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Park J, Jung J, Kim MS, Lim CM, Choi JE, Kim N, Kim JH, Chung CW. Damage-Free Plasma Source for Atomic-Scale Processing. NANO LETTERS 2024; 24:11462-11468. [PMID: 39239915 DOI: 10.1021/acs.nanolett.4c02598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/07/2024]
Abstract
As atomic-scale etching and deposition processes become necessary for manufacturing logic and memory devices at the sub-5 nm node, the limitations of conventional plasma technology are becoming evident. For atomic-scale processes, precise critical dimension control at the sub-1 nm scale without plasma-induced damage and high selectivity between layers are required. In this paper, a plasma with very low electron temperature is applied for damage-free processing on the atomic scale. In plasmas with an ultralow electron temperature (ULET, Te < 0.5 eV), ion energies are very low, and the ion energy distribution is narrow. The absence of physical damage in ULET plasma is verified by exposing 2D structural material. In the ULET plasma, charging damage and radiation damage are also expected to be suppressed due to the extremely low Te. This ULET plasma source overcomes the limitations of conventional plasma sources and provides insights to achieve damage-free atomic-scale processes.
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Affiliation(s)
- Junyoung Park
- Department of Electrical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Jiwon Jung
- Department of Electrical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Min-Seok Kim
- Department of Electrical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Chang-Min Lim
- Department of Electrical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Jung-Eun Choi
- Department of Electrical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Nayeon Kim
- Department of Electrical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Ju-Ho Kim
- Department of Electrical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Chin-Wook Chung
- Department of Electrical Engineering, Hanyang University, Seoul 04763, South Korea
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2
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Yang J, Dang T, Ma S, Tang S, Ding Y, Seki M, Tabata H, Matsui H. Plasmon-Free Surface-Enhanced Raman Spectroscopy Using α-Type MoO 3 Semiconductor Nanorods with Strong Light Scattering in the Visible Regime. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 39048517 DOI: 10.1021/acsami.4c01435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Recent developments in semiconductor-based surface-enhanced Raman scattering (SERS) have achieved numerous advancements, primarily centered on the chemical mechanism. However, the role of the electromagnetic (electromagnetic mechanism) contribution in advancing semiconductor SERS substrates is still underexplored. In this study, we developed a SERS substrate based on densely aligned α-type MoO3 (α-MoO3) semiconductor nanorods (NRs) with rectangular parallelepiped ribbon shapes with width measuring several hundred nanometers. These structural attributes strongly affect light transport in the visible range by multiple light scattering generated in narrow gaps between NRs, contributing to the improvement of SERS performance. Engineering the nanostructure and chemical composition of NRs realized high SERS sensitivity with an enhancement factor of 2 × 108 and a low detection limit of 5 × 10-9 M for rhodamine 6G (R6G) molecules, which was achieved by the stoichiometric NR sample with strong light scattering. Furthermore, it was observed that the scattering length becomes significantly shorter compared with the excitation wavelength in the visible regime, which indicates that light transport is strongly modified by mesoscopic interference related to Anderson localization. Additionally, high electric fields were found to be localized on the NR surfaces, depending on the excitation wavelength, similar to the SERS response. These optical phenomena indicate that electromagnetic excitation processes play an important role in plasmon-free SERS platforms based on α-MoO3 NRs. We postulate that our study provides important guidance for designing effective EM-based SERS-active semiconductor substrates.
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Affiliation(s)
- Jiaqi Yang
- Department of Bioengineering, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tang Dang
- Department of Bioengineering, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Shuting Ma
- Department of Bioengineering, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Siyi Tang
- Department of Electric Engineering and Information Systems, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yan Ding
- Department of Bioengineering, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Munetoshi Seki
- Department of Electric Engineering and Information Systems, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Hitoshi Tabata
- Department of Bioengineering, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Electric Engineering and Information Systems, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Hiroaki Matsui
- Department of Bioengineering, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Electric Engineering and Information Systems, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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3
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Lei Y, Zhang T, Lin YC, Granzier-Nakajima T, Bepete G, Kowalczyk DA, Lin Z, Zhou D, Schranghamer TF, Dodda A, Sebastian A, Chen Y, Liu Y, Pourtois G, Kempa TJ, Schuler B, Edmonds MT, Quek SY, Wurstbauer U, Wu SM, Glavin NR, Das S, Dash SP, Redwing JM, Robinson JA, Terrones M. Graphene and Beyond: Recent Advances in Two-Dimensional Materials Synthesis, Properties, and Devices. ACS NANOSCIENCE AU 2022; 2:450-485. [PMID: 36573124 PMCID: PMC9782807 DOI: 10.1021/acsnanoscienceau.2c00017] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 12/30/2022]
Abstract
Since the isolation of graphene in 2004, two-dimensional (2D) materials research has rapidly evolved into an entire subdiscipline in the physical sciences with a wide range of emergent applications. The unique 2D structure offers an open canvas to tailor and functionalize 2D materials through layer number, defects, morphology, moiré pattern, strain, and other control knobs. Through this review, we aim to highlight the most recent discoveries in the following topics: theory-guided synthesis for enhanced control of 2D morphologies, quality, yield, as well as insights toward novel 2D materials; defect engineering to control and understand the role of various defects, including in situ and ex situ methods; and properties and applications that are related to moiré engineering, strain engineering, and artificial intelligence. Finally, we also provide our perspective on the challenges and opportunities in this fascinating field.
