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Irusta Y, Morón-Navarrete G, González C. Adsorption and dissociation of hydrogen molecules over S-vacancies in a Nb-doped MoS 2monolayer. NANOTECHNOLOGY 2024; 35:355703. [PMID: 38806004 DOI: 10.1088/1361-6528/ad50dd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 05/28/2024] [Indexed: 05/30/2024]
Abstract
Motivated by the recent interest in the hydrogen energy, we have carried out a complete study of the catalytic activity of a defective molybdenum disulfide monolayer (MoS2) by means of density functional theory (DFT) calculations. The MoS2monolayer is characterized by a nonreactive basal plane. In principle, its catalytic activity is concentrated at the edges, but an alternative way to increase such activity is obtained by creating active sites where the molecules can dissociate. These defects can be easily produced experimentally by different techniques. In our study, we have performed an atomic, energetic and electronic analysis of a hydrogen molecule adsorbed on a MoS2monolayer. In a first step, we have found that the H2molecule remains physisorbed over both doped-free and Nb-doped MoS2monolayers, showing that the Nb atom does not increase the poor reactivity of the clean MoS2layer. Interestingly, our energetic results suggest that the vacancies will prefer to be formed close to the Nb atoms in the doped monolayer, but the small energy difference would allow the formation in non-doped like sites. Theoretically, we found out the conditions for the molecular dissociation on a S vacancy. In both cases, with and without Nb, the molecule should rotate from the original perpendicular position to an almost parallel orientation jumping an energetic barrier. After that, the atoms are separated binding to the Mo atoms around the missing S atom. Ourab initiomolecular dynamics simulations show that for low pressure conditions (using one single molecule in the system) the H2prefers to desorb from the vacancy, while for larger pressures (when additional H2molecules are added to the system) the molecule is finally dissociated on the vacancy. Our long simulations confirm the great stability of the structure with the two H atoms binding to the Mo atoms close to the vacancy. Finally, the inclusion of a third (or a fourth) H atom in the vacancy leads to the formation and desorption of a H2molecule, leaving one (or two) atoms in the vacancy.
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Affiliation(s)
- Yako Irusta
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain
- Instituto de Magnetismo Aplicado, UCM-ADIF, E-28230 Las Rozas de Madrid, Spain
| | | | - César González
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain
- Instituto de Magnetismo Aplicado, UCM-ADIF, E-28230 Las Rozas de Madrid, Spain
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Tien NT, Dang NH, Bich Thao PT, Vo KD, Hoat DM, Nguyen DK. Adsorption effects of acetone and acetonitrile on defected penta-PdSe 2 nanoribbons: a DFT study. RSC Adv 2024; 14:16445-16458. [PMID: 38774611 PMCID: PMC11106654 DOI: 10.1039/d4ra02368d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 05/15/2024] [Indexed: 05/24/2024] Open
Abstract
Using DFT calculations, the structural and electronic properties of the ZZ7 p-PdSe2 nanoribbons (ZZ7) with the four kinds of vacancy defects, including ZZ7-VPd, ZZ7-VSe, ZZ7-VPd+Se, and ZZ7-V2Se are studied, in which their stability, diverse geometries, and altered electronic properties are determined through the formation energies, optimal structural parameters, electronic band structures, and DOSs. Specifically, the formation energies of all studied systems show significant negative values around -3.9 eV, evidencing their good thermal stability. The geometries of four defective structures exhibit different diversification, whereas only the ZZ7-V2Se structure possesses the highly enhanced feature, identified as the most effective substrate for the acetone and acetonitrile adsorption. On the electronic behaviors, the ZZ7 band structure displays the nonmagnetic metallic characteristics that become the ferromagnetic half-metallic band structures for the ZZ7-VPd and ZZ7-VSe and the ferromagnetic semi-metallic band structures for the ZZ7-VPd+Se and ZZ7-V2Se. For adsorption of the acetone and acetonitrile on the ZZ7-V2Se structure, the energetic stability, adsorption sites, adsorption distances, charge transfers, and electronic characteristics of the adsorbed systems are determined by the adsorption energies, optimal adsorption sites, adsorption distances, Mulliken populations, and DOSs. The adsorption energies of the acetone- and acetonitrile-adsorbed ZZ7-V2Se systems display significant values at -1.2 eV and -0.86 eV at the preferable sites of 8 and 11, respectively, indicating their great adsorption ability. The adsorption mechanism of the acetone- and acetonitrile-adsorbed systems belongs to the physisorption owing to absence of chemical bonds, in which the bond lengths of the ZZ7-V2Se substrate show a very small deviation. Under the acetone and acetonitrile adsorptions, the ferromagnetic semi-metallic DOSs of the ZZ7-V2Se become the ferromagnetic half-metallic DOSs for the ZZ7-V2Se-acetone-8 and the ferromagnetic semiconducting DOSs for the ZZ7-V2Se-acetonitrile-11. Our systematic results can provide a complete understanding of the acetone- and acetonitrile adsorptions on the potential ZZ7-V2Se structure, which is very useful for nanosensor application.
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Affiliation(s)
- Nguyen Thanh Tien
- College of Natural Sciences, Can Tho University 3-2 Road Can Tho City 900000 Vietnam
| | - Nguyen Hai Dang
- College of Natural Sciences, Can Tho University 3-2 Road Can Tho City 900000 Vietnam
| | - Pham Thi Bich Thao
- College of Natural Sciences, Can Tho University 3-2 Road Can Tho City 900000 Vietnam
| | - K Dien Vo
- Division of Applied Physics, Dong Nai Technology University Bien Hoa City Vietnam
- Faculty of Engineering, Dong Nai Technology University Bien Hoa City Vietnam
| | - D M Hoat
- Institute of Theoretical and Applied Research, Duy Tan University Ha Noi 100000 Vietnam
- Faculty of Natural Sciences, Duy Tan University Da Nang 550000 Vietnam
| | - Duy Khanh Nguyen
- Laboratory for Computational Physics, Institute for Computational Science and Artificial Intelligence, Van Lang University Ho Chi Minh City Vietnam
- Faculty of Mechanical - Electrical and Computer Engineering, School of Technology, Van Lang University Ho Chi Minh City Vietnam
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Rangel-Cortes E, Garcia-Islas JP, Gutierrez-Rodriguez J, Montes de Oca S, Garcia-Gonzalez JA, Nieto-Jalil JM, Miralrio A. Gas Sensing and Half-Metallic Materials Design Using Metal Embedded into S Vacancies in WS 2 Monolayers: Adsorption of NO, CO, and O 2 Molecules. Int J Mol Sci 2023; 24:15079. [PMID: 37894757 PMCID: PMC10606136 DOI: 10.3390/ijms242015079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 09/28/2023] [Accepted: 09/28/2023] [Indexed: 10/29/2023] Open
Abstract
The adsorption of CO, NO, and O2 molecules onto Cu, Ag, and Au atoms placed in the S vacancies of a WS2 monolayer was elucidated within dispersion-corrected density functional theory. The binding energies computed for embedded defects into S vacancies were 2.99 (AuS), 2.44 (AgS), 3.32 eV (CuS), 3.23 (Au2S2), 2.55 (Ag2S2), and 3.48 eV/atom (Cu2S2), respectively. The calculated diffusion energy barriers from an S vacancy to a nearby site for Cu, Ag, and Au were 2.29, 2.18, and 2.16 eV, respectively. Thus, the substitutional atoms remained firmly fixed at temperatures above 700 K. Similarly, the adsorption energies showed that nitric oxide and carbon oxide molecules exhibited stronger chemisorption than O2 molecules on any of the metal atoms (Au, Cu, or Ag) placed in the S vacancies of the WS2 monolayer. Therefore, the adsorption of O2 did not compete with NO or CO adsorption and did not displace them. The density of states showed that a WS2 monolayer modified with a Cu, Au, or Ag atom could be used to design sensing devices, based on electronic or magnetic properties, for atmospheric pollutants. More interestingly, the adsorption of CO changed only the electronic properties of the MoS2-AuS monolayer, which could be used for sensing applications. In contrast, the O2 molecule was chemisorbed more strongly than CO or NO on Au2S2, Cu2S2, or Ag2S2 placed into di-S vacancies. Thus, if the experimental system is exposed to air, the low quantities of O2 molecules present should result in the oxidation of the metallic atoms. Furthermore, the O2 molecules adsorbed on WS2-Au2S2 and WS2-CuS introduced a half-metallic behavior, making the system suitable for applications in spintronics.
