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Zhang X, Zhang Z, Jin C, Zhang M, Bian C, Chen Y, Zhu R, Wang Z, Cheng Z. Sm, Nd doped BiFeO 3epitaxial film for photodetector with extremely large on-off current ratio. NANOTECHNOLOGY 2024; 35:225202. [PMID: 38387098 DOI: 10.1088/1361-6528/ad2c5d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 02/21/2024] [Indexed: 02/24/2024]
Abstract
BiFeO3is one of the star materials in the field of ferroelectric photovoltaic for its relatively narrow bandgap (2.2-2.7 eV) and better visible light absorption. However, a high temperature over 600 °C is indispensable in the usual BiFeO3growth process, which may lead to impure phase, interdiffusion of components near the interface, oxygen vacancy and ferrous iron ions, which will result in large leakage current and greatly aggravate the ferroelectricity and photoelectric response. Here we prepared Sm, Nd doped epitaxial BiFeO3film via a rapid microwave assisted hydrothermal process at low temperature. The Bi0.9Sm0.5Nd0.5FeO3film exhibits narrow bandgap (1.35 eV) and photo response to red light, the on-off current ratio reaches over 105. The decrease in band gap and +2/+3 variable element doping are responsible for the excellent photo response. The excellent photo response performances are much better than any previously reported BiFeO3films, which has great potential for applications in photodetection, ferroelectric photovoltaic and optoelectronic devices.
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Affiliation(s)
- Xin Zhang
- School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing, 211167, People's Republic of China
| | - Ziyi Zhang
- School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing, 211167, People's Republic of China
| | - Chen Jin
- School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing, 211167, People's Republic of China
| | - Maoru Zhang
- School of Materials Science and Engineering, Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing, 211189, People's Republic of China
| | - Chengyang Bian
- School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing, 211167, People's Republic of China
| | - Ying Chen
- School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing, 211167, People's Republic of China
| | - Ruijian Zhu
- School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing, 211167, People's Republic of China
| | - Zengmei Wang
- School of Materials Science and Engineering, Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing, 211189, People's Republic of China
| | - Zhenxiang Cheng
- National Institute for Materials Science (NIMS), Sengen1-2-1, Tsukuba, 305-0047, Japan dInstitute for Superconducting and Electronics Materials, University of Wollongong, Innovation Campus, Fairy Meadow, NSW, 2519, Australia
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2
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Gradauskaite E, Meier QN, Gray N, Sarott MF, Scharsach T, Campanini M, Moran T, Vogel A, Del Cid-Ledezma K, Huey BD, Rossell MD, Fiebig M, Trassin M. Defeating depolarizing fields with artificial flux closure in ultrathin ferroelectrics. NATURE MATERIALS 2023; 22:1492-1498. [PMID: 37783942 PMCID: PMC10713449 DOI: 10.1038/s41563-023-01674-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 08/25/2023] [Indexed: 10/04/2023]
Abstract
Material surfaces encompass structural and chemical discontinuities that often lead to the loss of the property of interest in so-called dead layers. It is particularly problematic in nanoscale oxide electronics, where the integration of strongly correlated materials into devices is obstructed by the thickness threshold required for the emergence of their functionality. Here we report the stabilization of ultrathin out-of-plane ferroelectricity in oxide heterostructures through the design of an artificial flux-closure architecture. Inserting an in-plane-polarized ferroelectric epitaxial buffer provides the continuity of polarization at the interface; despite its insulating nature, we observe the emergence of polarization in our out-of-plane-polarized model of ferroelectric BaTiO3 from the very first unit cell. In BiFeO3, the flux-closure approach stabilizes a 251° domain wall. Its unusual chirality is probably associated with the ferroelectric analogue to the Dzyaloshinskii-Moriya interaction. We, thus, see that in an adaptively engineered geometry, the depolarizing-field-screening properties of an insulator can even surpass those of a metal and be a source of functionality. This could be a useful insight on the road towards the next generation of oxide electronics.
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Affiliation(s)
| | | | - Natascha Gray
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | | | | | | | - Thomas Moran
- Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, USA
| | | | - Karla Del Cid-Ledezma
- Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, USA
| | - Bryan D Huey
- Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, USA
| | | | - Manfred Fiebig
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Morgan Trassin
- Department of Materials, ETH Zurich, Zurich, Switzerland.
