1
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Chen J, Liu L, Chen H, Xu N, Deng S. Controlled Preparation of High Quality Bubble-Free and Uniform Conducting Interfaces of Vertical van der Waals Heterostructures of Arrays. ACS APPLIED MATERIALS & INTERFACES 2024; 16:10877-10885. [PMID: 38360529 DOI: 10.1021/acsami.3c16128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Sharp and clean interfaces of van der Waals (vdW) heterostructures are highly demanded in two-dimensional (2D) materials-based devices. However, current assembly methods usually cause interfacial bubbles and wrinkles, hindering carrier interlayer transport. The preparation of a large-scale vdW heterostructure with a bubble-free interface is still a challenge. Although many efforts have been made to eliminate bubbles, the evolution processes of the interfacial bubbles are rarely studied. Here, the interface bubble formation and evolution of the transferred 2D materials and their vdW heterostructure are systemically studied by the atomic force microscopy (AFM) technique and high-resolution surface current mapping. A thermal annealing procedure is developed to reduce the number of bubbles and to improve the quality of interfaces. In addition, influences of the interface residues and nanosteps on bubble evolution are also discussed. Further, we develop the polystyrene (PS)-mediated polydimethylsiloxane (PDMS) transfer technique to realize the high-quality transfer of heterostructure arrays. Finally, high-resolution surface current mapping results confirm that we can now produce highly uniform electrical conduction interfaces of heterojunctions. This study provides guidance for assembling high quality interfaces and paves the way for production of bubble-free heterostructure-based electronic devices with high performance and good uniformity.
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Affiliation(s)
- Jianwei Chen
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Liwei Liu
- Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
| | - Huanjun Chen
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Ningsheng Xu
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Shaozhi Deng
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
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2
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de-la-Huerta-Sainz S, Ballesteros A, Cordero NA. Gaussian Curvature Effects on Graphene Quantum Dots. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:95. [PMID: 36616005 PMCID: PMC9824217 DOI: 10.3390/nano13010095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/20/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
In the last few years, much attention has been paid to the exotic properties that graphene nanostructures exhibit, especially those emerging upon deforming the material. Here we present a study of the mechanical and electronic properties of bent hexagonal graphene quantum dots employing density functional theory. We explore three different kinds of surfaces with Gaussian curvature exhibiting different shapes-spherical, cylindrical, and one-sheet hyperboloid-used to bend the material, and several boundary conditions regarding what atoms are forced to lay on the chosen surface. In each case, we study the curvature energy and two quantum regeneration times (classic and revival) for different values of the curvature radius. A strong correlation between Gaussian curvature and these regeneration times is found, and a special divergence is observed for the revival time for the hyperboloid case, probably related to the pseudo-magnetic field generated by this curvature being capable of causing a phase transition.
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Affiliation(s)
| | | | - Nicolás A. Cordero
- Physics Department, Universidad de Burgos, E-09001 Burgos, Spain
- International Research Center in Critical Raw Materials for Advanced Industrial Technologies (ICCRAM), Unversidad de Burgos, E-09001 Burgos, Spain
- Institute Carlos I for Theoretical and Computational Physics (IC1), E-18016 Granada, Spain
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3
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Yi X, Song Q, Chen Q, Zhao C, Watanabe K, Taniguchi T, Chen Q, Yan C, Wang S. Quantum transport in CVD graphene synthesized with liquid carbon precursor. NANOTECHNOLOGY 2022; 33:355601. [PMID: 35609501 DOI: 10.1088/1361-6528/ac72b1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
Large-area high-quality graphene enabled by chemical vapor deposition (CVD) can possibly pave the path for advanced flexible electronics and spintronics. CVD-grown method utilizing liquid carbon precursor has recently been demonstrated as an appealing choice for mass graphene production, thanks to its low cost and safe operation. However, the quality of the graphene film has been the major obstacle for the implementation of the liquid-precursor-based CVD method. Here we report the growth of centimeter-scale easily-transferable single-layer graphene (SLG) using acetone as a liquid carbon precursor. The dry-transfer technique was used to prepare the graphene device. The typical mobility of the dry-transferred SLG device is as high as 12 500 cm2V-1s-1at room temperature. Thanks to the high quality of the device, the robust quantum Hall effect can survive up to room temperature. The excellent device quality also enables us to observe the Shubnikov-de Haas oscillation in the low magnetic field regime and systemically study the leading scattering mechanism. We extracted both the transport scattering timeτtand the quantum scattering timeτqover a wide range of carrier density. The ratio of the scattering times suggests that the charged-impurity resided near the surface of the graphene restricted the device performance.