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Affiliation(s)
- Eduardo Rangel-Cortes
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey 64849, N.L., Mexico; (J.P.G.-I.); (J.G.-R.); (S.M.d.O.); (J.A.G.-G.); (J.M.N.-J.)
| | | | | | | | | | | | - Alan Miralrio
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey 64849, N.L., Mexico; (J.P.G.-I.); (J.G.-R.); (S.M.d.O.); (J.A.G.-G.); (J.M.N.-J.)
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Ni P, Dieng M, Vanel JC, Florea I, Bouanis FZ, Yassar A. Liquid Shear Exfoliation of MoS 2: Preparation, Characterization, and NO 2-Sensing Properties. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2502. [PMID: 37764530 PMCID: PMC10537371 DOI: 10.3390/nano13182502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/24/2023] [Accepted: 08/31/2023] [Indexed: 09/29/2023]
Abstract
2D materials possess great potential to serve as gas-sensing materials due to their large, specific surface areas and strong surface activities. Among this family, transition metal chalcogenide materials exhibit different properties and are promising candidates for a wide range of applications, including sensors, photodetectors, energy conversion, and energy storage. Herein, a high-shear mixing method has been used to produce multilayered MoS2 nanosheet dispersions. MoS2 thin films were manufactured by vacuum-assisted filtration. The structural morphology of MoS2 was studied using ς-potential, UV-visible, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy (RS). The spectroscopic and microscopic analyses confirm the formation of a high-crystalline MoS2 thin film with good inter-sheet connectivity and relative thickness uniformity. The thickness of the MoS2 layer is measured to be approximately 250 nm, with a nanosheet size of 120 nm ± 40 nm and a number of layers between 6 and 9 layers. Moreover, the electrical characteristics clearly showed that the MoS2 thin film exhibits good conductivity and a linear I-V curve response, indicating good ohmic contact between the MoS2 film and the electrodes. As an example of applicability, we fabricated chemiresistive sensor devices with a MoS2 film as a sensing layer. The performance of the MoS2-chemiresistive sensor for NO2 was assessed by being exposed to different concentrations of NO2 (1 ppm to 10 ppm). This sensor shows a sensibility to low concentrations of 1 ppm, with a response time of 114 s and a recovery time of 420 s. The effect of thin-film thickness and operating temperatures on sensor response was studied. The results show that thinner film exhibits a higher response to NO2; the response decreases as the working temperature increases.
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Affiliation(s)
- Pingping Ni
- LPICM, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France; (P.N.); (M.D.); (J.-C.V.)
- COSYS-IMSE, University Gustave Eiffel, F-77454 Marne-la-Vallée, France
| | - Mbaye Dieng
- LPICM, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France; (P.N.); (M.D.); (J.-C.V.)
- COSYS-IMSE, University Gustave Eiffel, F-77454 Marne-la-Vallée, France
| | - Jean-Charles Vanel
- LPICM, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France; (P.N.); (M.D.); (J.-C.V.)
| | - Ileana Florea
- CRHEA, CNRS, Université Cote d’Azur, UMR7073, Rue Bernard Grégory, 06905 Sophia-Antipolis CEDEX, France;
| | - Fatima Zahra Bouanis
- LPICM, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France; (P.N.); (M.D.); (J.-C.V.)
- COSYS-IMSE, University Gustave Eiffel, F-77454 Marne-la-Vallée, France
| | - Abderrahim Yassar
- LPICM, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France; (P.N.); (M.D.); (J.-C.V.)
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5
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Gutierrez-Rodriguez J, Castro M, Nieto-Jalil JM, Medina DI, Montes de Oca S, García-González JA, Rangel-Cortes E, Miralrio A. Substitutional Coinage Metals as Promising Defects for Adsorption and Detection of Gases on MoS 2 Monolayers: A Computational Approach. Int J Mol Sci 2023; 24:10284. [PMID: 37373431 DOI: 10.3390/ijms241210284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/05/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
Defective molybdenum disulfide (MoS2) monolayers (MLs) modified with coinage metal atoms (Cu, Ag and Au) embedded in sulfur vacancies are studied at a dispersion-corrected density functional level. Atmospheric constituents (H2, O2 and N2) and air pollutants (CO and NO), known as secondary greenhouse gases, are adsorbed on up to two atoms embedded into sulfur vacancies in MoS2 MLs. The adsorption energies suggest that the NO (1.44 eV) and CO (1.24 eV) are chemisorbed more strongly than O2 (1.07 eV) and N2 (0.66 eV) on the ML with a cooper atom substituting for a sulfur atom. Therefore, the adsorption of N2 and O2 does not compete with NO or CO adsorption. Besides, NO adsorbed on embedded Cu creates a new level in the band gap. In addition, it was found that the CO molecule could directly react with the pre-adsorbed O2 molecule on a Cu atom, forming the complex OOCO, via the Eley-Rideal reaction mechanism. The adsorption energies of CO, NO and O2 on Au2S2, Cu2S2 and Ag2S2 embedded into two sulfur vacancies were competitive. Charge transference occurs from the defective MoS2 ML to the adsorbed molecules, oxidizing the later ones (NO, CO and O2) since they act as acceptors. The total and projected density of states reveal that a MoS2 ML modified with copper, gold and silver dimers could be used to design electronic or magnetic devices for sensing applications in the adsorption of NO, CO and O2 molecules. Moreover, NO and O2 molecules adsorbed on MoS2-Au2s2 and MoS2-Cu2s2 introduce a transition from metallic to half-metallic behavior for applications in spintronics. These modified monolayers are expected to exhibit chemiresistive behavior, meaning their electrical resistance changes in response to the presence of NO molecules. This property makes them suitable for detecting and measuring NO concentrations. Also, modified materials with half-metal behavior could be beneficial for spintronic devices, particularly those that require spin-polarized currents.
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Affiliation(s)
- Josue Gutierrez-Rodriguez
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey 64849, Mexico
| | - Miguel Castro
- Departamento de Física y Química Teórica, Division de Estudios de Posgrado, Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Del. Coyoacán, Ciudad de México 04510, Mexico
| | - Jose Manuel Nieto-Jalil
- Departamento de Física y Química Teórica, Division de Estudios de Posgrado, Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Del. Coyoacán, Ciudad de México 04510, Mexico
| | - Dora Iliana Medina
- Tecnologico de Monterrey, Institute of Advanced Materials for Sustainable Manufacturing, Monterrey 64849, Mexico
| | - Saul Montes de Oca
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey 64849, Mexico
| | - José Andrés García-González
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey 64849, Mexico
| | - Eduardo Rangel-Cortes
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey 64849, Mexico
| | - Alan Miralrio
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey 64849, Mexico
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Devi A, Dhiman N, Kumar N, Alfalasi W, Kumar A, Ahluwalia PK, Singh A, Tit N. Ferromagnetism in Defected TMD (MoX 2, X = S, Se) Monolayer and Its Sustainability under O 2, O 3, and H 2O Gas Exposure: DFT Study. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13101642. [PMID: 37242058 DOI: 10.3390/nano13101642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 04/28/2023] [Accepted: 04/30/2023] [Indexed: 05/28/2023]
Abstract
Spin-polarized density-functional theory (DFT) has been employed to study the effects of atmospheric gases on the electronic and magnetic properties of a defective transition-metal dichalcogenide (TMD) monolayer, MoX2 with X = S or Se. This study focuses on three single vacancies: (i) molybdenum "VMo"; (ii) chalcogenide "VX"; and (iii) di-chalcogenide "VX2". Five different samples of sizes ranging from 4 × 4 to 8 × 8 primitive cells (PCs) were considered in order to assess the effect of vacancy-vacancy interaction. The results showed that all defected samples were paramagnetic semiconductors, except in the case of VMo in MoSe2, which yielded a magnetic moment of 3.99 μB that was independent of the sample size. Moreover, the samples of MoSe2 with VMo and sizes of 4 × 4 and 5 × 5 PCs exhibited half-metallicity, where the spin-up state becomes conductive and is predominantly composed of dxy and dz2 orbital mixing attributed to Mo atoms located in the neighborhood of VMo. The requirement for the establishment of half-metallicity is confirmed to be the provision of ferromagnetic-coupling (FMC) interactions between localized magnetic moments (such as VMo). The critical distance for the existence of FMC is estimated to be dc≅ 16 Å, which allows small sample sizes in MoSe2 to exhibit half-metallicity while the FMC represents the ground state. The adsorption of atmospheric gases (H2O, O2, O3) can drastically change the electronic and magnetic properties, for instance, it can demolish the half-metallicity characteristics. Hence, the maintenance of half-metallicity requires keeping the samples isolated from the atmosphere. We benchmarked our theoretical results with the available data in the literature throughout our study. The conditions that govern the appearance/disappearance of half-metallicity are of great relevance for spintronic device applications.
