1
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Kim G, In JH, Lee Y, Rhee H, Park W, Song H, Park J, Jeon JB, Brown TD, Talin AA, Kumar S, Kim KM. Mott neurons with dual thermal dynamics for spatiotemporal computing. NATURE MATERIALS 2024; 23:1237-1244. [PMID: 38890486 DOI: 10.1038/s41563-024-01913-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 05/05/2024] [Indexed: 06/20/2024]
Abstract
Heat dissipation is a natural consequence of operating any electronic system. In nearly all computing systems, such heat is usually minimized by design and cooling. Here, we show that the temporal dynamics of internally produced heat in electronic devices can be engineered to both encode information within a single device and process information across multiple devices. In our demonstration, electronic NbOx Mott neurons, integrated on a flexible organic substrate, exhibit 18 biomimetic neuronal behaviours and frequency-based nociception within a single component by exploiting both the thermal dynamics of the Mott transition and the dynamical thermal interactions with the organic substrate. Further, multiple interconnected Mott neurons spatiotemporally communicate purely via heat, which we use for graph optimization by consuming over 106 times less energy when compared with the best digital processors. Thus, exploiting natural thermal processes in computing can lead to functionally dense, energy-efficient and radically novel mixed-physics computing primitives.
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Affiliation(s)
- Gwangmin Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Jae Hyun In
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Younghyun Lee
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Hakseung Rhee
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Woojoon Park
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Hanchan Song
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Juseong Park
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Jae Bum Jeon
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | | | - A Alec Talin
- Sandia National Laboratories, Livermore, CA, USA
| | - Suhas Kumar
- Sandia National Laboratories, Livermore, CA, USA.
| | - Kyung Min Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.
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2
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Bisquert J, Ilyassov B, Tessler N. Switching Response in Organic Electrochemical Transistors by Ionic Diffusion and Electronic Transport. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2404182. [PMID: 39052878 PMCID: PMC11423187 DOI: 10.1002/advs.202404182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 06/24/2024] [Indexed: 07/27/2024]
Abstract
The switching response in organic electrochemical transistors (OECT) is a basic effect in which a transient current occurs in response to a voltage perturbation. This phenomenon has an important impact on different aspects of the application of OECT, such as the equilibration times, the hysteresis dependence on scan rates, and the synaptic properties for neuromorphic applications. Here we establish a model that unites vertical ion diffusion and horizontal electronic transport for the analysis of the time-dependent current response of OECTs. We use a combination of tools consisting of a physical analytical model; advanced 2D drift-diffusion simulation; and the experimental measurement of a poly(3-hexylthiophene) (P3HT) OECT. We show the reduction of the general model to simple time-dependent equations for the average ionic/hole concentration inside the organic film, which produces a Bernards-Malliaras conservation equation coupled with a diffusion equation. We provide a basic classification of the transient response to a voltage pulse, and the correspondent hysteresis effects of the transfer curves. The shape of transients is basically related to the main control phenomenon, either the vertical diffusion of ions during doping and dedoping, or the equilibration of electronic current along the channel length.
