1
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Meng J, Lee C, Li Z. Adjustment methods of Schottky barrier height in one- and two-dimensional semiconductor devices. Sci Bull (Beijing) 2024; 69:1342-1352. [PMID: 38490891 DOI: 10.1016/j.scib.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/10/2024] [Accepted: 02/02/2024] [Indexed: 03/17/2024]
Abstract
The Schottky contact which is a crucial interface between semiconductors and metals is becoming increasingly significant in nano-semiconductor devices. A Schottky barrier, also known as the energy barrier, controls the depletion width and carrier transport across the metal-semiconductor interface. Controlling or adjusting Schottky barrier height (SBH) has always been a vital issue in the successful operation of any semiconductor device. This review provides a comprehensive overview of the static and dynamic adjustment methods of SBH, with a particular focus on the recent advancements in nano-semiconductor devices. These methods encompass the work function of the metals, interface gap states, surface modification, image-lowering effect, external electric field, light illumination, and piezotronic effect. We also discuss strategies to overcome the Fermi-level pinning effect caused by interface gap states, including van der Waals contact and 1D edge metal contact. Finally, this review concludes with future perspectives in this field.
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Affiliation(s)
- Jianping Meng
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, China; School of Nanoscience and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; Center for Intelligent Sensors and MEMS, National University of Singapore, Singapore 117608, Singapore.
| | - Zhou Li
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, China; School of Nanoscience and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
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2
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Koh EK, Dananjaya PA, Poh HY, Liu L, Lee CXX, Thong JR, You YS, Lew WS. Unraveling the origins of the coexisting localized-interfacial mechanism in oxide-based memristors in CMOS-integrated synaptic device implementations. NANOSCALE HORIZONS 2024; 9:828-842. [PMID: 38450438 DOI: 10.1039/d3nh00554b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
The forefront of neuromorphic research strives to develop devices with specific properties, i.e., linear and symmetrical conductance changes under external stimuli. This is paramount for neural network accuracy when emulating a biological synapse. A parallel exploration of resistive memory as a replacement for conventional computing memory ensues. In search of a holistic solution, the proposed memristive device in this work is uniquely poised to address this elusive gap as a unified memory solution. Opposite biasing operations are leveraged to achieve stable abrupt and gradual switching characteristics within a single device, addressing the demands for lower latency and energy consumption for binary switching applications, and graduality for neuromorphic computing applications. We evaluated the underlying principles of both switching modes, attributing the anomalous gradual switching to the modulation of oxygen-deficient layers formed between the active electrode and oxide switching layer. The memristive cell (1R) was integrated with 40 nm transistor technology (1T) to form a 1T-1R memory cell, demonstrating a switching speed of 50 ns with a pulse amplitude of ±2.5 V in its forward-biased mode. Applying pulse trains of 20 ns to 490 ns in the reverse-biased mode exhibited synaptic weight properties, obtaining a nonlinearity (NL) factor of <0.5 for both potentiation and depression. The devices in both modes also demonstrated an endurance of >106 cycles, and their conductance states were also stable under temperature stress at 85 °C for 104 s. With the duality of the two switching modes, our device can be used for both memory and synaptic weight-storing applications.
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Affiliation(s)
- Eng Kang Koh
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
- GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D Street 2, Singapore 738406, Singapore
| | - Putu Andhita Dananjaya
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
| | - Han Yin Poh
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
- GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D Street 2, Singapore 738406, Singapore
| | - Lingli Liu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
| | - Calvin Xiu Xian Lee
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
- GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D Street 2, Singapore 738406, Singapore
| | - Jia Rui Thong
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
- GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D Street 2, Singapore 738406, Singapore
| | - Young Seon You
- GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D Street 2, Singapore 738406, Singapore
| | - Wen Siang Lew
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
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3
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Jeong T, Yeu IW, Ye KH, Yoon S, Kim D, Hwang CS, Choi JH. Study of a charge transition-driven resistive switching mechanism in TiO 2-based random access memory via density functional theory. NANOSCALE 2024; 16:6949-6960. [PMID: 38494908 DOI: 10.1039/d3nr06614b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
The nature of the conducting filament (CF) with a high concentration of oxygen vacancies (VOs) in oxide thin film-based resistive random access memory (RRAM) remains unclear. The VOs in the CF have been assumed to be positively charged (VO2+) to explain the field-driven switching of RRAM, but VO2+ clusters in high concentration encounter Coulomb repulsion, rendering the CF unstable. Therefore, this study examined the oxidation state of VOs in the CF and their effects on the switching behavior via density functional theory calculations using a Pt/TiO2/Ti model system. It was concluded that the VOs in the CF are in a low oxidation state but are transformed to VO2+ immediately after release from the CF. In addition, the short-range interactions between VOs were confirmed to facilitate the rupture and rejuvenation of the CF by reducing the required activation energy. Finally, an improved switching model was proposed by considering the charge transition of VOs, providing a plausible explanation for the reported coexistence of two opposite bipolar switching polarities: the eight-wise and the counter-eight-wise polarities.
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Affiliation(s)
- Taeyoung Jeong
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea.
- Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea.
| | - In Won Yeu
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea.
| | - Kun Hee Ye
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea.
- Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea.
| | - Seungjae Yoon
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea.
- Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea.
| | - Dohyun Kim
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea.
- Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea.
| | - Cheol Seong Hwang
- Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, Korea.
| | - Jung-Hae Choi
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea.
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4
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Franco M, Kiazadeh A, Deuermeier J, Lanceros-Méndez S, Martins R, Carlos E. Inkjet printed IGZO memristors with volatile and non-volatile switching. Sci Rep 2024; 14:7469. [PMID: 38553556 PMCID: PMC10980760 DOI: 10.1038/s41598-024-58228-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/26/2024] [Indexed: 04/02/2024] Open
Abstract
Solution-based memristors deposited by inkjet printing technique have a strong technological potential based on their scalability, low cost, environmentally friendlier processing by being an efficient technique with minimal material waste. Indium-gallium-zinc oxide (IGZO), an oxide semiconductor material, shows promising resistive switching properties. In this work, a printed Ag/IGZO/ITO memristor has been fabricated. The IGZO thickness influences both memory window and switching voltage of the devices. The devices show both volatile counter8wise (c8w) and non-volatile 8wise (8w) switching at low operating voltage. The 8w switching has a SET and RESET voltage lower than 2 V and - 5 V, respectively, a retention up to 105 s and a memory window up to 100, whereas the c8w switching shows volatile characteristics with a low threshold voltage (Vth < - 0.65 V) and a characteristic time (τ) of 0.75 ± 0.12 ms when a single pulse of - 0.65 V with width of 0.1 ms is applied. The characteristic time alters depending on the number of pulses. These volatile characteristics allowed them to be tested on different 4-bit pulse sequences, as an initial proof of concept for temporal signal processing applications.
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Affiliation(s)
- Miguel Franco
- Center of Physics, University of Minho and Laboratory of Physics for Materials and Emergent Technologies, LapMET, Campus de Gualtar, 4710-057, Braga, Portugal
- CENIMAT|i3N, Department of Materials Science, School of Science and Technology, NOVA University Lisbon and CEMOP/UNINOVA, Caparica, Portugal
| | - Asal Kiazadeh
- CENIMAT|i3N, Department of Materials Science, School of Science and Technology, NOVA University Lisbon and CEMOP/UNINOVA, Caparica, Portugal.
| | - Jonas Deuermeier
- CENIMAT|i3N, Department of Materials Science, School of Science and Technology, NOVA University Lisbon and CEMOP/UNINOVA, Caparica, Portugal
| | - S Lanceros-Méndez
- Center of Physics, University of Minho and Laboratory of Physics for Materials and Emergent Technologies, LapMET, Campus de Gualtar, 4710-057, Braga, Portugal
- BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain
- IKERBASQUE, Basque Foundation for Science, 48009, Bilbao, Spain
| | - Rodrigo Martins
- CENIMAT|i3N, Department of Materials Science, School of Science and Technology, NOVA University Lisbon and CEMOP/UNINOVA, Caparica, Portugal
| | - Emanuel Carlos
- CENIMAT|i3N, Department of Materials Science, School of Science and Technology, NOVA University Lisbon and CEMOP/UNINOVA, Caparica, Portugal.
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5
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Álvarez-Martínez V, Ramos R, Leborán V, Sarantopoulos A, Dittmann R, Rivadulla F. Interfacial Thermal Resistive Switching in (Pt,Cr)/SrTiO 3 Devices. ACS APPLIED MATERIALS & INTERFACES 2024; 16:15043-15049. [PMID: 38477897 PMCID: PMC10982933 DOI: 10.1021/acsami.3c19285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Revised: 02/23/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024]
Abstract
The operation of oxide-based memristive devices relies on the fast accumulation and depletion of oxygen vacancies by an electric field close to the metal-oxide interface. Here, we show that the reversible change of the local concentration of oxygen vacancies at this interface also produces a change in the thermal boundary resistance (TBR), i.e., a thermal resistive switching effect. We used frequency domain thermoreflectance to monitor the interfacial metal-oxide TBR in (Pt,Cr)/SrTiO3 devices, showing a change of ≈20% under usual SET/RESET operation voltages, depending on the structure of the device. Time-dependent thermal relaxation experiments suggest ionic rearrangement along the whole area of the metal/oxide interface, apart from the ionic filament responsible for the electrical conductivity switching. The experiments presented in this work provide valuable knowledge about oxide ion dynamics in redox-based memristive devices.
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Affiliation(s)
- Víctor Álvarez-Martínez
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS), Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
- Departamento
de Química-Física, Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Rafael Ramos
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS), Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
- Departamento
de Química-Física, Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Víctor Leborán
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS), Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Alexandros Sarantopoulos
- Peter
Gruenberg Institute (PGI-7) Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Regina Dittmann
- Peter
Gruenberg Institute (PGI-7) Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Francisco Rivadulla
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS), Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
- Departamento
de Química-Física, Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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6
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Pattnaik DP, Andrews C, Cropper MD, Gabbitas A, Balanov AG, Savel'ev S, Borisov P. Gamma radiation-induced nanodefects in diffusive memristors and artificial neurons. NANOSCALE 2023; 15:15665-15674. [PMID: 37724437 DOI: 10.1039/d3nr01853a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/20/2023]
Abstract
Gamma photons with an average energy of 1.25 MeV are well-known to generate large amounts of defects in semiconductor electronic devices. Here we investigate the novel effect of gamma radiation on diffusive memristors based on metallic silver nanoparticles dispersed in a dielectric matrix of silica. Our experimental findings show that after exposure to radiation, the memristors and artificial neurons made of them demonstrate much better performance in terms of stable volatile resistive switching and higher spiking frequencies, respectively, compared to the pristine samples. At the same time we observe partial oxidation of silver and reduction of silicon within the switching silica layer. We propose nanoinclusions of reduced silicon distributed across the silica layer to be the backbone for metallic nanoparticles to form conductive filaments, as supported by our theoretical simulations of radiation-induced changes in the diffusion process. Our findings propose a new opportunity to engineer the required characteristics of diffusive memristors in order to emulate biological neurons and develop bio-inspired computational technology.
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Affiliation(s)
- D P Pattnaik
- Department of Physics, Loughborough University, Loughborough, LE11 3TU, UK.
| | - C Andrews
- University of Manchester, Dalton Cumbrian Facility, Westlakes Science Park, Moor Row, CA24 3HA, UK
| | - M D Cropper
- Department of Physics, Loughborough University, Loughborough, LE11 3TU, UK.
| | - A Gabbitas
- Department of Physics, Loughborough University, Loughborough, LE11 3TU, UK.
| | - A G Balanov
- Department of Physics, Loughborough University, Loughborough, LE11 3TU, UK.
| | - S Savel'ev
- Department of Physics, Loughborough University, Loughborough, LE11 3TU, UK.
| | - P Borisov
- Department of Physics, Loughborough University, Loughborough, LE11 3TU, UK.