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Affiliation(s)
- Xin Yi
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Qiyang Song
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Qiao Chen
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Chuanwen Zhao
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Qiao Chen
- Gemmological Institute, China University of Geosciences, Wuhan 430074, People's Republic of China
| | - Chengyu Yan
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Shun Wang
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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4
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de-la-Huerta-Sainz S, Ballesteros A, Cordero NA. Quantum Revivals in Curved Graphene Nanoflakes. NANOMATERIALS 2022; 12:nano12121953. [PMID: 35745291 PMCID: PMC9230044 DOI: 10.3390/nano12121953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 06/01/2022] [Accepted: 06/03/2022] [Indexed: 12/04/2022]
Abstract
Graphene nanostructures have attracted a lot of attention in recent years due to their unconventional properties. We have employed Density Functional Theory to study the mechanical and electronic properties of curved graphene nanoflakes. We explore hexagonal flakes relaxed with different boundary conditions: (i) all atoms on a perfect spherical sector, (ii) only border atoms forced to be on the spherical sector, and (iii) only vertex atoms forced to be on the spherical sector. For each case, we have analysed the behaviour of curvature energy and of quantum regeneration times (classical and revival) as the spherical sector radius changes. Revival time presents in one case a divergence usually associated with a phase transition, probably caused by the pseudomagnetic field created by the curvature. This could be the first case of a phase transition in graphene nanostructures without the presence of external electric or magnetic fields.
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Affiliation(s)
| | - Angel Ballesteros
- Physics Department, Universidad de Burgos, E-09001 Burgos, Spain; (S.d.-l.-H.-S.); (A.B.)
| | - Nicolás A. Cordero
- Physics Department, Universidad de Burgos, E-09001 Burgos, Spain; (S.d.-l.-H.-S.); (A.B.)
- International Research Center in Critical Raw Materials for Advanced Industrial Technologies (ICCRAM), Universidad de Burgos, E-09001 Burgos, Spain
- Institute Carlos I for Theoretical and Computational Physics (IC1), E-18016 Granada, Spain
- Correspondence:
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5
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Pandey M, Kumar R. Polymer curing assisted formation of optically visible sub-micron blisters of multilayer graphene for local strain engineering. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:245401. [PMID: 35344935 DOI: 10.1088/1361-648x/ac61b4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
The local or global straining techniques are used to modulate the electronic, vibrational and optical properties of the two-dimensional (2D) materials. However, manipulating the physical properties of a 2D material under a local strain is comparatively more challenging. In this work, we demonstrate an easy and efficient polymer curing assisted technique for the formation of optically visible multilayer graphene (MLG) blisters of different shapes and sizes. The detailed spectroscopic and morphological analyses have been employed for exploring the dynamics of the confined matter inside the sub-micron blisters, which confirms that the confined matter inside the blister is liquid (water). From further analyses, we find the nonlinear elastic plate model as an acceptable model under certain limits for the mechanical analyses of the MLG blisters over the (poly)vinyl alcohol (PVA) polymer film to estimate the MLG-substrate interfacial adhesion energy and confinement pressure inside the blisters. The findings open new pathways for exploiting the technique for the formation of sub-micron blisters of the 2D materials for local strain-engineering applications, as well as the temperature-controlled release of the confined matter.