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3
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Lin C, Zhang Z, Dai Z, Wu M, Liu S, Chen J, Hua C, Lu Y, Zhang F, Lou H, Dong H, Zeng Q, Ma J, Pi X, Zhou D, Wu Y, Tian H, Rappe AM, Ren Z, Han G. Solution epitaxy of polarization-gradient ferroelectric oxide films with colossal photovoltaic current. Nat Commun 2023; 14:2341. [PMID: 37095113 PMCID: PMC10126087 DOI: 10.1038/s41467-023-37823-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 03/27/2023] [Indexed: 04/26/2023] Open
Abstract
Solution growth of single-crystal ferroelectric oxide films has long been pursued for the low-cost development of high-performance electronic and optoelectronic devices. However, the established principles of vapor-phase epitaxy cannot be directly applied to solution epitaxy, as the interactions between the substrates and the grown materials in solution are quite different. Here, we report the successful epitaxy of single-domain ferroelectric oxide films on Nb-doped SrTiO3 single-crystal substrates by solution reaction at a low temperature of ~200 oC. The epitaxy is mainly driven by an electronic polarization screening effect at the interface between the substrates and the as-grown ferroelectric oxide films, which is realized by the electrons from the doped substrates. Atomic-level characterization reveals a nontrivial polarization gradient throughout the films in a long range up to ~500 nm because of a possible structural transition from the monoclinic phase to the tetragonal phase. This polarization gradient generates an extremely high photovoltaic short-circuit current density of ~2.153 mA/cm2 and open-circuit voltage of ~1.15 V under 375 nm light illumination with power intensity of 500 mW/cm2, corresponding to the highest photoresponsivity of ~4.306×10-3 A/W among all known ferroelectrics. Our results establish a general low-temperature solution route to produce single-crystal gradient films of ferroelectric oxides and thus open the avenue for their broad applications in self-powered photo-detectors, photovoltaic and optoelectronic devices.
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Affiliation(s)
- Chen Lin
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Zijun Zhang
- Center of Electron Microscope, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Zhenbang Dai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104-6323, USA
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Mengjiao Wu
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Shi Liu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, 310024, China
| | - Jialu Chen
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Chenqiang Hua
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of physics, Zhejiang University, Hangzhou, 310027, China
| | - Yunhao Lu
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of physics, Zhejiang University, Hangzhou, 310027, China
| | - Fei Zhang
- Center for High Pressure Science and Technology Advanced Research, Shanghai, 201203, China
| | - Hongbo Lou
- Center for High Pressure Science and Technology Advanced Research, Shanghai, 201203, China
| | - Hongliang Dong
- Center for High Pressure Science and Technology Advanced Research, Shanghai, 201203, China
| | - Qiaoshi Zeng
- Center for High Pressure Science and Technology Advanced Research, Shanghai, 201203, China
| | - Jing Ma
- State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, 100091, China
| | - Xiaodong Pi
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
- Institute of Advanced Semiconductors & Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 311215, China
| | - Dikui Zhou
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
- Research Center for Intelligent Sensing, Zhejiang Lab, Hangzhou, 311100, China
| | - Yongjun Wu
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
- Research Center for Intelligent Sensing, Zhejiang Lab, Hangzhou, 311100, China
| | - He Tian
- Center of Electron Microscope, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China.
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104-6323, USA
| | - Zhaohui Ren
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China.
- Research Center for Intelligent Sensing, Zhejiang Lab, Hangzhou, 311100, China.
| | - Gaorong Han
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China.
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4
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Vogel A, Ruiz Caridad A, Nordlander J, Sarott MF, Meier QN, Erni R, Spaldin NA, Trassin M, Rossell MD. Origin of the Critical Thickness in Improper Ferroelectric Thin Films. ACS APPLIED MATERIALS & INTERFACES 2023; 15:18482-18492. [PMID: 36996320 DOI: 10.1021/acsami.3c00412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Improper ferroelectrics are expected to be more robust than conventional ferroelectrics against depolarizing field effects and to exhibit a much-desired absence of critical thickness. Recent studies, however, revealed the loss of ferroelectric response in epitaxial improper ferroelectric thin films. Here, we investigate improper ferroelectric hexagonal YMnO3 thin films and find that the polarization suppression, and hence functionality, in the thinner films is due to oxygen off-stoichiometry. We demonstrate that oxygen vacancies form on the film surfaces to provide the necessary charge to screen the large internal electric field resulting from the positively charged YMnO3 surface layers. Additionally, we show that by modifying the oxygen concentration of the films, the phase transition temperatures can be substantially tuned. We anticipate that our findings are also valid for other ferroelectric oxide films and emphasize the importance of controlling the oxygen content and cation oxidation states in ferroelectrics for their successful integration in nanoscale applications.