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7
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Zhang D, Dhall R, Song C, Ciston J, Schneider M, Kunwar S, Pettes M, McCabe R, Chen A. Operando STEM and EELS Study of Oxide Memristor Devices. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1311-1312. [PMID: 37613317 DOI: 10.1093/micmic/ozad067.671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Di Zhang
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, United States
| | - Rohan Dhall
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Lab, Berkeley, CA, United States
| | - Chengyu Song
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Lab, Berkeley, CA, United States
| | - Jim Ciston
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Lab, Berkeley, CA, United States
| | - Matt Schneider
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, United States
| | - Sundar Kunwar
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, United States
| | - Michael Pettes
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, United States
| | - Rodney McCabe
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, United States
| | - Aiping Chen
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, United States
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8
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Leal Martir R, José Sánchez M, Aguirre M, Quiñonez W, Ferreyra C, Acha C, Lecourt J, Lüders U, Rubi D. Oxygen vacancy dynamics in Pt/TiO x/TaO y/Pt memristors: exchange with the environment and internal electromigration. NANOTECHNOLOGY 2022; 34:095202. [PMID: 36541534 DOI: 10.1088/1361-6528/aca597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
Memristors are expected to be one of the key building blocks for the development of new bio-inspired nanoelectronics. Memristive effects in transition metal oxides are usually linked to the electromigration at the nanoscale of charged oxygen vacancies (OV). In this paper we address, for Pt/TiOx/TaOy/Pt devices, the exchange of OV between the device and the environment upon the application of electrical stress. From a combination of experiments and theoretical simulations we determine that both TiOxand TaOylayers oxidize, via environmental oxygen uptake, during the electroforming process. Once the memristive effect is stabilized (post-forming behavior) our results suggest that oxygen exchange with the environment is suppressed and the OV dynamics that drives the memristive behavior is restricted to an internal electromigration between TiOxand TaOylayers. Our work provides relevant information for the design of reliable binary oxide memristive devices.
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Affiliation(s)
- Rodrigo Leal Martir
- Departamento de Micro y Nanotecnologías, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Gral Paz. 1499 (1650), San Martín, Argentina
- Instituto de Nanociencia y Nanotecnología (INN), CONICET-CNEA, Buenos Aires and Bariloche, Argentina
| | - María José Sánchez
- Instituto de Nanociencia y Nanotecnología (INN), CONICET-CNEA, Buenos Aires and Bariloche, Argentina
- Centro Atómico Bariloche and Instituto Balseiro (Universidad Nacional de Cuyo), 8400 San Carlos de Bariloche, Río Negro, Argentina
| | - Myriam Aguirre
- Instituto de Nanociencia y Materiales de Aragón (INMA-CSIC) and Dpto. de Física de la Materia Condensada, Universidad de Zaragoza, Spain
- Laboratorio de Microscopías Avanzadas, Edificio I + D, Campus Rio Ebro C/Mariano Esquillor s/n, E-50018 Zaragoza, Spain
| | - Walter Quiñonez
- Departamento de Micro y Nanotecnologías, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Gral Paz. 1499 (1650), San Martín, Argentina
- Instituto de Nanociencia y Nanotecnología (INN), CONICET-CNEA, Buenos Aires and Bariloche, Argentina
| | - Cristian Ferreyra
- Departamento de Micro y Nanotecnologías, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Gral Paz. 1499 (1650), San Martín, Argentina
- Instituto de Nanociencia y Nanotecnología (INN), CONICET-CNEA, Buenos Aires and Bariloche, Argentina
| | - Carlos Acha
- Depto. de Física, FCEyN, Universidad de Buenos Aires and IFIBA, UBA-CONICET, Pab I, Ciudad Universitaria, Buenos Aires (1428), Argentina
| | - Jerome Lecourt
- CRISMAT, CNRS UMR 6508, ENSICAEN, 6 Boulevard Maréchal Juin, F-14050 Caen Cedex 4, France
| | - Ulrike Lüders
- CRISMAT, CNRS UMR 6508, ENSICAEN, 6 Boulevard Maréchal Juin, F-14050 Caen Cedex 4, France
| | - Diego Rubi
- Departamento de Micro y Nanotecnologías, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Gral Paz. 1499 (1650), San Martín, Argentina
- Instituto de Nanociencia y Nanotecnología (INN), CONICET-CNEA, Buenos Aires and Bariloche, Argentina
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9
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Milano G, Aono M, Boarino L, Celano U, Hasegawa T, Kozicki M, Majumdar S, Menghini M, Miranda E, Ricciardi C, Tappertzhofen S, Terabe K, Valov I. Quantum Conductance in Memristive Devices: Fundamentals, Developments, and Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2201248. [PMID: 35404522 DOI: 10.1002/adma.202201248] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/23/2022] [Indexed: 06/14/2023]
Abstract
Quantum effects in novel functional materials and new device concepts represent a potential breakthrough for the development of new information processing technologies based on quantum phenomena. Among the emerging technologies, memristive elements that exhibit resistive switching, which relies on the electrochemical formation/rupture of conductive nanofilaments, exhibit quantum conductance effects at room temperature. Despite the underlying resistive switching mechanism having been exploited for the realization of next-generation memories and neuromorphic computing architectures, the potentialities of quantum effects in memristive devices are still rather unexplored. Here, a comprehensive review on memristive quantum devices, where quantum conductance effects can be observed by coupling ionics with electronics, is presented. Fundamental electrochemical and physicochemical phenomena underlying device functionalities are introduced, together with fundamentals of electronic ballistic conduction transport in nanofilaments. Quantum conductance effects including quantum mode splitting, stability, and random telegraph noise are analyzed, reporting experimental techniques and challenges of nanoscale metrology for the characterization of memristive phenomena. Finally, potential applications and future perspectives are envisioned, discussing how memristive devices with controllable atomic-sized conductive filaments can represent not only suitable platforms for the investigation of quantum phenomena but also promising building blocks for the realization of integrated quantum systems working in air at room temperature.
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Affiliation(s)
- Gianluca Milano
- Advanced Materials Metrology and Life Sciences Division, INRiM (Istituto Nazionale di Ricerca Metrologica), Strada delle Cacce 91, Torino, 10135, Italy
| | - Masakazu Aono
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Luca Boarino
- Advanced Materials Metrology and Life Sciences Division, INRiM (Istituto Nazionale di Ricerca Metrologica), Strada delle Cacce 91, Torino, 10135, Italy
| | - Umberto Celano
- IMEC, Kapeldreef 75, Heverlee, Leuven, B-3001, Belgium
- Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, Enschede, NB, 7522, The Netherlands
| | - Tsuyoshi Hasegawa
- Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo, 169-8555, Japan
| | - Michael Kozicki
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA
| | - Sayani Majumdar
- VTT Technical Research Centre of Finland Ltd., VTT, P.O. Box 1000, Espoo, FI-02044, Finland
| | | | - Enrique Miranda
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona (UAB), Barcelona, 08193, Spain
| | - Carlo Ricciardi
- Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino, 10129, Italy
| | - Stefan Tappertzhofen
- Chair for Micro- and Nanoelectronics, Department of Electrical Engineering and Information Technology, TU Dortmund University, Emil-Figge-Straße 68, D-44227, Dortmund, Germany
| | - Kazuya Terabe
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Ilia Valov
- JARA - Fundamentals for Future Information Technology, 52425, Jülich, Germany
- Peter-Grünberg-Institut (PGI 7), Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52425, Jülich, Germany
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10
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Zhang Y, Wang C, Wu X. Review of electrical stimulus methods of in situ transmission electron microscope to study resistive random access memory. NANOSCALE 2022; 14:9542-9552. [PMID: 35762914 DOI: 10.1039/d2nr01872a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Resistive random access memory (RRAM) devices have been demonstrated to be a promising solution for the implementation of a neuromorphic system with high-density synapses due to the simple device structure, nanoscale dimension, high switching speed, and low power consumption. Various electrical stimuli applied to RRAM devices could cause various working modes of the bionic synapses. The application of RRAM devices needs to understand the micromechanism of the resistive switching process, which is inseparable from advanced characterization techniques. In situ transmission electron microscopy (TEM) with high-resolution imaging and versatile external fields plays an important role in the static characterization and dynamic manipulation of nanoscale devices. Focused on in situ TEM techniques, this review article introduces in situ TEM setups and the corresponding sample fabrication process for RRAM research. Then, the electrical stimulating methodologies including pulse and direct current voltage applied to RRAM are introduced, followed by the summary of electron holography to characterize the electrical potential distribution. By applying various electrical stimuli to the RRAM samples, the working mode of bionic synapses could be changed according to the requirement. Finally, the outlook of the RRAM study with in situ TEM is proposed. This review demonstrates the electrical stimulus capability of in situ TEM to understand the physical mechanism of various types of RRAM devices.
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Affiliation(s)
- Yewei Zhang
- In Situ Devices Center, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China.
| | - Chaolun Wang
- In Situ Devices Center, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China.
| | - Xing Wu
- In Situ Devices Center, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China.
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11
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Chen S, Valov I. Design of Materials Configuration for Optimizing Redox-Based Resistive Switching Memories. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2105022. [PMID: 34695257 DOI: 10.1002/adma.202105022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/19/2021] [Indexed: 06/13/2023]
Abstract
Redox-based resistive random access memories (ReRAMs) are based on electrochemical processes of oxidation and reduction within the devices. The selection of materials and material combinations strongly influence the related nanoscale processes, playing a crucial role in resistive switching properties and functionalities. To date, however, comprehensive studies on device design accounting for a combination of factors such as electrodes, electrolytes, and capping layer materials related to their thicknesses and interactions are scarce. In this work, the impact of materials' configuration on interfacial redox reactions in HfO2 -based electrochemical metallization memory (ECM) and valence-change memory (VCM) systems is reported. The redox processes are studied by cyclic voltammetry, and the corresponding resistive switching characteristics are investigated. In ECM cells, the overall cell resistance depends on the electrocatalytic activity of the counter electrode. Nonetheless, the capping layer material further influences the cell resistance and the SET and RESET voltages. In VCM systems, the influence of the electrode material configuration is also pronounced, and is capable of modulating the active resistive switching interface. For both types of memory cells, the switching behavior changes significantly with variation of the oxide thickness. The results present important materials selection criteria for rationale design of ReRAM cells for various memristive applications.