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Affiliation(s)
- Mukesh Pandey
- T-GraMS Laboratory, Department of Physics, Indian Institute of Technology Ropar, Rupnagar, Punjab - 140001, India
| | - Rakesh Kumar
- T-GraMS Laboratory, Department of Physics, Indian Institute of Technology Ropar, Rupnagar, Punjab - 140001, India
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6
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Hua X, Axenie T, Goldaraz MN, Kang K, Yang EH, Watanabe K, Taniguchi T, Hone J, Kim B, Herman IP. Improving the Optical Quality of MoSe 2 and WS 2 Monolayers with Complete h-BN Encapsulation by High-Temperature Annealing. ACS APPLIED MATERIALS & INTERFACES 2022; 14:2255-2262. [PMID: 34969239 DOI: 10.1021/acsami.1c18991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We improved the optical quality and stability of an exfoliated monolayer (ML) MoSe2 and chemical vapor deposition (CVD)-grown WS2 MLs by encapsulating and sealing them with both top and bottom few-layer h-BN, as tested by subsequent high-temperature annealing up to 873 K and photoluminescence (PL) measurements. These transition-metal dichalcogenide (TMD) MLs remained stable up to this maximum temperature, as seen visually. After the heating/cooling cycle, the integrated photoluminescence (PL) intensity at 300 K in the MoSe2 ML was ∼4 times larger than that before heating and that from exciton and trion PL in the analogous WS2 ML sample was ∼14 times and ∼2.5 times larger at 77 K and the exciton peak was ∼9.5 times larger at 300 K. This is attributed to the reduction of impurities, the lateral expulsion of contamination leading to clean and atomically flat surfaces, and the sealing provided by the h-BN layers that prevents the diffusion of molecules such as trace O2 and H2O to the TMD ML. Stability and optical performance are much improved compared to that in earlier work using top h-BN only, in which the WS2 ML PL intensity decreased even for an optimal gas environment. This complete encapsulation is particularly promising for CVD-grown TMD MLs because they have relatively more charge and other impurities than do exfoliated MLs. These results open a new route for improving the optical properties of TMD MLs and their performance and applications both at room and higher temperatures.
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Affiliation(s)
- Xiang Hua
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| | - Theodor Axenie
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| | - Mateo Navarro Goldaraz
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| | - Kyungnam Kang
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Eui-Hyeok Yang
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Bumho Kim
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Irving P Herman
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
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7
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Rosati R, Lengers F, Carmesin C, Florian M, Kuhn T, Jahnke F, Lorke M, Reiter DE. Electron Dynamics in a Two-Dimensional Nanobubble: A Two-Level System Based on Spatial Density. NANO LETTERS 2021; 21:9896-9902. [PMID: 34812637 DOI: 10.1021/acs.nanolett.1c02864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nanobubbles formed in monolayers of transition metal dichalcogenides (TMDCs) on top of a substrate feature localized potentials in which electrons can be captured. We show that the captured electronic density can exhibit a nontrivial spatiotemporal dynamics, whose movements can be mapped to states in a two-level system illustrated as points of an electronic Poincaré sphere. These states can be fully controlled, i.e, initialized and switched, by multiple electronic wave packets. Our results could be the foundation for novel implementations of quantum circuits.
