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Zhu Z, Yasui T, Zhao X, Liu Q, Morita S, Li Y, Yonezu A, Nagashima K, Takahashi T, Osada M, Matsuda R, Yanagida T, Baba Y. Engineering Interface Defects and Interdiffusion at the Degenerate Conductive In 2O 3/Al 2O 3 Interface for Stable Electrodes in a Saline Solution. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37486017 DOI: 10.1021/acsami.3c03603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
A low-temperature Al2O3 deposition process provides a simplified method to form a conductive two-dimensional electron gas (2DEG) at the metal oxide/Al2O3 heterointerface. However, the impact of key factors of the interface defects and cation interdiffusion on the interface is still not well understood. Furthermore, there is still a blank space in terms of applications that go beyond the understanding of the interface's electrical conductivity. In this work, we carried out a systematic experimental study by oxygen plasma pretreatment and thermal annealing post-treatment to study the impact of interface defects and cation interdiffusion at the In2O3/Al2O3 interface on the electrical conductance, respectively. Combining the trends in electrical conductance with the structural characteristics, we found that building a sharp interface with a high concentration of interface defects provides a reliable approach to producing such a conductive interface. After applying this conductive interface as electrodes for fabricating a field-effect transistor (FET) device, we found that this interface electrode exhibited ultrastability in phosphate-buffered saline (PBS), a commonly used biological saline solution. This study provides new insights into the formation of conductive 2DEGs at metal oxide/Al2O3 interfaces and lays the foundation for further applications as electrodes in bioelectronic devices.
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Affiliation(s)
- Zetao Zhu
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
- Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Takao Yasui
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
- Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
- Department of Life Science and Technology, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8501, Japan
- Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Kawaguchi 332-0012, Saitama, Japan
| | - Xixi Zhao
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Quanli Liu
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Shu Morita
- Department of Materials Chemistry & Institute of Materials and Systems for Sustainability (IMaSS), Nagoya University, Nagoya 464-8603, Japan
| | - Yan Li
- Department of Materials Chemistry & Institute of Materials and Systems for Sustainability (IMaSS), Nagoya University, Nagoya 464-8603, Japan
| | - Akira Yonezu
- Department of Materials Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Kazuki Nagashima
- Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Kawaguchi 332-0012, Saitama, Japan
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Tsunaki Takahashi
- Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Kawaguchi 332-0012, Saitama, Japan
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Minoru Osada
- Department of Materials Chemistry & Institute of Materials and Systems for Sustainability (IMaSS), Nagoya University, Nagoya 464-8603, Japan
| | - Ryotaro Matsuda
- Department of Materials Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Takeshi Yanagida
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga 816-8580, Fukuoka, Japan
| | - Yoshinobu Baba
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
- Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
- Institute of Quantum Life Science, National Institutes for Quantum Science and Technology (QST), Anagawa 4-9-1, Inage-ku, Chiba 263-8555, Japan
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Wang J, Fang H, Nie F, Chen Y, Tian G, Shi C, He B, Lü W, Zheng L. Domain Switching in BaTiO 3 Films Induced by an Ultralow Mechanical Force. ACS APPLIED MATERIALS & INTERFACES 2022; 14:48917-48925. [PMID: 36281808 DOI: 10.1021/acsami.2c15062] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Low-energy switching of ferroelectrics has been intensively studied for energy-efficient nanoelectronics. Mechanical force is considered as a low-energy consumption technique for switching the polarization of ferroelectric films due to the flexoelectric effect. Reduced threshold force is always desirable for the considerations of energy saving, easy domain manipulation, and sample surface protection. In this work, the mechanical switching behaviors of BaTiO3/SrRuO3 epitaxial heterostructure grown on Nb:SrTiO3 (001) substrate are reported. Domain switching is found to be induced by an extremely low tip force of 320 nN (estimated pressure ∼0.09 GPa), which is the lowest value ever reported. This low mechanical threshold is attributed to the small compressive strain, the low oxygen vacancy concentration in BaTiO3 film, and the high conductivity of the SrRuO3 electrode. The flexoelectricity under both perpendicular mechanical load (point measurement) and sliding load (scanning measurement) are investigated. The sliding mode shows a much stronger flexoelectric field for its strong trailing field. The mechanical written domains show several advantages in comparison with the electrically written ones: low charge injection, low energy consumption, high density, and improved stability. The ultralow-pressure switching in this work presents opportunities for next-generation low-energy and high-density memory electronics.
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Affiliation(s)
- Jie Wang
- Functional Materials and Acousto-Optic Instruments Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin150080, China
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Hong Fang
- Functional Materials and Acousto-Optic Instruments Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin150080, China
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Fang Nie
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan250100, China
| | - Yanan Chen
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Gang Tian
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan250100, China
| | - Chaoqun Shi
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Bin He
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Weiming Lü
- Functional Materials and Acousto-Optic Instruments Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin150080, China
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Limei Zheng
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan250100, China
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Mechanical writing of electrical polarization in poly (L-lactic) acid. Acta Biomater 2022; 139:249-258. [PMID: 34111519 DOI: 10.1016/j.actbio.2021.05.057] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 05/11/2021] [Accepted: 05/29/2021] [Indexed: 01/21/2023]
Abstract
Stimuli responsive materials are found in a broad range of applications, from energy harvesters to biomolecular sensors. Here, we report the production of poly (L-lactic acid) (PLLA) thin films that exhibit a mechanical stress responsive behaviour. By simply applying a mechanical stress through an AFM tip, a local electrical polarization was generated and measured by Kelvin Probe Force Microscopy. We showed that the magnitude of the stress generated electrical polarization can be manipulated by varying the thickness or crystallization state of the PLLA thin films. Besides exhibiting a mechanical stress-response behaviour with potential for energy harvesting and sensor applications, we show by AFM that these platforms react to mechanical forces with physiological relevance: interaction forces as low as a cell sheet migrating over a substrate or larger ones as the fluid induced stresses in bone tissue. In living tissues, as most mechanical stimuli are transduced as strain gradients for the anatomical structures, these mechanically responsive substrates can be used as ex vivo platforms to study the protein and cells response over a large range of electrical stimuli amplitude. As a proof of concept, selective adsorption of a human fibronectin was demonstrated by local patterning of the stimuli responsive PLLA films. STATEMENT OF SIGNIFICANCE: Bioelectricity is inherent to the formation and repair of living tissues and electrical stimulation has been recognized for promoting regeneration. Given the proven beneficial effects of electric fields and the absence of a suitable method of stimulation, there is a clinical need for smart substrates, which can generate a polarization (charges) to promote tissue regeneration without the need of external devices. In this work, we report the fabrication of poly(L-lactic) acid platforms that exhibit a mechanical stress responsive behaviour when subjected to physiologically relevant forces. This behaviour can be tailored by varying the thickness or crystallization state of the PLLA films. We further demonstrate the biofunctionality of such platforms by exploiting the mechanically-induced charge for adhesion protein adsorption.
