenide show a drastic change in gas sensing performance compared to the monolayer thin films at room temperature. Nevertheless, the WSe2/MoS2-based sensor was found to have an excellent selectivity toward NO2 gas with a particularly high sensitivity of 10 ppb. The sensing behavior is explained on the basis of a change in electrical resistance as well as carrier localization prospects. Favorably, by developing a heterojunction of diselenide and disulfide nanomaterials, one may find a simple way of improving the sensing capabilities of gas sensors at room temperature.
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Affiliation(s)
- Ashwani Kumar
- Nanoscience Laboratory, Institute Instrumentation Centre, IIT Roorkee, Roorkee 247667, India
- Department of Physics, Graphic Era (Deemed to be University), Dehradun, Uttarakhand 248002, India
| | - Amit Sanger
- Department of Physics, Netaji Subhas University of Technology, Dwarka Sector-3, New Delhi 110078, India
| | - Sung Bum Kang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ramesh Chandra
- Nanoscience Laboratory, Institute Instrumentation Centre, IIT Roorkee, Roorkee 247667, India
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5
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Maity D, Sharma R, Sahoo KR, Panda JJ, Lal A, Puthirath AB, Ajayan PM, Narayanan TN. On the electronic and spin-valley coupling of vanadium doped MoS 2(1-x)Se 2xmonolayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:505002. [PMID: 37708898 DOI: 10.1088/1361-648x/acf9d5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 09/14/2023] [Indexed: 09/16/2023]
Abstract
Monolayers of MoS2with tunable bandgap and valley positions are highly demanding for their applications in opto-spintronics. Herein, selenium (Se) and vanadium (V) co-doped MoS2monolayers (vanadium doped MoS2(1-x)Se2x(V-MoSSe)) are developed and showed their variations in the electronic and optical properties with dopant content. Vanadium gets substitutionally (in place of Mo) doped within the MoS2lattice while selenium doped in place of sulfur, as shown by a detailed microstructure and spectroscopy analyses. The bandgap tunability with selenium doping can be achieved while valley shift is occurred due to the doping of vanadium. Chemical vapor deposition assisted grown MoS2(also selenium doped MoS2as shown here) is known for its n-type transport behavior while vanadium doping is found to be changing its nature to p-doping. Chirality dependent photoexcitation studies indicate a room temperature valley splitting in V-MoSSe (∼8 meV), where such a valley splitting is verified using density functional theory based calculations.
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Affiliation(s)
- Dipak Maity
- Tata Institute of Fundamental Research-Hyderabad, Serilingampally Mandal, Hyderabad 500046, India
| | - Rahul Sharma
- Tata Institute of Fundamental Research-Hyderabad, Serilingampally Mandal, Hyderabad 500046, India
| | - Krishna Rani Sahoo
- Tata Institute of Fundamental Research-Hyderabad, Serilingampally Mandal, Hyderabad 500046, India
| | - Janmey Jay Panda
- Tata Institute of Fundamental Research-Hyderabad, Serilingampally Mandal, Hyderabad 500046, India
| | - Ashique Lal
- Tata Institute of Fundamental Research-Hyderabad, Serilingampally Mandal, Hyderabad 500046, India
| | - Anand B Puthirath
- Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX 77005, United States of America
| | - Pulickel M Ajayan
- Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX 77005, United States of America
| | - Tharangattu N Narayanan
- Tata Institute of Fundamental Research-Hyderabad, Serilingampally Mandal, Hyderabad 500046, India
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6
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Jaiswal S, Fathi-Hafshejani P, Yakupoglu B, Boebinger MG, Azam N, Unocic RR, Hamilton MC, Mahjouri-Samani M. Wafer-Scale Synthesis of 2D Materials by an Amorphous Phase-Mediated Crystallization Approach. ACS APPLIED MATERIALS & INTERFACES 2023; 15:39697-39706. [PMID: 37579298 DOI: 10.1021/acsami.3c06009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The interest in the wafer-scale growth of two-dimensional (2D) materials, including transition metal dichalcogenides (TMDCs), has been rising for transitioning from lab-scale devices to commercial-scale systems. Among various synthesis techniques, physical vapor deposition, such as pulsed laser deposition (PLD), has shown promise for the wafer-scale growth of 2D materials. However, due to the high volatility of chalcogen atoms (e.g., S and Se), films deposited by PLD usually suffer from a lack of stoichiometry and chalcogen deficiency. To mitigate this issue, excess chalcogen is necessary during the deposition, which results in problems like uniformity or not being repeatable. This study demonstrates a condensed-phase or amorphous phase-mediated crystallization (APMC) approach for the wafer-scale synthesis of 2D materials. This method uses a room-temperature PLD process for the deposition and formation of amorphous precursors with controlled