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Affiliation(s)
- Anjna Devi
- Department of Physics, Himachal Pradesh University, Shimla 171005, India
- Department of Physics, Swami Vivekanand Government College, Shimla-Kangra Rd, Ghumarwin 174021, India
| | - Neha Dhiman
- Department of Physics, Swami Vivekanand Government College, Shimla-Kangra Rd, Ghumarwin 174021, India
| | - Narender Kumar
- Department of Physics, Swami Vivekanand Government College, Shimla-Kangra Rd, Ghumarwin 174021, India
- Department of Physics, College of Science, United Arab Emirates University, Al-Ain P.O. Box 15551, United Arab Emirates
- National Water and Energy Center, United Arab Emirates University, Al-Ain P.O. Box 15551, United Arab Emirates
| | - Wadha Alfalasi
- Department of Physics, College of Science, United Arab Emirates University, Al-Ain P.O. Box 15551, United Arab Emirates
- National Water and Energy Center, United Arab Emirates University, Al-Ain P.O. Box 15551, United Arab Emirates
| | - Arun Kumar
- Department of Physics, Swami Vivekanand Government College, Shimla-Kangra Rd, Ghumarwin 174021, India
| | - P K Ahluwalia
- Department of Physics, Himachal Pradesh University, Shimla 171005, India
| | - Amarjeet Singh
- Department of Physics, Himachal Pradesh University, Shimla 171005, India
| | - Nacir Tit
- Department of Physics, College of Science, United Arab Emirates University, Al-Ain P.O. Box 15551, United Arab Emirates
- National Water and Energy Center, United Arab Emirates University, Al-Ain P.O. Box 15551, United Arab Emirates
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Giri A, Park G, Jeong U. Layer-Structured Anisotropic Metal Chalcogenides: Recent Advances in Synthesis, Modulation, and Applications. Chem Rev 2023; 123:3329-3442. [PMID: 36719999 PMCID: PMC10103142 DOI: 10.1021/acs.chemrev.2c00455] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Indexed: 02/01/2023]
Abstract
The unique electronic and catalytic properties emerging from low symmetry anisotropic (1D and 2D) metal chalcogenides (MCs) have generated tremendous interest for use in next generation electronics, optoelectronics, electrochemical energy storage devices, and chemical sensing devices. Despite many proof-of-concept demonstrations so far, the full potential of anisotropic chalcogenides has yet to be investigated. This article provides a comprehensive overview of the recent progress made in the synthesis, mechanistic understanding, property modulation strategies, and applications of the anisotropic chalcogenides. It begins with an introduction to the basic crystal structures, and then the unique physical and chemical properties of 1D and 2D MCs. Controlled synthetic routes for anisotropic MC crystals are summarized with example advances in the solution-phase synthesis, vapor-phase synthesis, and exfoliation. Several important approaches to modulate dimensions, phases, compositions, defects, and heterostructures of anisotropic MCs are discussed. Recent significant advances in applications are highlighted for electronics, optoelectronic devices, catalysts, batteries, supercapacitors, sensing platforms, and thermoelectric devices. The article ends with prospects for future opportunities and challenges to be addressed in the academic research and practical engineering of anisotropic MCs.
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Affiliation(s)
- Anupam Giri
- Department
of Chemistry, Faculty of Science, University
of Allahabad, Prayagraj, UP-211002, India
| | - Gyeongbae Park
- Department
of Materials Science and Engineering, Pohang
University of Science and Technology, Cheongam-Ro 77, Nam-Gu, Pohang, Gyeongbuk790-784, Korea
- Functional
Materials and Components R&D Group, Korea Institute of Industrial Technology, Gwahakdanji-ro 137-41, Sacheon-myeon, Gangneung, Gangwon-do25440, Republic of Korea
| | - Unyong Jeong
- Department
of Materials Science and Engineering, Pohang
University of Science and Technology, Cheongam-Ro 77, Nam-Gu, Pohang, Gyeongbuk790-784, Korea
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Filipovic L, Selberherr S. Application of Two-Dimensional Materials towards CMOS-Integrated Gas Sensors. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:nano12203651. [PMID: 36296844 PMCID: PMC9611560 DOI: 10.3390/nano12203651] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/29/2022] [Accepted: 10/07/2022] [Indexed: 06/01/2023]
Abstract
During the last few decades, the microelectronics industry has actively been investigating the potential for the functional integration of semiconductor-based devices beyond digital logic and memory, which includes RF and analog circuits, biochips, and sensors, on the same chip. In the case of gas sensor integration, it is necessary that future devices can be manufactured using a fabrication technology which is also compatible with the processes applied to digital logic transistors. This will likely involve adopting the mature complementary metal oxide semiconductor (CMOS) fabrication technique or a technique which is compatible with CMOS due to the inherent low costs, scalability, and potential for mass production that this technology provides. While chemiresistive semiconductor metal oxide (SMO) gas sensors have been the principal semiconductor-based gas sensor technology investigated in the past, resulting in their eventual commercialization, they need high-temperature operation to provide sufficient energies for the surface chemical reactions essential for the molecular detection of gases in the ambient. Therefore, the integration of a microheater in a MEMS structure is a requirement, which can be quite complex. This is, therefore, undesirable and room temperature, or at least near-room temperature, solutions are readily being investigated and sought after. Room-temperature SMO operation has been achieved using UV illumination, but this further complicates CMOS integration. Recent studies suggest that two-dimensional (2D) materials may offer a solution to this problem since they have a high likelihood for integration with sophisticated CMOS fabrication while also providing a high sensitivity towards a plethora of gases of interest, even at room temperature. This review discusses many types of promising 2D materials which show high potential for integration as channel materials for digital logic field effect transistors (FETs) as well as chemiresistive and FET-based sensing films, due to the presence of a sufficiently wide band gap. This excludes graphene from this review, while recent achievements in gas sensing with graphene oxide, reduced graphene oxide, transition metal dichalcogenides (TMDs), phosphorene, and MXenes are examined.
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Garcia-Esparza AT, Park S, Abroshan H, Paredes Mellone OA, Vinson J, Abraham B, Kim TR, Nordlund D, Gallo A, Alonso-Mori R, Zheng X, Sokaras D. Local Structure of Sulfur Vacancies on the Basal Plane of Monolayer MoS 2. ACS NANO 2022; 16:6725-6733. [PMID: 35380038 DOI: 10.1021/acsnano.2c01388] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The nature of the S-vacancy is central to controlling the electronic properties of monolayer MoS2. Understanding the geometric and electronic structures of the S-vacancy on the basal plane of monolayer MoS2 remains elusive. Here, operando S K-edge X-ray absorption spectroscopy shows the formation of clustered S-vacancies on the basal plane of monolayer MoS2 under reaction conditions (H2 atmosphere, 100-600 °C). First-principles calculations predict spectral fingerprints consistent with the experimental results. The Mo K-edge extended X-ray absorption fine structure shows the local structure as coordinatively unsaturated Mo with 4.1 ± 0.4 S atoms as nearest neighbors (above 400 °C in an H2 atmosphere). Conversely, the 6-fold Mo-Mo coordination in the crystal remains unchanged. Electrochemistry confirms similar active sites for hydrogen evolution. The identity of the S-vacancy defect on the basal plane of monolayer MoS2 is herein elucidated for applications in optoelectronics and catalysis.
