1
|
Moon T, Soh K, Kim JS, Kim JE, Chun SY, Cho K, Yang JJ, Yoon JH. Leveraging volatile memristors in neuromorphic computing: from materials to system implementation. MATERIALS HORIZONS 2024; 11:4840-4866. [PMID: 39189179 DOI: 10.1039/d4mh00675e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
Inspired by the functions of biological neural networks, volatile memristors are essential for implementing neuromorphic computing. These devices enable large-scale and energy-efficient data processing by emulating neural functionalities through dynamic resistance changes. The threshold switching characteristics of volatile memristors, which are driven by various mechanisms in materials ranging from oxides to chalcogenides, make them versatile and suitable for neuromorphic computing systems. Understanding these mechanisms and selecting appropriate devices for specific applications are crucial for optimizing the performance. However, the existing literature lacks a comprehensive review of switching mechanisms, their compatibility with different applications, and a deeper exploration of the spatiotemporal processing capabilities and inherent stochasticity of volatile memristors. This review begins with a detailed analysis of the operational principles and material characteristics of volatile memristors. Their diverse applications are then explored, emphasizing their role in crossbar arrays, artificial receptors, and neurons. Furthermore, the potential of volatile memristors in artificial inference systems and reservoir computing is discussed, due to their spatiotemporal processing capabilities. Hardware security applications and probabilistic computing are also examined, where the inherent stochasticity of the devices can improve the system robustness and adaptability. To conclude, the suitability of different switching mechanisms for various applications is evaluated, and future perspectives for the development and implementation of volatile memristors are presented. This review aims to fill the gaps in existing research and highlight the potential of volatile memristors to drive innovation in neuromorphic computing, paving the way for more efficient and powerful computational paradigms.
Collapse
Affiliation(s)
- Taehwan Moon
- Department of Intelligence Semiconductor Engineering, Ajou University, Suwon 16499, Republic of Korea
| | - Keunho Soh
- Electronic Materials Research Center, Korea Institute of Science and Technology (KIST), Seoul 02791, Republic of Korea
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Jong Sung Kim
- Electronic Materials Research Center, Korea Institute of Science and Technology (KIST), Seoul 02791, Republic of Korea
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
- Convergence Research Center for Solutions to Electromagnetic Interference in Future-mobility (SEIF), Korea Institute of Science and Technology (KIST), Seoul 02791, Republic of Korea
| | - Ji Eun Kim
- Electronic Materials Research Center, Korea Institute of Science and Technology (KIST), Seoul 02791, Republic of Korea
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Suk Yeop Chun
- Electronic Materials Research Center, Korea Institute of Science and Technology (KIST), Seoul 02791, Republic of Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea
| | - Kyungjune Cho
- Convergence Research Center for Solutions to Electromagnetic Interference in Future-mobility (SEIF), Korea Institute of Science and Technology (KIST), Seoul 02791, Republic of Korea
| | - J Joshua Yang
- Electrical and Computer Engineering, University of Southern California, LA 90089, USA.
| | - Jung Ho Yoon
- School of Advanced Materials and Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea.
| |
Collapse
|
2
|
Meng Q, Shi J, Zhang J, Liu Y, Wang W, Webster RF, Zhao D, Zhu Y, Hao B, Qu B, Lin X, Lin CH, Qiao L, Zu X, Huang JK, Li W, Wang D, Yang J, Li S. Elastic Properties of Low-Dimensional Single-Crystalline Dielectric Oxides through Controlled Large-Area Wrinkle Generation. ACS APPLIED MATERIALS & INTERFACES 2024; 16:28980-28990. [PMID: 38768264 DOI: 10.1021/acsami.4c00260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Freestanding single-crystalline SrTiO3 membranes, as high-κ dielectrics, hold significant promise as the gate dielectric in two-dimensional (2D) flexible electronics. Nevertheless, the mechanical properties of the SrTiO3 membranes, such as elasticity, remain a critical piece of the puzzle to adequately address the viability of their applications in flexible devices. Here, we report statistical analysis on plane-strain effective Young's modulus of large-area SrTiO3 membranes (5 × 5 mm2) over a series of thicknesses (from 6.5 to 32.2 nm), taking advantage of a highly efficient buckling-based method, which reveals its evident thickness-dependent behavior ranging from 46.01 to 227.17 GPa. Based on microscopic and theoretical results, we elucidate these thickness-dependent behaviors and statistical data deviation with a bilayer model, which consists of a surface layer and a bulk-like layer. The analytical results show that the ∼3.1 nm surface layer has a significant elastic softening compared to the bulk-like layer, while the extracted modulus of the bulk-like layer shows a variation of ∼40 GPa. This variation is considered as a combined contribution from oxygen deficiency presenting in SrTiO3 membranes, and the alignment between applied strain and the crystal orientation. Upon comparison of the extracted elastic properties and electrostatic control capability to those of other typical gate dielectrics, the superior performance of single-crystalline SrTiO3 membranes has been revealed in the context of flexible gate dielectrics, indicating the significant potential of their application in high-performance flexible 2D electronics.