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Affiliation(s)
- Juan Bisquert
- Instituto de Tecnología Química (Universitat Politècnica de València-Agencia Estatal Consejo Superior de Investigaciones Científicas), Av. dels Tarongers, València, 46022, Spain
- Institute of Advanced Materials (INAM), Universitat Jaume I, Castelló, 12006, Spain
| | - Baurzhan Ilyassov
- Astana IT University, Mangilik El 55/11, EXPO C1, Astana, 010000, Kazakhstan
| | - Nir Tessler
- Andrew & Erna Viterbi Department of Electrical and Computer Engineering, Technion-Israel Institute of Technology, Haifa, 32000, Israel
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3
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Yuan Y, Patel RK, Banik S, Reta TB, Bisht RS, Fong DD, Sankaranarayanan SKRS, Ramanathan S. Proton Conducting Neuromorphic Materials and Devices. Chem Rev 2024; 124:9733-9784. [PMID: 39038231 DOI: 10.1021/acs.chemrev.4c00071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Neuromorphic computing and artificial intelligence hardware generally aims to emulate features found in biological neural circuit components and to enable the development of energy-efficient machines. In the biological brain, ionic currents and temporal concentration gradients control information flow and storage. It is therefore of interest to examine materials and devices for neuromorphic computing wherein ionic and electronic currents can propagate. Protons being mobile under an external electric field offers a compelling avenue for facilitating biological functionalities in artificial synapses and neurons. In this review, we first highlight the interesting biological analog of protons as neurotransmitters in various animals. We then discuss the experimental approaches and mechanisms of proton doping in various classes of inorganic and organic proton-conducting materials for the advancement of neuromorphic architectures. Since hydrogen is among the lightest of elements, characterization in a solid matrix requires advanced techniques. We review powerful synchrotron-based spectroscopic techniques for characterizing hydrogen doping in various materials as well as complementary scattering techniques to detect hydrogen. First-principles calculations are then discussed as they help provide an understanding of proton migration and electronic structure modification. Outstanding scientific challenges to further our understanding of proton doping and its use in emerging neuromorphic electronics are pointed out.
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Affiliation(s)
- Yifan Yuan
- Department of Electrical & Computer Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Ranjan Kumar Patel
- Department of Electrical & Computer Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Suvo Banik
- Department of Mechanical and Industrial Engineering, University of Illinois, Chicago, Illinois 60607, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Tadesse Billo Reta
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Ravindra Singh Bisht
- Department of Electrical & Computer Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Dillon D Fong
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Subramanian K R S Sankaranarayanan
- Department of Mechanical and Industrial Engineering, University of Illinois, Chicago, Illinois 60607, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Shriram Ramanathan
- Department of Electrical & Computer Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
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4
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Bongartz LM, Kantelberg R, Meier T, Hoffmann R, Matthus C, Weissbach A, Cucchi M, Kleemann H, Leo K. Bistable organic electrochemical transistors: enthalpy vs. entropy. Nat Commun 2024; 15:6819. [PMID: 39122689 PMCID: PMC11316041 DOI: 10.1038/s41467-024-51001-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
Organic electrochemical transistors (OECTs) underpin a range of emerging technologies, from bioelectronics to neuromorphic computing, owing to their unique coupling of electronic and ionic charge carriers. In this context, various OECT systems exhibit significant hysteresis in their transfer curve, which is frequently leveraged to achieve non-volatility. Meanwhile, a general understanding of its physical origin is missing. Here, we introduce a thermodynamic framework that readily explains the emergence of bistable OECT operation via the interplay of enthalpy and entropy. We validate this model through temperature-resolved characterizations, material manipulation, and thermal imaging. Further, we reveal deviations from Boltzmann statistics for the subthreshold swing and reinterpret existing literature. Capitalizing on these findings, we finally demonstrate a single-OECT Schmitt trigger, thus compacting a multi-component circuit into a single device. These insights provide a fundamental advance for OECT physics and its application in non-conventional computing, where symmetry-breaking phenomena are pivotal to unlock new paradigms of information processing.
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Affiliation(s)
- Lukas M Bongartz
- IAPP Dresden, Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01187, Dresden, Germany.