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Kim D, Lim J, Lee S, Soufiani AM, Choi E, Ievlev AV, Borodinov N, Liu Y, Ovchinnikova OS, Ahmadi M, Lim S, Sharma P, Seidel J, Noh JH, Yun JS. Microstructural Evaluation of Phase Instability in Large Bandgap Metal Halide Perovskites. ACS NANO 2021; 15:20391-20402. [PMID: 34846843 DOI: 10.1021/acsnano.1c08726] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The optoelectronic performance of organic-inorganic halide perovskite (OIHP)-based devices has been improved in recent years. Particularly, solar cells fabricated using mixed-cations and mixed-halides have outperformed their single-cation and single-halide counterparts. Yet, a systematic evaluation of the microstructural behavior of mixed perovskites is missing despite their known composition-dependent photoinstability. Here, we explore microstructural inhomogeneity in (FAPbI3)x(MAPbBr3)1-x using advanced scanning probe microscopy techniques. Contact potential difference (CPD) maps measured by Kelvin probe force microscopy show an increased fraction of grains exhibiting a low CPD with flat topography as MAPbBr3 concentration is increased. The higher portion of low CPD contributes to asymmetric CPD distribution curves. Chemical analysis reveals these grains being rich in MA, Pb, and I. The composition-dependent phase segregation upon illumination, reflected on the emergence of a low-energy peak emission in the original photoluminescence spectra, arises from the formation of such grains with flat topology. Bias-dependent piezo-response force microscopy measurements, in these grains, further confirm vigorous ion migration and cause a hysteretic piezo-response. Our results, therefore, provide insights into the microstructural evaluation of phase segregation and ion migration in OIHPs pointing toward process optimization as a mean to further enhance their optoelectronic performance.
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Affiliation(s)
- Dohyung Kim
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
- Joint Institute for Advanced Materials, Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jihoo Lim
- Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Seungmin Lee
- School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Arman Mahboubi Soufiani
- Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Eunyoung Choi
- Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Anton V Ievlev
- The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Nikolay Borodinov
- The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yongtao Liu
- The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Olga S Ovchinnikova
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Mahshid Ahmadi
- Joint Institute for Advanced Materials, Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Sean Lim
- Electron Microscope Unit, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Pankaj Sharma
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Jan Seidel
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Jun Hong Noh
- School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Jae Sung Yun
- Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
- Department of Electrical and Electronic Engineering, Advanced Technology Institute (ATI), University of Surrey, Guildford GU2 7XH, U.K
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Yao L, Inkinen S, Komsa HP, van Dijken S. Structural Phase Transitions to 2D and 3D Oxygen Vacancy Patterns in a Perovskite Film Induced by Electrical and Mechanical Nanoprobing. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2006273. [PMID: 33590636 DOI: 10.1002/smll.202006273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 01/12/2021] [Indexed: 06/12/2023]
Abstract
Oxygen vacancy migration and ordering in perovskite oxides enable manipulation of material properties through changes in the cation oxidation state and the crystal lattice. In thin-films, oxygen vacancies conventionally order into equally spaced planes. Here, it is shown that the planar 2D symmetry is broken if a mechanical nanoprobe restricts the chemical lattice expansion that the vacancies generate. Using in situ scanning transmission electron microscopy, a transition from a perovskite structure to a 3D vacancy-ordered phase in an epitaxial La2/3 Sr1/3 MnO3- δ film during voltage pulsing under local mechanical straining is imaged. The never-before-seen ordering pattern consists of a complex network of distorted oxygen tetrahedra, pentahedra, and octahedra that, together, produce a corrugated atomic structure with lattice constants varying between 3.5 and 4.6 Å. The giant lattice distortions respond sensitively to strain variations, offering prospects for non-volatile nanoscale physical property control driven by voltage and gated by strain.
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Affiliation(s)
- Lide Yao
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, Aalto, FI-00076, Finland
| | - Sampo Inkinen
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, Aalto, FI-00076, Finland
| | - Hannu-Pekka Komsa
- Department of Applied Physics, Aalto University School of Science, P.O. Box 11100, Aalto, FI-00076, Finland
- Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, FI-90014, Finland
| | - Sebastiaan van Dijken
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, Aalto, FI-00076, Finland
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Ding J, Cheng J, Dogan F, Li Y, Lin W, Yao Y, Manchon A, Yang K, Wu T. Two-Dimensional Electron Gas at the Spinel/Perovskite Interface: Suppression of Polar Catastrophe by an Ultrathin Layer of Interfacial Defects. ACS APPLIED MATERIALS & INTERFACES 2020; 12:42982-42991. [PMID: 32829635 DOI: 10.1021/acsami.0c13337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional electron gas (2DEG) at the interface between two insulating perovskite oxides has attracted much interest for both fundamental physics and potential applications. Here, we report the discovery of a new 2DEG formed at the interface between spinel MgAl2O4 and perovskite SrTiO3. Transport measurements, electron microscopy imaging, and first-principles calculations reveal that the interfacial 2DEG is closely related to the symmetry breaking at the MgAl2O4/SrTiO3 interface. The critical film thickness for the insulator-to-metal transition is approximately 32 Å, which is twice as thick as that reported on the widely studied LaAlO3/SrTiO3 system. Scanning transmission electron microscopy imaging indicates the formation of interfacial Ti-Al antisite defects with a thickness of ∼4 Å. First-principles density functional theory calculations indicate that the coexistence of the antisite defects and surface oxygen vacancies may explain the formation of interfacial 2DEG as well as the observed critical film thickness. The discovery of 2DEG at the spinel/perovskite interface introduces a new material platform for designing oxide interfaces with desired characteristics.