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Affiliation(s)
- Shaochuan Chen
- Institut für Werkstoffe der Elektrotechnik II, RWTH Aachen University, Sommerfeldstraße 24, 52074, Aachen, Germany
| | - Ilia Valov
- Institut für Werkstoffe der Elektrotechnik II, RWTH Aachen University, Sommerfeldstraße 24, 52074, Aachen, Germany
- Peter Grünberg Institut 7 and JARA-FIT, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52425, Jülich, Germany
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12
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Ribet SM, Murthy AA, Roth EW, Dos Reis R, Dravid VP. Making the Most of your Electrons: Challenges and Opportunities in Characterizing Hybrid Interfaces with STEM. MATERIALS TODAY (KIDLINGTON, ENGLAND) 2021; 50:100-115. [PMID: 35241968 PMCID: PMC8887695 DOI: 10.1016/j.mattod.2021.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Inspired by the unique architectures composed of hard and soft materials in natural and biological systems, synthetic hybrid structures and associated soft-hard interfaces have recently evoked significant interest. Soft matter is typically dominated by fluctuations even at room temperature, while hard matter (which often serves as the substrate or anchor for the soft component) is governed by rigid mechanical behavior. This dichotomy offers considerable opportunities to leverage the disparate properties offered by these components across a wide spectrum spanning from basic science to engineering insights with significant technological overtones. Such hybrid structures, which include polymer nanocomposites, DNA functionalized nanoparticle superlattices and metal organic frameworks to name a few, have delivered promising insights into the areas of catalysis, environmental remediation, optoelectronics, medicine, and beyond. The interfacial structure between these hard and soft phases exists across a variety of length scales and often strongly influence the functionality of hybrid systems. While scanning/transmission electron microscopy (S/TEM) has proven to be a valuable tool for acquiring intricate molecular and nanoscale details of these interfaces, the unusual nature of hybrid composites presents a suite of challenges that make assessing or establishing the classical structure-property relationships especially difficult. These include challenges associated with preparing electron-transparent samples and obtaining sufficient contrast to resolve the interface between dissimilar materials given the dose sensitivity of soft materials. We discuss each of these challenges and supplement a review of recent developments in the field with additional experimental investigations and simulations to present solutions for attaining a nano or atomic-level understanding of these interfaces. These solutions present a host of opportunities for investigating and understanding the role interfaces play in this unique class of functional materials.
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Affiliation(s)
- Stephanie M Ribet
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL
| | - Akshay A Murthy
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL
- International Institute of Nanotechnology, Northwestern University, Evanston, IL
| | - Eric W Roth
- The NUANCE Center, Northwestern University, Evanston, IL
| | - Roberto Dos Reis
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL
- The NUANCE Center, Northwestern University, Evanston, IL
| | - Vinayak P Dravid
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL
- International Institute of Nanotechnology, Northwestern University, Evanston, IL
- The NUANCE Center, Northwestern University, Evanston, IL
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13
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Salev P, Fratino L, Sasaki D, Berkoun R, Del Valle J, Kalcheim Y, Takamura Y, Rozenberg M, Schuller IK. Transverse barrier formation by electrical triggering of a metal-to-insulator transition. Nat Commun 2021; 12:5499. [PMID: 34535660 PMCID: PMC8448889 DOI: 10.1038/s41467-021-25802-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 08/19/2021] [Indexed: 11/08/2022] Open
Abstract
Application of an electric stimulus to a material with a metal-insulator transition can trigger a large resistance change. Resistive switching from an insulating into a metallic phase, which typically occurs by the formation of a conducting filament parallel to the current flow, is a highly active research topic. Using the magneto-optical Kerr imaging, we found that the opposite type of resistive switching, from a metal into an insulator, occurs in a reciprocal characteristic spatial pattern: the formation of an insulating barrier perpendicular to the driving current. This barrier formation leads to an unusual N-type negative differential resistance in the current-voltage characteristics. We further demonstrate that electrically inducing a transverse barrier enables a unique approach to voltage-controlled magnetism. By triggering the metal-to-insulator resistive switching in a magnetic material, local on/off control of ferromagnetism is achieved using a global voltage bias applied to the whole device.
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Affiliation(s)
- Pavel Salev
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA, USA.
| | - Lorenzo Fratino
- Université Paris-Saclay, CNRS Laboratoire de Physique des Solides, 91405, Orsay, France
| | - Dayne Sasaki
- Department of Materials Science and Engineering, University of California Davis, Davis, CA, USA
| | - Rani Berkoun
- Université Paris-Saclay, CNRS Laboratoire de Physique des Solides, 91405, Orsay, France
| | - Javier Del Valle
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA, USA
- Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland
| | - Yoav Kalcheim
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA, USA
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yayoi Takamura
- Department of Materials Science and Engineering, University of California Davis, Davis, CA, USA
| | - Marcelo Rozenberg
- Université Paris-Saclay, CNRS Laboratoire de Physique des Solides, 91405, Orsay, France
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA, USA
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14
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Zhang Q, Li X, Zhu J. Direct Observation of Interface-Dependent Multidomain State in the BaTiO 3 Tunnel Barrier of a Multiferroic Tunnel Junction Memristor. ACS APPLIED MATERIALS & INTERFACES 2021; 13:43641-43647. [PMID: 34473930 DOI: 10.1021/acsami.1c11661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Multiferroic tunnel junctions (MFTJs), normally consisting of a four-state resistance, have been studied extensively as a potential candidate for nonvolatile memory devices. More interestingly, the MFTJs whose resistance can be tuned continuously with applied voltage were also reported recently. Since the performance of MFTJs is closely related to their interfacial structures, it is necessary to investigate MFTJs at the atomic scale. In this work, atomic-resolution HAADF, ABF, and EELS of the La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 MFTJ memristor have been obtained with aberration-corrected scanning transmission electron microscopy (STEM). These results demonstrate varied degree of interfacial cation intermixing at the bottom BTO/LSMO interface, which has a direct influence on the polarization of the ferroelectric barrier BTO and the electronic structure of Mn near the interfaces. We also took advantage of a simplified model to explain the relation between the interfacial behavior and polarization states, which could be a contributing factor to the transport properties of this MFTJ.
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Affiliation(s)
- Qiqi Zhang
- National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084, People's Republic of China
- Ji Hua Laboratory, Foshan 528000, People's Republic of China
| | - Xiaoguang Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei 230000, People's Republic of China
| | - Jing Zhu
- National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084, People's Republic of China
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15
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Ader C, Falkenstein A, Martin M. Transition between bipolar and abnormal bipolar resistive switching in amorphous oxides with a mobility edge. Sci Rep 2021; 11:14384. [PMID: 34257338 PMCID: PMC8277833 DOI: 10.1038/s41598-021-93777-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/28/2021] [Indexed: 11/17/2022] Open
Abstract
Resistive switching is an important phenomenon for future memory devices such as resistance random access memories or neuronal networks. While there are different types of resistive switching, such as filament or interface switching, this work focuses on bulk switching in amorphous, binary oxides. Bulk switching was found experimentally in different oxides, for example in amorphous gallium oxide. The forms of the observed current-voltage curves differ, however, fundamentally. Even within the same material, both abnormal bipolar and normal bipolar resistive switching were found. Here, we use a new drift-diffusion model to theoretically investigate bulk switching in amorphous oxides where the electronic conductivity can be described by Mott's concept of a mobility edge. We show not only that a strong, non-linear dependence of the electronic conductivity on the oxygen content is necessary for bulk switching but also that changing the geometry of the memristive device causes the transition between abnormal and normal bipolar switching.
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Affiliation(s)
- Christiane Ader
- Institute of Physical Chemistry, RWTH Aachen University, 52074, Aachen, Germany
| | - Andreas Falkenstein
- Institute of Physical Chemistry, RWTH Aachen University, 52074, Aachen, Germany
| | - Manfred Martin
- Institute of Physical Chemistry, RWTH Aachen University, 52074, Aachen, Germany.
- JARA-CSD, Forschungszentrum Jülich and RWTH Aachen University, Aachen, Germany.
- JARA-FIT, Forschungszentrum Jülich and RWTH Aachen University, Aachen, Germany.
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16
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Baki A, Stöver J, Schulz T, Markurt T, Amari H, Richter C, Martin J, Irmscher K, Albrecht M, Schwarzkopf J. Influence of Sr deficiency on structural and electrical properties of SrTiO 3 thin films grown by metal-organic vapor phase epitaxy. Sci Rep 2021; 11:7497. [PMID: 33820911 PMCID: PMC8021553 DOI: 10.1038/s41598-021-87007-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/23/2021] [Indexed: 02/01/2023] Open
Abstract
Homoepitaxial growth of SrTiO3 thin films on 0.5 wt% niobium doped SrTiO3 (100) substrates with high structural perfection was developed using liquid-delivery spin metal-organic vapor phase epitaxy (MOVPE). Exploiting the advantage of adjusting the partial pressures of the individual constituents independently, we tuned the Sr/Ti ratio of the gas phase for realizing, stoichiometric, as well as Sr deficient layers. Quantitative energy dispersive X-ray spectroscopy in a scanning transmission electron microscope confirm Sr deficiency of up to 20% in nominally off-stoichiometrically grown films. Our MOVPE process allows to grow such layers in phase pure state and without extended defect formation. Indications for oxygen deficiency could not be identified. Sr deficient layers exhibit an increased permittivity of ɛr = 202 and a larger vertical lattice parameter. Current-voltage characteristics (IVCs) of metal-oxide-semiconductor (Pt/SrTiO3/SrTiO3:Nb) structures reveal that Sr deficient SrTiO3 films show an intrinsic resistive switching with on-off ratios of three orders of magnitude at RT and seven orders of magnitude at 10 K. There is strong evidence that a large deviation from stoichiometry pronounces the resistive switching behavior. IVCs conducted at 10 K indicate a defect-based mechanism instead of mass transport by ion diffusion. This is supported by in-situ STEM investigations that show filaments to form at significant higher voltages than those were resistive switching is observed in our samples.
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Affiliation(s)
- Aykut Baki
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany.
| | - Julian Stöver
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
| | - Tobias Schulz
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
| | - Toni Markurt
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
| | - Houari Amari
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
| | - Carsten Richter
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
| | - Jens Martin
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
| | - Klaus Irmscher
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
| | - Martin Albrecht
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
| | - Jutta Schwarzkopf
- Leibniz-Institut Für Kristallzüchtung, Max-Born-Straße 2, 12489, Berlin, Germany
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17
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Voronkovskii VA, Aliev VS, Gerasimova AK, Perevalov TV, Prosvirin IP, Islamov DR. Influence of the active TaN/ZrO x /Ni memristor layer oxygen content on forming and resistive switching behavior. NANOTECHNOLOGY 2021; 32:185205. [PMID: 33620032 DOI: 10.1088/1361-6528/abce7b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The influence of oxygen content in active zirconium oxide layers on the electrophysical properties of TaN/ZrO x /Ni memristors is investigated. The [O]/[Zr] atomic ratio (x) in the oxide layers was varied in the range from 1.56 to 2.0 by changing the partial oxygen pressure during their deposition by ion-beam sputtering deposition. The ZrO x film compositions were analyzed using x-ray photoelectron spectroscopy and density functional theory simulations. The multiple resistive switching phenomenon in TaN/ZrO x /Ni memristors was found to occur in a certain range of x ≥ 1.78. With the x value decreasing in the oxide layers, the forming voltage of memristors decreased. Furthermore, at the lower edge of x values the switchable range, they no longer required forming. At the same time, as the x value decreased, the memory window (I ON/I OFF ratio) also decreased from 5 to 1 order of magnitude due to an increase in the memristor conductivity in the high resistance state. In order to identify the underlying conduction mechanism of TaN/ZrO x /Ni memristors, their current-voltage curves in low and high resistance states were analyzed in the temperature range from 250 to 400 K for the samples with x = 1.78 (forming-free) and 1.97 (which required forming). It was found that, for both samples, the conductivity in the low-resistance state is characterized by the trap-free space-charge-limited current (SCLC) model, whereas the conductivity in the high-resistance state is characterized by the trap-mediated SCLC model. The possible origins of structural defects involved in the memristor conductivity and resistive switching are discussed based on the obtained results.