thicknesses, followed by a post-deposition crystallization process to convert the amorphous materials to crystalline structures. This approach maintains the stoichiometry of the deposited materials throughout the deposition and crystallization process and enables the large-scale synthesis of crystalline 2D materials (e.g., MoS2 and WSe2) on Si/SiO2 substrates, which is critical for future wafer-scale electronics. We show that the thickness of the layers can be digitally controlled by the number of laser pulses during the PLD phase. Optical spectroscopy is used to monitor the crystallization dynamics of amorphous layers as a function of annealing temperature. The crystalline quality, domain sizes, and the number of layers were explored using nanoscale and atomistic characterization (e.g., AFM, STEM, and EDS) along with electrical characterization to explore process-structure-performance relationships. This growth technique is a promising method that could potentially be adopted in conventional semiconductor industries for wafer-scale manufacturing of next-generation electronic and optoelectronic devices.
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Affiliation(s)
- Suman Jaiswal
- Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Parvin Fathi-Hafshejani
- Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Baha Yakupoglu
- Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Matthew G Boebinger
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Nurul Azam
- Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Raymond R Unocic
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Michael C Hamilton
- Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Masoud Mahjouri-Samani
- Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849, United States
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7
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Harris SB, Lin YC, Puretzky AA, Liang L, Dyck O, Berlijn T, Eres G, Rouleau CM, Xiao K, Geohegan DB. Real-Time Diagnostics of 2D Crystal Transformations by Pulsed Laser Deposition: Controlled Synthesis of Janus WSSe Monolayers and Alloys. ACS NANO 2023; 17:2472-2486. [PMID: 36649648 DOI: 10.1021/acsnano.2c09952] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Energetic processing methods such as hyperthermal implantation hold special promise to achieve the precision synthesis of metastable two-dimensional (2D) materials such as Janus monolayers; however, they require precise control. Here, we report a feedback approach to reveal and control the transformation pathways in materials synthesis by pulsed laser deposition (PLD) and apply it to investigate the transformation kinetics of monolayer WS2 crystals into Janus WSSe and WSe2 by implantation of Se clusters with different maximum kinetic energies (<42 eV/Se-atom) generated by laser ablation of a Se target. Real-time Raman spectroscopy and photoluminescence are used to assess the structure, composition, and optoelectronic quality of the monolayer crystal as it is implanted with well-controlled fluxes of selenium for different kinetic energies that are regulated with in situ ICCD imaging, ion probe, and spectroscopy diagnostics. First-principles calculations, XPS, and atomic-resolution HAADF STEM imaging are used to understand the intermediate alloy compositions and their vibrational modes to identify transformation pathways. The real-time kinetics measurements reveal highly selective top-layer conversion as WS2 transforms through WS2(1-x)Se2x alloys to WSe2 and provide the means to adjust processing conditions to achieve fractional and complete Janus WSSe monolayers as metastable transition states. The general approach demonstrates a real-time feedback method to achieve Janus layers or other metastable alloys of the desired composition, and a general means to adjust the structure and quality of materials grown by PLD, addressing priority research directions for precision synthesis with real-time adaptive control.
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Affiliation(s)
- Sumner B Harris
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Yu-Chuan Lin
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania16802, United States
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Liangbo Liang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Ondrej Dyck
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Tom Berlijn
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Gyula Eres
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Christopher M Rouleau
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Kai Xiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - David B Geohegan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
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8
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R. R, Prasannakumar AT, Mohan RR, V. M, Varma SJ. Advances in 2D Molybdenum Disulfide‐Based Functional Materials for Supercapacitor Applications. ChemistrySelect 2022. [DOI: 10.1002/slct.202203068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Rohith. R.