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Affiliation(s)
- Angel T Garcia-Esparza
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, United States
| | - Sangwook Park
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, United States
| | - Hadi Abroshan
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Oscar A Paredes Mellone
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - John Vinson
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Baxter Abraham
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Taeho R Kim
- Stanford Nano Shared Facilities, Stanford University, Stanford, California 94305, United States
| | - Dennis Nordlund
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Alessandro Gallo
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Xiaolin Zheng
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, United States
| | - Dimosthenis Sokaras
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
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10
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Di Bernardo I, Blyth J, Watson L, Xing K, Chen YH, Chen SY, Edmonds MT, Fuhrer MS. Defects, band bending and ionization rings in MoS 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:174002. [PMID: 35081526 DOI: 10.1088/1361-648x/ac4f1d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Chalcogen vacancies in transition metal dichalcogenides are widely acknowledged as both donor dopants and as a source of disorder. The electronic structure of sulphur vacancies in MoS2however is still controversial, with discrepancies in the literature pertaining to the origin of the in-gap features observed via scanning tunneling spectroscopy (STS) on single sulphur vacancies. Here we use a combination of scanning tunnelling microscopy and STS to study embedded sulphur vacancies in bulk MoS2crystals. We observe spectroscopic features dispersing in real space and in energy, which we interpret as tip position- and bias-dependent ionization of the sulphur vacancy donor due to tip induced band bending. The observations indicate that care must be taken in interpreting defect spectra as reflecting in-gap density of states, and may explain discrepancies in the literature.
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Affiliation(s)
- Iolanda Di Bernardo
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - James Blyth
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Liam Watson
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Kaijian Xing
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Yi-Hsun Chen
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Shao-Yu Chen
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Mark T Edmonds
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
- Monash Centre for Atomically Thin Materials, Monash University, Clayton, 3800, VIC, Australia
| | - Michael S Fuhrer
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
- Monash Centre for Atomically Thin Materials, Monash University, Clayton, 3800, VIC, Australia
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11
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Bao H, Miao Y, Ma F. Effect of point defects and nanopores on the fracture behaviors in single-layer MoS2 nanosheets. NANO EXPRESS 2021. [DOI: 10.1088/2632-959x/ac3635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Abstract
Point defects and nanopores are inevitable and particularly noticeable in single-layer (SL) MoS2. Molecular dynamics (MD) simulations have been done to comprehensively study the influences of point defects and nanopores on tensile deformation behaviors of SLMoS2 nanosheets, and the dependences of fracture properties on defect type and concentration, pore size, temperature and strain rate are discussed. The formation energy of S vacancy (VS) is the lowest one, but that of VMoS6 is the highest one, corresponding to the highest and lowest fracture stress, respectively. The local stress concentration around point defects and nanopores might lead to the early bond breaking and subsequent nucleation of cracks and brittle fracture upon tensile loading. A modified Griffith criterion is proposed to describe the defect concentration and pore size dependent fracture stress and strain. These findings provide us an important guideline for the structural design of 2D materials in future applications.
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12
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Qiu X, Wang Y, Jiang Y. Dopants and grain boundary effects in monolayer MoS 2: a first-principles study. Phys Chem Chem Phys 2021; 23:11937-11943. [PMID: 33999067 DOI: 10.1039/d1cp00156f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The structural, electronic and magnetic properties of large area chemical vapor deposited monolayer MoS2 rely significantly on the presence of grain boundaries (GBs) and defects. In this study, first-principles calculations were performed to investigate the electronic and magnetic properties of transition metal doped MoS2 GBs. The experimentally observed 60° tilt GBs were demonstrated with four different atomic configurations and the nonmagnetic 4|8ud GB has the lowest formation energy among the considered models. Further calculations of 4|8ud GBs doped with TMs, such as V, Cr, Mn, Fe, Co and Ni, indicate that dopants can significantly lower the formation energies of the doped GBs compared to the perfect monolayer MoS2 by occupying the GB region instead of within the grains. Magnetism can be achieved in doped GB systems by careful defect engineering. CoMo, MnMo and Niint in 4|8ud GBs are predicted to be magnetic and simultaneously energetically favorable. The electron coupling between the doped TM and surrounding GB atoms is expected to induce magnetism and high electron mobilities into the systems. This study may pave the way for optimal design of MoS2-based electronic and spintronic devices.
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Affiliation(s)
- Xiaoqian Qiu
- Key Laboratory for Nonferrous Metal Materials Science and Engineering (MOE), School of Materials Science and Engineering, Central South University, Changsha, 410083, China
| | - Yiren Wang
- Key Laboratory for Nonferrous Metal Materials Science and Engineering (MOE), School of Materials Science and Engineering, Central South University, Changsha, 410083, China
| | - Yong Jiang
- Key Laboratory for Nonferrous Metal Materials Science and Engineering (MOE), School of Materials Science and Engineering, Central South University, Changsha, 410083, China
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13
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Bertoldo F, Unocic RR, Lin YC, Sang X, Puretzky AA, Yu Y, Miakota D, Rouleau CM, Schou J, Thygesen KS, Geohegan DB, Canulescu S. Intrinsic Defects in MoS 2 Grown by Pulsed Laser Deposition: From Monolayers to Bilayers. ACS NANO 2021; 15:2858-2868. [PMID: 33576605 DOI: 10.1021/acsnano.0c08835] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pulsed laser deposition (PLD) can be considered a powerful method for the growth of two-dimensional (2D) transition-metal dichalcogenides (TMDs) into van der Waals heterostructures. However, despite significant progress, the defects in 2D TMDs grown by PLD remain largely unknown and yet to be explored. Here, we combine atomic resolution images and first-principles calculations to reveal the atomic structure of defects, grains, and grain boundaries in mono- and bilayer MoS2 grown by PLD. We find that sulfur vacancies and MoS antisites are the predominant point defects in 2D MoS2. We predict that the aforementioned point defects are thermodynamically favorable under a Mo-rich/S-poor environment. The MoS2 monolayers are polycrystalline and feature nanometer size grains connected by a high density of grain boundaries. In particular, the coalescence of nanometer grains results in the formation of 180° mirror twin boundaries consisting of distinct 4- and 8-membered rings. We show that PLD synthesis of bilayer MoS2 results in various structural symmetries, including AA' and AB, but also turbostratic with characteristic moiré patterns. Moreover, we report on the experimental demonstration of an electron beam-driven transition between the AB and AA' stacking orientations in bilayer MoS2. These results provide a detailed insight into the atomic structure of monolayer MoS2 and the role of the grain boundaries on the growth of bilayer MoS2, which has importance for future applications in optoelectronics.
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Affiliation(s)
- Fabian Bertoldo
- CAMD and Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Raymond R Unocic
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yu-Chuan Lin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Xiahan Sang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 Wuhan, China
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yiling Yu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Denys Miakota
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
| | - Christopher M Rouleau
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jørgen Schou
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
| | - Kristian S Thygesen
- CAMD and Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - David B Geohegan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Stela Canulescu
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
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14
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Hus SM, Ge R, Chen PA, Liang L, Donnelly GE, Ko W, Huang F, Chiang MH, Li AP, Akinwande D. Observation of single-defect memristor in an MoS 2 atomic sheet. NATURE NANOTECHNOLOGY 2021; 16:58-62. [PMID: 33169008 DOI: 10.1038/s41565-020-00789-w] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 10/01/2020] [Indexed: 05/23/2023]
Abstract
Non-volatile resistive switching, also known as memristor1 effect, where an electric field switches the resistance states of a two-terminal device, has emerged as an important concept in the development of high-density information storage, computing and reconfigurable systems2-9. The past decade has witnessed substantial advances in non-volatile resistive switching materials such as metal oxides and solid electrolytes. It was long believed that leakage currents would prevent the observation of this phenomenon for nanometre-thin insulating layers. However, the recent discovery of non-volatile resistive switching in two-dimensional monolayers of transition metal dichalcogenide10,11 and hexagonal boron nitride12 sandwich structures (also known as atomristors) has refuted this belief and added a new materials dimension owing to the benefits of size scaling10,13. Here we elucidate the origin of the switching mechanism in atomic sheets using monolayer MoS2 as a model system. Atomistic imaging and spectroscopy reveal that metal substitution into a sulfur vacancy results in a non-volatile change in the resistance, which is corroborated by computational studies of defect structures and electronic states. These findings provide an atomistic understanding of non-volatile switching and open a new direction in precision defect engineering, down to a single defect, towards achieving the smallest memristor for applications in ultra-dense memory, neuromorphic computing and radio-frequency communication systems2,3,11.
