Article
Nanoscience & Nanotechnology
Taehyun Kim, Seung-Hwan Kim, Jae-Hyeun Park, June Park, Euyjin Park, Seung-Geun Kim, Hyun-Yong Yu
Summary: The study proposes a versatile artificial neuron based on the bipolar electrochemical metallization threshold switch, which exhibits four key features for a spiking neuron and unique characteristics for changing synaptic weight. Utilizing a filament confinement technique, the neuron achieves high on/off ratio, low threshold voltage, low variability, and endurance over 10^6 cycles, paving the way for advanced large-scale neuromorphic systems.
ADVANCED ELECTRONIC MATERIALS
(2021)
Article
Engineering, Electrical & Electronic
Yongzhou Wang, Hui Xu, Wei Wang, Xumeng Zhang, Zuheng Wu, Ran Gu, Qingjiang Li, Qi Liu
Summary: In this letter, the authors present a configurable neuron constructed using Memristors, which have simple structures and high-density integration. They design a memristor with a tunable threshold and demonstrate its ability to construct configurable neurons with different response curves. The results suggest that the device is suitable for maintaining homeostasis and improving the stability of computing systems.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Fan Ye, Fatemeh Kiani, Yi Huang, Qiangfei Xia
Summary: This research improves the uniformity of relaxation time in diffusive memristors by engineering the device stack, and achieves tunability in relaxation time. An algorithm utilizing the tunable and uniform relaxation behavior for spike generation is implemented, and achieves high accuracy in object recognition.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Dongjun Seong, Su Yeon Lee, Hyun Kyu Seo, Jong-Woo Kim, Minsoo Park, Min Kyu Yang
Summary: A new architecture is needed to address the power consumption and latency problems of the von Neumann architecture. A neuromorphic memory system, particularly a crossbar array, shows promise for processing large amounts of digital information. However, the biggest challenge for crossbar arrays is the sneak current issue, which can cause misreadings and misoperations. This study explores the use of chalcogenide-based ovonic threshold switches as powerful selectors to mitigate the sneak current problem.
Article
Telecommunications
Hyeryung Jang, Nicolas Skatchkovsky, Osvaldo Simeone
Summary: Spiking Neural Networks (SNNs) are biologically inspired machine learning models that process binary and sparse spiking signals. They can be implemented on energy-efficient neuromorphic computing platforms and have been validated for their capabilities in detecting and generating spatial patterns through experiments.
IEEE COMMUNICATIONS LETTERS
(2021)
Article
Computer Science, Artificial Intelligence
Man Yao, Guangshe Zhao, Hengyu Zhang, Yifan Hu, Lei Deng, Yonghong Tian, Bo Xu, Guoqi Li
Summary: This paper studies the application of attention mechanisms in brain-inspired spiking neural networks (SNNs). By optimizing the membrane potentials using a multi-dimensional attention module, the performance and energy efficiency of SNNs are improved. Experimental results demonstrate that SNNs with attention achieve better performance and sparser spiking firing in event-based action recognition and image classification tasks. The effectiveness of attention SNNs is theoretically proven and further analyzed using a proposed spiking response visualization method. This work highlights the potential of SNNs as a general backbone for various applications in the field of SNN research.
IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE
(2023)
Article
Neurosciences
Suk-Min Yap, I-Ting Wang, Ming-Hung Wu, Tuo-Hung Hou
Summary: In this study, a V-t Model was constructed to predict and simulate the spiking behavior of threshold-switching selector-based neurons. The model successfully depicted the history-dependent threshold voltage of TS selectors and analyzed the currently reported TS devices, comparing the behaviors of the predicted neurons. The outcome suggests that the OTS neuron is the most promising and provides an engineering pathway.