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Affiliation(s)
- V A Voronkovskii
- Rzhanov Institute of Semiconductor Physics SB RAS, 13 Lavrentiev Ave., Novosibirsk, 630090, Russia
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18
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Sun B, Guo T, Zhou G, Wu J, Chen Y, Zhou YN, Wu YA. A Battery-Like Self-Selecting Biomemristor from Earth-Abundant Natural Biomaterials. ACS APPLIED BIO MATERIALS 2021; 4:1976-1985. [PMID: 35014467 DOI: 10.1021/acsabm.1c00015] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using the earth-abundant natural biomaterials to manufacture functional electronic devices meets the sustainable requirement of green electronics, especially for the practical application of memristors in data storage and neuromorphic computing. However, the sneak currents flowing though the unselected cells in a large-scale cross-bar memristor array is one of the major problems which need to be tackled. The self-selecting memristors can solve the problem to develop compact and concise integrated circuits. Here, a sustainable natural biomaterial (anthocyanin, C15H11O6) extracted from plant tissue is demonstrated for ions and electron transport. The capacitive-coupled memristive behavior of as-prepared bioelectronic device can be significantly modulated by diethylmethyl(2-methoxyethyl)ammoium bis(trifluoromethylsulfonyl)imide (DEME-TFSI) ionic liquid (IL). Furthermore, graphene was inserted into biomaterial matrix to manipulate the memristive effects by graphene protonation. This results in a battery-like self-selective memristive effect. This phenomenon is explained by a physical model and density functional theory (DFT) based first-principles calculations. Finally, the self-selective behavior was applied in 0T-1R array configuration, which indicates the battery-like self-selecting biomemristor has potential applications in the brain-inspired computing, data storage systems, and high-density device integration.
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Affiliation(s)
- Bai Sun
- Department of Mechanical and Mechatronics Engineering, Waterloo Institute for Nanotechnology, Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.,School of Physical Science and Technology, Key Laboratory of Advanced Technology of Materials (Ministry of Education of China), Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - Tao Guo
- Department of Mechanical and Mechatronics Engineering, Waterloo Institute for Nanotechnology, Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Guangdong Zhou
- School of Artificial Intelligence, Southwest University, Chongqing 400715, China
| | - Jinggao Wu
- Key Laboratory of Rare Earth Optoelectronic Materials & Devices, College of Chemistry and Materials Engineering, Huaihua University, Huaihua 418000, China
| | - Yuanzheng Chen
- School of Physical Science and Technology, Key Laboratory of Advanced Technology of Materials (Ministry of Education of China), Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - Y Norman Zhou
- Department of Mechanical and Mechatronics Engineering, Waterloo Institute for Nanotechnology, Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Yimin A Wu
- Department of Mechanical and Mechatronics Engineering, Waterloo Institute for Nanotechnology, Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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19
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Spring J, Sediva E, Hood ZD, Gonzalez-Rosillo JC, O'Leary W, Kim KJ, Carrillo AJ, Rupp JLM. Toward Controlling Filament Size and Location for Resistive Switches via Nanoparticle Exsolution at Oxide Interfaces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2003224. [PMID: 32939986 DOI: 10.1002/smll.202003224] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 07/22/2020] [Indexed: 06/11/2023]
Abstract
Memristive devices are among the most prominent candidates for future computer memory storage and neuromorphic computing. Though promising, the major hurdle for their industrial fabrication is their device-to-device and cycle-to-cycle variability. These occur due to the random nature of nanoionic conductive filaments, whose rupture and formation govern device operation. Changes in filament location, shape, and chemical composition cause cycle-to-cycle variability. This challenge is tackled by spatially confining conductive filaments with Ni nanoparticles. Ni nanoparticles are integrated on the bottom La0.2 Sr0.7 Ti0.9 Ni0.1 O3- δ electrode by an exsolution method, in which, at high temperatures under reducing conditions, Ni cations migrate to the perovskite surface, generating metallic nanoparticles. This fabrication method offers fine control over particle size and density and ensures strong particle anchorage in the bottom electrode, preventing movement and agglomeration. In devices based on amorphous SrTiO3 , it is demonstrated that as the exsolved Ni nanoparticle diameter increases up to ≈50 nm, the ratio between the ON and OFF resistance states increases from single units to 180 and the variability of the low resistance state reaches values below 5%. Exsolution is applied for the first time to engineer solid-solid interfaces extending its realm of application to electronic devices.
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Affiliation(s)
- Jonathan Spring
- Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
- Electrochemical Materials, Department of Materials, ETHZ, Hönggerbergring 64, Zurich, 8093, Switzerland
| | - Eva Sediva
- Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
- Electrochemical Materials, Department of Materials, ETHZ, Hönggerbergring 64, Zurich, 8093, Switzerland
| | - Zachary D Hood
- Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
| | - Juan Carlos Gonzalez-Rosillo
- Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
| | - Willis O'Leary
- Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
| | - Kun Joong Kim
- Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
| | - Alfonso J Carrillo
- Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
| | - Jennifer L M Rupp
- Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
- Electrochemical Materials, Department of Materials, ETHZ, Hönggerbergring 64, Zurich, 8093, Switzerland
- Electrochemical Materials, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA, 02139, USA
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20
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Tian X, Brennecka GL, Tan X. Direct Observations of Field-Intensity-Dependent Dielectric Breakdown Mechanisms in TiO 2 Single Nanocrystals. ACS NANO 2020; 14:8328-8334. [PMID: 32530595 DOI: 10.1021/acsnano.0c02346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
One of the main challenges for next-generation electric power systems and electronics is to avoid premature dielectric breakdown in insulators and capacitors and to ensure reliable operations at higher electric fields and higher efficiencies. However, dielectric breakdown is a complex phenomenon and often involves many different processes simultaneously. Here we show distinctly different defect-related and intrinsic breakdown processes by studying individual, single-crystalline TiO2 nanoparticles using in situ transmission electron microscopy (TEM). As the applied electric field intensity rises, rutile-to-anatase phase transition, local amorphization/melting, and ablation are identified as the corresponding breakdown processes, the field intensity thresholds of which are found to be related to the position of the intensified field and the duration of the applied bias relative to the time of charged defects accumulation. Our observations reveal an intensity-dependent dielectric response of crystalline oxides at breakdown and suggest possible routes to suppress the initiation of premature dielectric breakdown. Hence, they will aid the design and development of next-generation robust and efficient solid dielectrics.
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Affiliation(s)
- Xinchun Tian
- Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, United States
| | - Geoff Lee Brennecka
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Xiaoli Tan
- Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, United States
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21
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Comparative study of electron-beam crystallization of amorphous hafnium oxides HfO2 and HfOx (x = 1.82). SN APPLIED SCIENCES 2020. [DOI: 10.1007/s42452-020-3102-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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22
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Ma Y, Cullen DA, Goodwill JM, Xu Q, More KL, Skowronski M. Exchange of Ions across the TiN/TaO x Interface during Electroformation of TaO x-Based Resistive Switching Devices. ACS APPLIED MATERIALS & INTERFACES 2020; 12:27378-27385. [PMID: 32441092 DOI: 10.1021/acsami.0c06960] [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
The valence change model describes the resistive switching in metal oxide-based devices as due to electroreduction of the oxide and subsequent electromigration of oxygen vacancies. Here, we present cross-sectional X-ray energy-dispersive spectroscopy elemental maps of Ta, O, N, and Ti in electroformed TiN/TaO2.0/TiN structures. O, N, and Ti were exchanged between the anode and the functional oxide in devices formed at high power (∼1 mW), but the exchange was below the detection limit at low power (<0.5 mW). All structures exhibit a similar Ta-enriched and O-depleted filament formed by the elemental segregation in the functional oxide by the temperature gradient. The elemental interchange is interpreted as due to Fick's diffusion caused by high temperatures in the gap of the filament and is not an essential part of electroformation.
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Affiliation(s)
- Yuanzhi Ma
- Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - David A Cullen
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jonathan M Goodwill
- Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Qiyun Xu
- Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Karren L More
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Marek Skowronski
- Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States
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23
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Heo KJ, Kim HS, Lee JY, Kim SJ. Filamentary Resistive Switching and Capacitance-Voltage Characteristics of the a-IGZO/TiO 2 Memory. Sci Rep 2020; 10:9276. [PMID: 32518357 PMCID: PMC7283246 DOI: 10.1038/s41598-020-66339-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 05/19/2020] [Indexed: 12/03/2022] Open
Abstract
In this study, molybdenum tungsten/amorphous InGaZnO (a-IGZO)/TiO2/n-type Si-based resistive random access memory (ReRAM) is manufactured. After deposition of the a-IGZO, annealing was performed at 200, 300, 400, and 500 °C for approximately 1 h in order to analyze the effect of temperature change on the ReRAM after post annealing in a furnace. As a result of measuring the current-voltage curve, the a-IGZO/TiO2-based ReRAM annealed at 400 °C reached compliance current in a low-resistance state, and showed the most complete hysteresis curve. In the a-IGZO layer annealed at 400 °C, the O1/Ototal value increased most significantly, to approximately 78.2%, and the O3/Ototal value decreased the most, to approximately 2.6%. As a result, the a-IGZO/TiO2-based ReRAM annealed at 400 °C reduced conductivity and prevented an increase in leakage current caused by oxygen vacancies with sufficient recovery of the metal-oxygen bond. Scanning electron microscopy analysis revealed that the a-IGZO surface showed hillocks at a high post annealing temperature of 500 °C, which greatly increased the surface roughness and caused the surface area performance to deteriorate. Finally, as a result of measuring the capacitance-voltage curve in the a-IGZO/TiO2-based ReRAM in the range of −2 V to 4 V, the accumulation capacitance value of the ReRAM annealed at 400 °C increased most in a nonvolatile behavior.
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Affiliation(s)
- Kwan-Jun Heo
- College of Electrical and Computer Engineering, Chungbuk National University, Cheongju, 28644, Korea.,R&D center, SK hynix, 2091, Gyeongchung-daero, Bubal-eup, Icheon-si, Gyeonggi-do, 13558, Korea
| | - Han-Sang Kim
- College of Electrical and Computer Engineering, Chungbuk National University, Cheongju, 28644, Korea
| | - Jae-Yun Lee
- College of Electrical and Computer Engineering, Chungbuk National University, Cheongju, 28644, Korea
| | - Sung-Jin Kim
- College of Electrical and Computer Engineering, Chungbuk National University, Cheongju, 28644, Korea.
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Chen X, Suen CH, Yau HM, Zhou F, Chai Y, Tang X, Zhou X, Onofrio N, Dai JY. A dual mode electronic synapse based on layered SnSe films fabricated by pulsed laser deposition. NANOSCALE ADVANCES 2020; 2:1152-1160. [PMID: 36133057 PMCID: PMC9418994 DOI: 10.1039/c9na00447e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 01/16/2020] [Indexed: 06/13/2023]
Abstract
An artificial synapse, such as a memristive electronic synapse, has caught world-wide attention due to its potential in neuromorphic computing, which may tremendously reduce computer volume and energy consumption. The introduction of layered two-dimensional materials has been reported to enhance the performance of the memristive electronic synapse. However, it is still a challenge to fabricate large-area layered two-dimensional films by scalable methods, which has greatly limited the industrial application potential of two-dimensional materials. In this work, a scalable pulsed laser deposition (PLD) method has been utilized to fabricate large-area layered SnSe films, which are used as the functional layers of the memristive electronic synapse with dual modes. Both long-term memristive behaviour with gradually changed resistance (Mode 1) and short-term memristive behavior with abruptly reduced resistance (Mode 2) have been achieved in this SnSe-based memristive electronic synapse. The switching between Mode 1 and Mode 2 can be realized by a series of voltage sweeping and programmed pulses. The formation and recovery of Sn vacancies were believed to induce the short-term memristive behaviour, and the joint action of Ag filament formation/rupture and Schottky barrier modulation can be the origin of long-term memristive behaviour. DFT calculations were performed to further illustrate how Ag atoms and Sn vacancies diffuse through the SnSe layer and form filaments. The successful emulation of synaptic functions by the layered chalcogenide memristor fabricated by the PLD method suggests the application potential in future neuromorphic computers.
