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Guido R, Mikolajick T, Schroeder U, Lomenzo PD. Role of Defects in the Breakdown Phenomenon of Al 1-xSc xN: From Ferroelectric to Filamentary Resistive Switching. NANO LETTERS 2023; 23:7213-7220. [PMID: 37523481 DOI: 10.1021/acs.nanolett.3c02351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Aluminum scandium nitride (Al1-xScxN), with its large remanent polarization, is an attractive material for high-density ferroelectric random-access memories. However, the cycling endurance of Al1-xScxN ferroelectric capacitors is far below what can be achieved in other ferroelectric materials. Understanding the nature and dynamics of the breakdown mechanism is of the utmost importance for improving memory reliability. The breakdown phenomenon in ferroelectric Al1-xScxN is proposed to be an impulse thermal filamentary-driven process along preferential defective pathways. For the first time, stable and robust bipolar filamentary resistive switching in ferroelectric Al1-xScxN is reported. A hot atom damage defect generation model illustrates how filament formation and ferroelectric switching are connected. The model reveals the tendency of the ferroelectric wurtzite-type Al1-xScxN system to reach internal symmetry with bipolar electric field cycling. Defects generated from bipolar electric field cycling influence both the energy barrier between the polarization states and that required for the filament formation.
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Affiliation(s)
- Roberto Guido
- Namlab gGmbH, Nöthnitzer Strasse 64a, 01187 Dresden, Germany
| | - Thomas Mikolajick
- Namlab gGmbH, Nöthnitzer Strasse 64a, 01187 Dresden, Germany
- Chair of Nanoelectronics, TU Dresden, 01187 Dresden, Germany
| | - Uwe Schroeder
- Namlab gGmbH, Nöthnitzer Strasse 64a, 01187 Dresden, Germany
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Zhang K, Ganesh P, Cao Y. Deterministic Conductive Filament Formation and Evolution for Improved Switching Uniformity in Embedded Metal-Oxide-Based Memristors─A Phase-Field Study. ACS APPLIED MATERIALS & INTERFACES 2023; 15:21219-21227. [PMID: 37083295 DOI: 10.1021/acsami.3c00371] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The extreme device-to-device variation of switching performance is one of the major obstacles preventing the applications of metal-oxide-based memristors in large-scale memory storage and resistive neural networks. Recent experimental works have reported that embedding metal nano-islands (NIs) in metal oxides can effectively improve the uniformity of the memristors, but the underlying role of the NIs is not fully understood. Here, to address this specific problem, we develop a physical model to understand the origin of the variability and how the embedded NIs can improve the performance and uniformity of memristors. We find that due to the dimension confinement effect, embedding metal NIs can modulate the electric field distribution and lead to a more deterministic formation of the conductive filament (CF) from their vicinity, in contrast to the random growth of CFs without embedded NIs. This deterministic CF formation, via vacancy nucleation, further reduces the forming, reset, and set voltages and enhances the uniformity of the operation voltages and current ON/OFF ratios. We further demonstrate that modifying the shapes of the metal NIs can modulate the field strengths/distributions around the NIs and that choosing the NI metal composition and shape that chemically facilitate vacancy formations can further optimize the CF morphology, reduce the operation voltages, and improve the switching performance. Our work thus provides a fundamental understanding of how embedded metal NIs improve the resistive switching performance in oxide-based memristors and could potentially guide the selection of embedded NIs to realize a more uniform memristor that also operates at a higher efficiency than present materials.
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Affiliation(s)
- Kena Zhang
- Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Panchapakesan Ganesh
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Ye Cao
- Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019, United States
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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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Vishwanath SK, Woo H, Jeon S. Enhancement of resistive switching properties in Al 2O 3 bilayer-based atomic switches: multilevel resistive switching. NANOTECHNOLOGY 2018; 29:235202. [PMID: 29629710 DOI: 10.1088/1361-6528/aab6a3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Atomic switches are considered to be building blocks for future non-volatile data storage and internet of things. However, obtaining device structures capable of ultrahigh density data storage, high endurance, and long data retention, and more importantly, understanding the switching mechanisms are still a challenge for atomic switches. Here, we achieved improved resistive switching performance in a bilayer structure containing aluminum oxide, with an oxygen-deficient oxide as the top switching layer and stoichiometric oxide as the bottom switching layer, using atomic layer deposition. This bilayer device showed a high on/off ratio (105) with better endurance (∼2000 cycles) and longer data retention (104 s) than single-oxide layers. In addition, depending on the compliance current, the bilayer device could be operated in four different resistance states. Furthermore, the depth profiles of the hourglass-shaped conductive filament of the bilayer device was observed by conductive atomic force microscopy.
