1
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Ding D, Qu Z, Han X, Han C, Zhuang Q, Yu XL, Niu R, Wang Z, Li Z, Gan Z, Wu J, Lu J. Multivalley Superconductivity in Monolayer Transition Metal Dichalcogenides. NANO LETTERS 2022; 22:7919-7926. [PMID: 36173038 DOI: 10.1021/acs.nanolett.2c02947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In transition metal dichalcogenides (TMDs), Ising superconductivity with an antisymmetric spin texture on the Fermi surface has attracted wide interest due to the exotic pairing and topological properties. However, it is not clear whether the Q valley with a giant spin splitting is involved in the superconductivity of heavily doped semiconducting 2H-TMDs. Here by taking advantage of a high-quality monolayer WS2 on hexagonal boron nitride flakes, we report an ionic-gating induced superconducting dome with a record high critical temperature of ∼6 K, accompanied by an emergent nonlinear Hall effect. The nonlinearity indicates the development of an additional high-mobility channel, which (corroborated by first principle calculations) can be ascribed to the population of Q valleys. Thus, multivalley population at K and Q is suggested to be a prerequisite for developing superconductivity. The involvement of Q valleys also provides insights to the spin textured Fermi surface of Ising superconductivity in the large family of transition metal dichalcogenides.
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Affiliation(s)
- Dongdong Ding
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuangzhuang Qu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Xiangyan Han
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Chunrui Han
- Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Quan Zhuang
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), Inner Mongolia Minzu University, Tongliao 028000, China
| | - Xiang-Long Yu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Ruirui Niu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhiyu Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuoxian Li
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zizhao Gan
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jiansheng Wu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Jianming Lu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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2
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Piatti E, Guglielmero L, Tofani G, Mezzetta A, Guazzelli L, D'Andrea F, Roddaro S, Pomelli CS. Ionic liquids for electrochemical applications: Correlation between molecular structure and electrochemical stability window. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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3
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Zerger CZ, Rodenbach LK, Chen YT, Safvati B, Brubaker MZ, Tran S, Chen TA, Li MY, Li LJ, Goldhaber-Gordon D, Manoharan HC. Nanoscale Electronic Transparency of Wafer-Scale Hexagonal Boron Nitride. NANO LETTERS 2022; 22:4608-4615. [PMID: 35536749 DOI: 10.1021/acs.nanolett.1c04274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Monolayer hexagonal boron nitride (hBN) has attracted interest as an ultrathin tunnel barrier or environmental protection layer. Recently, wafer-scale hBN growth on Cu(111) was developed for semiconductor chip applications. For basic research and technology, understanding how hBN perturbs underlying electronically active layers is critical. Encouragingly, hBN/Cu(111) has been shown to preserve the Cu(111) surface state (SS), but it was unknown how tunneling into this SS through hBN varies spatially. Here, we demonstrate that the Cu(111) SS under wafer-scale hBN is homogeneous in energy and spectral weight over nanometer length scales and across atomic terraces. In contrast, a new spectral feature─not seen on bare Cu(111)─varies with atomic registry and shares the spatial periodicity of the hBN/Cu(111) moiré. This work demonstrates that, for some 2D electron systems, an hBN overlayer can act as a protective yet remarkably transparent window on fragile low-energy electronic structure below.
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Affiliation(s)
- Caleb Z Zerger
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Linsey K Rodenbach
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Yi-Ting Chen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Benjamin Safvati
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Morgan Z Brubaker
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Steven Tran
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Tse-An Chen
- Corporate Research, Taiwan Semiconductor Manufacturing Company (TSMC), Hsinchu 300, Taiwan
| | - Ming-Yang Li
- Corporate Research, Taiwan Semiconductor Manufacturing Company (TSMC), Hsinchu 300, Taiwan
| | - Lain-Jong Li
- Corporate Research, Taiwan Semiconductor Manufacturing Company (TSMC), Hsinchu 300, Taiwan
- Department of Mechanical Engineering, University of Hong Kong, Pok Fu Lam, Hong Kong
| | - David Goldhaber-Gordon
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Hari C Manoharan
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Stanford University, Stanford, California 94305, United States
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4
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Piatti E, Montagna Bozzone J, Daghero D. Anomalous Metallic Phase in Molybdenum Disulphide Induced via Gate-Driven Organic Ion Intercalation. NANOMATERIALS 2022; 12:nano12111842. [PMID: 35683696 PMCID: PMC9181884 DOI: 10.3390/nano12111842] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/16/2022]
Abstract
Transition metal dichalcogenides exhibit rich phase diagrams dominated by the interplay of superconductivity and charge density waves, which often result in anomalies in the electric transport properties. Here, we employ the ionic gating technique to realize a tunable, non-volatile organic ion intercalation in bulk single crystals of molybdenum disulphide (MoS2). We demonstrate that this gate-driven organic ion intercalation induces a strong electron doping in the system without changing the pristine 2H crystal symmetry and triggers the emergence of a re-entrant insulator-to-metal transition. We show that the gate-induced metallic state exhibits clear anomalies in the temperature dependence of the resistivity with a natural explanation as signatures of the development of a charge-density wave phase which was previously observed in alkali-intercalated MoS2. The relatively large temperature at which the anomalies are observed (∼150 K), combined with the absence of any sign of doping-induced superconductivity down to ∼3 K, suggests that the two phases might be competing with each other to determine the electronic ground state of electron-doped MoS2.
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Mikheev E, Zimmerling T, Estry A, Moll PJW, Goldhaber-Gordon D. Ionic Liquid Gating of SrTiO 3 Lamellas Fabricated with a Focused Ion Beam. NANO LETTERS 2022; 22:3872-3878. [PMID: 35576585 DOI: 10.1021/acs.nanolett.1c04447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In this work, we combine two previously incompatible techniques for defining electronic devices: shaping three-dimensional crystals by focused ion beam (FIB), and two-dimensional electrostatic accumulation of charge carriers. The principal challenge for this integration is nanometer-scale surface damage inherent to any FIB-based fabrication. We address this by using a sacrificial protective layer to preserve a selected pristine surface. The test case presented here is accumulation of 2D carriers by ionic liquid gating at the surface of a micron-scale SrTiO3 lamella. Preservation of surface quality is reflected in superconductivity of the accumulated carriers. This technique opens new avenues for realizing electrostatic charge tuning in materials that are not available as large or exfoliatable single crystals, and for patterning the geometry of the accumulated carriers.
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Affiliation(s)
- Evgeny Mikheev
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Tino Zimmerling
- Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Amelia Estry
- Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Laboratory of Quantum Materials (QMAT), Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Philip J W Moll
- Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Laboratory of Quantum Materials (QMAT), Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - David Goldhaber-Gordon
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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6
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Mikheev E, Rosen IT, Goldhaber-Gordon D. Quantized critical supercurrent in SrTiO 3-based quantum point contacts. SCIENCE ADVANCES 2021; 7:eabi6520. [PMID: 34597141 PMCID: PMC10938545 DOI: 10.1126/sciadv.abi6520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Superconductivity in SrTiO3 occurs at remarkably low carrier densities and therefore, unlike conventional superconductors, can be controlled by electrostatic gates. Here, we demonstrate nanoscale weak links connecting superconducting leads, all within a single material, SrTiO3. Ionic liquid gating accumulates carriers in the leads, and local electrostatic gates are tuned to open the weak link. These devices behave as superconducting quantum point contacts with a quantized critical supercurrent. This is a milestone toward establishing SrTiO3 as a single-material platform for mesoscopic superconducting transport experiments that also intrinsically contains the necessary ingredients to engineer topological superconductivity.