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Affiliation(s)
- Saban M Hus
- Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Ruijing Ge
- Texas Materials Institute, The University of Texas at Austin, Austin, TX, USA
| | - Po-An Chen
- Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Liangbo Liang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Gavin E Donnelly
- School of Mathematics and Physics, Queen's University Belfast, Belfast, UK
| | - Wonhee Ko
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Fumin Huang
- School of Mathematics and Physics, Queen's University Belfast, Belfast, UK
| | - Meng-Hsueh Chiang
- Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - An-Ping Li
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Deji Akinwande
- Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, USA.
- Texas Materials Institute, The University of Texas at Austin, Austin, TX, USA.
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15
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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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16
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Mallet P, Chiapello F, Okuno H, Boukari H, Jamet M, Veuillen JY. Bound Hole States Associated to Individual Vanadium Atoms Incorporated into Monolayer WSe_{2}. PHYSICAL REVIEW LETTERS 2020; 125:036802. [PMID: 32745415 DOI: 10.1103/physrevlett.125.036802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
Doping a two-dimensional semiconductor with magnetic atoms is a possible route to induce magnetism in the material. We report on the atomic structure and electronic properties of monolayer WSe_{2} intentionally doped with vanadium atoms by means of scanning transmission electron microscopy and scanning tunneling microscopy and spectroscopy. Most of the V atoms incorporate at W sites. These V_{W} dopants are negatively charged, which induces a localized bound state located 140 meV above the valence band maximum. The overlap of the electronic potential of two charged V_{W} dopants generates additional in-gap states. Eventually, the negative charge may suppress the magnetic moment on the V_{W} dopants.
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Affiliation(s)
- Pierre Mallet
- Université Grenoble Alpes, Institut Neel, F-38042 Grenoble, France
- CNRS, Institut Neel, F-38042 Grenoble, France
| | - Florian Chiapello
- Université Grenoble Alpes, Institut Neel, F-38042 Grenoble, France
- CNRS, Institut Neel, F-38042 Grenoble, France
| | - Hanako Okuno
- Université Grenoble Alpes, CEA, IRIG-MEM, 38000 Grenoble, France
| | - Hervé Boukari
- Université Grenoble Alpes, Institut Neel, F-38042 Grenoble, France
- CNRS, Institut Neel, F-38042 Grenoble, France
| | - Matthieu Jamet
- Université Grenoble Alpes, CEA, CNRS, Grenoble INP, IRIG-SPINTEC, 38000 Grenoble, France
| | - Jean-Yves Veuillen
- Université Grenoble Alpes, Institut Neel, F-38042 Grenoble, France
- CNRS, Institut Neel, F-38042 Grenoble, France
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17
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Mitterreiter E, Schuler B, Cochrane KA, Wurstbauer U, Weber-Bargioni A, Kastl C, Holleitner AW. Atomistic Positioning of Defects in Helium Ion Treated Single-Layer MoS 2. NANO LETTERS 2020; 20:4437-4444. [PMID: 32368920 DOI: 10.1021/acs.nanolett.0c01222] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Structuring materials with atomic precision is the ultimate goal of nanotechnology and is becoming increasingly relevant as an enabling technology for quantum electronics/spintronics and quantum photonics. Here, we create atomic defects in monolayer MoS2 by helium ion (He-ion) beam lithography with a spatial fidelity approaching the single-atom limit in all three dimensions. Using low-temperature scanning tunneling microscopy (STM), we confirm the formation of individual point defects in MoS2 upon He-ion bombardment and show that defects are generated within 9 nm of the incident helium ions. Atom-specific sputtering yields are determined by analyzing the type and occurrence of defects observed in high-resolution STM images and compared with Monte Carlo simulations. Both theory and experiment indicate that the He-ion bombardment predominantly generates sulfur vacancies.
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Affiliation(s)
- Elmar Mitterreiter
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
| | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Katherine A Cochrane
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Ursula Wurstbauer
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Institute of Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str.10, 48149 Münster, Germany
| | - Alexander Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Christoph Kastl
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
| | - Alexander W Holleitner
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 München, Germany
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18
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McCreary KM, Cobas ED, Hanbicki AT, Rosenberger MR, Chuang HJ, Sivaram SV, Oleshko VP, Jonker BT. Synthesis of High-Quality Monolayer MoS 2 by Direct Liquid Injection. ACS APPLIED MATERIALS & INTERFACES 2020; 12:9580-9588. [PMID: 31999089 DOI: 10.1021/acsami.9b19561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report the synthesis of high-quality single monolayer MoS2 samples using a novel technique that utilizes direct liquid injection (DLI) for the delivery of precursors. The DLI system vaporizes a liquid consisting of a selected precursor dissolved in a solvent into small, micron-sized droplets in an expansion chamber maintained at a selected temperature and pressure, before delivery to the deposition chamber. We demonstrate the synthesis of monolayer MoS2 on SiO2/Si substrates using the DLI technique with film quality superior to exfoliated samples or those grown by traditional tube furnace chemical vapor deposition (CVD) methods. Photoluminescence measurements of DLI monolayers exhibit consistently brighter emission, narrower line width, and higher emission energy than their exfoliated and CVD counterparts. Conductive atomic force microscopy identifies a defect density of 8.3 × 1011/cm2 in DLI MoS2, lower than the measured density in CVD material and nearly an order of magnitude improvement over the exfoliated MoS2 investigated under the same conditions. The DLI method is directly applicable to many other van der Waals materials, which require the use of challenging low vapor pressure precursors, to the growth of alloys, and sequential growths of dissimilar materials leading to van der Waals heterostructures.
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Affiliation(s)
- Kathleen M McCreary
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
| | - Enrique D Cobas
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
| | - Aubrey T Hanbicki
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
| | - Matthew R Rosenberger
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
| | - Hsun-Jen Chuang
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
| | - Saujan V Sivaram
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
| | - Vladimir P Oleshko
- Material Science and Engineering Division, Material Measurement Laboratory , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Berend T Jonker
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
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19
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Zhu B, Lang J, Hu YH. S-Vacancy induced indirect-to-direct band gap transition in multilayer MoS2. Phys Chem Chem Phys 2020; 22:26005-26014. [DOI: 10.1039/d0cp04201c] [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
Two-dimensional (2D) MoS2 has a tunable band structure.
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Affiliation(s)
- Bingyu Zhu
- School of Environmental Science and Engineering
- Shanghai Jiao Tong University
- Shanghai 200240
- P. R. China
| | - Junyu Lang
- School of Environmental Science and Engineering
- Shanghai Jiao Tong University
- Shanghai 200240
- P. R. China
| | - Yun Hang Hu
- School of Environmental Science and Engineering
- Shanghai Jiao Tong University
- Shanghai 200240
- P. R. China
- Department of Materials Science and Engineering
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20
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Wei W, Huang B, Dai Y. Photoexcited charge carrier behaviors in solar energy conversion systems from theoretical simulations. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2019. [DOI: 10.1002/wcms.1441] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Wei Wei
- School of Physics, State Key Laboratory of Crystal Materials Shandong University Jinan China
| | - Baibiao Huang
- School of Physics, State Key Laboratory of Crystal Materials Shandong University Jinan China
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials Shandong University Jinan China
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21
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Zheng YJ, Chen Y, Huang YL, Gogoi PK, Li MY, Li LJ, Trevisanutto PE, Wang Q, Pennycook SJ, Wee ATS, Quek SY. Point Defects and Localized Excitons in 2D WSe 2. ACS NANO 2019; 13:6050-6059. [PMID: 31074961 DOI: 10.1021/acsnano.9b02316] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Identifying the point defects in 2D materials is important for many applications. Recent studies have proposed that W vacancies are the predominant point defect in 2D WSe2, in contrast to theoretical studies, which predict that chalcogen vacancies are the most likely intrinsic point defects in transition metal dichalcogenide semiconductors. We show using first-principles calculations, scanning tunneling microscopy (STM), and scanning transmission electron microscopy experiments that W vacancies are not present in our CVD-grown 2D WSe2. We predict that O-passivated Se vacancies (OSe) and O interstitials (Oins) are present in 2D WSe2, because of facile O2 dissociation at Se vacancies or due to the presence of WO3 precursors in CVD growth. These defects give STM images in good agreement with experiment. The optical properties of point defects in 2D WSe2 are important because single-photon emission (SPE) from 2D WSe2 has been observed experimentally. While strain gradients funnel the exciton in real space, point defects are necessary for the localization of the exciton at length scales that enable photons to be emitted one at a time. Using state-of-the-art GW-Bethe-Salpeter-equation calculations, we predict that only Oins defects give localized excitons within the energy range of SPE in previous experiments, making them a likely source of previously observed SPE. No other point defects (OSe, Se vacancies, W vacancies, and SeW antisites) give localized excitons in the same energy range. Our predictions suggest ways to realize SPE in related 2D materials and point experimentalists toward other energy ranges for SPE in 2D WSe2.