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Affiliation(s)
- Alexander Vogel
- Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Department of Materials, Eidgenössische Technische Hochschule Zürich, 8092 Zürich, Switzerland
| | - Alicia Ruiz Caridad
- Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Johanna Nordlander
- Department of Materials, Eidgenössische Technische Hochschule Zürich, 8092 Zürich, Switzerland
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Martin F Sarott
- Department of Materials, Eidgenössische Technische Hochschule Zürich, 8092 Zürich, Switzerland
| | - Quintin N Meier
- Université Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France
| | - Rolf Erni
- Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Nicola A Spaldin
- Department of Materials, Eidgenössische Technische Hochschule Zürich, 8092 Zürich, Switzerland
| | - Morgan Trassin
- Department of Materials, Eidgenössische Technische Hochschule Zürich, 8092 Zürich, Switzerland
| | - Marta D Rossell
- Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
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5
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Huxter WS, Sarott MF, Trassin M, Degen CL. Imaging ferroelectric domains with a single-spin scanning quantum sensor. NATURE PHYSICS 2023; 19:644-648. [PMID: 37205126 PMCID: PMC10185469 DOI: 10.1038/s41567-022-01921-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 12/14/2022] [Indexed: 05/21/2023]
Abstract
The ability to sensitively image electric fields is important for understanding many nanoelectronic phenomena, including charge accumulation at surfaces1 and interfaces2 and field distributions in active electronic devices3. A particularly exciting application is the visualization of domain patterns in ferroelectric and nanoferroic materials4,5, owing to their potential in computing and data storage6-8. Here, we use a scanning nitrogen-vacancy (NV) microscope, well known for its use in magnetometry9, to image domain patterns in piezoelectric (Pb[Zr0.2Ti0.8]O3) and improper ferroelectric (YMnO3) materials through their electric fields. Electric field detection is enabled by measuring the Stark shift of the NV spin10,11 using a gradiometric detection scheme12. Analysis of the electric field maps allows us to discriminate between different types of surface charge distributions, as well as to reconstruct maps of the three-dimensional electric field vector and charge density. The ability to measure both stray electric and magnetic fields9,13 under ambient conditions opens opportunities for the study of multiferroic and multifunctional materials and devices8,14.
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Affiliation(s)
| | | | - Morgan Trassin
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Christian L. Degen
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Quantum Center, ETH Zurich, Zurich, Switzerland
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6
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Multilevel polarization switching in ferroelectric thin films. Nat Commun 2022; 13:3159. [PMID: 35672404 PMCID: PMC9174202 DOI: 10.1038/s41467-022-30823-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 05/19/2022] [Indexed: 11/11/2022] Open
Abstract
Ferroic order is characterized by hystereses with two remanent states and therefore inherently binary. The increasing interest in materials showing non-discrete responses, however, calls for a paradigm shift towards continuously tunable remanent ferroic states. Device integration for oxide nanoelectronics furthermore requires this tunability at the nanoscale. Here we demonstrate that we can arbitrarily set the remanent ferroelectric polarization at nanometric dimensions. We accomplish this in ultrathin epitaxial PbZr0.52Ti0.48O3 films featuring a dense pattern of decoupled nanometric 180° domains with a broad coercive-field distribution. This multilevel switching is achieved by driving the system towards the instability at the morphotropic phase boundary. The phase competition near this boundary in combination with epitaxial strain increases the responsiveness to external stimuli and unlocks new degrees of freedom to nano-control the polarization. We highlight the technological benefits of non-binary switching by demonstrating a quasi-continuous tunability of the non-linear optical response and of tunnel electroresistance. Setting any polarization value in ferroelectric thin films is a key step for their implementation in neuromorphic devices. Here, the authors demonstrate continuous modulation of the remanent polarization at the nanoscale in PbZr0.52Ti0.48O3 films.