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Affiliation(s)
- Evgeny Mikheev
- Department of Physics, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Ilan T. Rosen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - David Goldhaber-Gordon
- Department of Physics, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
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7
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Prete D, Demontis V, Zannier V, Rodriguez-Douton MJ, Guazzelli L, Beltram F, Sorba L, Rossella F. Impact of electrostatic doping on carrier concentration and mobility in InAs nanowires. NANOTECHNOLOGY 2021; 32:145204. [PMID: 33361570 DOI: 10.1088/1361-6528/abd659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We fabricate dual-gated electric double layer (EDL) field effect transistors based on InAs nanowires gated with an ionic liquid, and we perform electrical transport measurements in the temperature range from room temperature to 4.2 K. By adjusting the spatial distribution of ions inside the ionic liquid employed as gate dielectric, we electrostatically induce doping in the nanostructures under analysis. We extract low-temperature carrier concentration and mobility in very different doping regimes from the analysis of current-voltage characteristics and transconductances measured exploiting global back-gating. In the liquid gate voltage interval from -2 to 2 V, carrier concentration can be enhanced up to two orders of magnitude. Meanwhile, the effect of the ionic accumulation on the nanowire surface turns out to be detrimental to the electron mobility of the semiconductor nanostructure: the electron mobility is quenched irrespectively to the sign of the accumulated ionic species. The reported results shine light on the effective impact on crucial transport parameters of EDL gating in semiconductor nanodevices and they should be considered when designing experiments in which electrostatic doping of semiconductor nanostructures via electrolyte gating is involved.
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Affiliation(s)
- Domenic Prete
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, I-56127, Pisa, Italy
| | - Valeria Demontis
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, I-56127, Pisa, Italy
| | - Valentina Zannier
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, I-56127, Pisa, Italy
| | | | - Lorenzo Guazzelli
- Università di Pisa, Dipartimento di Farmacia, via Bonanno 33, I-56126 Pisa, Italy
| | - Fabio Beltram
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, I-56127, Pisa, Italy
| | - Lucia Sorba
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, I-56127, Pisa, Italy
| | - Francesco Rossella
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, I-56127, Pisa, Italy
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8
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Das S, Debnath K, Chakraborty B, Singh A, Grover S, Muthu DVS, Waghmare UV, Sood AK. Symmetry induced phonon renormalization in few layers of 2H-MoTe 2 transistors: Raman and first-principles studies. NANOTECHNOLOGY 2021; 32:045202. [PMID: 33036010 DOI: 10.1088/1361-6528/abbfd6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Understanding of electron-phonon coupling (EPC) in two-dimensional (2D) materials manifesting as phonon renormalization is essential to their possible applications in nanoelectronics. Here we report in situ Raman measurements of electrochemically top-gated 2, 3 and 7 layered 2H-MoTe2 channel based field-effect transistors. While the [Formula: see text] and B2g phonon modes exhibit frequency softening and linewidth broadening with hole doping concentration (p) up to ∼2.3 × 1013/cm2, A1g shows relatively small frequency hardening and linewidth sharpening. The dependence of frequency renormalization of the [Formula: see text] mode on the number of layers in these 2D crystals confirms that hole doping occurs primarily in the top two layers, in agreement with recent predictions. We present first-principles density functional theory analysis of bilayer MoTe2 that qualitatively captures our observations, and explain that a relatively stronger coupling of holes with [Formula: see text] or B2g modes as compared with the A1g mode originates from the in-plane orbital character and symmetry of the states at valence band maximum. The contrast between the manifestation of EPC in monolayer MoS2 and those observed here in a few-layered MoTe2 demonstrates the role of the symmetry of phonons and electronic states in determining the EPC in these isostructural systems.
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Affiliation(s)
- Subhadip Das
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Koyendrila Debnath
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India
| | | | - Anjali Singh
- Center for Study of Science, Technology & Policy (CSTEP), Bangalore 560094, India
| | - Shivani Grover
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India
| | - D V S Muthu
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - U V Waghmare
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India
| | - A K Sood
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
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9
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Das S, Prasad S, Chakraborty B, Jariwala B, Shradha S, Muthu DVS, Bhattacharya A, Waghmare UV, Sood AK. Doping controlled Fano resonance in bilayer 1T'-ReS 2: Raman experiments and first-principles theoretical analysis. NANOSCALE 2021; 13:1248-1256. [PMID: 33404576 DOI: 10.1039/d0nr06583h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In the bilayer ReS2 channel of a field-effect transistor (FET), we demonstrate using Raman spectroscopy that electron doping (n) results in softening of frequency and broadening of linewidth for the in-plane vibrational modes, leaving the out-of-plane vibrational modes unaffected. The largest change is observed for the in-plane Raman mode at ∼151 cm-1, which also shows doping induced Fano resonance with the Fano parameter 1/q = -0.17 at a doping concentration of ∼3.7 × 1013 cm-2. A quantitative understanding of our results is provided by first-principles density functional theory (DFT), showing that the electron-phonon coupling (EPC) of in-plane modes is stronger than that of out-of-plane modes, and its variation with doping is independent of the layer stacking. The origin of large EPC is traced to 1T to 1T' structural phase transition of ReS2 involving in-plane displacement of atoms whose instability is driven by the nested Fermi surface of the 1T structure. Results are compared with those of the isostructural trilayer ReSe2.
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Affiliation(s)
- Subhadip Das
- Department of Physics, Indian Institute of Science, Bangalore 560012, India.
| | - Suchitra Prasad
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | | | - Bhakti Jariwala
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Sai Shradha
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - D V S Muthu
- Department of Physics, Indian Institute of Science, Bangalore 560012, India.
| | - Arnab Bhattacharya
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - U V Waghmare
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - A K Sood
- Department of Physics, Indian Institute of Science, Bangalore 560012, India.
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Song D, Xue D, Zeng S, Li C, Venkatesan T, Ariando A, Pennycook SJ. Atomic Origin of Interface-Dependent Oxygen Migration by Electrochemical Gating at the LaAlO 3-SrTiO 3 Heterointerface. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2000729. [PMID: 32775157 PMCID: PMC7404156 DOI: 10.1002/advs.202000729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/30/2020] [Indexed: 06/11/2023]
Abstract
Electrical control of material properties based on ionic liquids (IL) has seen great development and emerging applications in the field of functional oxides, mainly understood by the electrostatic and electrochemical gating mechanisms. Compared to the fast, flexible, and reproducible electrostatic gating, electrochemical gating is less controllable owing to the complex behaviors of ion migration. Here, the interface-dependent oxygen migration by electrochemical gating is resolved at the atomic scale in the LaAlO3-SrTiO3 system through ex situ IL gating experiments and on-site atomic-resolution characterization. The difference between interface structures leads to the controllable electrochemical oxygen migration by filling oxygen vacancies. The findings not only provide an atomic-scale insight into the origin of interface-dependent electrochemical gating but also demonstrate an effective way of engineering interface structure to control the electrochemical gating.