| | - Richard Kantelberg
- IAPP Dresden, Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01187, Dresden, Germany
| | - Tommy Meier
- IAPP Dresden, Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01187, Dresden, Germany
| | - Raik Hoffmann
- Fraunhofer Institute for Photonic Microsystems IPMS, Center Nanoelectronic Technologies, An der Bartlake 5, 01099, Dresden, Germany
| | - Christian Matthus
- Chair of Circuit Design and Network Theory (CCN), Faculty of Electrical and Computer Engineering, Technische Universität Dresden, Helmholtzstr. 18, 01069, Dresden, Germany
| | - Anton Weissbach
- IAPP Dresden, Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01187, Dresden, Germany
| | - Matteo Cucchi
- IAPP Dresden, Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01187, Dresden, Germany
| | - Hans Kleemann
- IAPP Dresden, Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01187, Dresden, Germany
| | - Karl Leo
- IAPP Dresden, Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01187, Dresden, Germany
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5
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van Doremaele ERW, Stevens T, Ringeling S, Spolaor S, Fattori M, van de Burgt Y. Hardware implementation of backpropagation using progressive gradient descent for in situ training of multilayer neural networks. SCIENCE ADVANCES 2024; 10:eado8999. [PMID: 38996020 PMCID: PMC11244533 DOI: 10.1126/sciadv.ado8999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 06/07/2024] [Indexed: 07/14/2024]
Abstract
Neural network training can be slow and energy-expensive due to the frequent transfer of weight data between digital memory and processing units. Neuromorphic systems can accelerate neural networks by performing multiply-accumulate operations in parallel using nonvolatile analog memory. However, executing the widely used backpropagation training algorithm in multilayer neural networks requires information-and therefore storage-of the partial derivatives of the weight values preventing suitable and scalable implementation in hardware. Here, we propose a hardware implementation of the backpropagation algorithm that progressively updates each layer using in situ stochastic gradient descent, avoiding this storage requirement. We experimentally demonstrate the in situ error calculation and the proposed progressive backpropagation method in a multilayer hardware-implemented neural network. We confirm identical learning characteristics and classification performance compared to conventional backpropagation in software. We show that our approach can be scaled to large and deep neural networks, enabling highly efficient training of advanced artificial intelligence computing systems.
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Affiliation(s)
- Eveline R. W. van Doremaele
- Department of Mechanical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
- Eindhoven Hendrik Casimir Institute, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
| | - Tim Stevens
- Department of Mechanical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
- Eindhoven Hendrik Casimir Institute, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
| | - Stijn Ringeling
- Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
| | - Simone Spolaor
- Department of Mechanical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
| | - Marco Fattori
- Eindhoven Hendrik Casimir Institute, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
- Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
| | - Yoeri van de Burgt
- Department of Mechanical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
- Eindhoven Hendrik Casimir Institute, Eindhoven University of Technology, Eindhoven 5612AP, Netherlands
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6
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Krauhausen I, Griggs S, McCulloch I, den Toonder JMJ, Gkoupidenis P, van de Burgt Y. Bio-inspired multimodal learning with organic neuromorphic electronics for behavioral conditioning in robotics. Nat Commun 2024; 15:4765. [PMID: 38834541 DOI: 10.1038/s41467-024-48881-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 05/13/2024] [Indexed: 06/06/2024] Open
Abstract
Biological systems interact directly with the environment and learn by receiving multimodal feedback via sensory stimuli that shape the formation of internal neuronal representations. Drawing inspiration from biological concepts such as exploration and sensory processing that eventually lead to behavioral conditioning, we present a robotic system handling objects through multimodal learning. A small-scale organic neuromorphic circuit locally integrates and adaptively processes multimodal sensory stimuli, enabling the robot to interact intelligently with its surroundings. The real-time handling of sensory stimuli via low-voltage organic neuromorphic devices with synaptic functionality forms multimodal associative connections that lead to behavioral conditioning, and thus the robot learns to avoid potentially dangerous objects. This work demonstrates that adaptive neuro-inspired circuitry with multifunctional organic materials, can accommodate locally efficient bio-inspired learning for advancing intelligent robotics.
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Affiliation(s)
- Imke Krauhausen
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
- Microsystems, Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Sophie Griggs
- Department of Chemistry, University of Oxford, Oxford, UK
| | - Iain McCulloch
- Department of Chemistry, University of Oxford, Oxford, UK
| | - Jaap M J den Toonder
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
- Microsystems, Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | | | - Yoeri van de Burgt
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands.