FRONTIERS IN NEUROSCIENCE
(2022)
Review
Automation & Control Systems
Fu-Xiang Liang, I-Ting Wang, Tuo-Hung Hou
Summary: This article reviews the recent progress of emerging spiking neuron devices and circuits, discussing the advantages and challenges in area and energy efficiency by benchmarking various technologies. Desirable properties include a small or even no membrane capacitor, a self-reset property, and a high spiking frequency.
ADVANCED INTELLIGENT SYSTEMS
(2021)
Article
Nanoscience & Nanotechnology
Hyun Kyu Seo, Jin Joo Ryu, Su Yeon Lee, Minsoo Park, Seong-Geon Park, Wooseok Song, Gun Hwan Kim, Min Kyu Yang
Summary: The study shows that the Se-doped GeTe active layer has the potential to improve thermal stability and endurance performance, and a device structural reconfiguration can reduce the operation voltage shift phenomenon.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Shogo Hatayama, Yuta Saito, Paul Fons, Yi Shuang, Mihyeon Kim, Yuji Sutou
Summary: This paper investigates the electronic structure of amorphous Si0.29Te0.71 using hard X-ray photoelectron spectroscopy (HAXPES) and density functional theory (DFT) calculations. It reveals that the amorphous network of Si0.29Te0.71 is composed of Te-Te, Te-Si, and Si-Si bonding. DFT calculations show the contributions of Si3p and Te5p states to bonding, while occupied non-bonding Te5p states form the top of the valence state. The presence of Te-Te dimers significantly influences the OTS behavior.
Article
Engineering, Electrical & Electronic
Taras Ravsher, Daniele Garbin, Andrea Fantini, Robin Degraeve, Sergiu Clima, Gabriele Luca Donadio, Shreya Kundu, Hubert Hody, Wouter Devulder, Jan Van Houdt, Valeri Afanas'ev, Romain Delhougne, Gouri Sankar Kar
Summary: Cross-point array architecture offers a path toward low-cost storage-class memory (SCM), but it requires a selector, such as an ovonic threshold switch (OTS), in series with the memory element, which increases the complexity of the bit cell. There is a demand for a new self-selecting memory cell, capable of overcoming the limitations of phase change memory (PCM). We propose a self-rectifying OTS-only memory (SR-OTSM) that greatly simplifies the integration process compared to conventional 1OTS-1PCM cell, enabled by the semi-persistent polarity-induced threshold voltage shift observed in OTS materials. The Si-Ge-As-Se OTS-based SR-OTSM demonstrates excellent memory performance, including ultralow Write current (<15 mu A), fast Read/Write operation (approximately 10 ns), and good endurance (>10^8 cycles).
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Neurosciences
Shiqing Zhang, Hui Xu, Zhiwei Li, Sen Liu, Bing Song, Qingjiang Li
Summary: Ovonic threshold switch (OTS) has been widely studied in neuromorphic computing due to its high-density synapse array support, but a simple and complete model for device simulation and integrated circuit design has been lacking. In this study, a compact physical model of OTS based on the Poole-Frenkel effect and thermal dissipation effect was developed for the first time, showing good agreement with experimental results and offering insights into device performance optimization.
FRONTIERS IN NEUROSCIENCE
(2021)
Article
Telecommunications
Nicolas Skatchkovsky, Hyeryung Jang, Osvaldo Simeone
Summary: The synergies between wireless communications and artificial intelligence are increasingly driving research at the intersection of the two fields. Machine learning can address algorithm and model deficits in the optimization of communication protocols, but implementing ML models on devices connected via bandwidth-constrained channels remains challenging.
IEEE COMMUNICATIONS LETTERS
(2021)
Article
Telecommunications
Nicolas Skatchkovsky, Hyeryung Jang, Osvaldo Simeone
Summary: This paper introduces the operation principle, training algorithms, and models of Spiking Neural Networks (SNNs) and compares two main methods. To address the non-differentiability of the spiking mechanism, a differentiable function approximating the threshold activation function is proposed, and an alternative method based on probability models is discussed. Finally, experimental results on accuracy and convergence under different SNN models are provided.