Collapse
Affiliation(s)
- Qingxiao Meng
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Junjie Shi
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Ji Zhang
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Yang Liu
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Wenxuan Wang
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Richard F Webster
- Electron Microscope Unit, Mark Wainwright Analytical Centre, UNSW, Sydney 2052, NSW, Australia
| | - Duoduo Zhao
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Yanda Zhu
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Bohan Hao
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Bo Qu
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
- UNSW Materials & Manufacturing Futures Institute, UNSW, Sydney 2052, NSW, Australia
| | - Xi Lin
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
- UNSW Materials & Manufacturing Futures Institute, UNSW, Sydney 2052, NSW, Australia
| | - Chun-Ho Lin
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Liang Qiao
- School of Physics, University of Electronic Science and Technology of China, Chengdu, Sichuan 611731, China
| | - Xiaotao Zu
- School of Physics, University of Electronic Science and Technology of China, Chengdu, Sichuan 611731, China
| | - Jing-Kai Huang
- Department of Systems Engineering, City University of Hong Kong, Kowloon 999077, Hong Kong SAR, China
| | - Wenxian Li
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Danyang Wang
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
| | - Jack Yang
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
- UNSW Materials & Manufacturing Futures Institute, UNSW, Sydney 2052, NSW, Australia
| | - Sean Li
- School of Materials Science and Engineering, UNSW, Sydney 2052, NSW, Australia
- UNSW Materials & Manufacturing Futures Institute, UNSW, Sydney 2052, NSW, Australia
| |
Collapse
|
3
|
Luo D, Chen Y, Wang Y, Cao X, Aung P, Jin K, Wang S. Electrical transport behavior of the oxygen vacancies-rich LaAlO 3/SrTiO 3heterogeneous interface at high temperature. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:095001. [PMID: 37972407 DOI: 10.1088/1361-648x/ad0d29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 11/16/2023] [Indexed: 11/19/2023]
Abstract
Oxygen vacancy is one of the original mechanisms of the two-dimensional electron gas (2DEG) at the LaAlO3(LAO) and SrTiO3(STO) heterogeneous interface, and it has an important impact on the electrical properties of LAO/STO heterojunction. In this work, the LAO thin films were grown on the STO substrates by pulsed laser deposition, and the electrical transport behavior of the LAO/STO interface at high temperature and high vacuum were systematically studied. It was found that at high temperature and high vacuum, the oxygen vacancies-rich LAO/STO heterojunction would undergo a metal-insulator transition, and return to metal conductivity when the temperature is further increased. At this time, the conduction mechanism of the sample is drift mode and the thermal activation energy is 0.87 eV. While during the temperature decreasing, the conduction mechanism would transfer to hopping conduction with the thermal activation energy of 0.014 eV and the resistance would increase dramatically and present a completely insulated state. However, when the oxygen vacancies-rich sample is exposed to air, the resistance would gradually decrease and recover.