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Affiliation(s)
- Roberto Rosati
- Department of Physics, Philipps-Universität Marburg, Renthof 7, D-35032 Marburg, Germany
| | - Frank Lengers
- Institut of Solid State Theory, University of Münster, 48149 Münster, Germany
| | - Christian Carmesin
- Institute for Theoretical Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany
| | - Matthias Florian
- Institute for Theoretical Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany
| | - Tilmann Kuhn
- Institut of Solid State Theory, University of Münster, 48149 Münster, Germany
| | - Frank Jahnke
- Institute for Theoretical Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany
| | - Michael Lorke
- Institute for Theoretical Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany
| | - Doris E Reiter
- Institut of Solid State Theory, University of Münster, 48149 Münster, Germany
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8
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Ben Gouider Trabelsi A, V. Kusmartsev F, Kusmartseva A, H. Alkallas F, AlFaify S, Shkir M. Raman Spectroscopy Imaging of Exceptional Electronic Properties in Epitaxial Graphene Grown on SiC. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2234. [PMID: 33187068 PMCID: PMC7696917 DOI: 10.3390/nano10112234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 11/17/2022]
Abstract
Graphene distinctive electronic and optical properties have sparked intense interest throughout the scientific community bringing innovation and progress to many sectors of academia and industry. Graphene manufacturing has rapidly evolved since its discovery in 2004. The diverse growth methods of graphene have many comparative advantages in terms of size, shape, quality and cost. Specifically, epitaxial graphene is thermally grown on a silicon carbide (SiC) substrate. This type of graphene is unique due to its coexistence with the SiC underneath which makes the process of transferring graphene layers for devices manufacturing simple and robust. Raman analysis is a sensitive technique extensively used to explore nanocarbon material properties. Indeed, this method has been widely used in graphene studies in fundamental research and application fields. We review the principal Raman scattering processes in SiC substrate and demonstrate epitaxial graphene growth. We have identified the Raman bands signature of graphene for different layers number. The method could be readily adopted to characterize structural and exceptional electrical properties for various epitaxial graphene systems. Particularly, the variation of the charge carrier concentration in epitaxial graphene of different shapes and layers number have been precisely imaged. By comparing the intensity ratio of 2D line and G line-"I2D/IG"-the density of charge across the graphene layers could be monitored. The obtained results were compared to previous electrical measurements. The substrate longitudinal optical phonon coupling "LOOPC" modes have also been examined for several epitaxial graphene layers. The LOOPC of the SiC substrate shows a precise map of the density of charge in epitaxial graphene systems for different graphene layers number. Correlations between the density of charge and particular graphene layer shape such as bubbles have been determined. All experimental probes show a high degree of consistency and efficiency. Our combined studies have revealed novel capacitor effect in diverse epitaxial graphene system. The SiC substrate self-compensates the graphene layer charge without any external doping. We have observed a new density of charge at the graphene-substrate interface. The located capacitor effects at epitaxial graphene-substrate interfaces give rise to an unexpected mini gap in graphene band structure.
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Affiliation(s)
- A. Ben Gouider Trabelsi
- Department of Physics, College of Science, Princess Nourah bint Abdulrahman University, Riyadh PO Box 84428, Saudi Arabia;
| | - F. V. Kusmartsev
- Department of Physics, Loughborough University, Loughborough LE11 3TU, UK; (F.V.K.); (A.K.)
- Micro/Nano Fabrication Laboratory, Microsystem & Terahertz Research Centre of CAEP, Chengdu, China
| | - A. Kusmartseva
- Department of Physics, Loughborough University, Loughborough LE11 3TU, UK; (F.V.K.); (A.K.)
| | - F. H. Alkallas
- Department of Physics, College of Science, Princess Nourah bint Abdulrahman University, Riyadh PO Box 84428, Saudi Arabia;
| | - S. AlFaify
- Department of Physics, Faculty of Sciences, King Khalid University, Abha PO Box 61421, Saudi Arabia; (S.A.); (M.S.)
| | - Mohd Shkir
- Department of Physics, Faculty of Sciences, King Khalid University, Abha PO Box 61421, Saudi Arabia; (S.A.); (M.S.)
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9
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Hu X, Gong X, Zhang M, Lu H, Xue Z, Mei Y, Chu PK, An Z, Di Z. Enhanced Peltier Effect in Wrinkled Graphene Constriction by Nano-Bubble Engineering. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1907170. [PMID: 32105406 DOI: 10.1002/smll.201907170] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 01/19/2020] [Indexed: 06/10/2023]
Abstract
Inspired by the promising applications in thermopower generation from waste heat and active on-chip cooling, the thermoelectric and electrothermal properties of graphene have been extensively pursued by seeking ingeniously designed structures with thermoelectric conversion capability. The graphene wrinkle is a ubiquitous structure formed inevitably during the synthesis of large-scale graphene films but the corresponding properties for thermoelectric and electrothermal applications are rarely investigated. Here, the electrothermal Peltier effect from the graphene wrinkle fabricated on a germanium substrate is reported. Peltier cooling and heating across the wrinkle are visualized unambiguously with polarities consistent with p-type doping and in accordance with the wrinkle spatial distribution. By direct patterning of the nano-bubble structure, the current density across the wrinkle can be boosted by current crowding to enhance the Peltier effect. The observed Peltier effect can be attributed to the nonequilibrium charge transport by interlayer tunneling across the van der Waals barrier of the graphene wrinkle. The graphene wrinkle in combination with nano-bubble engineering constitutes an innovative and agile platform to design graphene and other more general two-dimensional (2D) thermoelectrics and opens the possibility for realizing active on-chip cooling for 2D nanoelectronics with van der Waals junctions.