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Affiliation(s)
- Dongsheng Song
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
| | - Deqing Xue
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
| | - Shengwei Zeng
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
- Department of PhysicsNational University of SingaporeSingapore117542Singapore
| | - Changjian Li
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
| | - Thirumalai Venkatesan
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
- Department of PhysicsNational University of SingaporeSingapore117542Singapore
| | - Ariando Ariando
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
- Department of PhysicsNational University of SingaporeSingapore117542Singapore
| | - Stephen J. Pennycook
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
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11
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Zhuang Y, Cui B, Yang H, Gao F, Parkin SSP. Ionic Liquid Gate-Induced Modifications of Step Edges at SrCoO 2.5 Surfaces. ACS NANO 2020; 14:8562-8569. [PMID: 32609490 PMCID: PMC7467809 DOI: 10.1021/acsnano.0c02880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 07/01/2020] [Indexed: 06/11/2023]
Abstract
Intense electric fields developed during gating at the interface between an ionic liquid and an oxide layer have been shown to lead to significant structural and electronic phase transitions in the entire oxide layer. An archetypical example is the reversible transformation between the brownmillerite SrCoO2.5 and the perovskite SrCoO3 engendered by ionic liquid gating. Here we show using in situ atomic force microscopy studies with photothermal excitation detection, that allows for high quality measurements in the viscous environment of the ionic liquid that the edges of atomically smooth terraces at the surface of SrCoO2.5 films are significantly modified by ionic liquid gating but that the terraces themselves remain smooth. The edges develop ridges that we show, using complementary X-ray photoemission spectroscopy studies, result from the adsorption of hydroxyl groups. Our findings exhibit a way of electrically controlled surface modifications in emergent ionitronic applications.
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Affiliation(s)
| | | | - Hao Yang
- Max Planck Institute for Microstructure
Physics, Halle (Saale) 06120, Germany
| | - Fang Gao
- Max Planck Institute for Microstructure
Physics, Halle (Saale) 06120, Germany
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12
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Kulkarni MR, John RA, Tiwari N, Nirmal A, Ng SE, Nguyen AC, Mathews N. Field-Driven Athermal Activation of Amorphous Metal Oxide Semiconductors for Flexible Programmable Logic Circuits and Neuromorphic Electronics. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1901457. [PMID: 31120199 DOI: 10.1002/smll.201901457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/12/2019] [Indexed: 06/09/2023]
Abstract
Despite extensive research, large-scale realization of metal-oxide electronics is still impeded by high-temperature fabrication, incompatible with flexible substrates. Ideally, an athermal treatment modifying the electronic structure of amorphous metal oxide semiconductors (AMOS) to generate sufficient carrier concentration would help mitigate such high-temperature requirements, enabling realization of high-performance electronics on flexible substrates. Here, a novel field-driven athermal activation of AMOS channels is demonstrated via an electrolyte-gating approach. Facilitating migration of charged oxygen species across the semiconductor-dielectric interface, this approach modulates the local electronic structure of the channel, generating sufficient carriers for charge transport and activating oxygen-compensated thin films. The thin-film transistors (TFTs) investigated here depict an enhancement of linear mobility from 51 to 105.25 cm2 V-1 s-1 (ionic-gated) and from 8.09 to 14.49 cm2 V-1 s-1 (back-gated), by creating additional oxygen vacancies. The accompanying stochiometric transformations, monitored via spectroscopic measurements (X-ray photoelectron spectroscopy) corroborate the detailed electrical (TFT, current evolution) parameter analyses, providing critical insights into the underlying oxygen-vacancy generation mechanism and clearly demonstrating field-induced activation as a promising alternative to conventional high-temperature annealing strategies. Facilitating on-demand active programing of the operation modes of transistors (enhancement vs depletion), this technique paves way for facile fabrication of logic circuits and neuromorphic transistors for bioinspired computing.
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Affiliation(s)
- Mohit Rameshchandra Kulkarni
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Rohit Abraham John
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Nidhi Tiwari
- Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Singapore, 637553, Singapore
| | - Amoolya Nirmal
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Si En Ng
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Anh Chien Nguyen
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Nripan Mathews
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
- Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Singapore, 637553, Singapore
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13
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Leighton C. Electrolyte-based ionic control of functional oxides. NATURE MATERIALS 2019; 18:13-18. [PMID: 30542099 DOI: 10.1038/s41563-018-0246-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 11/12/2018] [Indexed: 05/23/2023]
Abstract
The use of electrolyte gating to electrically control electronic, magnetic and optical properties of materials has seen strong recent growth, driven by the potential of the many devices and applications that such control may enable. Contrary to initial expectations of a purely electrostatic response based on electron or hole doping, electrochemical mechanisms based on the motion of ions are now understood to be common, suggesting promising new electrical control concepts.
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Affiliation(s)
- Chris Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA.
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Gariglio S, Caviglia AD, Triscone JM, Gabay M. A spin-orbit playground: surfaces and interfaces of transition metal oxides. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2019; 82:012501. [PMID: 30058557 DOI: 10.1088/1361-6633/aad6ab] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Within the last twenty years, the status of the spin-orbit interaction has evolved from that of a simple atomic contribution to a key effect that modifies the electronic band structure of materials. It is regarded as one of the basic ingredients for spintronics, locking together charge and spin degrees of freedom and recently it is instrumental in promoting a new class of compounds, the topological insulators. In this review, we present the current status of the research on the spin-orbit coupling in transition metal oxides, discussing the case of two semiconducting compounds, [Formula: see text] and [Formula: see text], and the properties of surface and interfaces based on these. We conclude with the investigation of topological effects predicted to occur in different complex oxides.
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Affiliation(s)
- S Gariglio
- DQMP, University of Geneva, 24 Quai E.-Ansermet 1211, Geneva, Switzerland
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15
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Zeng SW, Yin XM, Herng TS, Han K, Huang Z, Zhang LC, Li CJ, Zhou WX, Wan DY, Yang P, Ding J, Wee ATS, Coey JMD, Venkatesan T, Rusydi A, Ariando A. Oxygen Electromigration and Energy Band Reconstruction Induced by Electrolyte Field Effect at Oxide Interfaces. PHYSICAL REVIEW LETTERS 2018; 121:146802. [PMID: 30339445 DOI: 10.1103/physrevlett.121.146802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Indexed: 06/08/2023]
Abstract
Electrolyte gating is a powerful means for tuning the carrier density and exploring the resultant modulation of novel properties on solid surfaces. However, the mechanism, especially its effect on the oxygen migration and electrostatic charging at the oxide heterostructures, is still unclear. Here we explore the electrolyte gating on oxygen-deficient interfaces between SrTiO_{3} (STO) crystals and LaAlO_{3} (LAO) overlayer through the measurements of electrical transport, x-ray absorption spectroscopy, and photoluminescence spectra. We found that oxygen vacancies (O_{vac}) were filled selectively and irreversibly after gating due to oxygen electromigration at the amorphous LAO/STO interface, resulting in a reconstruction of its interfacial band structure. Because of the filling of O_{vac}, the amorphous interface also showed an enhanced electron mobility and quantum oscillation of the conductance. Further, the filling effect could be controlled by the degree of the crystallinity of the LAO overlayer by varying the growth temperatures. Our results reveal the different effects induced by electrolyte gating, providing further clues to understand the mechanism of electrolyte gating on buried interfaces and also opening a new avenue for constructing high-mobility oxide interfaces.
