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Zhang YH, Sipling C, Qiu E, Schuller IK, Di Ventra M. Collective dynamics and long-range order in thermal neuristor networks. Nat Commun 2024; 15:6986. [PMID: 39143044 PMCID: PMC11324871 DOI: 10.1038/s41467-024-51254-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 08/04/2024] [Indexed: 08/16/2024] Open
Abstract
In the pursuit of scalable and energy-efficient neuromorphic devices, recent research has unveiled a novel category of spiking oscillators, termed "thermal neuristors." These devices function via thermal interactions among neighboring vanadium dioxide resistive memories, emulating biological neuronal behavior. Here, we show that the collective dynamical behavior of networks of these neurons showcases a rich phase structure, tunable by adjusting the thermal coupling and input voltage. Notably, we identify phases exhibiting long-range order that, however, does not arise from criticality, but rather from the time non-local response of the system. In addition, we show that these thermal neuristor arrays achieve high accuracy in image recognition and time series prediction through reservoir computing, without leveraging long-range order. Our findings highlight a crucial aspect of neuromorphic computing with possible implications on the functioning of the brain: criticality may not be necessary for the efficient performance of neuromorphic systems in certain computational tasks.
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Affiliation(s)
- Yuan-Hang Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Chesson Sipling
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Erbin Qiu
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Electrical and Computer Engineering, 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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Bidoul N, Roisin N, Flandre D. Tuning the Intrinsic Stochasticity of Resistive Switching in VO 2 Microresistors. NANO LETTERS 2024; 24:6201-6209. [PMID: 38757925 DOI: 10.1021/acs.nanolett.4c00184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Vanadium dioxide (VO2) microresistors exhibit resistive switching above a certain threshold voltage, allowing them to emulate neurons in neuromorphic systems. However, such devices present intrinsic cycle-to-cycle variations in their resistances and threshold voltages, which can be detrimental or beneficial, depending on their use. Here, we study this stochasticity in VO2 microresistors with various grain sizes and dimensions, through high-resolution electrical and optical measurements across numerous cycles. Our results highlight that the cycle-to-cycle variations in threshold voltage increase as the grain size becomes comparable to the device dimensions. We also present observations of multimodal threshold voltage distributions in the smaller-length resistors. To understand the underlying phenomenon, we investigate the relationship between the device insulating resistance and threshold voltage distributions, showing that these modes could correspond to distinct percolation paths and filaments. Our findings provide the first experimentally verified guidelines for designing VO2 devices with minimized/maximized stochasticity, depending on the targeted application.
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Affiliation(s)
- Noémie Bidoul
- Institute for Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), UCLouvain, Louvain-la-Neuve 1348, Belgium
| | - Nicolas Roisin
- Institute for Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), UCLouvain, Louvain-la-Neuve 1348, Belgium
| | - Denis Flandre
- Institute for Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), UCLouvain, Louvain-la-Neuve 1348, Belgium
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Das SK, Nandi SK, Marquez CV, Rúa A, Uenuma M, Puyoo E, Nath SK, Albertini D, Baboux N, Lu T, Liu Y, Haeger T, Heiderhoff R, Riedl T, Ratcliff T, Elliman RG. Physical Origin of Negative Differential Resistance in V 3 O 5 and Its Application as a Solid-State Oscillator. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208477. [PMID: 36461165 DOI: 10.1002/adma.202208477] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Oxides that exhibit an insulator-metal transition can be used to fabricate energy-efficient relaxation oscillators for use in hardware-based neural networks but there are very few oxides with transition temperatures above room temperature. Here the structural, electrical, and thermal properties of V3 O5 thin films and their application as the functional oxide in metal/oxide/metal relaxation oscillators are reported. The V3 O5 devices show electroforming-free volatile threshold switching and negative differential resistance (NDR) with stable (<3% variation) cycle-to-cycle operation. The physical mechanisms underpinning these characteristics are investigated using a combination of electrical measurements, in situ thermal imaging, and device modeling. This shows that conduction is confined to a narrow filamentary path due to self-confinement of the current distribution and that the NDR response is initiated at temperatures well below the insulator-metal transition temperature where it is dominated by the temperature-dependent conductivity of the insulating phase. Finally, the dynamics of individual and coupled V3 O5 -based relaxation oscillators is reported, showing that capacitively coupled devices exhibit rich non-linear dynamics, including frequency and phase synchronization. These results establish V3 O5 as a new functional material for volatile threshold switching and advance the development of robust solid-state neurons for neuromorphic computing.