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Affiliation(s)
- Xudong Hu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xue Gong
- State Key Laboratory of Surface Physics, Institute for Nanoelectronic Devices and Quantum Computing, Key Laboratory of Micro and Nano Photonics Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Miao Zhang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Huihui Lu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Zhongying Xue
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Yongfeng Mei
- Department of Materials Science, Fudan University, Shanghai, 200433, China
| | - Paul K Chu
- Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Zhenghua An
- State Key Laboratory of Surface Physics, Institute for Nanoelectronic Devices and Quantum Computing, Key Laboratory of Micro and Nano Photonics Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Zengfeng Di
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
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10
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Iwasaki T, Endo K, Watanabe E, Tsuya D, Morita Y, Nakaharai S, Noguchi Y, Wakayama Y, Watanabe K, Taniguchi T, Moriyama S. Bubble-Free Transfer Technique for High-Quality Graphene/Hexagonal Boron Nitride van der Waals Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2020; 12:8533-8538. [PMID: 32027115 DOI: 10.1021/acsami.9b19191] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bubbles at the interface of two-dimensional layered materials in van der Waals heterostructures cause deterioration in the quality of materials, thereby limiting the size and design of devices. In this paper, we report a simple all-dry transfer technique, with which the bubble formation can be avoided. As a key factor in the technique, a contact angle between a picked-up flake on a viscoelastic polymer stamp and another flake on a substrate was introduced by protrusion at the stamp surface. Using this technique, we demonstrated the fabrication of high-quality devices on the basis of graphene/hexagonal boron nitride heterostructures with a large bubble-free region. Additionally, the technique can be used to remove unnecessary flakes on a substrate under an optical microscopic scale. Most importantly, it improves the yield and throughput for the fabrication process of high-quality van der Waals heterostructure-based devices.
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Affiliation(s)
- Takuya Iwasaki
- International Center for Young Scientists (ICYS) , National Institute for Materials Science (NIMS) , Tsukuba , Ibaraki 305-0044 , Japan
| | - Kosuke Endo
- International Center for Materials Nanoarchitectonics (WPI-MANA), NIMS , Tsukuba , Ibaraki 305-0044 , Japan
- School of Science & Technology , Meiji University , Kawasaki 214-8571 , Japan
| | | | - Daiju Tsuya
- Nanofabrication Platform, NIMS , Tsukuba , Ibaraki 305-0047 , Japan
| | - Yoshifumi Morita
- Faculty of Engineering , Gunma University , Kiryu , Gunma 376-8515 , Japan
| | - Shu Nakaharai
- International Center for Materials Nanoarchitectonics (WPI-MANA), NIMS , Tsukuba , Ibaraki 305-0044 , Japan
| | - Yutaka Noguchi
- School of Science & Technology , Meiji University , Kawasaki 214-8571 , Japan
| | - Yutaka Wakayama
- International Center for Materials Nanoarchitectonics (WPI-MANA), NIMS , Tsukuba , Ibaraki 305-0044 , Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, NIMS , Tsukuba , Ibaraki 305-0044 , Japan
| | - Takashi Taniguchi
- Research Center for Functional Materials, NIMS , Tsukuba , Ibaraki 305-0044 , Japan
| | - Satoshi Moriyama
- International Center for Materials Nanoarchitectonics (WPI-MANA), NIMS , Tsukuba , Ibaraki 305-0044 , Japan
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11
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Effective Photoluminescence Imaging of Bubbles in hBN-Encapsulated WSe 2 Monolayer. NANOMATERIALS 2020; 10:nano10020350. [PMID: 32085486 PMCID: PMC7075156 DOI: 10.3390/nano10020350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 02/14/2020] [Indexed: 11/23/2022]
Abstract
Interfacial bubbles are unintentionally created during the transfer of atomically thin 2D layers, a required process in the fabrication of van der Waals heterostructures. By encapsulating a WSe2 monolayer in hBN, we study the differing photoluminescence (PL) properties of the structure resulting from bubble formation. Based on the differentiated absorption probabilities at the bubbles compared to the pristine areas, we demonstrate that the visibility of the bubbles in PL mapping is enhanced when the photoexcitation wavelength lies between the n = 1 and n = 2 resonances of the A-exciton. An appropriate choice of detection window, which includes localized exciton emission but excludes free exciton emission, further improves bubble imaging capability. The interfacial position dependence of the bubbles, whether they are located above or below the WSe2 monolayer, gives rise to measurable consequences in the PL shape.