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Affiliation(s)
- S W Zeng
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - X M Yin
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore 117603, Singapore
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - T S Herng
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
| | - K Han
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Z Huang
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - L C Zhang
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - C J Li
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
| | - W X Zhou
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - D Y Wan
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - P Yang
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore 117603, Singapore
| | - J Ding
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
| | - A T S Wee
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research, National University of Singapore, Singapore 117546, Singapore
| | - J M D Coey
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- School of Physics and CRANN, Trinity College, Dublin 2, Ireland
| | - T Venkatesan
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore
| | - A Rusydi
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore 117603, Singapore
| | - A Ariando
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore
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16
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Piatti E, De Fazio D, Daghero D, Tamalampudi SR, Yoon D, Ferrari AC, Gonnelli RS. Multi-Valley Superconductivity in Ion-Gated MoS 2 Layers. NANO LETTERS 2018; 18:4821-4830. [PMID: 29949374 DOI: 10.1021/acs.nanolett.8b01390] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Layers of transition metal dichalcogenides (TMDs) combine the enhanced effects of correlations associated with the two-dimensional limit with electrostatic control over their phase transitions by means of an electric field. Several semiconducting TMDs, such as MoS2, develop superconductivity (SC) at their surface when doped with an electrostatic field, but the mechanism is still debated. It is often assumed that Cooper pairs reside only in the two electron pockets at the K/K' points of the Brillouin Zone. However, experimental and theoretical results suggest that a multivalley Fermi surface (FS) is associated with the SC state, involving six electron pockets at Q/Q'. Here, we perform low-temperature transport measurements in ion-gated MoS2 flakes. We show that a fully multivalley FS is associated with the SC onset. The Q/Q' valleys fill for doping ≳ 2 × 1013 cm-2, and the SC transition does not appear until the Fermi level crosses both spin-orbit split sub-bands Q 1 and Q 2. The SC state is associated with the FS connectivity and promoted by a Lifshitz transition due to the simultaneous population of multiple electron pockets. This FS topology will serve as a guideline in the quest for new superconductors.
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Affiliation(s)
- Erik Piatti
- Department of Applied Science and Technology , Politecnico di Torino , 10129 Torino , Italy
| | - Domenico De Fazio
- Cambridge Graphene Centre , University of Cambridge , Cambridge CB3 OFA , United Kingdom
| | - Dario Daghero
- Department of Applied Science and Technology , Politecnico di Torino , 10129 Torino , Italy
| | | | - Duhee Yoon
- Cambridge Graphene Centre , University of Cambridge , Cambridge CB3 OFA , United Kingdom
| | - Andrea C Ferrari
- Cambridge Graphene Centre , University of Cambridge , Cambridge CB3 OFA , United Kingdom
| | - Renato S Gonnelli
- Department of Applied Science and Technology , Politecnico di Torino , 10129 Torino , Italy
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17
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Jnawali G, Lee H, Lee JW, Huang M, Hsu JF, Bi F, Zhou R, Cheng G, D'Urso B, Irvin P, Eom CB, Levy J. Graphene-Complex-Oxide Nanoscale Device Concepts. ACS NANO 2018; 12:6128-6136. [PMID: 29750506 DOI: 10.1021/acsnano.8b02457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The integration of graphene with complex-oxide heterostructures such as LaAlO3/SrTiO3 offers the opportunity to combine the multifunctional properties of an oxide interface with the exceptional electronic properties of graphene. The ability to control interface conduction through graphene and understanding how it affects the intrinsic properties of an oxide interface are critical to the technological development of multifunctional devices. Here we demonstrate several device archetypes in which electron transport at an oxide interface is modulated using a patterned graphene top-gate. Nanoscale devices are fabricated at the oxide interface by conductive atomic force microscope (c-AFM) lithography, and transport measurements are performed as a function of the graphene gate voltage. Experiments are performed with devices written adjacent to or directly underneath the graphene gate. Distinct capabilities of this approach include the ability to create highly flexible device configurations, the ability to modulate carrier density at the oxide interface, and the ability to control electron transport up to the single-electron tunneling regime, while maintaining intrinsic transport properties of the oxide interface. Our results facilitate the design of a variety of nanoscale devices that combine excellent transport properties of these two proximal two-dimensional electron systems.
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Affiliation(s)
- Giriraj Jnawali
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
| | - Hyungwoo Lee
- Department of Materials Science and Engineering , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Jung-Woo Lee
- Department of Materials Science and Engineering , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Mengchen Huang
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
| | - Jen-Feng Hsu
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
| | - Feng Bi
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
| | - Rongpu Zhou
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
| | - Guanglei Cheng
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics , University of Science and Technology of China , Hefei 230026 , China
| | - Brian D'Urso
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
| | - Patrick Irvin
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
| | - Chang-Beom Eom
- Department of Materials Science and Engineering , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Jeremy Levy
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh 15260 , United States
- Pittsburgh Quantum Institute , Pittsburgh , Pennsylvania 15260 , United States
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18
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Kumar A, Balakrishna Pillai P, Song X, De Souza MM. Negative Capacitance beyond Ferroelectric Switches. ACS APPLIED MATERIALS & INTERFACES 2018; 10:19812-19819. [PMID: 29788714 DOI: 10.1021/acsami.8b05093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Negative capacitance transistors are a unique class of switches capable of operation beyond the Boltzmann limit to realize subthermionic switching. To date, the negative capacitance effect has been predominantly attributed to devices employing an unstable insulator with ferroelectric properties, exhibiting a two-well energy landscape, in accordance with the Landau theory. The theory and operation of a solid electrolyte field effect transistor (SE-FET) of subthreshold swing less than 60 mV/dec in the absence of a ferroelectric gate dielectric are demonstrated in this work. Unlike ferroelectric FETs that rely on a sudden switching of dipoles to achieve negative capacitance, we demonstrate a distinctive mechanism that relies on the accumulation and dispersion of ions at the interfaces of the oxide, leading to a subthreshold slope (SS) as low as 26 mV/dec in these samples. The frequency of operation of these unscaled devices lies in a few millihertz because at higher or lower frequencies, the ions in the insulator are either too fast or too slow to produce voltage amplification. This is unlike Landau switches, where the SS remains below 60 mV/dec even under quasi-static sweep of the gate bias. The proposed FETs show a higher on-current with a thicker oxide in the entire range of gate voltage, clearly distinguishing their scaling laws from those of ferroelectric FETs. Our theory, validated with experiment, demonstrates a new class of devices capable of negative capacitance that opens up alternate methods of steep switching beyond the traditional approach of ferroelectric or memristive FETs.