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Affiliation(s)
- Junfeng Ding
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Jianli Cheng
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92093-0448, United States
| | - Fatih Dogan
- College of Engineering and Technology, American University of the Middle East, Kuwait
| | - Yangyang Li
- Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore
| | - Weinan Lin
- Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore
| | - Yingbang Yao
- School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, People's Republic of China
| | - Aurelien Manchon
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
- Aix-Marseille Univ, CNRS, CINaM, Marseille 13288, France
| | - Kesong Yang
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92093-0448, United States
| | - Tom Wu
- School of Materials Science and Engineering, University of New South Wales (UNSW), Sydney, NSW 2052, Australia
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Zhang G, Liu W, Chen J, Shen S. Nonlinear electrochemomechanical modelling of electrochemical strain microscopy imaging. NANOTECHNOLOGY 2020; 31:315704. [PMID: 32294633 DOI: 10.1088/1361-6528/ab898c] [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
Electrochemical strain microscopy (ESM) is a powerful tool to resolve ionic transport and electrochemical processes with a nanoscale resolution. To ascertain the underlying mechanism that governs the signal generation of ESM imaging, a fully coupled nonlinear electrochemomechanical model based on the finite element method is developed and applied to LiMn2O4 particles. The frequency dependence of the ESM response, in particular the response at high frequencies used in the detection regime, is investigated in detail. The performed analysis demonstrates that the error induced by the decoupling approximation increases with decreasing bias frequency due to the relatively large variation in ion concentration. In the high frequency regime, the results reveal that the stress effect is negligible and local electroneutrality holds, providing the simplification of numerical simulation for ESM imaging. By applying an alternative current voltage, we suggest that the detectable signal observed in ESM imaging can be attributed to the Vegard effect, which was controversial in previous linear models. The local distribution of ion concentration shows that the ionic reorganization only takes place near the tip-surface junction, the spatial extent of which can be described by two relevant lengths, the contact radius and ion drift length, which determine the spatial lateral resolution and depth resolution, respectively, in ESM imaging. Through a parametric study, the electromigration is proved to be dominant at high frequencies and the relationship between ESM amplitude and some parameters may offer a strategy to measure local electrochemical reactivity. The impact of contact force is evaluated and the results indicate that the local compression reduces ion concentration and the resultant ESM signal in the detection regime. Thus attention must be paid to the contact force when a comparison between different measurements is conducted. The combination of the numerical model and experiment holds the promise of quantitative probing of local electrochemical parameters in solids.
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Affiliation(s)
- Gongxi Zhang
- State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049 People's Republic of China
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Thomas L, Guérin D, Quinard B, Jacquet E, Mattana R, Seneor P, Vuillaume D, Mélin T, Lenfant S. Conductance switching at the nanoscale of diarylethene derivative self-assembled monolayers on La 0.7Sr 0.3MnO 3. NANOSCALE 2020; 12:8268-8276. [PMID: 32236177 DOI: 10.1039/c9nr09928j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report on the phosphonic acid route for the grafting of functional molecules, optical switch (dithienylethene diphosphonic acid, DDA), on La0.7Sr0.3MnO3 (LSMO). Compact self-assembled monolayers (SAMs) of DDA are formed on LSMO as studied by topographic atomic force microscopy (AFM), ellipsometry, water contact angle measurements and X-ray photoemission spectroscopy (XPS). The conducting AFM measurements show that the electrical conductance of LSMO/DDA is about 3 decades below that of a bare LSMO substrate. Moreover, the presence of the DDA SAM suppresses the known conductance switching of the LSMO substrate that is induced by mechanical and/or bias constraints during C-AFM measurements. A partial light-induced conductance switching between the open and closed forms of the DDA is observed for the LSMO/DDA/C-AFM tip molecular junctions (closed/open conductance ratio of about 8). We show that, in the case of long-time exposure to UV light, this feature can be masked by a non-reversible decrease (a factor of about 15) of the conductance of the LSMO electrode.
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Affiliation(s)
- L Thomas
- Institute for Electronics Microelectronics and Nanotechnology (IEMN), CNRS, Univ. Lille, 59652 Villeneuve d'Ascq, France.
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Bourlier Y, Bérini B, Frégnaux M, Fouchet A, Aureau D, Dumont Y. Transfer of Epitaxial SrTiO 3 Nanothick Layers Using Water-Soluble Sacrificial Perovskite Oxides. ACS APPLIED MATERIALS & INTERFACES 2020; 12:8466-8474. [PMID: 31971768 DOI: 10.1021/acsami.9b21047] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The integration of functional thin film materials with adaptable properties is essential for the development of new paradigms in information technology. Among them, complex oxides with perovskite structures have huge potential based on the particularly vast diversity of physical properties. Here, we demonstrate the possibility of transferring perovskite oxide materials like SrTiO3 onto a silicon substrate using an environmentally friendly process at the nanoscale by means of a water-soluble perovskite sacrificial layer, SrVO3. Based on in situ monitoring atomic force microscopy and photoemission studies, we reveal that the dissolution is initiated from a strontium-rich phase at the extreme surface of SrVO3. The nanothick SrTiO3-transferred layer onto silicon presents appropriate morphology and monocrystalline quality, providing a proof of concept for the integration and development of all-perovskite-oxide electronics or "oxitronics" onto any Si-based substrate.