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Affiliation(s)
- Yu Jie Zheng
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 , Singapore
- Centre for Advanced 2D Materials , National University of Singapore , Block S14, Level 6, 6 Science Drive 2 , 117546 , Singapore
| | - Yifeng Chen
- Centre for Advanced 2D Materials , National University of Singapore , Block S14, Level 6, 6 Science Drive 2 , 117546 , Singapore
| | - Yu Li Huang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 , Singapore
- Institute of Materials Research & Engineering (IMRE) , A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way , Innovis , 138634 , Singapore
| | - Pranjal Kumar Gogoi
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 , Singapore
| | - Ming-Yang Li
- Physical Sciences and Engineering , King Abdullah University of Science and Technology , Thuwal , 23955-6900 , Saudi Arabia
| | - Lain-Jong Li
- Physical Sciences and Engineering , King Abdullah University of Science and Technology , Thuwal , 23955-6900 , Saudi Arabia
| | - Paolo E Trevisanutto
- Centre for Advanced 2D Materials , National University of Singapore , Block S14, Level 6, 6 Science Drive 2 , 117546 , Singapore
| | - Qixing Wang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 , Singapore
| | - Stephen J Pennycook
- Department of Materials Science & Engineering , National University of Singapore , 9 Engineering Drive 1 , 117575 , Singapore
| | - Andrew T S Wee
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 , Singapore
- Centre for Advanced 2D Materials , National University of Singapore , Block S14, Level 6, 6 Science Drive 2 , 117546 , Singapore
| | - Su Ying Quek
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 , Singapore
- Centre for Advanced 2D Materials , National University of Singapore , Block S14, Level 6, 6 Science Drive 2 , 117546 , Singapore
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22
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Dong J, Zhang L, Ding F. Kinetics of Graphene and 2D Materials Growth. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1801583. [PMID: 30318816 DOI: 10.1002/adma.201801583] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 07/06/2018] [Indexed: 06/08/2023]
Abstract
During the last 10 years, remarkable achievements on the chemical vapor deposition (CVD) growth of 2D materials have been made, but the understanding of the underlying mechanisms is still relatively limited. Here, the current progress on the understanding of the growth kinetics of 2D materials, especially for their CVD synthesis, is reviewed. In order to present a complete picture of 2D materials' growth kinetics, the following factors are discussed: i) two types of growth modes, namely attachment-limited growth and diffusion-limited growth; ii) the etching of 2D materials, which offers an additional degree of freedom for growth control; iii) a number of experimental factors in graphene CVD synthesis, such as structure of the substrate, pressure of hydrogen or oxygen, temperature, etc., which are found to have profound effects on the growth kinetics; iv) double-layer and few-layer 2D materials' growth, which has distinct features different from the growth of single-layer 2D materials; and v) the growth of polycrystalline 2D materials by the coalescence of a few single crystalline domains. Finally, the current challenges and opportunities in future 2D materials' synthesis are summarized.
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Affiliation(s)
- Jichen Dong
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea
| | - Leining Zhang
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Feng Ding
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
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23
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Zhang C, Wang C, Yang F, Huang JK, Li LJ, Yao W, Ji W, Shih CK. Engineering Point-Defect States in Monolayer WSe 2. ACS NANO 2019; 13:1595-1602. [PMID: 30689361 DOI: 10.1021/acsnano.8b07595] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Defect engineering is a key approach for tailoring the properties of the emerging two-dimensional semiconductors. Here, we report an atomic engineering of the W vacancy in monolayer WSe2 by single potassium atom decoration. The K decoration alters the energy states and reshapes the wave function such that previously hidden midgap states become visible with well-resolved multiplets in scanning tunneling spectroscopy. Their energy levels are in good agreement with first-principle calculations. More interestingly, the calculations show that an unpaired electron donated by the K atom can lead to a local magnetic moment, exhibiting an on-off switching by the odd-even number of electron filling. Experimentally the Fermi level is pinned above all defect states due to the graphite substrate, corresponding to an off state. The close agreement between theory and experiment in the off state, on the other hand, suggests the possibility of gate-programmable magnetic moments at the defects.
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Affiliation(s)
- Chendong Zhang
- School of Physics and Technology , Wuhan University , Wuhan 430072 , China
- Department of Physics , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Cong Wang
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices , Renmin University of China , Beijing 100872 , China
| | - Feng Yang
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices , Renmin University of China , Beijing 100872 , China
| | - Jing-Kai Huang
- Physical Sciences and Engineering Division , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Lain-Jong Li
- Physical Sciences and Engineering Division , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Wang Yao
- Department of Physics and Center of Theoretical and Computational Physics , University of Hong Kong , Hong Kong , China
| | - Wei Ji
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices , Renmin University of China , Beijing 100872 , China
| | - Chih-Kang Shih
- Department of Physics , University of Texas at Austin , Austin , Texas 78712 , United States
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24
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Li L, Long R, Prezhdo OV. Why Chemical Vapor Deposition Grown MoS 2 Samples Outperform Physical Vapor Deposition Samples: Time-Domain ab Initio Analysis. NANO LETTERS 2018; 18:4008-4014. [PMID: 29772904 DOI: 10.1021/acs.nanolett.8b01501] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Two-dimensional transition metal dichalcogenides (TMDs) have drawn strong attention due to their unique properties and diverse applications. However, TMD performance depends strongly on material quality and defect morphology. Experiments show that samples grown by chemical vapor deposition (CVD) outperform those obtained by physical vapor deposition (PVD). Experiments also show that CVD samples exhibit vacancy defects, while antisite defects are frequently observed in PVD samples. Our time-domain ab initio study demonstrates that both antisites and vacancies accelerate trapping and nonradiative recombination of charge carriers, but antisites are much more detrimental than vacancies. Antisites create deep traps for both electrons and holes, reducing energy gaps for recombination, while vacancies trap primarily holes. Antisites also perturb band-edge states, creating significant overlap with the trap states. In comparison, vacancy defects overlap much less with the band-edge states. Finally, antisites can create pairs of electron and hole traps close to the Fermi energy, allowing trapping by thermal activation from the ground state and strongly contributing to charge scattering. As a result, antisites accelerate charge recombination by more than a factor of 8, while vacancies enhance the recombination by less than a factor of 2. Our simulations demonstrate a general principle that missing atoms are significantly more benign than misplaced atoms, such as antisites and adatoms. The study rationalizes the existing experimental data, provides theoretical insights into the diverse behavior of different classes of defects, and generates guidelines for defect engineering to achieve high-performance electronic, optoelectronic, and solar-cell devices.
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Affiliation(s)
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , PR China
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25
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Lin YC, Jariwala B, Bersch BM, Xu K, Nie Y, Wang B, Eichfeld SM, Zhang X, Choudhury TH, Pan Y, Addou R, Smyth CM, Li J, Zhang K, Haque MA, Fölsch S, Feenstra RM, Wallace RM, Cho K, Fullerton-Shirey SK, Redwing JM, Robinson JA. Realizing Large-Scale, Electronic-Grade Two-Dimensional Semiconductors. ACS NANO 2018; 12:965-975. [PMID: 29360349 DOI: 10.1021/acsnano.7b07059] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Atomically thin transition metal dichalcogenides (TMDs) are of interest for next-generation electronics and optoelectronics. Here, we demonstrate device-ready synthetic tungsten diselenide (WSe2) via metal-organic chemical vapor deposition and provide key insights into the phenomena that control the properties of large-area, epitaxial TMDs. When epitaxy is achieved, the sapphire surface reconstructs, leading to strong 2D/3D (i.e., TMD/substrate) interactions that impact carrier transport. Furthermore, we demonstrate that substrate step edges are a major source of carrier doping and scattering. Even with 2D/3D coupling, transistors utilizing transfer-free epitaxial WSe2/sapphire exhibit ambipolar behavior with excellent on/off ratios (∼107), high current density (1-10 μA·μm-1), and good field-effect transistor mobility (∼30 cm2·V-1·s-1) at room temperature. This work establishes that realization of electronic-grade epitaxial TMDs must consider the impact of the TMD precursors, substrate, and the 2D/3D interface as leading factors in electronic performance.