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7
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Liu S, Shan Y, Hong Y, Jin Y, Lin W, Zhang Z, Xu X, Wang Z, Yang Z. 3D Conformal Fabrication of Piezoceramic Films. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2106030. [PMID: 35484719 PMCID: PMC9218746 DOI: 10.1002/advs.202106030] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 04/05/2022] [Indexed: 05/05/2023]
Abstract
Piezoceramic films are an essential class of energy-conversion materials that have been widely used in the electronics industry. Although current methods create a great freedom for fabricating high-quality piezoceramic films, it requires well-controlled synthesis conditions, including special high-cost equipment and planar substrates particularly. The limited substrate selections hinder the applications of piezoceramic films in 3D conformal structures where most objects possess complex curvilinear surfaces. To overcome such limitations, a fast, energy-efficient, and cost-effective approach, named flame treated spray (FTS) coating, is developed for preparing piezoceramic films on free-form surfaces. The flame treatment significantly enhances the hydrophilicity of a substrate, assisting in forming a uniform and continuous thin film. The followed spray coating deposits hundreds of nanometers to several micrometers thick films on 3D free-form surfaces. Given the size controllability and arbitrary surface compatibility of the FTS method, a highly conformal piezoelectric tactile sensor array (4 × 4) is assembled on a spherical surface for mimicking robot fingers and an on-site thin-film sensor on the wing of an aircraft model to monitor the vibration in real-time during flight. The FTS film deposition offers a highly promising methodology for the application of functional thin-film from micro- to marcoscale devices, regardless of conformal problems.
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Affiliation(s)
- Shiyuan Liu
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
| | - Yao Shan
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
| | - Ying Hong
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
| | - Yuankai Jin
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
| | - Weikang Lin
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
| | - Zhuomin Zhang
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
| | - Xiaote Xu
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
| | - Zuankai Wang
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
| | - Zhengbao Yang
- Department of Mechanical EngineeringCity University of Hong KongHong KongChina
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8
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Alikin D, Abramov A, Turygin A, Ievlev A, Pryakhina V, Karpinsky D, Hu Q, Jin L, Shur V, Tselev A, Kholkin A. Exploring Charged Defects in Ferroelectrics by the Switching Spectroscopy Piezoresponse Force Microscopy. SMALL METHODS 2022; 6:e2101289. [PMID: 34967150 DOI: 10.1002/smtd.202101289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/15/2021] [Indexed: 06/14/2023]
Abstract
Monitoring the charged defect concentration at the nanoscale is of critical importance for both the fundamental science and applications of ferroelectrics. However, up-to-date, high-resolution study methods for the investigation of structural defects, such as transmission electron microscopy, X-ray tomography, etc., are expensive and demand complicated sample preparation. With an example of the lanthanum-doped bismuth ferrite ceramics, a novel method is proposed based on the switching spectroscopy piezoresponse force microscopy (SSPFM) that allows probing the electric potential from buried subsurface charged defects in the ferroelectric materials with a nanometer-scale spatial resolution. When compared with the composition-sensitive methods, such as neutron diffraction, X-ray photoelectron spectroscopy, and local time-of-flight secondary ion mass spectrometry, the SSPFM sensitivity to the variation of the electric potential from the charged defects is shown to be equivalent to less than 0.3 at% of the defect concentration. Additionally, the possibility to locally evaluate dynamics of the polarization screening caused by the charged defects is demonstrated, which is of significant interest for further understanding defect-mediated processes in ferroelectrics.
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Affiliation(s)
- Denis Alikin
- School of Natural Sciences and Mathematics, Ural Federal University, Ekaterinburg, 620000, Russia
| | - Alexander Abramov
- School of Natural Sciences and Mathematics, Ural Federal University, Ekaterinburg, 620000, Russia
| | - Anton Turygin
- School of Natural Sciences and Mathematics, Ural Federal University, Ekaterinburg, 620000, Russia
| | - Anton Ievlev
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Victoria Pryakhina
- School of Natural Sciences and Mathematics, Ural Federal University, Ekaterinburg, 620000, Russia
| | - Dmitry Karpinsky
- Scientific-Practical Materials Research Centre of NAS of Belarus, Minsk, 220072, Belarus
| | - Qingyuan Hu
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Li Jin
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Vladimir Shur
- School of Natural Sciences and Mathematics, Ural Federal University, Ekaterinburg, 620000, Russia
| | - Alexander Tselev
- Department of Physics & CICECO, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Andrei Kholkin
- School of Natural Sciences and Mathematics, Ural Federal University, Ekaterinburg, 620000, Russia
- Department of Physics & CICECO, University of Aveiro, 3810-193, Aveiro, Portugal
- Piezo- and Magnetoelectric Materials Research & Development Centre, Research School of Chemistry & Applied Biomedical Sciences, National Research Tomsk Polytechnic University, Tomsk, 634050, Russia
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9