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Affiliation(s)
- Yu Lei
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Institute
of Materials Research, Tsinghua Shenzhen
International Graduate School, Shenzhen, Guangdong 518055, China
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tianyi Zhang
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Yu-Chuan Lin
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tomotaroh Granzier-Nakajima
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - George Bepete
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Dorota A. Kowalczyk
- Department
of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, Lodz 90-236, Poland
| | - Zhong Lin
- Department
of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Da Zhou
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Thomas F. Schranghamer
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Akhil Dodda
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Amritanand Sebastian
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Yifeng Chen
- Department
of Materials Science and Engineering, National
University of Singapore, 9 Engineering Drive, Singapore 117456, Singapore
| | - Yuanyue Liu
- Texas
Materials Institute and Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | | | - Thomas J. Kempa
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21287, United States
| | - Bruno Schuler
- nanotech@surfaces
Laboratory, Empa − Swiss Federal
Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Mark T. Edmonds
- School
of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia
| | - Su Ying Quek
- Department
of Materials Science and Engineering, National
University of Singapore, 9 Engineering Drive, Singapore 117456, Singapore
| | - Ursula Wurstbauer
- Institute
of Physics, University of Münster, Wilhelm-Klemm-Str. 10, Münster 48149, Germany
| | - Stephen M. Wu
- Department
of Electrical and Computer Engineering & Department of Physics
and Astronomy, University of Rochester, Rochester, New York 14627, United States
| | - Nicholas R. Glavin
- Air
Force
Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Dayton, Ohio 45433, United States
| | - Saptarshi Das
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Saroj Prasad Dash
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, Göteborg SE-412 96, Sweden
| | - Joan M. Redwing
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joshua A. Robinson
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Mauricio Terrones
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Research
Initiative for Supra-Materials and Global Aqua Innovation Center, Shinshu University, 4-17-1Wakasato, Nagano 380-8553, Japan
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4
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Surnev S, Netzer FP. Tungsten and molybdenum oxide nanostructures: two-dimensional layers and nanoclusters. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:233001. [PMID: 35045403 DOI: 10.1088/1361-648x/ac4ceb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 01/19/2022] [Indexed: 06/14/2023]
Abstract
W- and Mo-oxides form an interesting class of materials, featuring structural complexities, stoichiometric flexibility, and versatile physical and chemical properties that render them attractive for many applications in diverse fields of nanotechnologies. In nanostructured form, novel properties and functionalities emerge as a result of quantum size and confinement effects. In this topical review, W- and Mo-oxide nanosystems are examined with particular emphasis on two-dimensional (2D) layers and small molecular-type clusters. We focus on the epitaxial growth of 2D layers on metal single crystal surfaces and investigate their novel geometries and structures by a surface science approach. The coupling between the oxide overlayer and the metal substrate surface is a decisive element in the formation of the oxide structures and interfacial strain and charge transfer are shown to determine the lowest energy structures. Atomic structure models as determined by density functional theory (DFT) simulations are reported and discussed for various interface situations, with strong and weak coupling. Free-standing (quasi-)2D oxide layers, so-called oxide nanosheets, are attracting a growing interest recently in the applied research community because of their easy synthesis via wet-chemical routes. Although they consist typically of several atomic layers thick-not always homogeneous-platelet systems, their quasi-2D character induces a number of features that make them attractive for optoelectronic, sensor or biotechnological device applications. A brief account of recently published preparation procedures of W- and Mo-oxide nanosheets and some prototypical examples of proof of concept applications are reported here. (MO3)3(M = W, Mo) clusters can be generated in the gas phase in nearly monodisperse form by a simple vacuum sublimation technique. These clusters, interesting molecular-type structures by their own account, can be deposited on a solid surface in a controlled way and be condensed into 2D W- and Mo-oxide layers; solid-state chemical reactions with pre-deposited surface oxide layers to form 2D ternary oxide compounds (tungstates, molybdates) have also been reported. The clusters have been proposed as model systems for molecular studies of reactive centres in catalytic reactions. Studies of the catalysis of (MO3)3clusters in unsupported and supported forms, using the conversion of alcohols as model reactions, are discussed. Finally, we close with a brief outlook of future perspectives.