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Affiliation(s)
- Yoan Bourlier
- Groupe d'Etude de la Matière Condensée (GEMaC) , Université de Versailles Saint-Quentin en Yvelines, Université Paris-Saclay CNRS , 45 Avenue des Etats-Unis , 78035 Versailles , France
- Institut Lavoisier de Versailles (ILV) , Université de Versailles Saint-Quentin en Yvelines, Université Paris-Saclay CNRS , 45 Avenue des Etats-Unis , 78035 Versailles , France
| | - Bruno Bérini
- Groupe d'Etude de la Matière Condensée (GEMaC) , Université de Versailles Saint-Quentin en Yvelines, Université Paris-Saclay CNRS , 45 Avenue des Etats-Unis , 78035 Versailles , France
| | - Mathieu Frégnaux
- Institut Lavoisier de Versailles (ILV) , Université de Versailles Saint-Quentin en Yvelines, Université Paris-Saclay CNRS , 45 Avenue des Etats-Unis , 78035 Versailles , France
| | - Arnaud Fouchet
- Normandie Univ, ENSICAEN, UNICAEN, CNRS, CRISMAT , 14000 Caen , France
| | - Damien Aureau
- Institut Lavoisier de Versailles (ILV) , Université de Versailles Saint-Quentin en Yvelines, Université Paris-Saclay CNRS , 45 Avenue des Etats-Unis , 78035 Versailles , France
| | - Yves Dumont
- Groupe d'Etude de la Matière Condensée (GEMaC) , Université de Versailles Saint-Quentin en Yvelines, Université Paris-Saclay CNRS , 45 Avenue des Etats-Unis , 78035 Versailles , France
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Zhu L, Chen S, Zhang H, Zhang J, Sun Y, Li X, Xu Z, Wang L, Sun J, Gao P, Wang W, Bai X. Strain-Inhibited Electromigration of Oxygen Vacancies in LaCoO 3. ACS APPLIED MATERIALS & INTERFACES 2019; 11:36800-36806. [PMID: 31539219 DOI: 10.1021/acsami.9b08406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The oxygen vacancy profile in LaCoO3 exhibits rich phases with distinct structures, symmetries, and magnetic properties. Exploration of the lattice degree of freedom of LaCoO3 in the transition between these different structural phases may provide a route to enable new functionality in oxide materials with potential applications. To date, the oxygen vacancy profile transition in LaCoO3 has mainly been induced by transition-metal doping or thermal treatment. Epitaxial strain was proposed to compete with the lattice degree of freedom but has not yet been rationalized. Here, the experimental findings of strain-inhibited structural transition from perovskite to brownmillerite during the electromigration of oxygen vacancies in epitaxial LaCoO3 thin films are demonstrated. The results indicate that the oxygen vacancy ordering phase induced by the electric field is suppressed locally by both epitaxial strain field and external loads shown by in situ aberration-corrected (scanning)/ transmission electron microscopy. The demonstrated complex interplay between the electric and strain fields in the structural transitions of LaCoO3 opens up prospects for manipulating new physical properties by external excitations and/or strain engineering of a substrate.
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Affiliation(s)
- Liang Zhu
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Shulin Chen
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
- State Key Laboratory of Advanced Welding and Joining , Harbin Institute of Technology , Harbin 150001 , China
| | - Hui Zhang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Jine Zhang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Yuanwei Sun
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
| | - Xiaomin Li
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
| | - Zhi Xu
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , China
| | - Lifen Wang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , China
| | - Peng Gao
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100871 , China
| | - Wenlong Wang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , China
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , China
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11
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Yang Q, Tao L, Zhang Y, Li M, Jiang Z, Tsymbal EY, Alexandrov V. Ferroelectric Tunnel Junctions Enhanced by a Polar Oxide Barrier Layer. NANO LETTERS 2019; 19:7385-7393. [PMID: 31514498 DOI: 10.1021/acs.nanolett.9b03056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ferroelectric tunnel junctions (FTJs) have recently aroused significant interest due to the interesting physics controlling their properties and potential application in nonvolatile memory devices. In this work, we propose a new concept to design high-performance FTJs based on ferroelectric/polar-oxide composite barriers. Using density functional theory calculations, we model electronic and transport properties of LaNiO3/PbTiO3/LaAlO3/LaNiO3 tunnel junctions and demonstrate that an ultrathin polar LaAlO3(001) layer strongly enhances their performance. We predict a tunneling electroresistance (TER) effect in these FTJs with an OFF/ON resistance ratio exceeding a factor of 104 and ON state resistance as low as about 1 kΩμm2. Such an enhanced performance is driven by the ionic charge at the PbTiO3/LaAlO3 interface, which significantly increases transmission across the FTJ when the ferroelectric polarization of PbTiO3 is pointing against the intrinsic electric field produced by this ionic charge. This is due to the formation of a two-dimensional (2D) electron or hole gas, depending on the LaAlO3 termination being (LaO)+ or (AlO2)-, respectively, which is formed to screen the polarization charge of the nonuniform polarization state. This 2D electron (hole) gas can be switched ON and OFF by the reversal of ferroelectric polarization, resulting in the giant TER effect. The proposed design suggests a new direction for creating FTJs with a stable and reversible ferroelectric polarization, a sizable TER effect, and a low-resistance-area product, as required for memory applications.