Collapse
Affiliation(s)
- Dianbing Luo
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - Yunhai Chen
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - Yifei Wang
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - Xinyu Cao
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - Phyo Aung
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - Kexin Jin
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - Shuanhu Wang
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| |
Collapse
|
4
|
Saito K, Takahashi Y, Kuwabara D, Watanabe Y. Electron Transfer Reduction by Hydrogen Creates Porosity in Tantalate Crystals and Produce Multifunctionality. ACS APPLIED MATERIALS & INTERFACES 2023; 15:53665-53670. [PMID: 37948622 DOI: 10.1021/acsami.3c10246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Contrary to partially substituted systems, WO3 molecular sieves that exclusively comprise a d0 transition metal ion and do not possess template ions in the cavity are a new class of materials for photocatalysis owing to their framework structure. Because WO3 thermodynamically lacks proton-reduction capability, exploring diverse synthetic approaches of other materials is desirable for facilitating utilization as H2 evolution and water splitting systems. Herein, we report an efficient approach for the protonation of Ag2Ta4O11 to afford H2Ta4O11 for application as a H2 molecular sieve. Hydrogen reduction of Ag2Ta4O11 at 300 °C and post-treatment using HNO3 afforded H2Ta4O11. Characterizations of H2Ta4O11, coupled with density functional theory (DFT) calculations, reveal that the intrinsic structure of Ag2Ta4O11 is maintained. Moreover, H+ is generated from H2 oxidation and forms OH, and the orientation of OH is parallel to that of the ab plane. Desorption and adsorption of H2 within H2Ta4O11 were achieved by heating H2Ta4O11 to above 90 °C. This is attributed to positive thermal expansion, as confirmed by high-temperature X-ray diffraction. H2Ta4O11 is an active heterogeneous photocatalyst for the half-reactions of water splitting. Moreover, deuteration experiments of H2Ta4O11 in D2O suggest its capability as a H2-D2 conversion catalyst. Furthermore, H2Ta4O11 functions as an active synthetic precursor for new tantalate materials, the direct synthesis of which is challenging.
Collapse
Affiliation(s)
- Kenji Saito
- Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Yuma Takahashi
- Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Daichi Kuwabara
- Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Yoshiki Watanabe
- Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| |
Collapse
|
5
|
Bayani A, Gebhardt J, Elsässer C. Electronic Bulk and Surface Properties of Titanium Dioxide Studied by DFT-1/2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:14922-14934. [PMID: 37830187 DOI: 10.1021/acs.langmuir.3c01698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Transparent conductive oxides, such as TiO2, are important functional materials for optoelectronic and photovoltaic devices. We investigate the electronic bulk properties of the TiO2 phases rutile and anatase with the DFT-1/2 method and obtain a quantitatively good description of their electronic band structures. We then applied this method to the (001) surfaces of rutile and anatase and calculated their ionization potentials (IPs) and work functions (WF). To relate these calculated surface properties with values from experiments, we evaluated the effect of varying the oxygen stoichiometry at the surface on both IP and WF.
Collapse
Affiliation(s)
- Amirhossein Bayani
- Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany
| | - Julian Gebhardt
- Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany
- Cluster of Excellence livMatS at FIT, Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
| | - Christian Elsässer
- Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany
- Cluster of Excellence livMatS at FIT, Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
- Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
| |
Collapse
|
6
|
A Parametric Study of the Crystal Phases on Au/TiO2 Photocatalysts for CO2 Gas-Phase Reduction in the Presence of Water. Catalysts 2022. [DOI: 10.3390/catal12121623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Au/TiO2 photocatalysts were studied, characterized, and compared for CO2 photocatalytic gas-phase reduction. The impact of the nature of the TiO2 support was studied. It was shown that the surface area/porosity/TiO2 crystal phase/density of specific exposed facets and oxygen vacancies were the key factors determining CH4 productivity under solar-light activation. A 0.84 wt.% Au/TiO2 SG (Sol Gel) calcined at 400 °C exhibited the best performance, leading to a continuous mean CH4 production rate of 50 μmol.h−1.g−1 over 5 h, associated with an electronic selectivity of 85%. This high activity was mainly attributed to the large surface area and accessible microporous volume, high density of exposed TiO2 (101) anatase facets, and oxygen vacancies acting as reactive defects sites for CO2 adsorption/activation/dissociation and charge carrier transport.
Collapse
|
7
|
Sengupta S, Ghatak A, Raychaudhuri AK. Effect of low temperature structural phase transitions in BaTiO 3on electrical transport through a metal-ferroelectric-metal multilayer of AuCr/BaTiO 3/Nb:SrTiO 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:465702. [PMID: 34388737 DOI: 10.1088/1361-648x/ac1d6e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
In this paper we report an investigation of electronic transport through the metal-ferroelectric-metal (MFM) multilayer consisting of AuCr/BaTiO3/Nb:SrTiO3over a temperature range of 100 K-300 K where BaTiO3(BTO) shows a series of structural phase transitions leading to change of magnitude as well as the orientation of the polarizationP→. We observed that the bias dependent barrier heights associated with the interfaces carry strong signature of the phase transitions in the BTO layer which lead to a strong temperature dependent asymmetric transport, when cooled down below room temperature. Specifically, it is observed that the temperature dependence is closely correlated to low temperature transitions in the BTO layer as revealed through the temperature dependent x-ray diffraction (XRD), capacitance as well as resistivity behavior of the BTO layer. There is substantial enhancement of the asymmetry in the device current that occurs at or close to temperaturesT2∼ 190 K where BTO shows a crystallographic phase change to the low temperature rhombohedral phase. The temperature dependent changes occur due to barrier modulation at the interfaces of AuCr/BaTiO3as well as BaTiO3/Nb:SrTiO3that softens on cooling due to inhomogenities present there. The change in barrier on change of the bias direction has been observed belowT2which arises from alignment of the polarization in-plane or out-of-plane as determined by tensile or compressive character of the in-plane strain in the BTO film. We also discuss the effect of space charge determined by the oxygen vacancies in the interface region, regulated by the applied bias.