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Affiliation(s)
- Svetlozar Surnev
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University Graz, A-8010 GRAZ, Austria
| | - Falko P Netzer
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University Graz, A-8010 GRAZ, Austria
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5
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Alam MH, Chowdhury S, Roy A, Wu X, Ge R, Rodder MA, Chen J, Lu Y, Stern C, Houben L, Chrostowski R, Burlison SR, Yang SJ, Serna MI, Dodabalapur A, Mangolini F, Naveh D, Lee JC, Banerjee SK, Warner JH, Akinwande D. Wafer-Scalable Single-Layer Amorphous Molybdenum Trioxide. ACS NANO 2022; 16:3756-3767. [PMID: 35188367 DOI: 10.1021/acsnano.1c07705] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Molybdenum trioxide (MoO3), an important transition metal oxide (TMO), has been extensively investigated over the past few decades due to its potential in existing and emerging technologies, including catalysis, energy and data storage, electrochromic devices, and sensors. Recently, the growing interest in two-dimensional (2D) materials, often rich in interesting properties and functionalities compared to their bulk counterparts, has led to the investigation of 2D MoO3. However, the realization of large-area true 2D (single to few atom layers thick) MoO3 is yet to be achieved. Here, we demonstrate a facile route to obtain wafer-scale monolayer amorphous MoO3 using 2D MoS2 as a starting material, followed by UV-ozone oxidation at a substrate temperature as low as 120 °C. This simple yet effective process yields smooth, continuous, uniform, and stable monolayer oxide with wafer-scale homogeneity, as confirmed by several characterization techniques, including atomic force microscopy, numerous spectroscopy methods, and scanning transmission electron microscopy. Furthermore, using the subnanometer MoO3 as the active layer sandwiched between two metal electrodes, we demonstrate the thinnest oxide-based nonvolatile resistive switching memory with a low voltage operation and a high ON/OFF ratio. These results (potentially extendable to other TMOs) will enable further exploration of subnanometer stoichiometric MoO3, extending the frontiers of ultrathin flexible oxide materials and devices.
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Affiliation(s)
- Md Hasibul Alam
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Sayema Chowdhury
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Anupam Roy
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Xiaohan Wu
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Ruijing Ge
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Michael A Rodder
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Jun Chen
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Yang Lu
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Chen Stern
- Faculty of Engineering, Bar-Ilan University, IL 52900, Israel
- Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, IL 5290002, Israel
| | - Lothar Houben
- Chemical Research Support, Weizmann Institute of Science, Rehovot, IL 76100, Israel
| | - Robert Chrostowski
- Texas Material Institute, The University of Texas at Austin, Austin, Texas 78712, United States
- Materials Science and Engineering Program, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Scott R Burlison
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Sung Jin Yang
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Martha I Serna
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Ananth Dodabalapur
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Filippo Mangolini
- Texas Material Institute, The University of Texas at Austin, Austin, Texas 78712, United States
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Doron Naveh
- Faculty of Engineering, Bar-Ilan University, IL 52900, Israel
- Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, IL 5290002, Israel
| | - Jack C Lee
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Sanjay K Banerjee
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
| | - Jamie H Warner
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
- Texas Material Institute, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Deji Akinwande
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States
- Texas Material Institute, The University of Texas at Austin, Austin, Texas 78712, United States
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6
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Lyu W, Teng H, Wu C, Zhang X, Guo X, Yang X, Dai Q. Anisotropic acoustic phonon polariton-enhanced infrared spectroscopy for single molecule detection. NANOSCALE 2021; 13:12720-12726. [PMID: 34477622 DOI: 10.1039/d1nr01701b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nanoscale Fourier transform infrared spectroscopy (nano-FTIR) based on scanning probe microscopy enables the identification of the chemical composition and structure of surface species with a high spatial resolution (∼10 nm), which is crucial for exploring catalytic reaction processes, cellular processes, virus detection, etc. However, the characterization of a single molecule with nano-FTIR is still challenging due to the weak coupling between the molecule and infrared light due to a large size mismatch. Here, we propose a novel structure (monolayer α-MoO3/air nanogap/Au) to excite anisotropic acoustic phonon polaritons (APhPs) with ultra-high field confinement (mode volume, VAPhPs∼ 10-11V0) and electromagnetic energy enhancement (>107), which largely enhance the interaction of single molecules with infrared light. In addition, the anisotropic APhP-assisted nano-FTIR can detect single molecular dipoles in directions both along and perpendicular to the probe axis, while pristine nano-FTIR mainly detects molecular dipoles along the probe axis. The proposed structure provides a way to detect a single molecule, which will impact the fields of biology, chemistry, energy, and environment through fundamental research and applications.