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Affiliation(s)
- Yu-Chuan Lin
- Department of Materials Science and Engineering, Materials Research Institute, and Center for 2D and Layered Materials (2DLM), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Bhakti Jariwala
- Department of Materials Science and Engineering, Materials Research Institute, and Center for 2D and Layered Materials (2DLM), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Brian M Bersch
- Department of Materials Science and Engineering, Materials Research Institute, and Center for 2D and Layered Materials (2DLM), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Ke Xu
- Department of Chemical and Petroleum Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15213, United States
| | - Yifan Nie
- Department of Materials Science and Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Baoming Wang
- Department of Mechanical Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Sarah M Eichfeld
- Department of Materials Science and Engineering, Materials Research Institute, and Center for 2D and Layered Materials (2DLM), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Xiaotian Zhang
- Department of Materials Science and Engineering, Materials Research Institute, and Center for 2D and Layered Materials (2DLM), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Tanushree H Choudhury
- Two-Dimensional Crystal Consortium (2DCC), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Yi Pan
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, Berlin 10117, Germany
| | - Rafik Addou
- Department of Materials Science and Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Christopher M Smyth
- Department of Materials Science and Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Jun Li
- Department of Physics, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Kehao Zhang
- Department of Materials Science and Engineering, Materials Research Institute, and Center for 2D and Layered Materials (2DLM), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - M Aman Haque
- Department of Mechanical Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Stefan Fölsch
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, Berlin 10117, Germany
| | - Randall M Feenstra
- Department of Physics, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Robert M Wallace
- Department of Materials Science and Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Kyeongjae Cho
- Department of Materials Science and Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Susan K Fullerton-Shirey
- Department of Chemical and Petroleum Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15213, United States
- Department of Electrical and Computer Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15213, United States
| | - Joan M Redwing
- Department of Materials Science and Engineering, Materials Research Institute, and Center for 2D and Layered Materials (2DLM), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
- Two-Dimensional Crystal Consortium (2DCC), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Joshua A Robinson
- Department of Materials Science and Engineering, Materials Research Institute, and Center for 2D and Layered Materials (2DLM), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
- Two-Dimensional Crystal Consortium (2DCC), The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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26
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Ju W, Li T, Su X, Li H, Li X, Ma D. Au cluster adsorption on perfect and defective MoS 2 monolayers: structural and electronic properties. Phys Chem Chem Phys 2018; 19:20735-20748. [PMID: 28740994 DOI: 10.1039/c7cp03062b] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The adsorption of Aun (n = 1-4) clusters on perfect and defective MoS2 monolayers is studied using density functional theory. For the pristine MoS2 monolayer, our results show that the electrons are transferred from the support to the adsorbed Au clusters, thus a p-doping effect is achieved in the pristine MoS2 monolayer by the Au cluster adsorption, which is in good agreement with the experimental findings. The adsorption of Au clusters can introduce mid-gap states, which modify the electronic and magnetic properties of the systems. The adsorbates containing an odd number of Au atoms can introduce a spin magnetic moment of 1 μB into the perfect MoS2 monolayer, while those systems containing an even number of Au atoms are spin-unpolarized. Two categories of defects, i.e., a single S vacancy and Mo antisite defect with one Mo atom replacing one S atom, are considered for the defective monolayer MoS2. Compared with the pristine MoS2 monolayer, the adsorption energies for Au clusters are significantly increased for the MoS2 monolayer with a single S vacancy, and there are more electrons transferred from the MoS2 monolayer with an S vacancy to the Au clusters. The mid-gap states and odd-even oscillation magnetic behavior can also be observed when Au clusters are adsorbed on the MoS2 monolayer with an S vacancy. For those systems of Au clusters on MoS2 monolayers with Mo antisite defects, the adsorption energies as well as the magnitude and the direction of transferred charge are similar to those for the MoS2 monolayer with an S vacancy. The spin-polarizations appear in all systems with Mo antisite defects. Our investigations suggest that the electronic and magnetic properties of MoS2 nanosheets can be effectively modulated by the adsorption of Au clusters.
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Affiliation(s)
- Weiwei Ju
- College of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China
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27
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Li L, Long R, Bertolini T, Prezhdo OV. Sulfur Adatom and Vacancy Accelerate Charge Recombination in MoS 2 but by Different Mechanisms: Time-Domain Ab Initio Analysis. NANO LETTERS 2017; 17:7962-7967. [PMID: 29172545 DOI: 10.1021/acs.nanolett.7b04374] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Two-dimensional transition metal dichalcogenides (TMDs) have appeared on the horizon of materials science and solid-state physics due to their unique properties and diverse applications. TMD performance depends strongly on material quality and defect morphology. Calculations predict that sulfur adatom and vacancy are among the most energetically favorable defects in MoS2 with vacancies frequently observed during chemical vapor deposition. By performing ab initio quantum dynamics calculations we demonstrate that both adatom and vacancy accelerate nonradiative charge carrier recombination but this happens through different mechanisms. Surprisingly, holes never significantly populate the shallow trap state created by the sulfur adatom because the trap is strongly localized and decoupled from free charges. Charge recombination bypasses the hole trap. Instead, it occurs directly between free electron and hole. The recombination is faster than in pristine MoS2 because the adatom strongly perturbs the MoS2 layer, breaks its symmetry, and allows more phonon modes to couple to the electronic subsystem. In contrast, the sulfur vacancy accelerates charge recombination by the traditional mechanism involving charge trapping, followed by recombination. This is because the hole and electron traps created by the vacancy are much less localized than the hole trap created by the adatom. Because the sulfur adatom accelerates charge recombination by a factor of 7.9, compared to 1.7 due to vacancy, sulfur adatoms should be strongly avoided. The generated insights highlight the diverse behavior of different types of defects, reveal unexpected features, and provide the mechanistic understanding of charge dynamics needed for tailoring TMD properties and building high-performance devices.
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Affiliation(s)
- Linqiu Li
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Beijing Normal University , Beijing, 100875, People's Republic of China
| | - Thomas Bertolini
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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28
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Dubey S, Lisi S, Nayak G, Herziger F, Nguyen VD, Le Quang T, Cherkez V, González C, Dappe YJ, Watanabe K, Taniguchi T, Magaud L, Mallet P, Veuillen JY, Arenal R, Marty L, Renard J, Bendiab N, Coraux J, Bouchiat V. Weakly Trapped, Charged, and Free Excitons in Single-Layer MoS 2 in the Presence of Defects, Strain, and Charged Impurities. ACS NANO 2017; 11:11206-11216. [PMID: 28992415 DOI: 10.1021/acsnano.7b05520] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Few- and single-layer MoS2 host substantial densities of defects. They are thought to influence the doping level, the crystal structure, and the binding of electron-hole pairs. We disentangle the concomitant spectroscopic expression of all three effects and identify to what extent they are intrinsic to the material or extrinsic to it, i.e., related to its local environment. We do so by using different sources of MoS2-a natural one and one prepared at high pressure and high temperature-and different substrates bringing varying amounts of charged impurities and by separating the contributions of internal strain and doping in Raman spectra. Photoluminescence unveils various optically active excitonic complexes. We discover a defect-bound state having a low binding energy of 20 meV that does not appear sensitive to strain and doping, unlike charged excitons. Conversely, the defect does not significantly dope or strain MoS2. Scanning tunneling microscopy and density functional theory simulations point to substitutional atoms, presumably individual nitrogen atoms at the sulfur site. Our work shows the way to a systematic understanding of the effect of external and internal fields on the optical properties of two-dimensional materials.