- Materials for Energy Storage and Optoelectronic Devices Group Department of Physics Sanatana Dharma College University of Kerala Alappuzha Kerala 688003 India
- Research Centre University of Kerala Thiruvananthapuram Kerala 695034 India
| | - Anandhu Thejas Prasannakumar
- Materials for Energy Storage and Optoelectronic Devices Group Department of Physics Sanatana Dharma College University of Kerala Alappuzha Kerala 688003 India
- Research Centre University of Kerala Thiruvananthapuram Kerala 695034 India
| | - Ranjini R. Mohan
- Division for Research in Advanced Materials Department of Physics Cochin University of Science and Technology Kochi Kerala 688022 India
| | - Manju. V.
- Materials for Energy Storage and Optoelectronic Devices Group Department of Physics Sanatana Dharma College University of Kerala Alappuzha Kerala 688003 India
- Research Centre University of Kerala Thiruvananthapuram Kerala 695034 India
| | - Sreekanth J. Varma
- Materials for Energy Storage and Optoelectronic Devices Group Department of Physics Sanatana Dharma College University of Kerala Alappuzha Kerala 688003 India
- Research Centre University of Kerala Thiruvananthapuram Kerala 695034 India
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9
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Kang T, Tang TW, Pan B, Liu H, Zhang K, Luo Z. Strategies for Controlled Growth of Transition Metal Dichalcogenides by Chemical Vapor Deposition for Integrated Electronics. ACS MATERIALS AU 2022; 2:665-685. [PMID: 36855548 PMCID: PMC9928416 DOI: 10.1021/acsmaterialsau.2c00029] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In recent years, transition metal dichalcogenide (TMD)-based electronics have experienced a prosperous stage of development, and some considerable applications include field-effect transistors, photodetectors, and light-emitting diodes. Chemical vapor deposition (CVD), a typical bottom-up approach for preparing 2D materials, is widely used to synthesize large-area 2D TMD films and is a promising method for mass production to implement them for practical applications. In this review, we investigate recent progress in controlled CVD growth of 2D TMDs, aiming for controlled nucleation and orientation, using various CVD strategies such as choice of precursors or substrates, process optimization, and system engineering. We then survey different patterning methods, such as surface patterning, metal precursor patterning, and postgrowth sulfurization/selenization/tellurization, to mass produce heterostructures for device applications. With these strategies, various well-designed architectures, such as wafer-scale single crystals, vertical and lateral heterostructures, patterned structures, and arrays, are achieved. In addition, we further discuss various electronics made from CVD-grown TMDs to demonstrate the diverse application scenarios. Finally, perspectives regarding the current challenges of controlled CVD growth of 2D TMDs are also suggested.
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Affiliation(s)
- Ting Kang
- Department
of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao
Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology,
William Mong Institute of Nano Science and Technology, and Hong Kong
Branch of Chinese National Engineering Research Center for Tissue
Restoration and Reconstruction, Hong Kong
University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong, P.R. China
| | - Tsz Wing Tang
- Department
of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao
Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology,
William Mong Institute of Nano Science and Technology, and Hong Kong
Branch of Chinese National Engineering Research Center for Tissue
Restoration and Reconstruction, Hong Kong
University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong, P.R. China
| | - Baojun Pan
- Macao
Institute of Materials Science and Engineering (MIMSE), Macau University of Science and Technology, Taipa, Macau 999078, P.R. China
| | - Hongwei Liu
- Department
of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao
Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology,
William Mong Institute of Nano Science and Technology, and Hong Kong
Branch of Chinese National Engineering Research Center for Tissue
Restoration and Reconstruction, Hong Kong
University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong, P.R. China
| | - Kenan Zhang
- Department
of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao
Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology,
William Mong Institute of Nano Science and Technology, and Hong Kong
Branch of Chinese National Engineering Research Center for Tissue
Restoration and Reconstruction, Hong Kong
University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong, P.R. China
| | - Zhengtang Luo
- Department
of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao
Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology,
William Mong Institute of Nano Science and Technology, and Hong Kong
Branch of Chinese National Engineering Research Center for Tissue
Restoration and Reconstruction, Hong Kong
University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong, P.R. China,
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10
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Sharma M, Singh A, Aggarwal P, Singh R. Large-Area Transfer of 2D TMDCs Assisted by a Water-Soluble Layer for Potential Device Applications. ACS OMEGA 2022; 7:11731-11741. [PMID: 35449938 PMCID: PMC9017105 DOI: 10.1021/acsomega.1c06855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
Layer transfer offers enormous potential for the industrial implementation of two-dimensional (2D) material technology platforms. However, the transfer method used must retain the as-grown uniformity and cleanliness in the transferred films for the fabrication of 2D material-based devices. Additionally, the method used must be capable of large-area transfer to maintain wafer-scale fabrication standards. Here, a facile route to transfer centimeter-scale synthesized 2D transition metal dichalcogenides (TMDCs) (3L MoS2, 1L WS2) onto various substrates such as sapphire, SiO2/Si, and flexible substrates (mica, polyimide) has been developed using a water-soluble layer (Na2S/Na2SO4) underneath the as-grown film. The developed transfer process represents a fast, clean, generic, and scalable technique to transfer 2D atomic layers. The key strategy used in this process includes the dissolution of the Na2S/Na2SO4 layer due to the penetration of NaOH solution between the growth substrate and hydrophobic 2D TMDC film. As a proof-of-concept device, a broadband photodetector has been fabricated onto the transferred 3L MoS2, which shows photoresponse behavior for a wide range of wavelengths ranging from near-infrared (NIR) to UV. The enhancement in photocurrent was found to be 100 times and 10 times the dark current in the UV and visible regions, respectively. The fabricated photodetector shows a higher responsivity of 8.6 mA/W even at a low applied voltage (1.5 V) and low power density (0.6 μW/mm2). The detector enables a high detectivity of 2.9 × 1011 Jones. This work opens up the pathway toward flexible electronics and optoelectronics.
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Affiliation(s)
- Madan Sharma
- Department
of Physics, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
| | - Aditya Singh
- Department
of Physics, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
| | - Pallavi Aggarwal
- Department
of Physics, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
| | - Rajendra Singh
- Department
of Physics, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
- Department
of Electrical Engineering, Indian Institute
of Technology Delhi, Hauz Khas, New Delhi 110016, India
- Nanoscale
Research Facility, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
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11
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Thomas CJ, Fonseca JJ, Spataru CD, Robinson JT, Ohta T. Electronic Structure and Stacking Arrangement of Tungsten Disulfide at the Gold Contact. ACS NANO 2021; 15:18060-18070. [PMID: 34623816 DOI: 10.1021/acsnano.1c06676] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
There is an intensive effort to control the nature of attractive interactions between ultrathin semiconductors and metals and to understand its impact on the electronic properties at the junction. Here, we present a photoelectron spectroscopy study on the interface between WS2 films and gold, with a focus on the occupied electronic states near the Brillouin zone center (i.e., the Γ point). To delineate the spectra of WS2 supported on crystalline Au from the suspended WS2, we employ a microscopy approach and a tailored sample structure, in which the WS2/Au junction forms a semi-epitaxial relationship and is adjacent to suspended WS2 regions. The photoelectron spectra, as a function of WS2 thickness, display the expected splitting of the highest occupied states at the Γ point. In multilayer WS2, we discovered variations in the electronic states that spatially align with the crystalline grains of underlying Au. Corroborated by density functional theory calculations, we attribute the electronic structure variations to stacking variations within the WS2 films. We propose that strong interactions exerted by Au grains cause slippage of the interfacing WS2 layer with respect to the rest of the WS2 film. Our findings illustrate that the electronic properties of transition metal dichalcogenides, and more generally 2D layered materials, are physically altered by the interactions with the interfacing materials, in addition to the electron screening and defects that have been widely considered.