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Affiliation(s)
- Ashwani Kumar
- Department of Electronic and Electrical Engineering , University of Sheffield , North Campus , S3 7HQ Sheffield , United Kingdom
| | - Premlal Balakrishna Pillai
- Department of Electronic and Electrical Engineering , University of Sheffield , North Campus , S3 7HQ Sheffield , United Kingdom
| | - Xiaoyao Song
- Department of Electronic and Electrical Engineering , University of Sheffield , North Campus , S3 7HQ Sheffield , United Kingdom
| | - Maria Merlyne De Souza
- Department of Electronic and Electrical Engineering , University of Sheffield , North Campus , S3 7HQ Sheffield , United Kingdom
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19
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ON the Nature of Ionic Liquid Gating of La2−xSrxCuO4. Int J Mol Sci 2018; 19:ijms19020566. [PMID: 29438349 PMCID: PMC5855788 DOI: 10.3390/ijms19020566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 02/07/2018] [Accepted: 02/09/2018] [Indexed: 01/19/2023] Open
Abstract
Ionic liquids have recently been used as means of modulating the charge carrier properties of cuprates. The mechanism behind it, however, is still a matter of debate. In this paper we report experiments on ionic liquid gated ultrathin La2−xSrxCuO4 films. Our results show that the electrostatic part of gating has limited influence in the conductance of the cuprate in the gate voltage range of 0 to −2 V. A non-electrostatic mechanism takes over for gate voltages below −2 V. This mechanism most likely changes the oxygen concentration of the film. The results presented are in line with previous X-ray based studies on ionic liquid gating induced oxygenation of the cuprate materials YBa2Cu3O7−x and La2−xSrxCuO4.
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20
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Pai YY, Tylan-Tyler A, Irvin P, Levy J. Physics of SrTiO 3-based heterostructures and nanostructures: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:036503. [PMID: 29424362 DOI: 10.1088/1361-6633/aa892d] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
This review provides a summary of the rich physics expressed within SrTiO3-based heterostructures and nanostructures. The intended audience is researchers who are working in the field of oxides, but also those with different backgrounds (e.g., semiconductor nanostructures). After reviewing the relevant properties of SrTiO3 itself, we will then discuss the basics of SrTiO3-based heterostructures, how they can be grown, and how devices are typically fabricated. Next, we will cover the physics of these heterostructures, including their phase diagram and coupling between the various degrees of freedom. Finally, we will review the rich landscape of quantum transport phenomena, as well as the devices that elicit them.
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Affiliation(s)
- Yun-Yi Pai
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, United States of America. Pittsburgh Quantum Institute, Pittsburgh, PA 15260, United States of America
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21
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Chen Y, Xing W, Wang X, Shen B, Yuan W, Su T, Ma Y, Yao Y, Zhong J, Yun Y, Xie XC, Jia S, Han W. Role of Oxygen in Ionic Liquid Gating on Two-Dimensional Cr 2Ge 2Te 6: A Non-oxide Material. ACS APPLIED MATERIALS & INTERFACES 2018; 10:1383-1388. [PMID: 29251913 DOI: 10.1021/acsami.7b14795] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ionic liquid gating can markedly modulate a material's carrier density so as to induce metallization, superconductivity, and quantum phase transitions. One of the main issues is whether the mechanism of ionic liquid gating is an electrostatic field effect or an electrochemical effect, especially for oxide materials. Recent observation of the suppression of the ionic liquid gate-induced metallization in the presence of oxygen for oxide materials suggests the electrochemical effect. However, in more general scenarios, the role of oxygen in the ionic liquid gating effect is still unclear. Here, we perform ionic liquid gating experiments on a non-oxide material: two-dimensional ferromagnetic Cr2Ge2Te6. Our results demonstrate that despite the large increase of the gate leakage current in the presence of oxygen, the oxygen does not affect the ionic liquid gating effect on the channel resistance of Cr2Ge2Te6 devices (<5% difference), which suggests the electrostatic field effect as the mechanism on non-oxide materials. Moreover, our results show that ionic liquid gating is more effective on the modulation of the channel resistances compared to the back gating across the 300 nm thick SiO2.
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Affiliation(s)
- Yangyang Chen
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Wenyu Xing
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Xirui Wang
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Bowen Shen
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Wei Yuan
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Tang Su
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Yang Ma
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Yunyan Yao
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Jiangnan Zhong
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Yu Yun
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - X C Xie
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
| | - Wei Han
- International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, PR China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, PR China
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22
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Niu W, Zhang Y, Gan Y, Christensen DV, Soosten MV, Garcia-Suarez EJ, Riisager A, Wang X, Xu Y, Zhang R, Pryds N, Chen Y. Giant Tunability of the Two-Dimensional Electron Gas at the Interface of γ-Al 2O 3/SrTiO 3. NANO LETTERS 2017; 17:6878-6885. [PMID: 28968124 DOI: 10.1021/acs.nanolett.7b03209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Two-dimensional electron gases (2DEGs) formed at the interface between two oxide insulators provide a rich platform for the next generation of electronic devices. However, their high carrier density makes it rather challenging to control the interface properties under a low electric field through a dielectric solid insulator, that is, in the configuration of conventional field-effect transistors. To surpass this long-standing limit, we used ionic liquids as the dielectric layer for electrostatic gating of oxide interfaces in an electric double layer transistor (EDLT) configuration. Herein, we reported giant tunability of the physical properties of 2DEGs at the spinel/perovskite interface of γ-Al2O3/SrTiO3 (GAO/STO). By modulating the carrier density thus the band filling with ionic-liquid gating, the system experiences a Lifshitz transition at a critical carrier density of 3.0 × 1013 cm-2, where a remarkably strong enhancement of Rashba spin-orbit interaction and an emergence of Kondo effect at low temperatures are observed. Moreover, as the carrier concentration depletes with decreasing gating voltage, the electron mobility is enhanced by more than 6 times in magnitude, leading to the observation of clear quantum oscillations. The great tunability of GAO/STO interface by EDLT gating not only shows promise for design of oxide devices with on-demand properties but also sheds new light on the electronic structure of 2DEG at the nonisostructural spinel/perovskite interface.