Collapse
Affiliation(s)
- Subhamita Sengupta
- Department of Condensed Matter Physics and Materials Sciences, S.N. Bose National Centre for Basic Sciences, JD Block, Sec-III, Salt Lake, Kolkata-700106, India
| | - Ankita Ghatak
- Technical Research Centre, S.N. Bose National Centre for Basic Sciences, JD Block, Sec-III, Salt Lake, Kolkata-700106, India
| | - Arup Kumar Raychaudhuri
- CSIR-Central Glass and Ceramic Research Institute, 196 Raja S. C. Mallick Road, Kolkata-700032, India
| |
Collapse
|
8
|
Zhu J, Lee JW, Lee H, Xie L, Pan X, De Souza RA, Eom CB, Nonnenmann SS. Probing vacancy behavior across complex oxide heterointerfaces. SCIENCE ADVANCES 2019; 5:eaau8467. [PMID: 30801011 PMCID: PMC6386560 DOI: 10.1126/sciadv.aau8467] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 01/11/2019] [Indexed: 06/09/2023]
Abstract
Oxygen vacancies ( V O • • ) play a critical role as defects in complex oxides in establishing functionality in systems including memristors, all-oxide electronics, and electrochemical cells that comprise metal-insulator-metal or complex oxide heterostructure configurations. Improving oxide-oxide interfaces necessitates a direct, spatial understanding of vacancy distributions that define electrochemically active regions. We show vacancies deplete over micrometer-level distances in Nb-doped SrTiO3 (Nb:SrTiO3) substrates due to deposition and post-annealing processes. We convert the surface potential across a strontium titanate/yttria-stabilized zirconia (STO/YSZ) heterostructured film to spatial (<100 nm) vacancy profiles within STO using (T = 500°C) in situ scanning probes and semiconductor analysis. Oxygen scavenging occurring during pulsed laser deposition reduces Nb:STO substantially, which partially reoxidizes in an oxygen-rich environment upon cooling. These results (i) introduce the means to spatially resolve quantitative vacancy distributions across oxide films and (ii) indicate the mechanisms by which oxide thin films enhance and then deplete vacancies within the underlying substrate.
Collapse
Affiliation(s)
- Jiaxin Zhu
- Department of Mechanical and Industrial Engineering, University of Massachusetts-Amherst, Amherst, MA 01003, USA
| | - Jung-Woo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hyungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Lin Xie
- Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, CA 92697, USA
| | - Xiaoqing Pan
- Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, CA 92697, USA
| | - Roger A. De Souza
- Institute of Physical Chemistry, RWTH Aachen University, Aachen 52056, Germany
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Stephen S. Nonnenmann
- Department of Mechanical and Industrial Engineering, University of Massachusetts-Amherst, Amherst, MA 01003, USA
| |
Collapse
|
9
|
Xiao H, Dong W, Guo Y, Wang Y, Zhong H, Li Q, Yang MM. Design for Highly Piezoelectric and Visible/Near-Infrared Photoresponsive Perovskite Oxides. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805802. [PMID: 30444031 DOI: 10.1002/adma.201805802] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/21/2018] [Indexed: 06/09/2023]
Abstract
Defect-engineered perovskite oxides that exhibit ferroelectric and photovoltaic properties are promising multifunctional materials. Though introducing gap states by transition metal doping on the perovskite B-site can obtain low bandgap (i.e., 1.1-3.8 eV), the electrically leaky perovskite oxides generally lose piezoelectricity mainly due to oxygen vacancies. Therefore, the development of highly piezoelectric ferroelectric semiconductor remains challenging. Here, inspired by point-defect-mediated large piezoelectricity in ferroelectrics especially at the morphotropic phase boundary (MPB) region, an efficient strategy is proposed by judiciously introducing the gap states at the MPB where defect-induced local polar heterogeneities are thermodynamically coupled with the host polarization to simultaneously achieve high piezoelectricity and low bandgap. A concrete example, Ni2+ -mediated (1-x)Na0.5 Bi0.5 TiO3 -xBa(Ti0.5 Ni0.5 )O3-δ (x = 0.02-0.08) composition is presented, which can show excellent piezoelectricity and unprecedented visible/near-infrared light absorption with a lowest ever bandgap ≈0.9 eV at room temperature. In particular, the MPB composition x = 0.05 shows the best ferroelectricity/piezoelectricity (d33 = 151 pC N-1 , Pr = 31.2 μC cm-2 ) and a largely enhanced photocurrent density approximately two orders of magnitude higher compared with classic ferroelectric (Pb,La)(Zr,Ti)O3 . This research provides a new paradigm for designing highly piezoelectric and visible/near-infrared photoresponsive perovskite oxides for solar energy conversion, near-infrared detection, and other multifunctional applications.