IEEE COMMUNICATIONS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Yun-Jae Lee, Minwoo Han, Su-Hyun Yoo, Aloysius Soon
Summary: The study investigates the tunability of OTS selector materials by exchanging isovalent cations with alkaline earth metals, focusing on ZnTe-based ternary chalcogenides. It explores the thermodynamic stability and electronic structure effects, providing an empirical model to predict tunable ranges of threshold voltage for appropriate OTS selector materials.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Computer Science, Information Systems
Suman Hu, Jaehyun Kang, Taeyoon Kim, Suyoun Lee, Jong Keuk Park, Inho Kim, Jaewook Kim, Joon Young Kwak, Jongkil Park, Gyu-Tae Kim, Shinhyun Choi, Yeonjoo Jeong
Summary: This paper investigates the STDP characteristics in a synapse with serially connected memristors. The results show that STDP properties are strongly influenced by device parameters and can even modify the shape of the STDP curve. These findings are significant for the design of future neuromorphic systems.
Article
Chemistry, Multidisciplinary
Junseok Lee, Seonjeong Kim, Seongjin Park, Jaesang Lee, Wonseop Hwang, Seong Won Cho, Kyuho Lee, Sun Mi Kim, Tae-Yeon Seong, Cheolmin Park, Suyoun Lee, Hyunjung Yi
Summary: This article reports an artificial tactile neuron that encodes material stiffness using spike frequency evolution patterns and achieves classification of breast tumor malignancy through learning based on a spiking neural network. It has high recognition accuracy and is significant for disease diagnosis and robot-assisted surgery with low power consumption and latency.
ADVANCED MATERIALS
(2022)
Article
Optics
Sehwan Chang, Junyoung Jin, Jihoon Kyhm, Tae Hwan Park, Jongtae Ahn, Sung-Yul L. Park, Suk In Park, Do Kyung Hwang, Sang Soo Choi, Tae-Yeon Seong, Jin-Dong Song, Gyu Weon Hwang
Summary: We fabricated a high-resolution 1 x 10 PbS QD photodiode array using a customized photolithographic process. The array showed good responsivity and uniformity under 1310-nm SWIR illumination. The response time and bandwidth were also satisfactory. This study demonstrated that the QD photodiode-based SWIR image sensor is a cost-effective and practical alternative.
Article
Computer Science, Information Systems
Yeji Jo, Kyusik Mun, Yeonjoo Jeong, Joon Young Kwak, Jongkil Park, Suyoun Lee, Inho Kim, Jong-Keuk Park, Gyu-Weon Hwang, Jaewook Kim
Summary: This paper proposes a novel Poisson process generator using multiple thermal noise amplifiers (TNAs) and a frequency-locked loop (FLL) to control the event rate. Increasing the number of TNAs extends the bandwidth and enhances the maximum event rate. Furthermore, a fundamental reaction building block with continuous-time multiplication and addition is presented, allowing for parallel stochastic simulations of biochemical reactions.
Article
Engineering, Electrical & Electronic
Jongkil Park, YeonJoo Jeong, Jaewook Kim, Suyoun Lee, Joon Young Kwak, Jong-Keuk Park, Inho Kim
Summary: In this study, a novel neuron implementation model is proposed, which enhances neural and synaptic dynamics using time-embedded floating-point arithmetic for better biological plausibility and low-power consumption. The proposed algorithm enables sharing temporal information with a membrane potential to minimize memory usage and reduce dynamic power consumption.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2023)
Article
Nanoscience & Nanotechnology
Seong Won Cho, In Hak Lee, Youngwoong Lee, Sangheon Kim, Yeong Gwang Khim, Seung-Young Park, Younghun Jo, Junwoo Choi, Seungwu Han, Young Jun Chang, Suyoun Lee
Summary: By studying the heterostructure of BSTS and CT, the hump structure observed is more likely to originate from two anomalous Hall effect channels, one attributed to the extrinsic contribution of CT and the other due to the intrinsic contribution of BSTS.