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Affiliation(s)
- Sujan Kumar Das
- Research School of Physics, The Australian National University, Canberra, ACT, 2601, Australia
- Department of Physics, Jahangirnagar University, Dhaka, 1342, Bangladesh
| | - Sanjoy Kumar Nandi
- Research School of Physics, The Australian National University, Canberra, ACT, 2601, Australia
| | | | - Armando Rúa
- Department of Physics, University of Puerto Rico, Mayaguez, PR, 00681, USA
| | - Mutsunori Uenuma
- Information Device Science Laboratory, Nara Institute of Science and Technology (NAIST), Nara, 630-0192, Japan
| | - Etienne Puyoo
- Université Lyon, INSA Lyon, CNRS, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CPE Lyon, INL, UMR5270, Villeurbanne, 69621, France
| | - Shimul Kanti Nath
- Research School of Physics, The Australian National University, Canberra, ACT, 2601, Australia
- Department of Electrical, Electronic and Computer Engineering, The University of Western Australia, Crawley, WA, 6009, Australia
| | - David Albertini
- Université Lyon, INSA Lyon, CNRS, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CPE Lyon, INL, UMR5270, Villeurbanne, 69621, France
| | - Nicolas Baboux
- Université Lyon, INSA Lyon, CNRS, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CPE Lyon, INL, UMR5270, Villeurbanne, 69621, France
| | - Teng Lu
- Research School of Chemistry, The Australian National University, Canberra, ACT, 2601, Australia
| | - Yun Liu
- Research School of Chemistry, The Australian National University, Canberra, ACT, 2601, Australia
| | - Tobias Haeger
- Institute of Electronic Devices, Wuppertal Center for Smart Materials & Systems, University of Wuppertal, Rainer-Gruenter-Strasse 21, 42119, Wuppertal, Germany
| | - Ralf Heiderhoff
- Institute of Electronic Devices, Wuppertal Center for Smart Materials & Systems, University of Wuppertal, Rainer-Gruenter-Strasse 21, 42119, Wuppertal, Germany
| | - Thomas Riedl
- Institute of Electronic Devices, Wuppertal Center for Smart Materials & Systems, University of Wuppertal, Rainer-Gruenter-Strasse 21, 42119, Wuppertal, Germany
| | - Thomas Ratcliff
- Research School of Physics, The Australian National University, Canberra, ACT, 2601, Australia
| | - Robert Glen Elliman
- Research School of Physics, The Australian National University, Canberra, ACT, 2601, Australia
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Voltage Pulse Driven VO2 Volatile Resistive Transition Devices as Leaky Integrate-and-Fire Artificial Neurons. ELECTRONICS 2022. [DOI: 10.3390/electronics11040516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In a hardware-based neuromorphic computation system, using emerging nonvolatile memory devices as artificial synapses, which have an inelastic memory characteristic, has attracted considerable interest. In contrast, the elastic artificial neurons have received much less attention. An ideal material system that is suitable for mimicking biological neurons is the one with volatile (or mono-stable) resistive change property. Vanadium dioxide (VO2) is a well-known material that exhibits an abrupt and volatile insulator-to-metal transition property. In this work, we experimentally demonstrate that pulse-driven two-terminal VO2 devices behave in a leaky integrate-and-fire (LIF) manner, and they elastically relax back to their initial value after firing, thus, mimicking the behavior of biological neurons. The VO2 device with a channel length of 20 µm can be driven to fire by a single long-duration pulse (>83 µs) or multiple short-duration pulses. We further model the VO2 devices as resistive networks based on their granular domain structure, with resistivities corresponding to the insulator or metallic states. Simulation results confirm that the volatile resistive transition under voltage pulse driving is caused by the formation of a metallic filament in an avalanche-like process, while this volatile metallic filament will relax back to the insulating state at the end of driving pulses. The simulation offers a microscopic view of the dynamic and abrupt filament formation process to explain the experimentally observed LIF behavior. These results suggest that VO2 insulator–metal transition could be exploited for artificial neurons.
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Ivanov AI, Prinz VY, Antonova IV, Gutakovskii AK. Resistive switching on individual V 2O 5 nanoparticles encapsulated in fluorinated graphene films. Phys Chem Chem Phys 2021; 23:20434-20443. [PMID: 34494063 DOI: 10.1039/d1cp02930d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Memristors currently attract much attention as basic building blocks for future neuromorphic electronics. Due to their unusual electronic, optical, magnetic, electrochemical, and structural properties, transition metal oxides offer much potential in the development of memristors. Recent trends in the design and fabrication of electronic devices have led to miniaturization of their working elements, with nanometer-sized structures enjoying increasing demand. In the present study, we investigated resistive switching on individual vanadium oxide (V2O5) crystal-hydrate nanoparticles, 2 to 10 nm in size, encapsulated in fluorinated graphene (FG). Measurements using a conductive atomic force microscope (c-AFM) probe showed that the core-shell V2O5/FG nanoparticles make it possible to achieve bipolar resistive switching, reproducible during 104 switching cycles, with the ON/OFF current ratio reaching 103-105. The switching voltage of the structures depends on the thickness of the FG shells of the composite particles and equals ∼2-4 V. It is shown that the encapsulation of V2O5 particles in fluorinated graphene ensures a high stability of the resistive switching effect and, simultaneously, prevents the escape of water from the crystalline vanadium oxide hydrates. A qualitative model is proposed to describe the bipolar resistive switching effect in examined structures. Results reported in the present article will prove useful in creating bipolar nanoswitches.
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Affiliation(s)
- Artem I Ivanov
- Rzhanov Institute of Semiconductor Physics SB RAS, Lavrentiev av. 13, 630090, Novosibirsk, Russia.
| | - Victor Ya Prinz
- Rzhanov Institute of Semiconductor Physics SB RAS, Lavrentiev av. 13, 630090, Novosibirsk, Russia.
| | - Irina V Antonova
- Rzhanov Institute of Semiconductor Physics SB RAS, Lavrentiev av. 13, 630090, Novosibirsk, Russia.
| | - Anton K Gutakovskii
- Rzhanov Institute of Semiconductor Physics SB RAS, Lavrentiev av. 13, 630090, Novosibirsk, Russia.
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Abstract
Modern massively-parallel Graphics Processing Units (GPUs) and Machine Learning (ML) frameworks enable neural network implementations of unprecedented performance and sophistication. However, state-of-the-art GPU hardware platforms are extremely power-hungry, while microprocessors cannot achieve the performance requirements. Biologically-inspired Spiking Neural Networks (SNN) have inherent characteristics that lead to lower power consumption. We thus present a bit-serial SNN-like hardware architecture. By using counters, comparators, and an indexing scheme, the design effectively implements the sum-of-products inherent in neurons. In addition, we experimented with various strength-reduction methods to lower neural network resource usage. The proposed Spiking Hybrid Network (SHiNe), validated on an FPGA, has been found to achieve reasonable performance with a low resource utilization, with some trade-off with respect to hardware throughput and signal representation.
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