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Affiliation(s)
- Qiong Yang
- Department of Chemical and Biomolecular Engineering , University of Nebraska , Lincoln , Nebraska 68588 , United States
- School of Materials Science and Engineering , Xiangtan University , Xiangtan , Hunan 411105 , China
| | - Lingling Tao
- Department of Physics and Astronomy , University of Nebraska , Lincoln , Nebraska 68588 , United States
| | - Yuke Zhang
- School of Materials Science and Engineering , Xiangtan University , Xiangtan , Hunan 411105 , China
| | - Ming Li
- Department of Physics and Astronomy , University of Nebraska , Lincoln , Nebraska 68588 , United States
| | - Zhen Jiang
- Department of Chemical and Biomolecular Engineering , University of Nebraska , Lincoln , Nebraska 68588 , United States
| | - Evgeny Y Tsymbal
- Department of Physics and Astronomy , University of Nebraska , Lincoln , Nebraska 68588 , United States
| | - Vitaly Alexandrov
- Department of Chemical and Biomolecular Engineering , University of Nebraska , Lincoln , Nebraska 68588 , United States
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12
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Zhang F, Lv P, Zhang Y, Huang S, Wong CM, Yau HM, Chen X, Wen Z, Jiang X, Zeng C, Hong J, Dai JY. Modulating the Electrical Transport in the Two-Dimensional Electron Gas at LaAlO_{3}/SrTiO_{3} Heterostructures by Interfacial Flexoelectricity. PHYSICAL REVIEW LETTERS 2019; 122:257601. [PMID: 31347866 DOI: 10.1103/physrevlett.122.257601] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 04/12/2019] [Indexed: 06/10/2023]
Abstract
Thin film flexoelectricity is attracting more attention because of its enhanced effect and potential application in electronic devices. Here we find that a mechanical bending induced flexoelectricity significantly modulates the electrical transport properties of the interfacial two-dimensional electron gas (2DEG) at the LaAlO_{3}/SrTiO_{3} (LAO/STO) heterostructure. Under variant bending states, both the carrier density and mobility of the 2DEG are changed according to the flexoelectric polarization direction, showing an electric field effect modulation. By measuring the flexoelectric response of LAO, it is found that the effective flexoelectricity in the LAO thin film is enhanced by 3 orders compared to its bulk. These results broaden the horizon of study on the flexoelectricity effect in the hetero-oxide interface and more research on the oxide interfacial flexoelectricity may be stimulated.
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Affiliation(s)
- Fan Zhang
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, 999077 Kowloon, Hong Kong
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina, 27606, USA
| | - Peng Lv
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Yiteng Zhang
- College of Physics, Qingdao University, Qingdao, 266071, China
| | - Shujin Huang
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina, 27606, USA
| | - Chi-Man Wong
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, 999077 Kowloon, Hong Kong
| | - Hei-Man Yau
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, 999077 Kowloon, Hong Kong
| | - Xinxin Chen
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, 999077 Kowloon, Hong Kong
| | - Zheng Wen
- College of Physics, Qingdao University, Qingdao, 266071, China
| | - Xiaoning Jiang
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina, 27606, USA
| | - Changgan Zeng
- International Center for Quantum Design of Functional Materials, Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Jiawang Hong
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Ji-Yan Dai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, 999077 Kowloon, Hong Kong
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13
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Yang MM, Iqbal AN, Peters JJP, Sanchez AM, Alexe M. Strain-gradient mediated local conduction in strained bismuth ferrite films. Nat Commun 2019; 10:2791. [PMID: 31243266 PMCID: PMC6594973 DOI: 10.1038/s41467-019-10664-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 05/15/2019] [Indexed: 11/27/2022] Open
Abstract
It has been recently shown that the strain gradient is able to separate the light-excited electron-hole pairs in semiconductors, but how it affects the photoelectric properties of the photo-active materials remains an open question. Here, we demonstrate the critical role of the strain gradient in mediating local photoelectric properties in the strained BiFeO3 thin films by systematically characterizing the local conduction with nanometre lateral resolution in both dark and illuminated conditions. Due to the giant strain gradient manifested at the morphotropic phase boundaries, the associated flexo-photovoltaic effect induces on one side an enhanced photoconduction in the R-phase, and on the other side a negative photoconductivity in the morphotropic \documentclass[12pt]{minimal}
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\begin{document}$$T\prime$$\end{document}T′-phase. This work offers insight and implication of the strain gradient on the electronic properties in both optoelectronic and photovoltaic devices. In semiconductors strain gradients can separate light induced electron-hole pairs via the flexo-photovoltaic effect. Here the authors show that this effect can also account for the enhancement of the photoconduction in certain phase regions at the morphotropic phase boundary in Bismuth Ferrite films.
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Affiliation(s)
- Ming-Min Yang
- Department of Physics, The University of Warwick, Coventry, CV4 7AL, UK.
| | - Affan N Iqbal
- Department of Physics, The University of Warwick, Coventry, CV4 7AL, UK
| | | | - Ana M Sanchez
- Department of Physics, The University of Warwick, Coventry, CV4 7AL, UK
| | - Marin Alexe
- Department of Physics, The University of Warwick, Coventry, CV4 7AL, UK.
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14
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Vasić B, Konstantinović Z, Pannunzio-Miner E, Valencia S, Abrudan R, Gajić R, Pomar A. Nanoscale mechanical control of surface electrical properties of manganite films with magnetic nanoparticles. NANOSCALE ADVANCES 2019; 1:1763-1771. [PMID: 36134228 PMCID: PMC9418570 DOI: 10.1039/c8na00301g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 02/18/2019] [Indexed: 06/11/2023]
Abstract
Mechanical control of electrical properties in complex heterostructures, consisting of magnetic FeO x nanoparticles on top of manganite films, is achieved using atomic force microscope (AFM) based methods. Under applied pressure of the AFM tip, drop of the electrical conductivity is observed inducing an electrically insulating state upon a critical normal load. Current and surface potential maps suggest that the switching process is mainly governed by the flexoelectric field induced at the sample surface. The relaxation process of the electrical surface potential indicates that the diffusion of oxygen vacancies from the bulk of the manganite films towards the sample surface is the dominant relaxation mechanism. The magnetic FeO x nanoparticles, staying attached to the sample surface after the rubbing, protect the underlying manganite films and provide stability of the observed resistive switching effect. The employed mechanical control gives a new freedom in the design of resistive switching devices since it does not depend on the film thickness, and biasing is not needed.