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Affiliation(s)
- Xinxin Chen
- Department of Applied Physics, The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
| | - Chun-Hung Suen
- Department of Applied Physics, The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
| | - Hei-Man Yau
- Department of Applied Physics, The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
| | - Feichi Zhou
- Department of Applied Physics, The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
| | - Yang Chai
- Department of Applied Physics, The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
| | - Xiaodan Tang
- College of Physics, Chongqing University Chongqing 401331 P. R. China
| | - Xiaoyuan Zhou
- College of Physics, Chongqing University Chongqing 401331 P. R. China
| | - Nicolas Onofrio
- Department of Applied Physics, The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
| | - Ji-Yan Dai
- Department of Applied Physics, The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
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High endurance of bipolar resistive switching in a Pt/LaNiO3/Nb:SrZrO3/Cu stack: The role of Cu modulating layer. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2019.137040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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26
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Tian J, Wu H, Fan Z, Zhang Y, Pennycook SJ, Zheng D, Tan Z, Guo H, Yu P, Lu X, Zhou G, Gao X, Liu JM. Nanoscale Topotactic Phase Transformation in SrFeO x Epitaxial Thin Films for High-Density Resistive Switching Memory. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1903679. [PMID: 31639262 DOI: 10.1002/adma.201903679] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 10/03/2019] [Indexed: 06/10/2023]
Abstract
Resistive switching (RS) memory has stayed at the forefront of next-generation nonvolatile memory technologies. Recently, a novel class of transition metal oxides (TMOs), which exhibit reversible topotactic phase transformation between insulating brownmillerite (BM) phase and conducting perovskite (PV) phase, has emerged as promising candidate materials for RS memories. Nevertheless, the microscopic mechanism of RS in these TMOs is still unclear. Furthermore, RS devices with simultaneously high density and superior memory performance are yet to be reported. Here, using SrFeOx as a model system, it is directly observed that PV SrFeO3 nanofilaments are formed and extend almost through the BM SrFeO2.5 matrix in the ON state and are ruptured in the OFF state, unambiguously revealing a filamentary RS mechanism. The nanofilaments are ≈10 nm in diameter, enabling to downscale Au/SrFeOx /SrRuO3 RS devices to the 100 nm range for the first time. These nanodevices exhibit good performance including ON/OFF ratio as high as ≈104 , retention time over 105 s, and endurance up to 107 cycles. This study significantly advances the understanding of the RS mechanism in TMOs exhibiting topotactic phase transformation, and it also demonstrates the potential of these materials for use in high-density RS memories.
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Affiliation(s)
- Junjiang Tian
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Haijun Wu
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Zhen Fan
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Yang Zhang
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Stephen J Pennycook
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Dongfeng Zheng
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Zhengwei Tan
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Haizhong Guo
- School of Physical Engineering, Zhengzhou University, Zhengzhou, 450001, China
| | - Pu Yu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Xubing Lu
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Xingsen Gao
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Jun-Ming Liu
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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Liao X, Zhang Y, Wang J, Kang J, Zhang J, Wang J, Zheng J, Wang H. Resistance Switching Behavior in Rectangle-Nano-Pattern SrTiO 3 Induced by Simple Annealing. MATERIALS (BASEL, SWITZERLAND) 2019; 12:ma12223698. [PMID: 31717524 PMCID: PMC6888333 DOI: 10.3390/ma12223698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/31/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
The tunability of semi-conductivity in SrTiO3 single crystal substrates has been realized by a simple encapsulated annealing method under argon atmosphere. This high temperature annealing-induced property changes are characterized by the transmission spectra, scanning electron microscopy (SEM) and synchrotron-based X-ray absorption (XAS). We find the optical property is strongly influenced by the annealing time (with significant decrease of transmittance). A sub gap absorption at ~427 nm is detected which is attributed to the introduction of oxygen vacancy. Interestingly, in the SEM images, annealing-induced regularly rectangle nano-patterns are directly observed which is contributed to the conducting filaments. The XAS of O K-edge spectra shows the changes of electronic structure by annealing. Very importantly, resistance switching response is displayed in the annealed SrTiO3 single crystal. This suggests a possible simplified route to tune the conductivity of SrTiO3 and further develop novel resistance switching materials.
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Affiliation(s)
- Xiaxia Liao
- School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China;
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
| | - Yufeng Zhang
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
| | - Jiaou Wang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049, China;
| | - Junyong Kang
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
| | - Jinbin Zhang
- College of Materials, Xiamen University, Xiamen 361005, China;
| | - Jizheng Wang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
| | - Jincheng Zheng
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
- Institute of Artificial Intelligence, Xiamen University Malaysia, Sepang 43900, Malaysia
| | - Huiqiong Wang
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
- Institute of Artificial Intelligence, Xiamen University Malaysia, Sepang 43900, Malaysia
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28
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Ahmed T, Walia S, Mayes ELH, Ramanathan R, Bansal V, Bhaskaran M, Sriram S, Kavehei O. Time and rate dependent synaptic learning in neuro-mimicking resistive memories. Sci Rep 2019; 9:15404. [PMID: 31659247 PMCID: PMC6817848 DOI: 10.1038/s41598-019-51700-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 10/01/2019] [Indexed: 12/27/2022] Open
Abstract
Memristors have demonstrated immense potential as building blocks in future adaptive neuromorphic architectures. Recently, there has been focus on emulating specific synaptic functions of the mammalian nervous system by either tailoring the functional oxides or engineering the external programming hardware. However, high device-to-device variability in memristors induced by the electroforming process and complicated programming hardware are among the key challenges that hinder achieving biomimetic neuromorphic networks. Here, a simple hybrid complementary metal oxide semiconductor (CMOS)-memristor approach is reported to implement different synaptic learning rules by utilizing a CMOS-compatible memristor based on oxygen-deficient SrTiO3-x (STOx). The potential of such hybrid CMOS-memristor approach is demonstrated by successfully imitating time-dependent (pair and triplet spike-time-dependent-plasticity) and rate-dependent (Bienenstosk-Cooper-Munro) synaptic learning rules. Experimental results are benchmarked against in-vitro measurements from hippocampal and visual cortices with good agreement. The scalability of synaptic devices and their programming through a CMOS drive circuitry elaborates the potential of such an approach in realizing adaptive neuromorphic computation and networks.
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Affiliation(s)
- Taimur Ahmed
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia.
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia.
| | - Sumeet Walia
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia
| | - Edwin L H Mayes
- RMIT Microscopy and Microanalysis Facility, RMIT University, Melbourne, VIC, 3001, Australia
| | - Rajesh Ramanathan
- Sir Ian Potter NanoBioSensing Facility, NanoBiotechnology Research Laboratory, School of Science, RMIT University, Melbourne, VIC, 3001, Australia
| | - Vipul Bansal
- Sir Ian Potter NanoBioSensing Facility, NanoBiotechnology Research Laboratory, School of Science, RMIT University, Melbourne, VIC, 3001, Australia
| | - Madhu Bhaskaran
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia
| | - Sharath Sriram
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia.
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia.
| | - Omid Kavehei
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia.
- Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, VIC, 3001, Australia.
- Faculty of Engineering, The University of Sydney, NWS, 2006, Sydney, Australia.
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29
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Srivastava S, Thomas JP, Leung KT. Programmable, electroforming-free TiO x/TaO x heterojunction-based non-volatile memory devices. NANOSCALE 2019; 11:18159-18168. [PMID: 31556429 DOI: 10.1039/c9nr06403f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electroforming-free resistive switching in memristors is essential to reliably achieving the performance of high switching speed, high endurance, good signal retention, and low power consumption expected for next-generation computing devices. Although there have been various approaches to resolve the issues observed with the electroforming process in oxide-based memory devices, most of them end up having high SET and RESET voltages and short lifetimes. We present a heterojunction interface of oxygen-vacancy-defect-rich ultrananocrystalline TiOx and TaOx films used as the switching matrix, which enables high-quality electroforming-free switching with a much lower programming voltage (+0.5-0.8 V), a high endurance of over 104 cycles and good retention performance with an estimated device lifetime of over 10 years. The electroforming-free switching behavior is governed by migration of oxygen vacancies driven by electric field localization that is imposed by the ultrananocrystalline nature of the TaOx film, serving as the switching matrix, with the TiOx film serving as an additional oxygen vacancy source to reduce the overall resistivity of TaOx and provide low-bias rectification. The ability to perform electroforming-free resistive switching along with excellent switching repeatability and retention capabilities for various digital and analog programmable voltages enables high scalability and large density integration of the cross-bar ReRAM framework.
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Affiliation(s)
- Saurabh Srivastava
- WATLab and Department of Chemistry, University of Waterloo, 200 University Ave. W., Waterloo, Ontario N2L 3G1, Canada.
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30
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Nallagatla VR, Heisig T, Baeumer C, Feyer V, Jugovac M, Zamborlini G, Schneider CM, Waser R, Kim M, Jung CU, Dittmann R. Topotactic Phase Transition Driving Memristive Behavior. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1903391. [PMID: 31441160 DOI: 10.1002/adma.201903391] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/26/2019] [Indexed: 06/10/2023]
Abstract
Redox-based memristive devices are one of the most attractive candidates for future nonvolatile memory applications and neuromorphic circuits, and their performance is determined by redox processes and the corresponding oxygen-ion dynamics. In this regard, brownmillerite SrFeO2.5 has been recently introduced as a novel material platform due to its exceptional oxygen-ion transport properties for resistive-switching memory devices. However, the underlying redox processes that give rise to resistive switching remain poorly understood. By using X-ray absorption spectromicroscopy, it is demonstrated that the reversible redox-based topotactic phase transition between the insulating brownmillerite phase, SrFeO2.5 , and the conductive perovskite phase, SrFeO3 , gives rise to the resistive-switching properties of SrFeOx memristive devices. Furthermore, it is found that the electric-field-induced phase transition spreads over a large area in (001) oriented SrFeO2.5 devices, where oxygen vacancy channels are ordered along the in-plane direction of the device. In contrast, (111)-grown SrFeO2.5 devices with out-of-plane oriented oxygen vacancy channels, reaching from the bottom to the top electrode, show a localized phase transition. These findings provide detailed insight into the resistive-switching mechanism in SrFeOx -based memristive devices within the framework of metal-insulator topotactic phase transitions.
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Affiliation(s)
- Venkata R Nallagatla
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
- Department of Physics and Oxide Research Centre, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Thomas Heisig
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
- Institute of Electronic Materials, IWE2, RWTH Aachen University, 52056, Aachen, Germany
| | - Christoph Baeumer
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
- Institute of Electronic Materials, IWE2, RWTH Aachen University, 52056, Aachen, Germany
| | - Vitaliy Feyer
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
- Fakultaet f. Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universitat Duisburg-Essen, 47048, Duisburg, Germany
| | - Matteo Jugovac
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
| | - Giovanni Zamborlini
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
- Technische Universitaet Dortmund, Experimentelle Physik VI, 44227, Dortmund, Germany
| | - Claus M Schneider
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
- Fakultaet f. Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universitat Duisburg-Essen, 47048, Duisburg, Germany
- Department of Physics, University of California, Davis, CA, 95616, USA
| | - Rainer Waser
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
- Institute of Electronic Materials, IWE2, RWTH Aachen University, 52056, Aachen, Germany
| | - Miyoung Kim
- Department of Material Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, South Korea
| | - Chang Uk Jung
- Department of Physics and Oxide Research Centre, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Regina Dittmann
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
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31
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Understanding memristive switching via in situ characterization and device modeling. Nat Commun 2019; 10:3453. [PMID: 31371705 PMCID: PMC6672015 DOI: 10.1038/s41467-019-11411-6] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Accepted: 07/07/2019] [Indexed: 11/23/2022] Open
Abstract
Owing to their attractive application potentials in both non-volatile memory and unconventional computing, memristive devices have drawn substantial research attention in the last decade. However, major roadblocks still remain in device performance, especially concerning relatively large parameter variability and limited cycling endurance. The response of the active region in the device within and between switching cycles plays the dominating role, yet the microscopic details remain elusive. This Review summarizes recent progress in scientific understanding of the physical origins of the non-idealities and propose a synergistic approach based on in situ characterization and device modeling to investigate switching mechanism. At last, the Review offers an outlook for commercialization viability of memristive technology. Memristor as the fourth basic element of electric circuits has drawn substantial attention for developing future computing technologies. Sun et al. report the progress and the challenges facing researchers on understanding memristive switching, and advocate continuous studies using a synergistic approach.