Article
Materials Science, Multidisciplinary
Jeong Ung Ahn, Jeehoon Jeon, Seong Won Cho, OukJae Lee, Suyoun Lee, Hyun Cheol Koo
Summary: Based on second-harmonic measurements, we successfully separated the thermal effect and spin-orbit torque in GeTe/NiFe bilayers. The second-harmonic resistance shows inseparable terms of damping-like torque and thermal effect. Additionally, different thermomagnetic effects like Nernst effect and spin Seebeck effect are also present in the second-harmonic signals. By analyzing their external magnetic field dependence, we were able to extract the significant thermal-related terms. Notably, the ordinary Nernst effect dominates over other thermal effects in GeTe/NiFe structures. Moreover, we examined the temperature and electric field dependence of the ordinary Nernst effect in the GeTe channel. These findings emphasize the importance of considering thermal effects in controlling spin-orbit-torque-induced switching in bulk Rashba devices.
CURRENT APPLIED PHYSICS
(2023)
Correction
Nanoscience & Nanotechnology
Seong Won Cho, In Hak Lee, Youngwoong Lee, Sangheon Kim, Yeong Gwang Khim, Seung-Young Park, Younghun Jo, Junwoo Choi, Seungwu Han, Young Jun Chang, Suyoun Lee
Article
Chemistry, Physical
Seong Won Cho, Young Woong Lee, Sang Heon Kim, Seungwu Han, Inho Kim, Jong-Keuk Park, Joon Young Kwak, Jaewook Kim, YeonJoo Jeong, Gyu Weon Hwang, Kyeong Seok Lee, Seongsik Park, Suyoun Lee
Summary: This study investigates the superlattices composed of Bi2Te3 and GeTe, finding that they have reduced carrier density and larger Rashba constant, which can enhance the ferroelectricity and spin-orbit coupling effect in GeTe material.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Jaesang Lee, Seong Won Cho, Young Woong Lee, Joon Young Kwak, Jaewook Kim, Yeonjoo Jeong, Gyu Weon Hwang, Seongsik Park, SangBum Kim, Suyoun Lee
Summary: This study investigates the electroforming phenomenon in OTS devices and finds that it leads to an increase in trap state density and a decrease in the distance from the Fermi energy to the conduction band. The local structure of the switching material plays a crucial role in mitigating the electroforming phenomenon. The findings provide important information for designing an electroforming-free OTS device.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Eunpyo Park, Jae Eun Seo, Gichang Noh, Yooyeon Jo, Dong Yeon Woo, In Soo Kim, Jongkil Park, Jaewook Kim, YeonJoo Jeong, Suyoun Lee, Inho Kim, Jong-Keuk Park, Sangbum Kim, Jiwon Chang, Joon Young Kwak
Summary: Two-dimensional materials have shown promising potential for applications in non-volatile memory and neuromorphic systems. By constructing a floating gate memory with a pentagonal 2D layered PdSe2 channel, we achieve low power consumption, reliable retention time, and multi-bit conductance states.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Samuel Shin, Dae Cheol Kang, Keonhee Kim, Yeonjoo Jeong, Jaewook Kim, Suyoun Lee, Joon Young Kwak, Jongkil Park, Gyu Weon Hwang, Kyeong-Seok Lee, Jong Keuk Park, Jian Li, Inho Kim
Summary: This study presents an organic mixed ionic-electronic conductor (OMIEC) memristor that mimics the short-term plasticity (STP) of biological synapses. By controlling the ion conductivity of the active layer, the behavior of neurotransmitters is emulated. The addition of salt influences the short-term memory behavior, making it similar to biological synapses. This memristor can be employed in SPICE simulations to modulate the spike-timing-dependent synaptic plasticity learning rule.
MATERIALS ADVANCES
(2022)