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Affiliation(s)
- Wei Lyu
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
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7
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Deokate RJ, Kate R, Shinde NM, Mane RS. Energy storage potential of sprayed α-MoO 3 thin films. NEW J CHEM 2021. [DOI: 10.1039/d0nj03910a] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Emerging phase pure energy storage electrodes synthesized with controlled morphology endow an enhanced supercapacitor properties.
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Affiliation(s)
- Ramesh J. Deokate
- Vidya Pratishthan's
- Arts Science and Commerce College
- Baramati-413 133
- India
| | - Ranjit Kate
- Vidya Pratishthan's
- Arts Science and Commerce College
- Baramati-413 133
- India
| | - Nanasaheb M. Shinde
- National Core Research Centre for Hybrid Materials Solution
- Pusan National University
- Busan 609-735
- Republic of Korea
| | - Rajaram S. Mane
- School of Physical Sciences
- Swami Ramanand Teerth Marathwada University
- Nanded 431606
- India
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8
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Fu Q, Zhuang N, Hu X, Chen J. Influence of choice of substrate and film thickness on magneto-optical properties of SmFeO 3 thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:105801. [PMID: 31698339 DOI: 10.1088/1361-648x/ab5540] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Herein, SmFeO3 thin films are prepared by using magnetron sputtering technology on quartz-glass and SrTiO3(STO)(1 0 0) substrates. The influence of film thickness and choice of substrate on film quality and growth orientation is studied in detail. Moreover, the impact of phase purity and growth orientation on optical, magnetic and magneto-optical properties is discussed. The results reveal that the film thickness and choice of substrate significantly influence the induced stresses at film/substrate interface and growth orientation of the annealed film. The as-fabricated SmFeO3 thin films have demonstrated highly crystalline structure, excellent transmittance and enhanced magneto-optical properties. Moreover, obvious anisotropy in magnetization and magneto-optical properties has been observed. The SmFeO3 films with excellent magneto-optical properties can be fabricated by selecting optimal film thickness and substrate. It is expected that SmFeO3 film is a promising material for integrated optical isolators and magneto-optical modulators.
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Affiliation(s)
- Qiuping Fu
- College of Chemical and Material Engineering, Guiyang University, Guiyang 550005, People's Republic of China
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9
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Behavior of Molybdenum⁻Vanadium Mixed Oxides in Selective Oxidation and Disproportionation of Toluene. MATERIALS 2019; 12:ma12050748. [PMID: 30841502 PMCID: PMC6427125 DOI: 10.3390/ma12050748] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 02/26/2019] [Accepted: 02/28/2019] [Indexed: 11/28/2022]
Abstract
This study deals with the behavior of molybdenum–vanadium (Mo/V) mixed oxides catalysts in both disproportionation and selective oxidation of toluene. Samples containing different Mo/V ratios were prepared by a modified method using tetradecyltrimethylammonium bromide and acetic acid. The catalysts were characterized using several techniques: nitrogen adsorption–desorption isotherms, X-Ray diffraction (XRD), ammonia temperature-programmed desorption (TPD-NH3), temperature-programmed reduction by hydrogen (H2-TPR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier-transform infrared-spectroscopy (FTIR) and ultraviolet-visible spectroscopies (UV–VIS). The XRD results evidenced the presence of orthorhombic α-MoO3 and V2O5 phases, as well as monoclinic β-MoO3 and V2MoO8 phases, their abundance depending on the Mo to V ratio, while the TPD-NH3 emphasized that, the total amount of the acid sites diminished with the increase of the Mo loading. The TPR investigations indicated that the samples with higher Mo/V ratio possess a higher reducibility. The main findings of this study led to the conclusion that the presence of strong acid sites afforded a high conversion in toluene disproportionation (Mo/V = 1), while a higher reducibility is a prerequisite to accomplishing high conversion in toluene oxidation (Mo/V = 2). The catalyst with Mo/V = 1 acquires the best yield to xylenes from the toluene disproportionation reaction, while the catalyst with Mo/V = 0.33 presents the highest yield to benzaldehyde.