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Affiliation(s)
- Cherrelle J Thomas
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Jose J Fonseca
- National Research Council Postdoctoral Fellow at the Naval Research Laboratory, Washington, District of Columbia 20375 United States
| | - Catalin D Spataru
- Sandia National Laboratories, Livermore, California 94551, United States
| | - Jeremy T Robinson
- U.S. Naval Research Laboratory, Washington, District of Columbia 20375 United States
| | - Taisuke Ohta
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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12
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Ludwiczak K, Da̧browska AK, Binder J, Tokarczyk M, Iwański J, Kurowska B, Turczyński J, Kowalski G, Bożek R, Stȩpniewski R, Pacuski W, Wysmołek A. Heteroepitaxial Growth of High Optical Quality, Wafer-Scale van der Waals Heterostrucutres. ACS APPLIED MATERIALS & INTERFACES 2021; 13:47904-47911. [PMID: 34606228 PMCID: PMC8517960 DOI: 10.1021/acsami.1c11867] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/16/2021] [Indexed: 05/05/2023]
Abstract
Transition metal dichalcogenides (TMDs) are materials that can exhibit intriguing optical properties like a change of the bandgap from indirect to direct when being thinned down to a monolayer. Well-resolved narrow excitonic resonances can be observed for such monolayers although only for materials of sufficient crystalline quality and so far mostly available in the form of micrometer-sized flakes. A further significant improvement of optical and electrical properties can be achieved by transferring the TMD on hexagonal boron nitride (hBN). To exploit the full potential of TMDs in future applications, epitaxial techniques have to be developed that not only allow the growth of large-scale, high-quality TMD monolayers but also allow the growth to be performed directly on large-scale epitaxial hBN. In this work, we address this problem and demonstrate that MoSe2 of high optical quality can be directly grown on epitaxial hBN on an entire 2 in. wafer. We developed a combined growth theme for which hBN is first synthesized at high temperature by metal organic vapor phase epitaxy (MOVPE) and as a second step MoSe2 is deposited on top by molecular beam epitaxy (MBE) at much lower temperatures. We show that this structure exhibits excellent optical properties, manifested by narrow excitonic lines in the photoluminescence spectra. Moreover, the material is homogeneous on the area of the whole 2 in. wafer with only ±0.14 meV deviation of excitonic energy. Our mixed growth technique may guide the way for future large-scale production of high quality TMD/hBN heterostructures.
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Affiliation(s)
- Katarzyna Ludwiczak
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | | | - Johannes Binder
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Mateusz Tokarczyk
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Jakub Iwański
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Bogusława Kurowska
- Institute
of Physics Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Jakub Turczyński
- Institute
of Physics Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Grzegorz Kowalski
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Rafał Bożek
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Roman Stȩpniewski
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Wojciech Pacuski
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Andrzej Wysmołek
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
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13
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Niedzwiecki DJ, DiPaolo B, Lin CY, Castan A, Keneipp R, Drndić M. Devices for Nanoscale Guiding of DNA through a 2D Nanopore. ACS Sens 2021; 6:2534-2545. [PMID: 34228425 DOI: 10.1021/acssensors.1c00829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We fabricate on-chip solid-state nanofluidic-2D nanopore systems that can limit the range of motion for DNA in the sensing region of a nanopore. We do so by creating devices containing one or more silicon nitride pores and silicon nitride pillars supporting a 2D pore that orient DNA within a nanopore device to a restricted geometry, yet allow the free motion of ions to maintain a high signal-to-noise ratio. We discuss two concepts with two and three independent electrical connections and corresponding nanopore chip device architectures to achieve this goal in practice. Here, we describe device fabrication and transmission electron microscope (TEM) images, and provide simulated translocations based on the finite element analysis in 3D to demonstrate its merit. In both methods, there is a main 2D nanopore which we refer to as a "sensing" nanopore (monolayer MoS2 in this paper). A secondary layer is either an array of guiding pores sharing the same electrode pair as the sensing pore (Method 1) or a single, independently contacted, guiding pore (Method 2). These pores are constructed parallel to the "sensing" pore and serve as "guiding" elements to stretch and feed DNA into the atomically thin sensing pore. We discuss the practical implementation of these concepts with nanofluidic and Si-based technology, including detailed fabrication steps and challenges involved for DNA applications in solution.