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Affiliation(s)
- Borislav Vasić
- Graphene Laboratory of Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade Pregrevica 118 11080 Belgrade Serbia
| | - Zorica Konstantinović
- Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade Pregrevica 118 11080 Belgrade Serbia
| | - Elisa Pannunzio-Miner
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC Campus de la UAB 08193 Bellaterra Spain
| | - Sergio Valencia
- Helmholtz-Zentrum Berlin für Materialien und Energie Albert-Einstein-Str. 15 12489 Berlin Germany
| | - Radu Abrudan
- Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum 44780 Bochum Germany
| | - Radoš Gajić
- Graphene Laboratory of Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade Pregrevica 118 11080 Belgrade Serbia
| | - Alberto Pomar
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC Campus de la UAB 08193 Bellaterra Spain
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15
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Luo ZD, Park DS, Yang MM, Alexe M. Light-Controlled Nanoscopic Writing of Electronic Memories Using the Tip-Enhanced Bulk Photovoltaic Effect. ACS APPLIED MATERIALS & INTERFACES 2019; 11:8276-8283. [PMID: 30719908 DOI: 10.1021/acsami.8b22638] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The light control of nonvolatile nanoscale memories could represent a fundamental step toward novel optoelectronic devices with memory and logic functionalities. However, most of the proposed devices exhibit insufficient control in terms of the reversibility, data retention, photosensitivity, limited-photoactive area, and so forth. Here, in a proof-of-concept work, we demonstrate the use of the tip-enhanced bulk photovoltaic (BPV) effect to realize programmable nanoscopic writing of nonphotoactive electronic devices by light control. We show that electronic properties of solid-state memory devices can be reversibly and location-precisely manipulated in the nanoscale using the BPV effect in combination with the nanoscale contact connection, that is, atomic force microscopy (AFM) probe technique in this work. More than 105% reversible switching of tunneling electroresistance of ferroelectric tunnel junctions is exclusively achieved by light control. Using the same light-controlled AFM probe technique, we also present precise nanoscopic and multiple-state writing of LaAlO3/SrTiO3 two-dimensional electron gas (2DEG)-based field-effect transistors. The tip-enhanced BPV effect can offer a novel avenue for reversible and multistate light control of a wide range of electronic memory devices in the nanoscale and may lead to more sophisticated functionalities in optoelectronic applications.
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Affiliation(s)
- Zheng-Dong Luo
- Department of Physics , University of Warwick , Coventry CV4 7AL , U.K
| | - Dae-Sung Park
- Centre for Innovation Competence SiLi-nano , Martin-Luther-University Halle-Wittenberg , Halle (Saale) 06120 , Germany
| | - Ming-Min Yang
- Department of Physics , University of Warwick , Coventry CV4 7AL , U.K
| | - Marin Alexe
- Department of Physics , University of Warwick , Coventry CV4 7AL , U.K
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16
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Iglesias L, Gómez A, Gich M, Rivadulla F. Tuning Oxygen Vacancy Diffusion through Strain in SrTiO 3 Thin Films. ACS APPLIED MATERIALS & INTERFACES 2018; 10:35367-35373. [PMID: 30249093 DOI: 10.1021/acsami.8b12019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Understanding diffusion of oxygen vacancies in oxides under different external stimuli is crucial for the design of ion-based electronic devices, improvement of catalytic performance, and so forth. In this manuscript, using an external electric field produced by an atomic force microscopy tip, we obtain the room-temperature diffusion coefficient of oxygen-vacancies in thin films of SrTiO3 under compressive/tensile epitaxial strain. Tensile strain produces a substantial increase of the diffusion coefficient, facilitating the mobility of vacancies through the film. Additionally, the effect of tip bias, pulse time, and temperature on the local concentration of vacancies is investigated. These are important parameters of control in the production and stabilization of nonvolatile states in ion-based devices. Our findings show the key role played by strain for the control of oxygen vacancy migration in thin-film oxides.
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Affiliation(s)
- Lucia Iglesias
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Departamento de Química-Física , Universidade de Santiago de Compostela , 15782 Santiago de Compostela , Spain
| | - Andrés Gómez
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , Campus UAB , Bellaterra , Catalonia 08193 , Spain
| | - Martí Gich
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , Campus UAB , Bellaterra , Catalonia 08193 , Spain
| | - Francisco Rivadulla
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Departamento de Química-Física , Universidade de Santiago de Compostela , 15782 Santiago de Compostela , Spain
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17
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Seol D, Yang SM, Jesse S, Choi M, Hwang I, Choi T, Park BH, Kalinin SV, Kim Y. Dynamic mechanical control of local vacancies in NiO thin films. NANOTECHNOLOGY 2018; 29:275709. [PMID: 29658891 DOI: 10.1088/1361-6528/aabe59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The manipulation of local ionic behavior via external stimuli in oxide systems is of great interest because it can help in directly tuning material properties. Among external stimuli, mechanical force has attracted intriguing attention as novel stimulus for ionic modulation. Even though effectiveness of mechanical force on local ionic modulation has been validated in terms of static effect, its real-time i.e., dynamic, behavior under an application of the force is barely investigated in spite of its crucial impact on device performance such as force or pressure sensors. In this study, we explore dynamic ionic behavior modulated by mechanical force in NiO thin films using electrochemical strain microscopy (ESM). Ionically mediated ESM hysteresis loops were significantly varied under an application of mechanical force. Based on these results, we were able to investigate relative relationship between the force and voltage effects on ionic motion and, further, control effectively ionic behavior through combination of mechanical and electrical stimuli. Our results can provide comprehensive information on the effect of mechanical forces on ionic dynamics in ionic systems.