- Microsystems, Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
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7
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Oh J, Park S, Lee SH, Kim S, Lee H, Lee C, Hong W, Cha J, Kang M, Jin JH, Im SG, Kim MJ, Choi S. Ultrathin All-Solid-State MoS 2-Based Electrolyte Gated Synaptic Transistor with Tunable Organic-Inorganic Hybrid Film. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2308847. [PMID: 38566434 PMCID: PMC11187882 DOI: 10.1002/advs.202308847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/24/2024] [Indexed: 04/04/2024]
Abstract
Electrolyte-gated synaptic transistors (EGSTs) have attracted considerable attention as synaptic devices owing to their adjustable conductance, low power consumption, and multi-state storage capabilities. To demonstrate high-density EGST arrays, 2D materials are recommended owing to their excellent electrical properties and ultrathin profile. However, widespread implementation of 2D-based EGSTs has challenges in achieving large-area channel growth and finding compatible nanoscale solid electrolytes. This study demonstrates large-scale process-compatible, all-solid-state EGSTs utilizing molybdenum disulfide (MoS2) channels grown through chemical vapor deposition (CVD) and sub-30 nm organic-inorganic hybrid electrolyte polymers synthesized via initiated chemical vapor deposition (iCVD). The iCVD technique enables precise modulation of the hydroxyl group density in the hybrid matrix, allowing the modulation of proton conduction, resulting in adjustable synaptic performance. By leveraging the tunable iCVD-based hybrid electrolyte, the fabricated EGSTs achieve remarkable attributes: a wide on/off ratio of 109, state retention exceeding 103, and linear conductance updates. Additionally, the device exhibits endurance surpassing 5 × 104 cycles, while maintaining a low energy consumption of 200 fJ/spike. To evaluate the practicality of these EGSTs, a subset of devices is employed in system-level simulations of MNIST handwritten digit recognition, yielding a recognition rate of 93.2%.
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Affiliation(s)
- Jungyeop Oh
- School of Electrical EngineeringGraduate School of Semiconductor TechnologyKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
| | - Seohak Park
- School of Electrical EngineeringGraduate School of Semiconductor TechnologyKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
| | - Sang Hun Lee
- School of Electrical EngineeringGraduate School of Semiconductor TechnologyKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
| | - Sungkyu Kim
- Department of Nanotechnology and Advanced Materials EngineeringSejong University209 Neungdong‐ro, Gwangjin‐guSeoul05006Republic of Korea
| | - Hyeonji Lee
- School of Electrical EngineeringGraduate School of Semiconductor TechnologyKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
| | - Changhyeon Lee
- Department of Chemical and Biomolecular EngineeringGraphene/2D Materials Research CenterKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
| | - Woonggi Hong
- School of Electronics and Electrical EngineeringDankook UniversityGyeonggi16890Republic of Korea
| | - Jun‐Hwe Cha
- School of Electrical EngineeringGraduate School of Semiconductor TechnologyKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
| | - Mingu Kang
- School of Electrical EngineeringGraduate School of Semiconductor TechnologyKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
| | - Jun Hyup Jin
- School of Electronics and Electrical EngineeringDankook UniversityGyeonggi16890Republic of Korea
| | - Sung Gap Im
- Department of Chemical and Biomolecular EngineeringGraphene/2D Materials Research CenterKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
| | - Min Ju Kim
- School of Electronics and Electrical EngineeringDankook UniversityGyeonggi16890Republic of Korea
| | - Sung‐Yool Choi
- School of Electrical EngineeringGraduate School of Semiconductor TechnologyKorea Advanced Institute of Science and Technology (KAIST)291 Daehak‐ro, Yuseong‐guDaejeon34141Republic of Korea
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8
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Kim K, Song MS, Hwang H, Hwang S, Kim H. A comprehensive review of advanced trends: from artificial synapses to neuromorphic systems with consideration of non-ideal effects. Front Neurosci 2024; 18:1279708. [PMID: 38660225 PMCID: PMC11042536 DOI: 10.3389/fnins.2024.1279708] [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: 08/18/2023] [Accepted: 03/14/2024] [Indexed: 04/26/2024] Open
Abstract
A neuromorphic system is composed of hardware-based artificial neurons and synaptic devices, designed to improve the efficiency of neural computations inspired by energy-efficient and parallel operations of the biological nervous system. A synaptic device-based array can compute vector-matrix multiplication (VMM) with given input voltage signals, as a non-volatile memory device stores the weight information of the neural network in the form of conductance or capacitance. However, unlike software-based neural networks, the neuromorphic system unavoidably exhibits non-ideal characteristics that can have an adverse impact on overall system performance. In this study, the characteristics required for synaptic devices and their importance are discussed, depending on the targeted application. We categorize synaptic devices into two types: conductance-based and capacitance-based, and thoroughly explore the operations and characteristics of each device. The array structure according to the device structure and the VMM operation mechanism of each structure are analyzed, including recent advances in array-level implementation of synaptic devices. Furthermore, we reviewed studies to minimize the effect of hardware non-idealities, which degrades the performance of hardware neural networks. These studies introduce techniques in hardware and signal engineering, as well as software-hardware co-optimization, to address these non-idealities through compensation approaches.