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Affiliation(s)
- David J. Niedzwiecki
- Goeppert LLC, Pennovation, 3401 Grays Ferry Avenue, Philadelphia, Pennsylvania 19146, United States
| | - Brian DiPaolo
- Goeppert LLC, Pennovation, 3401 Grays Ferry Avenue, Philadelphia, Pennsylvania 19146, United States
| | - Chih-Yuan Lin
- Department of Physics and Astronomy, David Rittenhouse Laboratory, University of Pennsylvania, 209 South 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Alice Castan
- Department of Physics and Astronomy, David Rittenhouse Laboratory, University of Pennsylvania, 209 South 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Rachael Keneipp
- Department of Physics and Astronomy, David Rittenhouse Laboratory, University of Pennsylvania, 209 South 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Marija Drndić
- Department of Physics and Astronomy, David Rittenhouse Laboratory, University of Pennsylvania, 209 South 33rd Street, Philadelphia, Pennsylvania 19104, United States
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Zhang D, Wen C, Mcclimon JB, Masih Das P, Zhang Q, Leone GA, Mandyam SV, Drndić M, Johnson ATC, Zhao MQ. Rapid Growth of Monolayer MoSe 2 Films for Large-Area Electronics. ADVANCED ELECTRONIC MATERIALS 2021; 7:2001219. [PMID: 36111247 PMCID: PMC9473491 DOI: 10.1002/aelm.202001219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Indexed: 05/12/2023]
Abstract
The large-scale growth of semiconducting thin films on insulating substrates enables batch fabrication of atomically thin electronic and optoelectronic devices and circuits without film transfer. Here an efficient method to achieve rapid growth of large-area monolayer MoSe2 films based on spin coating of Mo precursor and assisted by NaCl is reported. Uniform monolayer MoSe2 films up to a few inches in size are obtained within a short growth time of 5 min. The as-grown monolayer MoSe2 films are of high quality with large grain size (up to 120 μm). Arrays of field-effect transistors are fabricated from the MoSe2 films through a photolithographic process; the devices exhibit high carrier mobility of ≈27.6 cm2 V-1 s-1 and on/off ratios of ≈105. The findings provide insight into the batch production of uniform thin transition metal dichalcogenide films and promote their large-scale applications.
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Affiliation(s)
- Danzhen Zhang
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
- State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Chengyu Wen
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Electrical and System Engineering, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, USA
| | - John Brandon Mcclimon
- Department of Mechanical Engineering & Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paul Masih Das
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Qicheng Zhang
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Grace A Leone
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Srinivas V Mandyam
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marija Drndić
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alan T Charlie Johnson
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Meng-Qiang Zhao
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
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15
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Patil V, Kim J, Agrawal K, Park T, Yi J, Aoki N, Watanabe K, Taniguchi T, Kim GH. High mobility field-effect transistors based on MoS 2crystals grown by the flux method. NANOTECHNOLOGY 2021; 32:325603. [PMID: 33845468 DOI: 10.1088/1361-6528/abf6f1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 04/12/2021] [Indexed: 06/12/2023]
Abstract
Two-dimensional (2D) molybdenum disulphide (MoS2) transition metal dichalcogenides (TMDs) have great potential for use in optical and electronic device applications; however, the performance of MoS2is limited by its crystal quality, which serves as a measure of the defects and grain boundaries in the grown material. Therefore, the high-quality growth of MoS2crystals continues to be a critical issue. In this context, we propose the formation of high-quality MoS2crystals via the flux method. The resulting electrical properties demonstrate the significant impact of crystal morphology on the performance of MoS2field-effect transistors. MoS2made with a relatively higher concentration of sulphur (a molar ratio of 2.2) and at a cooling rate of 2.5 °C h-1yielded good quality and optimally sized crystals. The room-temperature and low-temperature (77 K) electrical transport properties of MoS2field-effect transistors (FETs) were studied in detail, with and without the use of a hexagonal boron nitride (h-BN) dielectric to address the mobility degradation issue due to scattering at the SiO2/2D material interface. A maximum field-effect mobility of 113 cm2V-1s-1was achieved at 77 K for the MoS2/h-BN FET following high-quality crystal formation by the flux method. Our results confirm the achievement of large-scale high-quality crystal growth with reduced defect density using the flux method and are key to achieving higher mobility in MoS2FET devices in parallel with commercially accessible MoS2crystals.