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Affiliation(s)
- Wei Niu
- Department of Energy Conversion and Storage, Technical University of Denmark , Risø Campus, 4000 Roskilde, Denmark
- National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University , 210093 Nanjing, China
| | - Yu Zhang
- Department of Energy Conversion and Storage, Technical University of Denmark , Risø Campus, 4000 Roskilde, Denmark
| | - Yulin Gan
- Department of Energy Conversion and Storage, Technical University of Denmark , Risø Campus, 4000 Roskilde, Denmark
| | - Dennis V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark , Risø Campus, 4000 Roskilde, Denmark
| | - Merlin V Soosten
- Department of Energy Conversion and Storage, Technical University of Denmark , Risø Campus, 4000 Roskilde, Denmark
| | - Eduardo J Garcia-Suarez
- Center for Catalysis and Sustainable Chemistry, Department of Chemistry, Technical University of Denmark , 2800 Lyngby, Denmark
| | - Anders Riisager
- Center for Catalysis and Sustainable Chemistry, Department of Chemistry, Technical University of Denmark , 2800 Lyngby, Denmark
| | - Xuefeng Wang
- National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University , 210093 Nanjing, China
| | - Yongbing Xu
- National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University , 210093 Nanjing, China
| | - Rong Zhang
- National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University , 210093 Nanjing, China
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark , Risø Campus, 4000 Roskilde, Denmark
| | - Yunzhong Chen
- Department of Energy Conversion and Storage, Technical University of Denmark , Risø Campus, 4000 Roskilde, Denmark
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23
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Kühne M, Paolucci F, Popovic J, Ostrovsky PM, Maier J, Smet JH. Ultrafast lithium diffusion in bilayer graphene. NATURE NANOTECHNOLOGY 2017; 12:895-900. [PMID: 28581509 DOI: 10.1038/nnano.2017.108] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 04/28/2017] [Indexed: 05/12/2023]
Abstract
Solids that simultaneously conduct electrons and ions are key elements for the mass transfer and storage required in battery electrodes. Single-phase materials with a high electronic and high ionic conductivity at room temperature are hard to come by, and therefore multiphase systems with separate ion and electron channels have been put forward instead. Here we report on bilayer graphene as a single-phase mixed conductor that demonstrates Li diffusion faster than in graphite and even surpassing the diffusion of sodium chloride in liquid water. To measure Li diffusion, we have developed an on-chip electrochemical cell architecture in which the redox reaction that forces Li intercalation is localized only at a protrusion of the device so that the graphene bilayer remains unperturbed from the electrolyte during operation. We performed time-dependent Hall measurements across spatially displaced Hall probes to monitor the in-plane Li diffusion kinetics within the graphene bilayer and measured a diffusion coefficient as high as 7 × 10-5 cm2 s-1.
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Affiliation(s)
- Matthias Kühne
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Federico Paolucci
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56126 Pisa, Italy
| | - Jelena Popovic
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Pavel M Ostrovsky
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
- L. D. Landau Institute for Theoretical Physics RAS, 119334 Moscow, Russia
| | - Joachim Maier
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Jurgen H Smet
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
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24
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Petach TA, Reich KV, Zhang X, Watanabe K, Taniguchi T, Shklovskii BI, Goldhaber-Gordon D. Disorder from the Bulk Ionic Liquid in Electric Double Layer Transistors. ACS NANO 2017; 11:8395-8400. [PMID: 28753312 DOI: 10.1021/acsnano.7b03864] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ionic liquid gating has a number of advantages over solid-state gating, especially for flexible or transparent devices and for applications requiring high carrier densities. However, the large number of charged ions near the channel inevitably results in Coulomb scattering, which limits the carrier mobility in otherwise clean systems. We develop a model for this Coulomb scattering. We validate our model experimentally using ionic liquid gating of graphene across varying thicknesses of hexagonal boron nitride, demonstrating that disorder in the bulk ionic liquid often dominates the scattering.
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Affiliation(s)
- Trevor A Petach
- Department of Applied Physics, Stanford University , Palo Alto, California 94305, United States
- Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Konstantin V Reich
- Fine Theoretical Physics Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
- Ioffe Institute , St Petersburg, 194021, Russia
| | - Xiao Zhang
- Department of Applied Physics, Stanford University , Palo Alto, California 94305, United States
| | - Kenji Watanabe
- National Institute for Materials Science , 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science , 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Boris I Shklovskii
- Fine Theoretical Physics Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - David Goldhaber-Gordon
- Department of Applied Physics, Stanford University , Palo Alto, California 94305, United States
- Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
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25
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Kim H, Ovchinnikov D, Deiana D, Unuchek D, Kis A. Suppressing Nucleation in Metal-Organic Chemical Vapor Deposition of MoS 2 Monolayers by Alkali Metal Halides. NANO LETTERS 2017; 17:5056-5063. [PMID: 28700239 DOI: 10.1021/acs.nanolett.7b02311] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Toward the large-area deposition of MoS2 layers, we employ metal-organic precursors of Mo and S for a facile and reproducible van der Waals epitaxy on c-plane sapphire. Exposing c-sapphire substrates to alkali metal halide salts such as KI or NaCl together with the Mo precursor prior to the start of the growth process results in increasing the lateral dimensions of single crystalline domains by more than 2 orders of magnitude. The MoS2 grown this way exhibits high crystallinity and optoelectronic quality comparable to single-crystal MoS2 produced by conventional chemical vapor deposition methods. The presence of alkali metal halides suppresses the nucleation and enhances enlargement of domains while resulting in chemically pure MoS2 after transfer. Field-effect measurements in polymer electrolyte-gated devices result in promising electron mobility values close to 100 cm2 V-1 s-1 at cryogenic temperatures.
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Affiliation(s)
- HoKwon Kim
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Dmitry Ovchinnikov
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Davide Deiana
- Interdisciplinary Center for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Dmitrii Unuchek
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Andras Kis
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
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26
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Chen MW, Ovchinnikov D, Lazar S, Pizzochero M, Whitwick MB, Surrente A, Baranowski M, Sanchez OL, Gillet P, Plochocka P, Yazyev OV, Kis A. Highly Oriented Atomically Thin Ambipolar MoSe 2 Grown by Molecular Beam Epitaxy. ACS NANO 2017; 11:6355-6361. [PMID: 28530829 PMCID: PMC5492213 DOI: 10.1021/acsnano.7b02726] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 05/22/2017] [Indexed: 05/19/2023]
Abstract
Transition metal dichalcogenides (TMDCs), together with other two-dimensional (2D) materials, have attracted great interest due to the unique optical and electrical properties of atomically thin layers. In order to fulfill their potential, developing large-area growth and understanding the properties of TMDCs have become crucial. Here, we have used molecular beam epitaxy (MBE) to grow atomically thin MoSe2 on GaAs(111)B. No intermediate compounds were detected at the interface of as-grown films. Careful optimization of the growth temperature can result in the growth of highly aligned films with only two possible crystalline orientations due to broken inversion symmetry. As-grown films can be transferred onto insulating substrates, allowing their optical and electrical properties to be probed. By using polymer electrolyte gating, we have achieved ambipolar transport in MBE-grown MoSe2. The temperature-dependent transport characteristics can be explained by the 2D variable-range hopping (2D-VRH) model, indicating that the transport is strongly limited by the disorder in the film.