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Affiliation(s)
- Sudipta Dubey
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Simone Lisi
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Goutham Nayak
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Felix Herziger
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Van-Dung Nguyen
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Toai Le Quang
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Vladimir Cherkez
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - César González
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay , 91191 Gif-sur-Yvette Cedex, France
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autonoma de Madrid , E-28049 Madrid, Spain
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay , 91191 Gif-sur-Yvette Cedex, France
| | - Kenji Watanabe
- National Institute for Materials Science , Tsukuba, 305-0044, Japan
| | | | - Laurence Magaud
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Pierre Mallet
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Jean-Yves Veuillen
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Raul Arenal
- Laboratorio de Microscopiías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza , 50018 Zaragoza, Spain
- ARAID Foundation , 50018 Zaragoza, Spain
| | - Laëtitia Marty
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Julien Renard
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Nedjma Bendiab
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Johann Coraux
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Vincent Bouchiat
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
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29
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Bampoulis P, van Bremen R, Yao Q, Poelsema B, Zandvliet HJW, Sotthewes K. Defect Dominated Charge Transport and Fermi Level Pinning in MoS 2/Metal Contacts. ACS APPLIED MATERIALS & INTERFACES 2017; 9:19278-19286. [PMID: 28508628 PMCID: PMC5465510 DOI: 10.1021/acsami.7b02739] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/16/2017] [Indexed: 05/19/2023]
Abstract
Understanding the electronic contact between molybdenum disulfide (MoS2) and metal electrodes is vital for the realization of future MoS2-based electronic devices. Natural MoS2 has the drawback of a high density of both metal and sulfur defects and impurities. We present evidence that subsurface metal-like defects with a density of ∼1011 cm-2 induce negative ionization of the outermost S atom complex. We investigate with high-spatial-resolution surface characterization techniques the effect of these defects on the local conductance of MoS2. Using metal nanocontacts (contact area < 6 nm2), we find that subsurface metal-like defects (and not S-vacancies) drastically decrease the metal/MoS2 Schottky barrier height as compared to that in the pristine regions. The magnitude of this decrease depends on the contact metal. The decrease of the Schottky barrier height is attributed to strong Fermi level pinning at the defects. Indeed, this is demonstrated in the measured pinning factor, which is equal to ∼0.1 at defect locations and ∼0.3 at pristine regions. Our findings are in good agreement with the theoretically predicted values. These defects provide low-resistance conduction paths in MoS2-based nanodevices and will play a prominent role as the device junction contact area decreases in size.
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Affiliation(s)
- Pantelis Bampoulis
- Physics
of Interfaces and Nanomaterials and Physics of Fluids and J.M. Burgers Centre
for Fluid Mechanics, MESA+ Institute for
Nanotechnology, University of Twente,
P.O. Box 217, 7500AE Enschede, The Netherlands
- E-mail: (P.B.)
| | - Rik van Bremen
- Physics
of Interfaces and Nanomaterials and Physics of Fluids and J.M. Burgers Centre
for Fluid Mechanics, MESA+ Institute for
Nanotechnology, University of Twente,
P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Qirong Yao
- Physics
of Interfaces and Nanomaterials and Physics of Fluids and J.M. Burgers Centre
for Fluid Mechanics, MESA+ Institute for
Nanotechnology, University of Twente,
P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Bene Poelsema
- Physics
of Interfaces and Nanomaterials and Physics of Fluids and J.M. Burgers Centre
for Fluid Mechanics, MESA+ Institute for
Nanotechnology, University of Twente,
P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Harold J. W. Zandvliet
- Physics
of Interfaces and Nanomaterials and Physics of Fluids and J.M. Burgers Centre
for Fluid Mechanics, MESA+ Institute for
Nanotechnology, University of Twente,
P.O. Box 217, 7500AE Enschede, The Netherlands
| | - Kai Sotthewes
- Physics
of Interfaces and Nanomaterials and Physics of Fluids and J.M. Burgers Centre
for Fluid Mechanics, MESA+ Institute for
Nanotechnology, University of Twente,
P.O. Box 217, 7500AE Enschede, The Netherlands
- E-mail: (K.S.)
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30
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Pierucci D, Henck H, Ben Aziza Z, Naylor CH, Balan A, Rault JE, Silly MG, Dappe YJ, Bertran F, Le Fèvre P, Sirotti F, Johnson ATC, Ouerghi A. Tunable Doping in Hydrogenated Single Layered Molybdenum Disulfide. ACS NANO 2017; 11:1755-1761. [PMID: 28146631 DOI: 10.1021/acsnano.6b07661] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Structural defects in the molybdenum disulfide (MoS2) monolayer are widely known for strongly altering its properties. Therefore, a deep understanding of these structural defects and how they affect MoS2 electronic properties is of fundamental importance. Here, we report on the incorporation of atomic hydrogen in monolayered MoS2 to tune its structural defects. We demonstrate that the electronic properties of single layer MoS2 can be tuned from the intrinsic electron (n) to hole (p) doping via controlled exposure to atomic hydrogen at room temperature. Moreover, this hydrogenation process represents a viable technique to completely saturate the sulfur vacancies present in the MoS2 flakes. The successful incorporation of hydrogen in MoS2 leads to the modification of the electronic properties as evidenced by high resolution X-ray photoemission spectroscopy and density functional theory calculations. Micro-Raman spectroscopy and angle resolved photoemission spectroscopy measurements show the high quality of the hydrogenated MoS2 confirming the efficiency of our hydrogenation process. These results demonstrate that the MoS2 hydrogenation could be a significant and efficient way to achieve tunable doping of transition metal dichalcogenides (TMD) materials with non-TMD elements.
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Affiliation(s)
- Debora Pierucci
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, F91460 Marcoussis, France
| | - Hugo Henck
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, F91460 Marcoussis, France
| | - Zeineb Ben Aziza
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, F91460 Marcoussis, France
| | - Carl H Naylor
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Adrian Balan
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Julien E Rault
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Mathieu G Silly
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay , CEA Saclay, F91191 Gif-sur-Yvette Cedex, France
| | - François Bertran
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Patrick Le Fèvre
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Fausto Sirotti
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - A T Charlie Johnson
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Abdelkarim Ouerghi
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, F91460 Marcoussis, France
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31
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González C, Biel B, Dappe YJ. Adsorption of small inorganic molecules on a defective MoS2monolayer. Phys Chem Chem Phys 2017; 19:9485-9499. [DOI: 10.1039/c7cp00544j] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Different molecules physisorbed, chemisorbed or dissociated on a defective MoS2layer.
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Affiliation(s)
- César González
- Departamento de Electrónica y Tecnología de Computadores
- Campus de Fuente Nueva & CITIC
- Universidad de Granada
- E-18071 Granada
- Spain
| | - Blanca Biel
- Departamento de Electrónica y Tecnología de Computadores
- Campus de Fuente Nueva & CITIC
- Universidad de Granada
- E-18071 Granada
- Spain
| | - Yannick J. Dappe
- SPEC
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay 91191 Gif-sur-Yvette Cedex
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Addou R, Wallace RM. Surface Analysis of WSe 2 Crystals: Spatial and Electronic Variability. ACS APPLIED MATERIALS & INTERFACES 2016; 8:26400-26406. [PMID: 27599557 DOI: 10.1021/acsami.6b08847] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Layered semiconductor compounds represent alternative electronic materials beyond graphene. WSe2 is one of the two-dimensional materials with wide potential in opto- and nanoelectronics and is often used to construct novel three-dimensional architectures with new functionalities. Here, we report the topography and the electronic property of the WSe2 characterized by means of scanning tunneling microscopy and spectroscopy (STM and STS), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma mass spectrometry. The STM images reveal the presence of atomic-size imperfections and a variation in the electronic structure caused by the presence of defects and impurities below the detection limit of XPS. Both STS and photoemission reveal a spatial variation in the Fermi level position. The analysis of the core levels indicates the presence of different doping levels. The presence of a large concentration of defects and impurities has a strong impact on the electronic properties of the WSe2 surface. Our findings demonstrate that the growth of controllable and high quality two-dimensional materials at nanometer scale is one of the most challenging tasks that requires further attention.
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Affiliation(s)
- Rafik Addou
- Department of Materials Science, Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Robert M Wallace
- Department of Materials Science, Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
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