Collapse
Affiliation(s)
- Hongyuan Xiao
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wen Dong
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Yiping Guo
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yufeng Wang
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Haoyin Zhong
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Qian Li
- Advanced Photon Source Facility, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Ming-Min Yang
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| |
Collapse
|
10
|
Hensling FVE, Keeble DJ, Zhu J, Brose S, Xu C, Gunkel F, Danylyuk S, Nonnenmann SS, Egger W, Dittmann R. UV radiation enhanced oxygen vacancy formation caused by the PLD plasma plume. Sci Rep 2018; 8:8846. [PMID: 29892095 PMCID: PMC5996021 DOI: 10.1038/s41598-018-27207-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/29/2018] [Indexed: 11/08/2022] Open
Abstract
Pulsed Laser Deposition is a commonly used non-equilibrium physical deposition technique for the growth of complex oxide thin films. A wide range of parameters is known to influence the properties of the used samples and thin films, especially the oxygen-vacancy concentration. One parameter has up to this point been neglected due to the challenges of separating its influence from the influence of the impinging species during growth: the UV-radiation of the plasma plume. We here present experiments enabled by a specially designed holder to allow a separation of these two influences. The influence of the UV-irradiation during pulsed laser deposition on the formation of oxygen-vacancies is investigated for the perovskite model material SrTiO3. The carrier concentration of UV-irradiated samples is nearly constant with depth and time. By contrast samples not exposed to the radiation of the plume show a depth dependence and a decrease in concentration over time. We reveal an increase in Ti-vacancy-oxygen-vacancy-complexes for UV irradiated samples, consistent with the different carrier concentrations. We find a UV enhanced oxygen-vacancy incorporation rate as responsible mechanism. We provide a complete picture of another influence parameter to be considered during pulsed laser depositions and unravel the mechanism behind persistent-photo-conductivity in SrTiO3.
Collapse
Affiliation(s)
- F V E Hensling
- Peter Grüneberg Institut 7, Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - D J Keeble
- Carnegie Laboratory of Physics, SUPA, School of Science and Engineering, University of Dundee, Dundee, DD1 4HN, United Kingdom
| | - J Zhu
- Mechanical and Industrial Enginnering, University of Massachusetts, Amherst, MA, 01003-2210, USA
| | - S Brose
- Chair for Technology of Optical Systems, RWTH Aachen University, Steinbachstr. 15, 52074, Aachen, Germany
| | - C Xu
- Peter Grüneberg Institut 7, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - F Gunkel
- Institute of Electronic Materials (IWE2), RWTH Aachen University, 52074, Aachen, Germany
| | - S Danylyuk
- Chair for Technology of Optical Systems, RWTH Aachen University, Steinbachstr. 15, 52074, Aachen, Germany
| | - S S Nonnenmann
- Mechanical and Industrial Enginnering, University of Massachusetts, Amherst, MA, 01003-2210, USA
| | - W Egger
- Universität Bundeswehr München, 85577, Neubiberg, Germany
| | - R Dittmann
- Peter Grüneberg Institut 7, Forschungszentrum Jülich, 52425, Jülich, Germany
| |
Collapse
|
11
|
Vaz DC, Lesne E, Sander A, Naganuma H, Jacquet E, Santamaria J, Barthélémy A, Bibes M. Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures. J Vis Exp 2018. [PMID: 29553560 DOI: 10.3791/56951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide electronics community. One of its hallmark features is the existence of a critical LAO thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. Although electrostatic mechanisms have been proposed in the past to describe the existence of this critical thickness, the importance of chemical defects has been recently accentuated. Here, we describe the growth of metal/LAO/STO heterostructures in an ultra-high vacuum (UHV) cluster system combining pulsed laser deposition (to grow the LAO), magnetron sputtering (to grow the metal) and X-ray photoelectron spectroscopy (XPS). We study step by step the formation and evolution of the q2DES and the chemical interactions that occur between the metal and the LAO/STO. Additionally, magnetotransport experiments elucidate on the transport and electronic properties of the q2DES. This systematic work not only demonstrates a way to study the electrostatic and chemical interplay between the q2DES and its environment, but also unlocks the possibility to couple multifunctional capping layers with the rich physics observed in two-dimensional electron systems, allowing the fabrication of new types of devices.