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Affiliation(s)
- Ming-Wei Chen
- Electrical
Engineering Institute, École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Dmitry Ovchinnikov
- Electrical
Engineering Institute, École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sorin Lazar
- FEI
Electron Optics, 5600 KA Eindhoven, The Netherlands
| | - Michele Pizzochero
- Institute
of Physics, École Polytechnique Fédérale
de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Michael Brian Whitwick
- Electrical
Engineering Institute, École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Alessandro Surrente
- Laboratoire
National
des Champs Magnétiques Intenses CNRS-UGA-UPS-INSA, 143 avenue de Rangueil, 31400 Toulouse, France
| | - Michał Baranowski
- Laboratoire
National
des Champs Magnétiques Intenses CNRS-UGA-UPS-INSA, 143 avenue de Rangueil, 31400 Toulouse, France
- Department
of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wrocław, Poland
| | - Oriol Lopez Sanchez
- Electrical
Engineering Institute, École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Philippe Gillet
- Institute
of Physics, École Polytechnique Fédérale
de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Paulina Plochocka
- Laboratoire
National
des Champs Magnétiques Intenses CNRS-UGA-UPS-INSA, 143 avenue de Rangueil, 31400 Toulouse, France
| | - Oleg V. Yazyev
- Institute
of Physics, École Polytechnique Fédérale
de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Andras Kis
- Electrical
Engineering Institute, École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- E-mail:
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27
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Hao J, Li B, Jung HY, Liu F, Hong S, Jung YJ, Kar S. Vapor-Phase-Gating-Induced Ultrasensitive Ion Detection in Graphene and Single-Walled Carbon Nanotube Networks. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1606883. [PMID: 28393408 DOI: 10.1002/adma.201606883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/13/2017] [Indexed: 06/07/2023]
Abstract
Designing ultrasensitive detectors often requires complex architectures, high-voltage operations, and sophisticated low-noise measurements. In this work, it is shown that simple low-bias two-terminal DC-conductance values of graphene and single-walled carbon nanotubes are extremely sensitive to ionized gas molecules. Incident ions form an electrode-free, dielectric- or electrolyte-free, bias-free vapor-phase top-gate that can efficiently modulate carrier densities up to ≈0.6 × 1013 cm-2 . Surprisingly, the resulting current changes are several orders of magnitude larger than that expected from conventional electrostatic gating, suggesting the possible role of a current-gain inducing mechanism similar to those seen in photodetectors. These miniature detectors demonstrate charge-current amplification factor values exceeding 108 A C-1 in vacuum with undiminished responses in open air, and clearly distinguish between positive and negative ions sources. At extremely low rates of ion incidence, detector currents show stepwise changes with time, and calculations suggest that these stepwise changes can result from arrival of individual ions. These sensitive ion detectors are used to demonstrate a proof-of-concept low-cost, amplifier-free, light-emitting-diode-based low-power ion-indicator.
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Affiliation(s)
- Ji Hao
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Bo Li
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA
- Department of Mechanical Engineering, Villanova University, Villanova, PA, 19085, USA
| | - Hyun Young Jung
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA
- Department of Energy Engineering, Gyeongnam National University of Science and Technology, Jinju-Si, Gyeongnam, 660-758, South Korea
| | - Fangze Liu
- Department of Physics, Northeastern University, Boston, MA, 02115, USA
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Sanghyun Hong
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Yung Joon Jung
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Swastik Kar
- Department of Physics, Northeastern University, Boston, MA, 02115, USA
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, P. R. China
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28
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Highly gate-tuneable Rashba spin-orbit interaction in a gate-all-around InAs nanowire metal-oxide-semiconductor field-effect transistor. Sci Rep 2017; 7:930. [PMID: 28424473 PMCID: PMC5430424 DOI: 10.1038/s41598-017-01080-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 03/27/2017] [Indexed: 11/08/2022] Open
Abstract
III-V semiconductors have been intensively studied with the goal of realizing metal-oxide-semiconductor field-effect transistors (MOSFETs) with high mobility, a high on-off ratio, and low power consumption as next-generation transistors designed to replace current Si technology. Of these semiconductors, a narrow band-gap semiconductor InAs has strong Rashba spin-orbit interaction, thus making it advantageous in terms of both high field-effect transistor (FET) performance and efficient spin control. Here we report a high-performance InAs nanowire MOSFET with a gate-all-around (GAA) structure, where we simultaneously control the spin precession using the Rashba interaction. Our FET has a high on-off ratio (104~106) and a high field-effect mobility (1200 cm2/Vs) and both values are comparable to those of previously reported nanowire FETs. Simultaneously, GAA geometry combined with high- κ dielectric enables the creation of a large and uniform coaxial electric field (>107 V/m), thereby achieving highly controllable Rashba coupling (1 × 10-11 eVm within a gate-voltage swing of 1 V), i.e. an operation voltage one order of magnitude smaller than those of back-gated nanowire MOSFETs. Our demonstration of high FET performance and spin controllability offers a new way of realizing low-power consumption nanoscale spin MOSFETs.
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29
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Chen Z, Yuan H, Xie Y, Lu D, Inoue H, Hikita Y, Bell C, Hwang HY. Dual-Gate Modulation of Carrier Density and Disorder in an Oxide Two-Dimensional Electron System. NANO LETTERS 2016; 16:6130-6136. [PMID: 27605459 DOI: 10.1021/acs.nanolett.6b02348] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Carrier density and disorder are two crucial parameters that control the properties of correlated two-dimensional electron systems. In order to disentangle their individual contributions to quantum phenomena, independent tuning of these two parameters is required. Here, by utilizing a hybrid liquid/solid electric dual-gate geometry acting on the conducting LaAlO3/SrTiO3 heterointerface, we obtain an additional degree of freedom to strongly modify the electron confinement profile and thus the strength of interfacial scattering, independent from the carrier density. A dual-gate controlled nonlinear Hall effect is a direct manifestation of this profile, which can be quantitatively understood by a Poisson-Schrödinger sub-band model. In particular, the large nonlinear dielectric response of SrTiO3 enables a very wide range of tunable density and disorder, far beyond that for conventional semiconductors. Our study provides a broad framework for understanding various reported phenomena at the LaAlO3/SrTiO3 interface.
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Affiliation(s)
- Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
| | - Hongtao Yuan
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Yanwu Xie
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Di Lu
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
| | - Hisashi Inoue
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Christopher Bell
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- H.H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
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30
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Xi X, Berger H, Forró L, Shan J, Mak KF. Gate Tuning of Electronic Phase Transitions in Two-Dimensional NbSe_{2}. PHYSICAL REVIEW LETTERS 2016; 117:106801. [PMID: 27636485 DOI: 10.1103/physrevlett.117.106801] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Indexed: 06/06/2023]
Abstract
Recent experimental advances in atomically thin transition metal dichalcogenide (TMD) metals have unveiled a range of interesting phenomena including the coexistence of charge-density-wave (CDW) order and superconductivity down to the monolayer limit. The atomic thickness of two-dimensional (2D) TMD metals also opens up the possibility for control of these electronic phase transitions by electrostatic gating. Here, we demonstrate reversible tuning of superconductivity and CDW order in model 2D TMD metal NbSe_{2} by an ionic liquid gate. A variation up to ∼50% in the superconducting transition temperature has been observed. Both superconductivity and CDW order can be strengthened (weakened) by increasing (reducing) the carrier density in 2D NbSe_{2}. The doping dependence of these phase transitions can be understood as driven by a varying electron-phonon coupling strength induced by the gate-modulated carrier density and the electronic density of states near the Fermi surface.
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Affiliation(s)
- Xiaoxiang Xi
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Helmuth Berger
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - László Forró
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Jie Shan
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Kin Fai Mak
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
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31
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Ovchinnikov D, Gargiulo F, Allain A, Pasquier DJ, Dumcenco D, Ho CH, Yazyev OV, Kis A. Disorder engineering and conductivity dome in ReS2 with electrolyte gating. Nat Commun 2016; 7:12391. [PMID: 27499375 PMCID: PMC4979068 DOI: 10.1038/ncomms12391] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/29/2016] [Indexed: 11/09/2022] Open
Abstract
Atomically thin rhenium disulphide (ReS2) is a member of the transition metal dichalcogenide family of materials. This two-dimensional semiconductor is characterized by weak interlayer coupling and a distorted 1T structure, which leads to anisotropy in electrical and optical properties. Here we report on the electrical transport study of mono- and multilayer ReS2 with polymer electrolyte gating. We find that the conductivity of monolayer ReS2 is completely suppressed at high carrier densities, an unusual feature unique to monolayers, making ReS2 the first example of such a material. Using dual-gated devices, we can distinguish the gate-induced doping from the electrostatic disorder induced by the polymer electrolyte itself. Theoretical calculations and a transport model indicate that the observed conductivity suppression can be explained by a combination of a narrow conduction band and Anderson localization due to electrolyte-induced disorder.