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Signatures of enhanced out-of-plane polarization in asymmetric BaTiO 3 superlattices integrated on silicon. Nat Commun 2022; 13:265. [PMID: 35017533 PMCID: PMC8752726 DOI: 10.1038/s41467-021-27898-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 12/17/2021] [Indexed: 11/30/2022] Open
Abstract
In order to bring the diverse functionalities of transition metal oxides into modern electronics, it is imperative to integrate oxide films with controllable properties onto the silicon platform. Here, we present asymmetric LaMnO3/BaTiO3/SrTiO3 superlattices fabricated on silicon with layer thickness control at the unit-cell level. By harnessing the coherent strain between the constituent layers, we overcome the biaxial thermal tension from silicon and stabilize c-axis oriented BaTiO3 layers with substantially enhanced tetragonality, as revealed by atomically resolved scanning transmission electron microscopy. Optical second harmonic generation measurements signify a predominant out-of-plane polarized state with strongly enhanced net polarization in the tricolor superlattices, as compared to the BaTiO3 single film and conventional BaTiO3/SrTiO3 superlattice grown on silicon. Meanwhile, this coherent strain in turn suppresses the magnetism of LaMnO3 as the thickness of BaTiO3 increases. Our study raises the prospect of designing artificial oxide superlattices on silicon with tailored functionalities. Integrating multifunctional oxides on silicon is highly desirable. Here, the authors present asymmetric BaTiO3 superlattices on silicon exhibiting enhanced out-of-plane polarization by harnessing the interfacial strain and broken inversion symmetry.
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10
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Sarott MF, Gradauskaite E, Nordlander J, Strkalj N, Trassin M. In situmonitoring of epitaxial ferroelectric thin-film growth. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:293001. [PMID: 33873174 DOI: 10.1088/1361-648x/abf979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
In ferroelectric thin films, the polarization state and the domain configuration define the macroscopic ferroelectric properties such as the switching dynamics. Engineering of the ferroelectric domain configuration during synthesis is in permanent evolution and can be achieved by a range of approaches, extending from epitaxial strain tuning over electrostatic environment control to the influence of interface atomic termination. Exotic polar states are now designed in the technologically relevant ultrathin regime. The promise of energy-efficient devices based on ultrathin ferroelectric films depends on the ability to create, probe, and manipulate polar states in ever more complex epitaxial architectures. Because most ferroelectric oxides exhibit ferroelectricity during the epitaxial deposition process, the direct access to the polarization emergence and its evolution during the growth process, beyond the realm of existing structuralin situdiagnostic tools, is becoming of paramount importance. We review the recent progress in the field of monitoring polar states with an emphasis on the non-invasive probes allowing investigations of polarization during the thin film growth of ferroelectric oxides. A particular importance is given to optical second harmonic generationin situ. The ability to determine the net polarization and domain configuration of ultrathin films and multilayers during the growth of multilayers brings new insights towards a better understanding of the physics of ultrathin ferroelectrics and further control of ferroelectric-based heterostructures for devices.
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Affiliation(s)
- Martin F Sarott
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Elzbieta Gradauskaite
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Johanna Nordlander
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Nives Strkalj
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Morgan Trassin
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
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11
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Efe I, Spaldin NA, Gattinoni C. On the happiness of ferroelectric surfaces and its role in water dissociation: The example of bismuth ferrite. J Chem Phys 2021; 154:024702. [PMID: 33445895 DOI: 10.1063/5.0033897] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
We investigate, using density functional theory, how the interaction between the ferroelectric polarization and the chemical structure of the (001) surfaces of bismuth ferrite influences the surface properties and reactivity of this material. A precise understanding of the surface behavior of ferroelectrics is necessary for their use in surface science applications such as catalysis as well as for their incorporation in microelectronic devices. Using the (001) surface of bismuth ferrite as a model system, we show that the most energetically favored surface geometries are combinations of surface termination and polarization direction that lead to uncharged stable surfaces. On the unfavorable charged surfaces, we explore the compensation mechanisms of surface charges provided by the introduction of point defects and adsorbates, such as water. Finally, we propose that the special surface properties of bismuth ferrite (001) could be used to produce an effective water splitting cycle through cyclic polarization switching.
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Affiliation(s)
- Ipek Efe
- Materials Theory, Department of Materials, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
| | - Nicola A Spaldin
- Materials Theory, Department of Materials, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
| | - Chiara Gattinoni
- Materials Theory, Department of Materials, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
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