Collapse
Affiliation(s)
| | - Edouard Lesne
- Unité Mixte de Physique CNRS/Thales, Université Paris-Saclay; Max Planck Institut für Mikrostrukturphysik
| | - Anke Sander
- Unité Mixte de Physique CNRS/Thales, Université Paris-Saclay
| | - Hiroshi Naganuma
- Unité Mixte de Physique CNRS/Thales, Université Paris-Saclay; Department of Applied Physics, Tohoku University
| | - Eric Jacquet
- Unité Mixte de Physique CNRS/Thales, Université Paris-Saclay
| | - Jacobo Santamaria
- Unité Mixte de Physique CNRS/Thales, Université Paris-Saclay; Instituto de Magnetismo Aplicado, Universidad Complutense de Madrid
| | | | - Manuel Bibes
- Unité Mixte de Physique CNRS/Thales, Université Paris-Saclay
| |
Collapse
|
12
|
Second Harmonic Generation Response in Thermally reconstructed Multiferroic β'- Gd 2(MoO 4) 3 Thin Films. Sci Rep 2017; 7:11800. [PMID: 28924152 PMCID: PMC5603551 DOI: 10.1038/s41598-017-12370-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 09/08/2017] [Indexed: 11/14/2022] Open
Abstract
Gd2(MoO4)3 (GMO) is a well-studied multiferroic material that exhibits full ferroelectric and ferroelastic behavior at room temperature. However, its difficult stabilization in thin films has prevented the study and exploitation of its multiferroic properties in different architectures. Here, we report on the study of GMO thin films deposited on Si(001) substrates by Pulsed Laser Deposition (PLD). The physicochemical properties of the films are discussed and studied. Results obtained by X-ray diffraction, X-ray photoelectron spectroscopy, high resolution transmission microscopy and second harmonic generation show that the orthorhombic (β′-GMO) multiferroic phase can be stabilized and homogenized by post deposition thermal reconstruction. Finally, the reconstruction process takes place via a complex surface mechanism with a clear leaf-like behavior.
Collapse
|
13
|
Dholabhai PP, Martínez E, Brown NT, Uberuaga BP. On the mobility of carriers at semi-coherent oxide heterointerfaces. Phys Chem Chem Phys 2017; 19:23122-23130. [PMID: 28820196 DOI: 10.1039/c7cp04884j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the quest to develop new materials with enhanced ionic conductivity for battery and fuel cell applications, nano-structured oxides have attracted attention. Experimental reports indicate that oxide heterointerfaces can lead to enhanced ionic conductivity, but these same reports cannot elucidate the origin of this enhancement, often vaguely referring to pipe diffusion at misfit dislocations as a potential explanation. However, this highlights the need to understand the role of misfit dislocation structure at semi-coherent oxide heterointerfaces in modifying carrier mobilities. Here, we use atomistic and kinetic Monte Carlo (KMC) simulations to develop a model of oxygen vacancy migration at SrTiO3/MgO interfaces, chosen because the misfit dislocation structure can be modified by changing the termination chemistry. We use atomistic simulations to determine the energetics of oxygen vacancies at both SrO and TiO2 terminated interfaces, which are then used as the basis of the KMC simulations. While this model is approximate (as revealed by select nudged elastic band calculations), it highlights the role of the misfit dislocation structure in modifying the oxygen vacancy dynamics. We find that oxygen vacancy mobility is significantly reduced at either interface, with slight differences at each interface due to the differing misfit dislocation structure. We conclude that if such semi-coherent oxide heterointerfaces induce enhanced ionic conductivity, it is not a consequence of higher carrier mobility.
Collapse
Affiliation(s)
- Pratik P Dholabhai
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
| | - Enrique Martínez
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
| | - Nicholas T Brown
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
| | - Blas Pedro Uberuaga
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
| |
Collapse
|