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Affiliation(s)
- Daehee Seol
- School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
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18
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Alsubaie A, Sharma P, Lee JH, Kim JY, Yang CH, Seidel J. Uniaxial Strain-Controlled Ferroelastic Domain Evolution in BiFeO 3. ACS APPLIED MATERIALS & INTERFACES 2018; 10:11768-11775. [PMID: 29557167 DOI: 10.1021/acsami.8b01711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We investigate the effect of variable uniaxial tensile strain on the evolution of 71° ferroelastic domains in (001)-oriented epitaxial BiFeO3 (BFO) thin films using piezoresponse force microscopy (PFM). For this purpose, a newly designed bending stage has been employed, which allows tensile bending as wells as in situ PFM characterization. In situ PFM imaging reveals polarization-strain correlations at the nanoscale. Specifically, ferroelastic domains with in-plane polarization along the direction of applied tensile strain expand, whereas the adjoining domains with orthogonal in-plane polarization contract. The switching is mediated by significant domain wall roughening and opposite displacement of the successive walls. Further, the domains with long-range order are more susceptible to an applied external mechanical stimulus compared to the domains, which exhibit short-range periodicity. In addition, the imprint state of film reverses direction under applied tensile strain. Finally, the strain-induced changes in the domain structure and wall motion are fully reversible and revert to their as-grown state upon release of the applied stress. The strain-induced non-180° polarization rotation constitutes a route to control connected functionalities, such as magnetism, via coupled in-plane rotation of the magnetic plane in multiferroic BFO thin films.
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Affiliation(s)
- Abdullah Alsubaie
- School of Materials Science and Engineering , UNSW Sydney , Sydney , NSW 2052 , Australia
- School of Physics , Taif University , Taif 26571 , Kingdom of Saudi Arabia
| | - Pankaj Sharma
- School of Materials Science and Engineering , UNSW Sydney , Sydney , NSW 2052 , Australia
| | - Jin Hong Lee
- Unité Mixte de Physique , CNRS, Thales, Université Paris Sud, Université Paris-Saclay , 91767 Palaiseau , France
| | | | | | - Jan Seidel
- School of Materials Science and Engineering , UNSW Sydney , Sydney , NSW 2052 , Australia
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19
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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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20
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Frenkel Y, Haham N, Shperber Y, Bell C, Xie Y, Chen Z, Hikita Y, Hwang HY, Salje EKH, Kalisky B. Imaging and tuning polarity at SrTiO 3 domain walls. NATURE MATERIALS 2017; 16:1203-1208. [PMID: 28920939 DOI: 10.1038/nmat4966] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 07/13/2017] [Indexed: 06/07/2023]
Abstract
Electrostatic fields tune the ground state of interfaces between complex oxide materials. Electronic properties, such as conductivity and superconductivity, can be tuned and then used to create and control circuit elements and gate-defined devices. Here we show that naturally occurring twin boundaries, with properties that are different from their surrounding bulk, can tune the LaAlO3/SrTiO3 interface 2DEG at the nanoscale. In particular, SrTiO3 domain boundaries have the unusual distinction of remaining highly mobile down to low temperatures, and were recently suggested to be polar. Here we apply localized pressure to an individual SrTiO3 twin boundary and detect a change in LaAlO3/SrTiO3 interface current distribution. Our data directly confirm the existence of polarity at the twin boundaries, and demonstrate that they can serve as effective tunable gates. As the location of SrTiO3 domain walls can be controlled using external field stimuli, our findings suggest a novel approach to manipulate SrTiO3-based devices on the nanoscale.
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Affiliation(s)
- Yiftach Frenkel
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Noam Haham
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yishai Shperber
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Christopher Bell
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Yanwu Xie
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Zhejiang University, Hangzhou 310027, China
- Department of Applied Physics, Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford University, Stanford, California 94305, USA
| | - Zhuoyu Chen
- Department of Applied Physics, Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford University, Stanford, California 94305, USA
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford University, Stanford, California 94305, USA
| | - Ekhard K H Salje
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
| | - Beena Kalisky
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
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21
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Controlled manipulation of oxygen vacancies using nanoscale flexoelectricity. Nat Commun 2017; 8:615. [PMID: 28931810 PMCID: PMC5607007 DOI: 10.1038/s41467-017-00710-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 07/18/2017] [Indexed: 11/09/2022] Open
Abstract
Oxygen vacancies, especially their distribution, are directly coupled to the electromagnetic properties of oxides and related emergent functionalities that have implications for device applications. Here using a homoepitaxial strontium titanate thin film, we demonstrate a controlled manipulation of the oxygen vacancy distribution using the mechanical force from a scanning probe microscope tip. By combining Kelvin probe force microscopy imaging and phase-field simulations, we show that oxygen vacancies can move under a stress-gradient-induced depolarisation field. When tailored, this nanoscale flexoelectric effect enables a controlled spatial modulation. In motion, the scanning probe tip thereby deterministically reconfigures the spatial distribution of vacancies. The ability to locally manipulate oxygen vacancies on-demand provides a tool for the exploration of mesoscale quantum phenomena and engineering multifunctional oxide devices.The properties of complex oxides such as strontium titanate are strongly affected by the presence and distribution of oxygen vacancies. Here, the authors demonstrate that a scanning probe microscope tip can be used to manipulate vacancies by the flexoelectric effect.