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32
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Kwon DH, Lee S, Kang CS, Choi YS, Kang SJ, Cho HL, Sohn W, Jo J, Lee SY, Oh KH, Noh TW, De Souza RA, Martin M, Kim M. Unraveling the Origin and Mechanism of Nanofilament Formation in Polycrystalline SrTiO 3 Resistive Switching Memories. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1901322. [PMID: 31106484 DOI: 10.1002/adma.201901322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Indexed: 06/09/2023]
Abstract
Three central themes in the study of the phenomenon of resistive switching are the nature of the conducting phase, why it forms, and how it forms. In this study, the answers to all three questions are provided by performing switching experiments in situ in a transmission electron microscope on thin films of the model system polycrystalline SrTiO3 . On the basis of high-resolution transmission electron microscopy, electron-energy-loss spectroscopy and in situ current-voltage measurements, the conducting phase is identified to be SrTi11 O20 . This phase is only observed at specific grain boundaries, and a Ruddlesden-Popper phase, Sr3 Ti2 O7 , is typically observed adjacent to the conducting phase. These results allow not only the proposal that filament formation in this system has a thermodynamic origin-it is driven by electrochemical polarization and the local oxygen activity in the film decreasing below a critical value-but also the deduction of a phase diagram for strongly reduced SrTiO3 . Furthermore, why many conducting filaments are nucleated at one electrode but only one filament wins the race to the opposite electrode is also explained. The work thus provides detailed insights into the origin and mechanisms of filament generation and rupture.
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Affiliation(s)
- Deok-Hwang Kwon
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Shinbuhm Lee
- Department of Emerging Materials Science, Daegu-Gyeongbuk Institute of Science and Technology, Daegu, 42988, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Chan Soon Kang
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yong Seok Choi
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sung Jin Kang
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hae Lim Cho
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Woonbae Sohn
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Janghyun Jo
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Seung-Yong Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Kyu Hwan Oh
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Tae Won Noh
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
| | - Roger A De Souza
- Institute of Physical Chemistry, RWTH Aachen University, Aachen, 52074, Germany
| | - Manfred Martin
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Institute of Physical Chemistry, RWTH Aachen University, Aachen, 52074, Germany
| | - Miyoung Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
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33
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Li J, Li N, Ge C, Huang H, Sun Y, Gao P, He M, Wang C, Yang G, Jin K. Giant Electroresistance in Ferroionic Tunnel Junctions. iScience 2019; 16:368-377. [PMID: 31220760 PMCID: PMC6584484 DOI: 10.1016/j.isci.2019.05.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/07/2019] [Accepted: 05/29/2019] [Indexed: 11/24/2022] Open
Abstract
Oxide-based resistive switching devices, including ferroelectric tunnel junctions and resistance random access memory, are promising candidates for the next-generation non-volatile memory technology. In this work, we propose a ferroionic tunnel junction to realize a giant electroresistance. It functions as a ferroelectric tunnel junction at low resistance state and as a Schottky junction at high resistance state, due to interface engineering through the field-induced migration of oxygen vacancies. An extremely large electroresistance with ON/OFF ratios of 5.1×107 at room temperature and 2.1×109 at 10 K is achieved, using an ultrathin BaTiO3-δ layer as the ferroelectric barrier and a semiconducting Nb-doped SrTiO3 substrate as the bottom electrode. The results point toward an appealing way for the design of high-performance resistive switching devices based on ultrathin oxide heterostructures by ionic controlled interface engineering.
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Affiliation(s)
- Jiankun Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Ning Li
- International Center for Quantum Materials and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Chen Ge
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Key Laboratory of Polar Materials and Devices, Ministry of Education, Shanghai 200241, China.
| | - Heyi Huang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuanwei Sun
- International Center for Quantum Materials and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Peng Gao
- International Center for Quantum Materials and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Centre of Quantum Matter, Beijing 100871, China.
| | - Meng He
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Can 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
| | - Guozhen Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Kuijuan Jin
- 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.
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34
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Chen X, Zeng K, Zhu X, Ding G, Zou T, Zhang C, Zhou K, Zhou Y, Han S. Light Driven Active Transition of Switching Modes in Homogeneous Oxides/Graphene Heterostructure. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1900213. [PMID: 31179227 PMCID: PMC6548956 DOI: 10.1002/advs.201900213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 02/26/2019] [Indexed: 05/30/2023]
Abstract
Depending on the mobile species involved in the resistive switching process, redox random access memories and conductive bridge random access memories are widely studied with distinct switching mechanisms. Although the two resistance switching types have faithfully proved to be electrochemically linked in metal oxide-based memristive devices, the corresponding photo-induced transition has not yet been realized. Here, a photo-induced transition through the integration of a graphene layer into a titanium oxide-based memory device is demonstrated. Coupled with Raman mapping and an electron energy loss spectroscopy technique, the photo-induced interaction at the heterostructure of graphene/titanium oxide are considered to dominate the transition process. Moreover, a negative differential resistance effect is observed by controlling the applied voltage, which can be credited to the saturation of trap centers (oxygen vacancies) and the increase of interfacial barrier at the graphene/titanium oxide heterojunction.
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Affiliation(s)
- Xiaoli Chen
- Shenzhen Key Laboratory of Flexible Memory Materials and DevicesCollege of Electronic Science and TechnologyShenzhen UniversityShenzhenGuangdong518060P. R. China
| | - Kelin Zeng
- Institute for Advanced StudyShenzhen UniversityShenzhenGuangdong518060P. R. China
| | - Xin Zhu
- Institute for Advanced StudyShenzhen UniversityShenzhenGuangdong518060P. R. China
| | - Guanglong Ding
- Shenzhen Key Laboratory of Flexible Memory Materials and DevicesCollege of Electronic Science and TechnologyShenzhen UniversityShenzhenGuangdong518060P. R. China
| | - Ting Zou
- College of Chemistry and Environmental EngineeringShenzhen UniversityShenzhenGuangdong518071P. R. China
| | - Chen Zhang
- Shenzhen Key Laboratory of Flexible Memory Materials and DevicesCollege of Electronic Science and TechnologyShenzhen UniversityShenzhenGuangdong518060P. R. China
| | - Kui Zhou
- Shenzhen Key Laboratory of Flexible Memory Materials and DevicesCollege of Electronic Science and TechnologyShenzhen UniversityShenzhenGuangdong518060P. R. China
| | - Ye Zhou
- Institute for Advanced StudyShenzhen UniversityShenzhenGuangdong518060P. R. China
| | - Su‐Ting Han
- Shenzhen Key Laboratory of Flexible Memory Materials and DevicesCollege of Electronic Science and TechnologyShenzhen UniversityShenzhenGuangdong518060P. R. China
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35
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Torres-Costa V, Mäkilä E, Granroth S, Kukk E, Salonen J. Synaptic and Fast Switching Memristance in Porous Silicon-Based Structures. NANOMATERIALS 2019; 9:nano9060825. [PMID: 31159254 PMCID: PMC6631600 DOI: 10.3390/nano9060825] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 05/27/2019] [Accepted: 05/28/2019] [Indexed: 11/16/2022]
Abstract
Memristors are two terminal electronic components whose conductance depends on the amount of charge that has flown across them over time. This dependence can be gradual, such as in synaptic memristors, or abrupt, as in resistive switching memristors. Either of these memory effects are very promising for the development of a whole new generation of electronic devices. For the successful implementation of practical memristors, however, the development of low cost industry compatible memristive materials is required. Here the memristive properties of differently processed porous silicon structures are presented, which are suitable for different applications. Electrical characterization and SPICE simulations show that laser-carbonized porous silicon shows a strong synaptic memristive behavior influenced by defect diffusion, while wet-oxidized porous silicon has strong resistance switching properties, with switching ratios over 8000. Results show that practical memristors of either type can be achieved with porous silicon whose memristive properties can be adjusted by the proper material processing. Thus, porous silicon may play an important role for the successful realization of practical memristorics with cost-effective materials and processes.
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Affiliation(s)
- Vicente Torres-Costa
- Deptartamento de Física Aplicada and Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
| | - Ermei Mäkilä
- Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
| | - Sari Granroth
- Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
| | - Edwin Kukk
- Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
| | - Jarno Salonen
- Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
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36
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Solid-State Electrochemical Process and Performance Optimization of Memristive Materials and Devices. CHEMISTRY 2019. [DOI: 10.3390/chemistry1010005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
As an emerging technology, memristors are nanoionic-based electrochemical systems that retains their resistance state based on the history of the applied voltage/current. They can be used for on-chip memory and storage, biologically inspired computing, and in-memory computing. However, the underlying physicochemical processes of memristors still need deeper understanding for the optimization of the device properties to meet the practical application requirements. Herein, we review recent progress in understanding the memristive mechanisms and influential factors for the optimization of memristive switching performances. We first describe the working mechanisms of memristors, including the dynamic processes of active metal ions, native oxygen ions and other active ions in ECM cells, VCM devices and ion gel-based devices, and the switching mechanisms in organic devices, along with discussions on the influential factors of the device performances. The optimization of device properties by electrode/interface engineering, types/configurations of dielectric materials and bias scheme is then illustrated. Finally, we discuss the current challenges and the future development of the memristor.
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Gao S, Liu G, Yang H, Hu C, Chen Q, Gong G, Xue W, Yi X, Shang J, Li RW. An Oxide Schottky Junction Artificial Optoelectronic Synapse. ACS NANO 2019; 13:2634-2642. [PMID: 30730696 DOI: 10.1021/acsnano.9b00340] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The rapid development of artificial intelligence techniques and future advanced robot systems sparks emergent demand on the accurate perception and understanding of the external environments via visual sensing systems that can co-locate the self-adaptive detecting, processing, and memorizing of optical signals. In this contribution, a simple indium-tin oxide/Nb-doped SrTiO3 (ITO/Nb:SrTiO3) heterojunction artificial optoelectronic synapse is proposed and demonstrated. Through the light and electric field co-modulation of the Schottky barrier profile at the ITO/Nb:SrTiO3 interface, the oxide heterojunction device can respond to the entire visible light region in a neuromorphic manner, allowing synaptic paired-pulse facilitation, short/long-term memory, and "learning-experience" behavior for optical information manipulation. More importantly, the photoplasticity of the artificial synapse has been modulated by heterosynaptic means with a sub-1 V external voltage, not only enabling an optoelectronic analog of the mechanical aperture device showing adaptive and stable optical perception capability under different illuminating conditions but also making the artificial synapse suitable for the mimicry of interest-modulated human visual memories.