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Affiliation(s)
- Dmitry Ovchinnikov
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Fernando Gargiulo
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Adrien Allain
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Diego José Pasquier
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Dumitru Dumcenco
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ching-Hwa Ho
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan
| | - Oleg V Yazyev
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Andras Kis
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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32
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Kumar N, Kitoh A, Inoue IH. Anomalous enhancement of the sheet carrier density beyond the classic limit on a SrTiO3 surface. Sci Rep 2016; 6:25789. [PMID: 27174141 PMCID: PMC4865841 DOI: 10.1038/srep25789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/22/2016] [Indexed: 11/28/2022] Open
Abstract
Electrostatic carrier accumulation on an insulating (100) surface of SrTiO3 by fabricating a field effect transistor with Parylene-C (6 nm)/HfO2 (20 nm) bilayer gate insulator has revealed a mystifying phenomenon: sheet carrier density is about 10 times as large as ( is the sheet capacitance of the gate insulator, VG is the gate voltage, and e is the elementary charge). The channel is so clean to exhibit small subthreshod swing of 170 mV/decade and large mobility of 11 cm2/Vs for of 1 × 1014 cm−2 at room temperature. Since does not depend on either VG nor time duration, beyond is solely ascribed to negative charge compressibility of the carriers, which was in general considered as due to exchange interactions among electrons in the small limit. However, the observed is too large to be naively understood by the framework. Alternative ideas are proposed in this work.
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Affiliation(s)
- Neeraj Kumar
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Ai Kitoh
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Isao H Inoue
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
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33
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Petach TA, Mehta A, Marks R, Johnson B, Toney MF, Goldhaber-Gordon D. Voltage-Controlled Interfacial Layering in an Ionic Liquid on SrTiO3. ACS NANO 2016; 10:4565-4569. [PMID: 26959226 DOI: 10.1021/acsnano.6b00645] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
One prominent structural feature of ionic liquids near surfaces is formation of alternating layers of anions and cations. However, how this layering responds to an applied potential is poorly understood. We focus on the structure of 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate (BMPY-FAP) near the surface of a strontium titanate (SrTiO3) electric double-layer transistor. Using X-ray reflectivity, we show that at positive bias the individual layers in the ionic liquid double layer thicken and the layering persists further away from the interface. We model the reflectivity using a modified distorted crystal model with alternating cation and anion layers, which allows us to extract the charge density and the potential near the surface. We find that the charge density is strongly oscillatory with and without applied potential and that with an applied gate bias of 4.5 V the first two layers become significantly more cation rich than at zero bias, accumulating about 2.5 × 10(13) cm(-2) excess charge density.
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Affiliation(s)
- Trevor A Petach
- Department of Physics, Stanford University , Palo Alto, California 94305, United States
| | - Apurva Mehta
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Ronald Marks
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Bart Johnson
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Michael F Toney
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
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34
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Zeng S, Lü W, Huang Z, Liu Z, Han K, Gopinadhan K, Li C, Guo R, Zhou W, Ma HH, Jian L, Venkatesan T. Liquid-Gated High Mobility and Quantum Oscillation of the Two-Dimensional Electron Gas at an Oxide Interface. ACS NANO 2016; 10:4532-4537. [PMID: 26974812 DOI: 10.1021/acsnano.6b00409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electric field effect in electronic double layer transistor (EDLT) configuration with ionic liquids as the dielectric materials is a powerful means of exploring various properties in different materials. Here, we demonstrate the modulation of electrical transport properties and extremely high mobility of two-dimensional electron gas at LaAlO3/SrTiO3 (LAO/STO) interface through ionic liquid-assisted electric field effect. With a change of the gate voltages, the depletion of charge carrier and the resultant enhancement of electron mobility up to 19 380 cm(2)/(V s) are realized, leading to quantum oscillations of the conductivity at the LAO/STO interface. The present results suggest that high-mobility oxide interfaces, which exhibit quantum phenomena, could be obtained by ionic liquid-assisted field effect.
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Affiliation(s)
- Shengwei Zeng
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Weiming Lü
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Zhen Huang
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Zhiqi Liu
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Kun Han
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Kalon Gopinadhan
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Changjian Li
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) , 28 Medical Drive, Singapore 117456, Singapore
| | - Rui Guo
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Materials Science and Engineering, National University of Singapore , Singapore 117575, Singapore
| | - Wenxiong Zhou
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Haijiao Harsan Ma
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Linke Jian
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Thirumalai Venkatesan
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) , 28 Medical Drive, Singapore 117456, Singapore
- Department of Materials Science and Engineering, National University of Singapore , Singapore 117575, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore , Singapore 117576, Singapore
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35
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Controlling many-body states by the electric-field effect in a two-dimensional material. Nature 2015; 529:185-9. [PMID: 26700810 DOI: 10.1038/nature16175] [Citation(s) in RCA: 165] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Accepted: 10/19/2015] [Indexed: 12/23/2022]
Abstract
To understand the complex physics of a system with strong electron-electron interactions, the ideal is to control and monitor its properties while tuning an external electric field applied to the system (the electric-field effect). Indeed, complete electric-field control of many-body states in strongly correlated electron systems is fundamental to the next generation of condensed matter research and devices. However, the material must be thin enough to avoid shielding of the electric field in the bulk material. Two-dimensional materials do not experience electrical screening, and their charge-carrier density can be controlled by gating. Octahedral titanium diselenide (1T-TiSe2) is a prototypical two-dimensional material that reveals a charge-density wave (CDW) and superconductivity in its phase diagram, presenting several similarities with other layered systems such as copper oxides, iron pnictides, and crystals of rare-earth elements and actinide atoms. By studying 1T-TiSe2 single crystals with thicknesses of 10 nanometres or less, encapsulated in two-dimensional layers of hexagonal boron nitride, we achieve unprecedented control over the CDW transition temperature (tuned from 170 kelvin to 40 kelvin), and over the superconductivity transition temperature (tuned from a quantum critical point at 0 kelvin up to 3 kelvin). Electrically driving TiSe2 over different ordered electronic phases allows us to study the details of the phase transitions between many-body states. Observations of periodic oscillations of magnetoresistance induced by the Little-Parks effect show that the appearance of superconductivity is directly correlated with the spatial texturing of the amplitude and phase of the superconductivity order parameter, corresponding to a two-dimensional matrix of superconductivity. We infer that this superconductivity matrix is supported by a matrix of incommensurate CDW states embedded in the commensurate CDW states. Our results show that spatially modulated electronic states are fundamental to the appearance of two-dimensional superconductivity.
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