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22
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Lee PW, Singh VN, Guo GY, Liu HJ, Lin JC, Chu YH, Chen CH, Chu MW. Hidden lattice instabilities as origin of the conductive interface between insulating LaAlO3 and SrTiO3. Nat Commun 2016; 7:12773. [PMID: 27624682 PMCID: PMC5027288 DOI: 10.1038/ncomms12773] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 08/01/2016] [Indexed: 11/09/2022] Open
Abstract
The metallic interface between insulating LaAlO3 and SrTiO3 opens up the field of oxide electronics. With more than a decade of researches on this heterostructure, the origin of the interfacial conductivity, however, remains unsettled. Here we resolve this long-standing puzzle by atomic-scale observation of electron-gas formation for screening hidden lattice instabilities, rejuvenated near the interface by epitaxial strain. Using atomic-resolution imaging and electron spectroscopy, the generally accepted notions of polar catastrophe and cation intermixing for the metallic interface are discounted. Instead, the conductivity onset at the critical thickness of 4-unit cell LaAlO3 on SrTiO3 substrate is accompanied with head-to-head ferroelectric-like polarizations across the interface due to strain-rejuvenated ferroelectric-like instabilities in the materials. The divergent depolarization fields of the head-to-head polarizations cast the interface into an electron reservoir, forming screening electron gas in SrTiO3 with LaAlO3 hosting complementary localized holes. The ferroelectric-like polarizations and electron–hole juxtaposition reveal the cooperative nature of metallic LaAlO3/SrTiO3. The origin of interfacial conductivity between two insulating oxides, LaAlO3 and SrTiO3, remains elusive despite a long time research. Here, Lee et al. report atomic-scale observation of electron-gas formation for screening hidden ferroelectric-like lattice instabilities, discounting the role of polar catastrophe and cation intermixing.
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Affiliation(s)
- P W Lee
- Department of Physics, National Taiwan University, Taipei 106, Taiwan.,Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan
| | - V N Singh
- Department of Physics, National Taiwan University, Taipei 106, Taiwan.,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | - G Y Guo
- Department of Physics, National Taiwan University, Taipei 106, Taiwan.,Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan
| | - H-J Liu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan
| | - J-C Lin
- Institute of Physics, Academia Sinica, Taipei 105, Taiwan
| | - Y-H Chu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan.,Institute of Physics, Academia Sinica, Taipei 105, Taiwan
| | - C H Chen
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan.,Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - M-W Chu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan
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23
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Zhuang HL, Zhang L, Xu H, Kent PRC, Ganesh P, Cooper VR. Tunable one-dimensional electron gas carrier densities at nanostructured oxide interfaces. Sci Rep 2016; 6:25452. [PMID: 27151049 PMCID: PMC4858694 DOI: 10.1038/srep25452] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 04/15/2016] [Indexed: 11/29/2022] Open
Abstract
The emergence of two-dimensional metallic states at the LaAlO3/SrTiO3 (LAO/STO) heterostructure interface is known to occur at a critical thickness of four LAO layers. This insulator to-metal transition can be explained through the “polar catastrophe” mechanism arising from the divergence of the electrostatic potential at the LAO surface. Here, we demonstrate that nanostructuring can be effective in reducing or eliminating this critical thickness. Employing a modified “polar catastrophe” model, we demonstrate that the nanowire heterostructure electrostatic potential diverges more rapidly as a function of layer thickness than in a regular heterostructure. Our first-principles calculations indicate that for nanowire heterostructures a robust one-dimensional electron gas (1DEG) can be induced, consistent with recent experimental observations of 1D conductivity at LAO/STO steps. Similar to LAO/STO 2DEGs, we predict that the 1D charge density decays laterally within a few unit cells away from the nanowire; thus providing a mechanism for tuning the carrier dimensionality between 1D and 2D conductivity. Our work provides insight into the creation and manipulation of charge density at an oxide heterostructure interface and therefore may be beneficial for future nanoelectronic devices and for the engineering of novel quantum phases.
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Affiliation(s)
- Houlong L Zhuang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Lipeng Zhang
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Haixuan Xu
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - P R C Kent
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States.,Computer Science and Mathematics Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - P Ganesh
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Valentino R Cooper
- Materials Science and Technology Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
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Chernikova A, Kozodaev M, Markeev A, Negrov D, Spiridonov M, Zarubin S, Bak O, Buragohain P, Lu H, Suvorova E, Gruverman A, Zenkevich A. Ultrathin Hf0.5Zr0.5O2 Ferroelectric Films on Si. ACS APPLIED MATERIALS & INTERFACES 2016; 8:7232-7. [PMID: 26931409 DOI: 10.1021/acsami.5b11653] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Because of their immense scalability and manufacturability potential, the HfO2-based ferroelectric films attract significant attention as strong candidates for application in ferroelectric memories and related electronic devices. Here, we report the ferroelectric behavior of ultrathin Hf0.5Zr0.5O2 films, with the thickness of just 2.5 nm, which makes them suitable for use in ferroelectric tunnel junctions, thereby further expanding the area of their practical application. Transmission electron microscopy and electron diffraction analysis of the films grown on highly doped Si substrates confirms formation of the fully crystalline non-centrosymmetric orthorhombic phase responsible for ferroelectricity in Hf0.5Zr0.5O2. Piezoresponse force microscopy and pulsed switching testing performed on the deposited top TiN electrodes provide further evidence of the ferroelectric behavior of the Hf0.5Zr0.5O2 films. The electronic band lineup at the top TiN/Hf0.5Zr0.5O2 interface and band bending at the adjacent n(+)-Si bottom layer attributed to the polarization charges in Hf0.5Zr0.5O2 have been determined using in situ X-ray photoelectron spectroscopy analysis. The obtained results represent a significant step toward the experimental implementation of Si-based ferroelectric tunnel junctions.
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Affiliation(s)
- Anna Chernikova
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - Maksim Kozodaev
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - Andrei Markeev
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - Dmitrii Negrov
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - Maksim Spiridonov
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - Sergei Zarubin
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - Ohheum Bak
- Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States
| | - Pratyush Buragohain
- Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States
| | - Haidong Lu
- Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States
| | - Elena Suvorova
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
- École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland
- A.V. Shubnikov Institute of Crystallography, Leninsky pr. 59, Moscow 119333, Russia
| | - Alexei Gruverman
- Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States
| | - Andrei Zenkevich
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
- NRNU "Moscow Engineering Physics Institute", Moscow 115409, Russia
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