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Affiliation(s)
- Shuang Gao
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Gang Liu
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Huali Yang
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Chao Hu
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Qilai Chen
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Guodong Gong
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Wuhong Xue
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Xiaohui Yi
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Jie Shang
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
| | - Run-Wei Li
- CAS Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo , Zhejiang 315201 , China
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Waser R, Dittmann R, Menzel S, Noll T. Introduction to new memory paradigms: memristive phenomena and neuromorphic applications. Faraday Discuss 2019; 213:11-27. [PMID: 30740612 DOI: 10.1039/c8fd90058b] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article provides a brief introduction to the Faraday Discussion "New memory paradigms: memristive phenomena and neuromorphic applications" held in Aachen, Germany, 15-17 October 2018. It will cover basic definitions of memristive switching elements, their main switching modes, and their most important performance parameters as well as applications in neuromorphic computing. The article comprises parts from the following sources: General Introduction and Introduction to Part V of Nanoelectronics and Information Technology, ed. R. Waser, Wiley-VCH, 2012; Chapter 4 of Nanotechnology: Volume 3: Information Technology I, ed. R. Waser, Wiley-VCH, Weinheim, 2008; Chapters 3-9 of Emerging Nanoelectronic Devices, ed. A. Chen, J. Hutchby, V. Zhirnov and G. Bourianoff, Wiley, 2015; Chapter 1 of Resistive Switching, ed. D. Ielmini and R. Waser, Wiley-VCH, 2016 (with permission by Wiley-VCH).
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Affiliation(s)
- Rainer Waser
- Peter Gruenberg Institute 7, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
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39
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Wouters DJ, Menzel S, Rupp JAJ, Hennen T, Waser R. On the universality of the I-V switching characteristics in non-volatile and volatile resistive switching oxides. Faraday Discuss 2019; 213:183-196. [PMID: 30362486 DOI: 10.1039/c8fd00116b] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The I-V switching curves of bipolar switching non-volatile ReRAM devices show peculiar characteristics, such as an abrupt ON switching and the existence of a universal switching voltage. This switching behavior has been explained by the presence of a filamentary process, in which the width of a conductive filament changes during switching resulting in different resistance states. Vice versa, similar (ON) switching behavior, e.g. that of volatile switching Cr-doped V2O3 devices, has been interpreted as an indication of the presence of similar filamentary switching. In this paper, we want to review the correlation between filamentary (width) switching and the (SET) I-V characteristics by discussing the existing models. For the Cr-doped V2O3 devices, on the other hand, it is argued that a different, constant filament width switching mode may be present.
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Affiliation(s)
- Dirk J Wouters
- Institut für Werkstoffe der Elektrotechnik II (IWE II) RWTH Aachen, Sommerfeldstraße 24, 52072 Aachen, Germany.
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40
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Hou X, Pan R, Yu Q, Zhang K, Huang G, Mei Y, Zhang DW, Zhou P. Tubular 3D Resistive Random Access Memory Based on Rolled-Up h-BN Tube. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1803876. [PMID: 30624032 DOI: 10.1002/smll.201803876] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/05/2018] [Indexed: 06/09/2023]
Abstract
Due to their advantages compared with planar structures, rolled-up tubes have been applied in many fields, such as field-effect transistors, compact capacitors, inductors, and integrative sensors. On the other hand, because of its perfect insulating nature, ultrahigh mechanical strength and atomic thickness property, 2D hexagonal boron nitride (h-BN) is a very suitable material for rolled-up memory applications. In this work, a tubular 3D resistive random access memory (RRAM) device based on rolled-up h-BN tube is realized, which is achieved by self-rolled-up technology. The tubular RRAM device exhibits bipolar resistive switching behavior, nonvolatile data storage ability, and satisfactorily low programming current compared with other 2D material-based RRAM devices. Moreover, by releasing from the substrate, the footprint area of the tubular device is reduced by six times. This tubular RRAM device has great potential for increasing the data storage density, lowering the power consumption, and may be applied in the fields of rolled-up systems and sensing-storage integration.
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Affiliation(s)
- Xiang Hou
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, 200433, China
| | - Ruobing Pan
- Department of Materials, Fudan University, Shanghai, 200433, China
| | - Qiang Yu
- Suzhou Institute of Nano-Tech and Nano Bionics, CAS, Jiangsu, 215123, China
| | - Kai Zhang
- Suzhou Institute of Nano-Tech and Nano Bionics, CAS, Jiangsu, 215123, China
| | - Gaoshan Huang
- Department of Materials, Fudan University, Shanghai, 200433, China
| | - Yongfeng Mei
- Department of Materials, Fudan University, Shanghai, 200433, China
| | - David Wei Zhang
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, 200433, China
| | - Peng Zhou
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, 200433, China
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41
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Baeumer C, Funck C, Locatelli A, Menteş TO, Genuzio F, Heisig T, Hensling F, Raab N, Schneider CM, Menzel S, Waser R, Dittmann R. In-Gap States and Band-Like Transport in Memristive Devices. NANO LETTERS 2019; 19:54-60. [PMID: 30241437 DOI: 10.1021/acs.nanolett.8b03023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Point defects such as oxygen vacancies cause emergent phenomena such as resistive switching in transition-metal oxides, but their influence on the electron-transport properties is far from being understood. Here, we employ direct mapping of the electronic structure of a memristive device by spectromicroscopy. We find that oxygen vacancies result in in-gap states that we use as input for single-band transport simulations. Because the in-gap states are situated below the Fermi level, they do not contribute to the current directly but impact the shape of the conduction band. Accordingly, we can describe our devices with band-like transport and tunneling across the Schottky barrier at the interface.
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Affiliation(s)
- Christoph Baeumer
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Carsten Funck
- Institute for Electronic Materials, IWE2 , RWTH Aachen University , 52074 Aachen , Germany
| | - Andrea Locatelli
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 km - 163,5 in AREA Science Park , I-34149 Basovizza , Trieste , Italy
| | - Tevfik Onur Menteş
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 km - 163,5 in AREA Science Park , I-34149 Basovizza , Trieste , Italy
| | - Francesca Genuzio
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 km - 163,5 in AREA Science Park , I-34149 Basovizza , Trieste , Italy
| | - Thomas Heisig
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Felix Hensling
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Nicolas Raab
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Claus M Schneider
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Stephan Menzel
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Rainer Waser
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
- Institute for Electronic Materials, IWE2 , RWTH Aachen University , 52074 Aachen , Germany
| | - Regina Dittmann
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
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42
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Menzel S, von Witzleben M, Havel V, Böttger U. The ultimate switching speed limit of redox-based resistive switching devices. Faraday Discuss 2019; 213:197-213. [PMID: 30357198 DOI: 10.1039/c8fd00117k] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In contrast to classical charge-based memories, the binary information in redox-based resistive switching devices is decoded by a change of the atomic configuration rather than changing the amount of stored electrons. This offers in principle a higher scaling potential as ions are not prone to tunneling and the information is not lost by tunneling. The switching speed, however, is potentially smaller since the ionic mass is much higher than the electron mass. In this work, the ultimate switching speed limit of redox-based resistive switching devices is discussed. Based on a theoretical analysis of the underlying physical processes, it is derived that the switching speed is limited by the phonon frequency. This limit is identical when considering the acceleration of the underlying processes by local Joule heating or by high electric fields. Electro-thermal simulations show that a small filamentary volume can be heated up in picoseconds. Likewise, the characteristic charging time of a nanocrossbar device can be even below ps. In principle, temperature and voltage can be brought fast enough to the device to reach the ultimate switching limit. In addition, the experimental route and the challenges towards reaching the ultimate switching speed limit are discussed. So far, the experimental switching speed is limited by the measurement setup.
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Affiliation(s)
- Stephan Menzel
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-7), 52425 Jülich, Germany.
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43
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Raab N, Schmidt DO, Du H, Kruth M, Simon U, Dittmann R. Au Nanoparticles as Template for Defect Formation in Memristive SrTiO₃ Thin Films. NANOMATERIALS (BASEL, SWITZERLAND) 2018; 8:E869. [PMID: 30360546 PMCID: PMC6266280 DOI: 10.3390/nano8110869] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 10/05/2018] [Accepted: 10/18/2018] [Indexed: 01/24/2023]
Abstract
We investigated the possibility of tuning the local switching properties of memristive crystalline SrTiO 3 thin films by inserting nanoscale defect nucleation centers. For that purpose, we employed chemically-synthesized Au nanoparticles deposited on 0.5 wt%-Nb-doped SrTiO 3 single crystal substrates as a defect formation template for the subsequent growth of SrTiO 3 . We studied in detail the resulting microstructure and the local conducting and switching properties of the SrTiO 3 thin films. We revealed that the Au nanoparticles floated to the SrTiO 3 surface during growth, leaving behind a distorted thin film region in their vicinity. By employing conductive-tip atomic force microscopy, these distorted SrTiO 3 regions are identified as sites of preferential resistive switching. These findings can be attributed to the enhanced oxygen exchange reaction at the surface in these defective regions.
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Affiliation(s)
- Nicolas Raab
- Peter Grünberg Institut 7 and JARA-FIT, Forschungszentrum Jülich, 52425 Jülich, Germany.
| | - Dirk Oliver Schmidt
- Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany.
| | - Hongchu Du
- Ernst Ruska-Center for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
| | - Maximilian Kruth
- Ernst Ruska-Center for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
| | - Ulrich Simon
- Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany.
| | - Regina Dittmann
- Peter Grünberg Institut 7 and JARA-FIT, Forschungszentrum Jülich, 52425 Jülich, Germany.
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44
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Jeong DS, Hwang CS. Nonvolatile Memory Materials for Neuromorphic Intelligent Machines. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1704729. [PMID: 29667255 DOI: 10.1002/adma.201704729] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 01/18/2018] [Indexed: 06/08/2023]
Abstract
Recent progress in deep learning extends the capability of artificial intelligence to various practical tasks, making the deep neural network (DNN) an extremely versatile hypothesis. While such DNN is virtually built on contemporary data centers of the von Neumann architecture, physical (in part) DNN of non-von Neumann architecture, also known as neuromorphic computing, can remarkably improve learning and inference efficiency. Particularly, resistance-based nonvolatile random access memory (NVRAM) highlights its handy and efficient application to the multiply-accumulate (MAC) operation in an analog manner. Here, an overview is given of the available types of resistance-based NVRAMs and their technological maturity from the material- and device-points of view. Examples within the strategy are subsequently addressed in comparison with their benchmarks (virtual DNN in deep learning). A spiking neural network (SNN) is another type of neural network that is more biologically plausible than the DNN. The successful incorporation of resistance-based NVRAM in SNN-based neuromorphic computing offers an efficient solution to the MAC operation and spike timing-based learning in nature. This strategy is exemplified from a material perspective. Intelligent machines are categorized according to their architecture and learning type. Also, the functionality and usefulness of NVRAM-based neuromorphic computing are addressed.