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Affiliation(s)
- Vilas Patil
- School of Electronic and Electrical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Jihyun Kim
- Centre for Quantum Materials and Superconductivity (CQMS), Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Khushabu Agrawal
- School of Electronic and Electrical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Tuson Park
- Centre for Quantum Materials and Superconductivity (CQMS), Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Junsin Yi
- School of Electronic and Electrical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Nobuyuki Aoki
- Department of Materials Science, Chiba University, Chiba 263-8522, Japan
| | - Kenji Watanabe
- Research Centre for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Centre for Materials Nano-Architectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Gil-Ho Kim
- School of Electronic and Electrical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea
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16
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Computer vision AC-STEM automated image analysis for 2D nanopore applications. Ultramicroscopy 2021; 231:113249. [PMID: 33902953 DOI: 10.1016/j.ultramic.2021.113249] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 01/15/2021] [Accepted: 02/27/2021] [Indexed: 01/17/2023]
Abstract
Transmission electron microscopy (TEM) has led to important discoveries in atomic imaging and as an atom-by-atom fabrication tool. Using electron beams, atomic structures can be patterned, annealed and crystallized, and nanopores can be drilled in thin membranes. We review current progress in TEM analysis and implement a computer vision nanopore-detection algorithm that achieves a 96% pixelwise precision in TEM images of nanopores in 2D membranes (WS2), and discuss parameter optimization including a variation on the traditional grid search and gradient ascent. Such nanopores have applications in ion detection, water filtration, and DNA sequencing, where ionic conductance through the pore should be concordant with its TEM-measured size. Standard computer vision methods have their advantages as they are intuitive and do not require extensive training data. For completeness, we briefly comment on related machine learning for 2D materials analysis and discuss relevant progress in these fields. Image analysis alongside TEM allows correlated fabrication and analysis done simultaneously in situ to engineer devices at the atomic scale.
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Manamela L, Fru JN, Kyesmen PI, Diale M, Nombona N. Electrically Enhanced Transition Metal Dichalcogenides as Charge Transport Layers in Metallophthalocyanine-Based Solar Cells. Front Chem 2020; 8:612418. [PMID: 33344424 PMCID: PMC7746773 DOI: 10.3389/fchem.2020.612418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 11/13/2020] [Indexed: 11/13/2022] Open
Abstract
Transitional metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2) have found application in photovoltaic cells as a charge transporting layer due to their high carrier mobility, chemical stability, and flexibility. In this research, a photovoltaic device was fabricated consisting of copper phthalocyanine (CuPc) as the active layer, exfoliated and Au-doped MoS2, which are n-type and p-type as electron and hole transport layers, respectively. XRD studies showed prominent peaks at (002) and other weak reflections at (100), (103), (006), and (105) planes corresponding to those of bulky MoS2. The only maintained reflection at (002) was weakened for the exfoliated MoS2 compared to the bulk, which confirmed that the material was highly exfoliated. Additional peaks at (111) and (200) planes were observed for the Au doped MoS2. The interlayer spacing (d002) was calculated to be 0.62 nm for the trigonal prismatic MoS2 with the space group P6m2. Raman spectroscopy showed that theE 2 1 g (393 cm-1) and A1g (409 cm-1) peaks for exfoliated MoS2 are closer to each other compared to their bulk counterparts (378 and 408 cm-1, respectively) hence confirming exfoliation. Raman spectroscopy also confirmed doping of MoS2 by Au as the Au-S peak was observed at 320 cm-1. Exfoliation was further confirmed by SEM as when moving from bulky to exfoliated MoS2, a single nanosheet was observed. Doping was further proven by EDS, which detected Au in the sample suggesting the yield of a p-type Au-MoS2. The fabricated device had the architecture: Glass/FTO/Au-MoS2/CuPc/MoS2/Au. A quadratic relationship between I-V was observed suggesting little rectification from the device. Illuminated I-V characterization verified that the device was sensitive and absorbed visible light. Upon illumination, the device was able to absorb photons to create electron-hole pairs and it was evident that semipermeable junctions were formed between Au-MoS2/CuPc and CuPc/MoS2 as holes and electrons were extracted and separated at respective junctions generating current from light. This study indicates that the exfoliated and Au-MoS2 could be employed as an electron transporting layer (ETL) and hole transporting layer (HTL), respectively in fabricating photovoltaic devices.
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Affiliation(s)
- Lebogang Manamela
- Department of Chemistry, University of Pretoria, Pretoria, South Africa
| | - Juvet N. Fru
- Department of Physics, University of Pretoria, Pretoria, South Africa
| | - Pannan I. Kyesmen
- Department of Physics, University of Pretoria, Pretoria, South Africa
| | - Mmantsae Diale
- Department of Physics, University of Pretoria, Pretoria, South Africa
| | - Nolwazi Nombona
- Department of Chemistry, University of Pretoria, Pretoria, South Africa
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