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10
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Cai L, McClellan CJ, Koh AL, Li H, Yalon E, Pop E, Zheng X. Rapid Flame Synthesis of Atomically Thin MoO 3 down to Monolayer Thickness for Effective Hole Doping of WSe 2. NANO LETTERS 2017; 17:3854-3861. [PMID: 28537732 DOI: 10.1021/acs.nanolett.7b01322] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Two-dimensional (2D) molybdenum trioxide (MoO3) with mono- or few-layer thickness can potentially advance many applications, ranging from optoelectronics, catalysis, sensors, and batteries to electrochromic devices. Such ultrathin MoO3 sheets can also be integrated with other 2D materials (e.g., as dopants) to realize new or improved electronic devices. However, there is lack of a rapid and scalable method to controllably grow mono- or few-layer MoO3. Here, we report the first demonstration of using a rapid (<2 min) flame synthesis method to deposit mono- and few-layer MoO3 sheets (several microns in lateral dimension) on a wide variety of layered materials, including mica, MoS2, graphene, and WSe2, based on van der Waals epitaxy. The flame-grown ultrathin MoO3 sheet functions as an efficient hole doping layer for WSe2, enabling WSe2 to reach the lowest sheet and contact resistance reported to date among all the p-type 2D materials (∼6.5 kΩ/□ and ∼0.8 kΩ·μm, respectively). These results demonstrate that flame synthesis is a rapid and scalable pathway to growing atomically thin 2D metal oxides, opening up new opportunities for advancing 2D electronics.
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Affiliation(s)
- Lili Cai
- Department of Mechanical Engineering, Stanford University , Stanford, California 94305, United States
| | - Connor J McClellan
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
| | - Ai Leen Koh
- Stanford Nano Shared Facilities, Stanford University , Stanford, California 94305, United States
| | - Hong Li
- Department of Mechanical Engineering, Stanford University , Stanford, California 94305, United States
- School of Mechanical and Aerospace Engineering, Nanyang Technological University , Singapore 639798
| | - Eilam Yalon
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
| | - Eric Pop
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
| | - Xiaolin Zheng
- Department of Mechanical Engineering, Stanford University , Stanford, California 94305, United States
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Zhu H, Qin X, Cheng L, Azcatl A, Kim J, Wallace RM. Remote Plasma Oxidation and Atomic Layer Etching of MoS2. ACS APPLIED MATERIALS & INTERFACES 2016; 8:19119-26. [PMID: 27386734 DOI: 10.1021/acsami.6b04719] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Exfoliated molybdenum disulfide (MoS2) is shown to chemically oxidize in a layered manner upon exposure to a remote O2 plasma. X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), and atomic force microscopy (AFM) are employed to characterize the surface chemistry, structure, and topography of the oxidation process and indicate that the oxidation mainly occurs on the topmost layer without altering the chemical composition of underlying layer. The formation of S-O bonds upon short, remote plasma exposure pins the surface Fermi level to the conduction band edge, while the MoOx formation at high temperature modulates the Fermi level toward the valence band through band alignment. A uniform coverage of monolayer amorphous MoO3 is obtained after 5 min or longer remote O2 plasma exposure at 200 °C, and the MoO3 can be completely removed by annealing at 500 °C, leaving a clean ordered MoS2 lattice structure as verified by XPS, LEED, AFM, and scanning tunneling microscopy. This work shows that a remote O2 plasma can be useful for both surface functionalization and a controlled thinning method for MoS2 device fabrication processes.
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Affiliation(s)
- Hui Zhu
- Department of Materials Science and Engineering, University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Xiaoye Qin
- Department of Materials Science and Engineering, University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Lanxia Cheng
- Department of Materials Science and Engineering, University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Angelica Azcatl
- Department of Materials Science and Engineering, University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Jiyoung Kim
- Department of Materials Science and Engineering, University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Robert M Wallace
- Department of Materials Science and Engineering, University of Texas at Dallas , Richardson, Texas 75080, United States
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