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Affiliation(s)
- Doo Seok Jeong
- Center for Electronic Materials, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
- Division of Materials Science and Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul, 04763, South Korea
| | - Cheol Seong Hwang
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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Zhang H, Yoo S, Menzel S, Funck C, Cüppers F, Wouters DJ, Hwang CS, Waser R, Hoffmann-Eifert S. Understanding the Coexistence of Two Bipolar Resistive Switching Modes with Opposite Polarity in Pt/TiO 2/Ti/Pt Nanosized ReRAM Devices. ACS APPLIED MATERIALS & INTERFACES 2018; 10:29766-29778. [PMID: 30088755 DOI: 10.1021/acsami.8b09068] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Redox-type resistive random access memories based on transition-metal oxides are studied as adjustable two-terminal devices for integrated network applications beyond von Neumann computing. The prevailing, so-called, counter-eight-wise (c8w) polarity of the switching hysteresis in filamentary-type valence change mechanism devices originates from a temperature- and field-controlled drift-diffusion process of mobile ions, predominantly oxygen vacancies in the switching oxide. Recently, a bipolar resistive switching (BRS) process with opposite polarity, so-called, eight-wise (8w) switching, has been reported that, especially for TiO2 cells, is still not completely understood. Here, we report on nanosized (<0.01 μm2) asymmetric memristive cells from 3 to 6 nm thick TiO2 films by atomic layer deposition, which reveal a coexistence of c8w and 8w switching in the same cell. As important characteristics for the studied Pt/TiO2/Ti/Pt devices, the resistance states of both modes are nonvolatile and share one common state; i.e., the high-resistance state of the c8w mode equals the low-resistance state of the 8w-mode. A transition between the opposite hysteresis loops is possible by voltage control. Specifically, 8w BRS in the TiO2 cells is a self-limited low-energy nonvolatile switching process. Additionally, the 8w reset process enables the programming of multilevel high-resistance states. Combining the experimental results with data from simulation studies allows to propose a model, which explains 8w BRS by an oxygen transfer process across the Pt/TiO2 Schottky interface at the position of the c8w filament. Therefore, the coexistence of c8w and 8w BRS in the nanoscale asymmetric Pt/TiO2/Ti/Pt cells is understood from a competition between drift/diffusion of oxygen vacancies in the oxide layer and an oxygen exchange reaction across the Pt/TiO2 interface.
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Affiliation(s)
- Hehe Zhang
- Peter Grünberg Institute (PGI 7 & 10) and JARA-Fundamentals in Future Information Technology , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
| | - Sijung Yoo
- Department of Materials Science and Engineering and Inter-University Semiconductor Research Center , Seoul National University , 151-744 Seoul , Republic of Korea
| | - Stephan Menzel
- Peter Grünberg Institute (PGI 7 & 10) and JARA-Fundamentals in Future Information Technology , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
| | - Carsten Funck
- Institute of Materials in Electrical Engineering and Information Technology II , RWTH Aachen University , 52062 Aachen , Germany
| | - Felix Cüppers
- Peter Grünberg Institute (PGI 7 & 10) and JARA-Fundamentals in Future Information Technology , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
| | - Dirk J Wouters
- Institute of Materials in Electrical Engineering and Information Technology II , RWTH Aachen University , 52062 Aachen , Germany
| | - Cheol Seong Hwang
- Department of Materials Science and Engineering and Inter-University Semiconductor Research Center , Seoul National University , 151-744 Seoul , Republic of Korea
| | - Rainer Waser
- Peter Grünberg Institute (PGI 7 & 10) and JARA-Fundamentals in Future Information Technology , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
- Institute of Materials in Electrical Engineering and Information Technology II , RWTH Aachen University , 52062 Aachen , Germany
| | - Susanne Hoffmann-Eifert
- Peter Grünberg Institute (PGI 7 & 10) and JARA-Fundamentals in Future Information Technology , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
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Ahn Y, Shin HW, Lee TH, Kim WH, Son JY. Effects of a Nb nanopin electrode on the resistive random-access memory switching characteristics of NiO thin films. NANOSCALE 2018; 10:13443-13448. [PMID: 29972166 DOI: 10.1039/c8nr02986e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report the effects of bottom electrode shapes on resistive random-access memory (RRAM) devices composed of Nb (bottom electrode)/NiO (dielectric)/Nb (top electrode) structures. By adopting a nano-fabrication process using an anodic aluminum oxide (AAO) nanotemplate, a well-aligned Nb nanopin array bottom electrode was formed on the surface of a Si substrate. For comparison, a Nb thin film was employed as a different type of bottom electrode. Then, a NiO thin film dielectric was prepared on both the Nb bottom electrodes via a spin coating method, followed by Nb sputtering for the Nb top electrode. Both the RRAM devices with Nb nanopin and thin film bottom electrodes exhibited typical unipolar resistive switching behavior. However, a lower SET/RESET voltage was observed for the Nb nanopin electrode compared to the Nb thin film electrode by virtue of an enhanced electric field induced by the nanopin-shaped electrode. More significantly, on the basis of endurance and retention characteristics, the Nb nanopin electrode played a key role in minimizing the dispersion of the low- and high-resistance state currents and the variation in the SET/RESET voltage by developing more-concise conducting filaments in the conducting path. Therefore, we foresee that this approach can provide an insight into the optimal design of RRAM devices.
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Affiliation(s)
- Yoonho Ahn
- School of Liberal Arts, Korea University of Technology and Education, Cheonan 31253, Republic of Korea
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Skaja K, Andrä M, Rana V, Waser R, Dittmann R, Baeumer C. Reduction of the forming voltage through tailored oxygen non-stoichiometry in tantalum oxide ReRAM devices. Sci Rep 2018; 8:10861. [PMID: 30022129 PMCID: PMC6052165 DOI: 10.1038/s41598-018-28992-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 07/03/2018] [Indexed: 11/08/2022] Open
Abstract
In this study, we investigated the influence of oxygen non-stoichiometry on the resistive switching performance of tantalum oxide based memristive devices. Thin-films of tantalum oxide were deposited with varying sputter power and oxygen partial pressure. The electroforming voltage was found to decrease with increasing power density or decreased oxygen partial pressure, while the endurance remained stable and the resistance window ROFF/RON was found to increase. In-depth XPS analysis connects these observations to a controllable oxygen sub-stoichiometry in the sputter-deposited films. Our analysis shows that the decrease of the forming voltage results from an increase in carrier density in the as-prepared thin-films, which is induced by the presence of oxygen vacancies.
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Affiliation(s)
- Katharina Skaja
- Peter Grünberg Institute and JARA-FIT, FZ Jülich, D-52425, Jülich, Germany
| | - Michael Andrä
- Peter Grünberg Institute and JARA-FIT, FZ Jülich, D-52425, Jülich, Germany
| | - Vikas Rana
- Peter Grünberg Institute and JARA-FIT, FZ Jülich, D-52425, Jülich, Germany
| | - Rainer Waser
- Peter Grünberg Institute and JARA-FIT, FZ Jülich, D-52425, Jülich, Germany
- Institute for Electronic Materials, IWE2, RWTH Aachen University, D-52074, Aachen, Germany
| | - Regina Dittmann
- Peter Grünberg Institute and JARA-FIT, FZ Jülich, D-52425, Jülich, Germany
| | - Christoph Baeumer
- Peter Grünberg Institute and JARA-FIT, FZ Jülich, D-52425, Jülich, Germany.
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48
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Heisig T, Baeumer C, Gries UN, Mueller MP, La Torre C, Luebben M, Raab N, Du H, Menzel S, Mueller DN, Jia CL, Mayer J, Waser R, Valov I, De Souza RA, Dittmann R. Oxygen Exchange Processes between Oxide Memristive Devices and Water Molecules. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1800957. [PMID: 29882270 DOI: 10.1002/adma.201800957] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/18/2018] [Indexed: 06/08/2023]
Abstract
Resistive switching based on transition metal oxide memristive devices is suspected to be caused by the electric-field-driven motion and internal redistribution of oxygen vacancies. Deriving the detailed mechanistic picture of the switching process is complicated, however, by the frequently observed influence of the surrounding atmosphere. Specifically, the presence or absence of water vapor in the atmosphere has a strong impact on the switching properties, but the redox reactions between water and the active layer have yet to be clarified. To investigate the role of oxygen and water species during resistive switching in greater detail, isotope labeling experiments in a N2 /H218 O tracer gas atmosphere combined with time-of-flight secondary-ion mass spectrometry are used. It is explicitly demonstrated that during the RESET operation in resistive switching SrTiO3 -based memristive devices, oxygen is incorporated directly from water molecules or oxygen molecules into the active layer. In humid atmospheres, the reaction pathway via water molecules predominates. These findings clearly resolve the role of humidity as both oxidizing agent and source of protonic defects during the RESET operation.
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Affiliation(s)
- Thomas Heisig
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
| | - Christoph Baeumer
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
| | - Ute N Gries
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany
| | - Michael P Mueller
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany
| | - Camilla La Torre
- Institute of Electronic Materials, IWE2, RWTH Aachen University, 52056, Aachen, Germany
| | - Michael Luebben
- Institute of Electronic Materials, IWE2, RWTH Aachen University, 52056, Aachen, Germany
| | - Nicolas Raab
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
| | - Hongchu Du
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Juelich GmbH and RWTH Aachen University, 52425, Juelich, Germany
| | - Stephan Menzel
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
| | - David N Mueller
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
| | - Chun-Lin Jia
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Juelich GmbH and RWTH Aachen University, 52425, Juelich, Germany
| | - Joachim Mayer
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Juelich GmbH and RWTH Aachen University, 52425, Juelich, Germany
| | - Rainer Waser
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
- Institute of Electronic Materials, IWE2, RWTH Aachen University, 52056, Aachen, Germany
| | - Ilia Valov
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
| | - Roger A De Souza
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany
| | - Regina Dittmann
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425, Juelich, Germany
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49
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Influence of Dislocations in Transition Metal Oxides on Selected Physical and Chemical Properties. CRYSTALS 2018. [DOI: 10.3390/cryst8060241] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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50
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Swallow JG, Lee JK, Defferriere T, Hughes GM, Raja SN, Tuller HL, Warner JH, Van Vliet KJ. Atomic Resolution Imaging of Nanoscale Chemical Expansion in Pr xCe 1-xO 2-δ during In Situ Heating. ACS NANO 2018; 12:1359-1372. [PMID: 29338198 DOI: 10.1021/acsnano.7b07732] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Thin film nonstoichiometric oxides enable many high-temperature applications including solid oxide fuel cells, actuators, and catalysis. Large concentrations of point defects (particularly, oxygen vacancies) enable fast ionic conductivity or gas exchange kinetics in these materials but also manifest as coupling between lattice volume and chemical composition. This chemical expansion may be either detrimental or useful, especially in thin film devices that may exhibit enhanced performance through strain engineering or decreased operating temperatures. However, thin film nonstoichiometric oxides can differ from bulk counterparts in terms of operando defect concentrations, transport properties, and mechanical properties. Here, we present an in situ investigation of atomic-scale chemical expansion in PrxCe1-xO2-δ (PCO), a mixed ionic-electronic conducting oxide relevant to electrochemical energy conversion and high-temperature actuation. Through a combination of electron energy loss spectroscopy and transmission electron microscopy with in situ heating, we characterized chemical strains and changes in oxidation state in cross sections of PCO films grown on yttria-stabilized zirconia (YSZ) at temperatures reaching 650 °C. We quantified, both statically and dynamically, the nanoscale chemical expansion induced by changes in PCO redox state as a function of position and direction relative to the film-substrate interface. Additionally, we observed dislocations at the film-substrate interface, as well as reduced cation localization to threading defects within PCO films. These results illustrate several key aspects of atomic-scale structure and mechanical deformation in nonstoichiometric oxide films that clarify distinctions between films and bulk counterparts and that hold several implications for operando chemical expansion or "breathing" of such oxide films.
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Affiliation(s)
- Jessica G Swallow
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Ja Kyung Lee
- Department of Materials, University of Oxford , Oxford OX1 3PH, United Kingdom
| | - Thomas Defferriere
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Gareth M Hughes
- Department of Materials, University of Oxford , Oxford OX1 3PH, United Kingdom
| | - Shilpa N Raja
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Harry L Tuller
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Jamie H Warner
- Department of Materials, University of Oxford , Oxford OX1 3PH, United Kingdom
| | - Krystyn J Van Vliet
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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