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Affiliation(s)
- Kyuree Kim
- Department of Electrical and Computer Engineering, Inha University, Incheon, Republic of Korea
| | - Min Suk Song
- Division of Nanoscale Semiconductor Engineering, Hanyang University, Seoul, Republic of Korea
| | - Hwiho Hwang
- Division of Materials Science and Engineering, Hanyang University, Seoul, Republic of Korea
| | - Sungmin Hwang
- Department of AI Semiconductor Engineering, Korea University, Sejong, Republic of Korea
| | - Hyungjin Kim
- Division of Materials Science and Engineering, Hanyang University, Seoul, Republic of Korea
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9
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Qiu E, Zhang YH, Ventra MD, Schuller IK. Reconfigurable Cascaded Thermal Neuristors for Neuromorphic Computing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2306818. [PMID: 37770043 DOI: 10.1002/adma.202306818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/25/2023] [Indexed: 10/03/2023]
Abstract
While the complementary metal-oxide semiconductor (CMOS) technology is the mainstream for the hardware implementation of neural networks, an alternative route is explored based on a new class of spiking oscillators called "thermal neuristors", which operate and interact solely via thermal processes. Utilizing the insulator-to-metal transition (IMT) in vanadium dioxide, a wide variety of reconfigurable electrical dynamics mirroring biological neurons is demonstrated. Notably, inhibitory functionality is achieved just in a single oxide device, and cascaded information flow is realized exclusively through thermal interactions. To elucidate the underlying mechanisms of the neuristors, a detailed theoretical model is developed, which accurately reflects the experimental results. This study establishes the foundation for scalable and energy-efficient thermal neural networks, fostering progress in brain-inspired computing.
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Affiliation(s)
- Erbin Qiu
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Yuan-Hang Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | | | - Ivan K Schuller
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
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10
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Neumayer SM, Olunloyo O, Maksymovych P, Xiao K. Nanoscale Probing of Electrical Memory Effects in van der Waals Layered PdSe 2. ACS APPLIED MATERIALS & INTERFACES 2024; 16:3665-3673. [PMID: 38193383 DOI: 10.1021/acsami.3c14427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Tunable electronic materials that can be switched between different impedance states are fundamental to the hardware elements for neuromorphic computing architectures. This "brain-like" computing paradigm uses highly paralleled and colocated data processing, leading to greatly improved energy efficiency and performance compared to traditional architectures in which data have to be frequently transferred between processor and memory. In this work, we use scanning microwave impedance microscopy for nanoscale electrical and electronic characterization of two-dimensional layered semiconductor PdSe2 to probe neuromorphic properties. The local resolution of tens of nanometers reveals significant differences in electronic behavior between and within PdSe2 nanosheets (NSs). In particular, we detected both n-type and p-type behaviors, although previous reports only point to ambipolar n-type dominating characteristics. Nanoscale capacitance-voltage curves and subsequent calculation of characteristic maps revealed a hysteretic behavior originating from the creation and erasure of Se vacancies as well as the switching of defect charge states. In addition, stacks consisting of two NSs show enhanced resistive and capacitive switching, which is attributed to trapped charge carriers at the interfaces between the stacked NSs. Stacking n- and p-type NSs results in a combined behavior that allows one to tune electrical characteristics. As local inhomogeneities of electrical and electronic behavior can have a significant impact on the overall device performance, the demonstrated nanoscale characterization and analysis will be applicable to a wide range of semiconducting materials.