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Affiliation(s)
- Sujaya Kumar Vishwanath
- Korea Advanced Institute of Science and Technology (KAIST), School of Electrical Engineering, Daejeon, 34141, Republic of Korea
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Dirkmann S, Kaiser J, Wenger C, Mussenbrock T. Filament Growth and Resistive Switching in Hafnium Oxide Memristive Devices. ACS APPLIED MATERIALS & INTERFACES 2018; 10:14857-14868. [PMID: 29601180 DOI: 10.1021/acsami.7b19836] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on the resistive switching in TiN/Ti/HfO2/TiN memristive devices. A resistive switching model for the device is proposed, taking into account important experimental and theoretical findings. The proposed switching model is validated using 2D and 3D kinetic Monte Carlo simulation models. The models are consistently coupled to the electric field and different current transport mechanisms such as direct tunneling, trap-assisted tunneling, ohmic transport, and transport through a quantum point contact have been considered. We find that the numerical results are in excellent agreement with experimentally obtained data. Important device parameters, which are difficult or impossible to measure in experiments, are calculated. This includes the shape of the conductive filament, width of filament constriction, current density, and temperature distribution. To obtain insights in the operation of the device, consecutive cycles have been simulated. Furthermore, the switching kinetics for the forming and set process for different applied voltages is investigated. Finally, the influence of an annealing process on the filament growth, especially on the filament growth direction, is discussed.
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Affiliation(s)
- Sven Dirkmann
- Electrodynamics and Physical Electronics Group , Brandenburg University of Technology , 03046 Cottbus , Germany
| | - Jan Kaiser
- Institute of Theoretical Electrical Engineering , Ruhr University Bochum , 44780 Bochum , Germany
| | - Christian Wenger
- Innovations for High Performance (IHP) , 15236 Frankfurt (Oder) , Germany
- Brandenburg Medical School Theodor Fontane , 16816 Neuruppin , Germany
| | - Thomas Mussenbrock
- Electrodynamics and Physical Electronics Group , Brandenburg University of Technology , 03046 Cottbus , Germany
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Sun Y, Song C, Yin J, Chen X, Wan Q, Zeng F, Pan F. Guiding the Growth of a Conductive Filament by Nanoindentation To Improve Resistive Switching. ACS APPLIED MATERIALS & INTERFACES 2017; 9:34064-34070. [PMID: 28901743 DOI: 10.1021/acsami.7b09710] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Redox-based memristor devices, which are considered to have promising nonvolatile memory, mainly operate through the formation/rupture of nanoscale conductive filaments. However, the random growth of conductive filaments is an obstacle for the stability of memory devices and the cell-to-cell uniformity. Here, we investigate the guiding effect of nanoindentation on the growth of conductive filaments in resistive memory devices. The nanoindented top electrodes generate an electric field concentration and the resultant precise control of a conductive filament in two typical memory devices, Ag/SiO2/Pt and W/Ta2O5/Pt. The nanoindented cells possess a much larger ON/OFF ratio, a sharper RESET process, a higher response speed, and better cell-to-cell uniformity compared with the conventional cells. Our finding reflects that the use of large-scale nanotransfer printing might be a unique way to improve the performance of resistive random access memory.
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Affiliation(s)
- Yiming Sun
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China
| | - Cheng Song
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China
| | - Jun Yin
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China
| | - Xianzhe Chen
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China
| | - Qin Wan
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China
| | - Fei Zeng
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China
| | - Feng Pan
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China
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Dias C, Guerra LM, Bordalo BD, Lv H, Ferraria AM, Botelho do Rego AM, Cardoso S, Freitas PP, Ventura J. Voltage-polarity dependent multi-mode resistive switching on sputtered MgO nanostructures. Phys Chem Chem Phys 2017; 19:10898-10904. [PMID: 28401238 DOI: 10.1039/c7cp00062f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Resistive switching in metal-insulator-metal nanosctructures is being intensively studied for nonvolatile memory applications. Here, we report unipolar resistive switching in Pt/MgO/Ta/Ru structures, with a 30 nm oxide barrier. A forming process was needed to initiate the resistive switching, which was then observed for all Set and Reset voltage polarity combinations. We studied the influence of the voltage polarity on the variability of the Set/Reset voltages and ON/OFF resistances and revealed the importance of a thin TaOx layer working as an oxygen revervoir for resistive switching. The mechanism behind this phenomenon can be understood in terms of conductive filaments formation/rupture with a contribution from Joule heating. Resistance change is thus caused by a voltage-driven oxygen vacancy motion in the MgO layer and a filament model was proposed for each polarity mode. A OFF/ON resistance ratio of at least 2 orders of magnitude was obtained with resistive states stable up to 104 s. Our results open the prospect to improve switching performance in other resistive switching systems, by proving a better understanding of the differences between operation modes.
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Affiliation(s)
- Catarina Dias
- IFIMUP-IN and Department of Physics and Astronomy, Faculty of Sciences, Porto, Portugal.
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