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12
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Behera SK, Deb P. Spin-transfer-torque mediated quantum magnetotransport in MoS2/phosphorene vdW heterostructure based MTJs. Phys Chem Chem Phys 2020; 22:19139-19146. [DOI: 10.1039/d0cp00836b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Spin-transfer-torque mediated quantum magnetotransport behaviour can be realized via magnetization density switching in 2D van der Waals heterostructures for device applications.
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Affiliation(s)
- Sushant Kumar Behera
- Advanced Functional Material Laboratory (AFML)
- Department of Physics
- Tezpur University (Central University)
- Tezpur-784028
- India
| | - Pritam Deb
- Advanced Functional Material Laboratory (AFML)
- Department of Physics
- Tezpur University (Central University)
- Tezpur-784028
- India
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Kim H, Leconte N, Chittari BL, Watanabe K, Taniguchi T, MacDonald AH, Jung J, Jung S. Accurate Gap Determination in Monolayer and Bilayer Graphene/ h-BN Moiré Superlattices. NANO LETTERS 2018; 18:7732-7741. [PMID: 30457338 DOI: 10.1021/acs.nanolett.8b03423] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
High mobility single and few-layer graphene sheets are in many ways attractive as nanoelectronic circuit hosts but lack energy gaps, which are essential to the operation of field-effect transistors. One of the methods used to create gaps in the spectrum of graphene systems is to form long period moiré patterns by aligning the graphene and hexagonal boron nitride ( h-BN) substrate lattices. Here, we use planar tunneling devices with thin h-BN barriers to obtain direct and accurate tunneling spectroscopy measurements of the energy gaps in single-layer and bilayer graphene- h-BN superlattice structures at charge neutrality (first Dirac point) and at integer moiré band occupancies (second Dirac point, SDP) as a function of external electric and magnetic fields and the interface twist angle. In single-layer graphene, we find, in agreement with previous work, that gaps are formed at neutrality and at the hole-doped SDP, but not at the electron-doped SDP. Both primary and secondary gaps can be determined accurately by extrapolating Landau fan patterns to a zero magnetic field and are as large as ≈17 meV for devices in near-perfect alignment. For bilayer graphene, we find that gaps occur only at charge neutrality where they can be modified by an external electric field.
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Affiliation(s)
- Hakseong Kim
- Korea Research Institute of Standards and Science , Daejeon 34113 , Korea
| | - Nicolas Leconte
- Department of Physics , University of Seoul , Seoul 02504 , Korea
| | | | - Kenji Watanabe
- Advanced Materials Laboratory , National Institute for Materials Science , 1-1 Namiki , Tsukuba 305-0044 , Japan
| | - Takashi Taniguchi
- Advanced Materials Laboratory , National Institute for Materials Science , 1-1 Namiki , Tsukuba 305-0044 , Japan
| | - Allan H MacDonald
- Department of Physics , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Jeil Jung
- Department of Physics , University of Seoul , Seoul 02504 , Korea
| | - Suyong Jung
- Korea Research Institute of Standards and Science , Daejeon 34113 , Korea
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