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Affiliation(s)
- Sabine M Neumayer
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Olugbenga Olunloyo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Petro Maksymovych
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Kai Xiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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11
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Nikam RD, Lee J, Lee K, Hwang H. Exploring the Cutting-Edge Frontiers of Electrochemical Random Access Memories (ECRAMs) for Neuromorphic Computing: Revolutionary Advances in Material-to-Device Engineering. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2302593. [PMID: 37300356 DOI: 10.1002/smll.202302593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/23/2023] [Indexed: 06/12/2023]
Abstract
Advanced materials and device engineering has played a crucial role in improving the performance of electrochemical random access memory (ECRAM) devices. ECRAM technology has been identified as a promising candidate for implementing artificial synapses in neuromorphic computing systems due to its ability to store analog values and its ease of programmability. ECRAM devices consist of an electrolyte and a channel material sandwiched between two electrodes, and the performance of these devices depends on the properties of the materials used. This review provides a comprehensive overview of material engineering strategies to optimize the electrolyte and channel materials' ionic conductivity, stability, and ionic diffusivity to improve the performance and reliability of ECRAM devices. Device engineering and scaling strategies are further discussed to enhance ECRAM performance. Last, perspectives on the current challenges and future directions in developing ECRAM-based artificial synapses in neuromorphic computing systems are provided.
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Affiliation(s)
- Revannath Dnyandeo Nikam
- Center for Single Atom-based Semiconductor Device, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
- Department of Material Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
| | - Jongwon Lee
- Center for Single Atom-based Semiconductor Device, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
- Department of Material Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
| | - Kyumin Lee
- Center for Single Atom-based Semiconductor Device, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
- Department of Material Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
| | - Hyunsang Hwang
- Center for Single Atom-based Semiconductor Device, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
- Department of Material Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
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Keene ST, Rao A, Malliaras GG. The relationship between ionic-electronic coupling and transport in organic mixed conductors. SCIENCE ADVANCES 2023; 9:eadi3536. [PMID: 37647402 PMCID: PMC10468126 DOI: 10.1126/sciadv.adi3536] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/28/2023] [Indexed: 09/01/2023]
Abstract
Organic mixed ionic-electronic conductors (OMIECs) directly convert between ionic and electronic charge through electrochemical (de)doping, enabling a wide range of applications in bioelectronics, neuromorphic computing, and energy storage and conversion. While both ionic and electronic transport are individually well characterized, their combined transport has been difficult to describe self-consistently. We use in situ measurements of electrochemical (de)doping of an archetypal OMIEC to inform a quasi-field drift-diffusion model, which accurately captures experimentally measured ion transport across a range of potentials. We find that the chemical potential of holes, which is modulated by changes in doping level, represents a major driving force for mixed charge transport. Using numerical simulations at device-relevant time scales and potentials, we find that the competition between hole drift and diffusion leads to diffuse space charge regions despite high charge densities. This effect is unique to mixed conducting systems where mobile ionic charges can compensate the accumulation or depletion of electronic charge, thereby screening electrostatic driving forces.
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Affiliation(s)
- Scott T. Keene
- Department of Engineering, Electrical Engineering Division, University of Cambridge, Cambridge, CB3 0FA, UK
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Akshay Rao
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK
| | - George G. Malliaras
- Department of Engineering, Electrical Engineering Division, University of Cambridge, Cambridge, CB3 0FA, UK
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