Multilevel phase-change memory is an attractive technology to increase storage capacity and density owing to its high-speed,scalable and non-volatile characteristics.However,the contradiction between thermal stability...Multilevel phase-change memory is an attractive technology to increase storage capacity and density owing to its high-speed,scalable and non-volatile characteristics.However,the contradiction between thermal stability and operation speed is one of key factors to restrain the development of phase-change memory.Here,N-doped Ge_(2)Sb_(2)Te_(5)-based optoelectronic hybrid memory is proposed to simultaneously implement high thermal stability and ultrafast operation speed.The picosecond laser is adopted to write/erase information based on reversible phase transition characteristics whereas the resistance is detected to perform information readout.Results show that when N content is 27.4 at.%,N-doped Ge_(2)Sb_(2)Te_(5)film possesses high ten-year data retention temperature of 175℃and low resistance drift coefficient of 0.00024 at 85℃,0.00170 at 120℃,and 0.00249 at 150℃,respectively,owing to the formation of Ge–N,Sb–N,and Te–N bonds.The SET/RESET operation speeds of the film reach 520 ps/13 ps.In parallel,the reversible switching cycle of the corresponding device is realized with the resistance ratio of three orders of magnitude.Four-level reversible resistance states induced by various crystallization degrees are also obtained together with low resistance drift coefficients.Therefore,the N-doped Ge_(2)Sb_(2)Te_(5)thin film is a promising phase-change material for ultrafast multilevel optoelectronic hybrid storage.展开更多
Threshold switching(TS) memristors can be used as artificial neurons in neuromorphic systems due to their continuous conductance modulation, scalable and energy-efficient properties. In this paper, we propose a low po...Threshold switching(TS) memristors can be used as artificial neurons in neuromorphic systems due to their continuous conductance modulation, scalable and energy-efficient properties. In this paper, we propose a low power artificial neuron based on the Ag/MXene/GST/Pt device with excellent TS characteristics, including a low set voltage(0.38 V)and current(200 nA), an extremely steep slope(< 0.1 m V/dec), and a relatively large off/on ratio(> 10^(3)). Besides, the characteristics of integrate and fire neurons that are indispensable for spiking neural networks have been experimentally demonstrated. Finally, its memristive mechanism is interpreted through the first-principles calculation depending on the electrochemical metallization effect.展开更多
Mo,as a dopant,is doped into SbTe to improve its thermal stability.It is shown in this paper that the Mo-doped Sb_(2)Te_(3)(Mo_(0.26)Sb_(2)Te_(3),MST)material possesses phase change memory(PCM)applications.MST has bet...Mo,as a dopant,is doped into SbTe to improve its thermal stability.It is shown in this paper that the Mo-doped Sb_(2)Te_(3)(Mo_(0.26)Sb_(2)Te_(3),MST)material possesses phase change memory(PCM)applications.MST has better thermal stability than Sb_(2)Te_(3)(ST)and will crystallize only when the annealing temperature is higher than 250℃.With the good thermal stability,MST-based PCM cells have a fast crystallization time of 6 ns.Furthermore,endurance up to 4×10^(5) cycles with a resistance ratio of more than one order of magnitude makes MST a promising candidate for PCM applications.展开更多
Flexible tactile sensor has been extensively investigated as a key component for emerging electronics applications such as robotics,wearable devices,computer hardware,and security systems.Tactile sensors based on vari...Flexible tactile sensor has been extensively investigated as a key component for emerging electronics applications such as robotics,wearable devices,computer hardware,and security systems.Tactile sensors based on various one-dimensional materials have been widely explored.However,precise control of the direction and distribution of these nanomaterials remains a great challenge,and it has been difficult to scale down the device.Here,we introduce highly sensitive integrated flexible tactile sensors based on uniform phase-change Ge_(2)Sb_(2)Te_(5)(GST)thin films that can scale device size down,at least,to micrometer range.Significant piezoresistive effect has been observed in GST-based sensors,showing a giant gauge factor of 338.A proof of concept 5×5 sensor array functioning as a touch panel has been demonstrated.Also,the flexible GST tactile sensor has been utilized for monitoring of radial artery pulse.In addition to the well-known tunable electrical and optical properties,the piezoresistive GST films provide a versatile platform for the integration of sensing,recording,and displaying functions.展开更多
In order to fulfill the complex cognitive behaviors in neuromorphic systems with reduced peripheral circuits,the reliable electronic synapses mimicked by single device that achieves diverse long-term and short-term pl...In order to fulfill the complex cognitive behaviors in neuromorphic systems with reduced peripheral circuits,the reliable electronic synapses mimicked by single device that achieves diverse long-term and short-term plasticity are essential.Phase change random access memory(PCRAM)is of great potential for artificial synapses,which faces,however,difficulty to realize short-term plasticity due to the long-lasting resistance drift.This work reports the ruthenium-doped Ge_(2)Sb_(2)Te_(5)(RuGST)based PCRAM,demonstrating a series of synaptic behaviors of short-term potentiation,pair-pulse facilitation,longterm depression,and short-term plasticity in the same single device.The optimized RuGST electronic synapse with the high transformation temperature of hexagonal phase>380C,the outstanding endurance>108 cycles,the low resistance drift factor of 0.092,as well as the extremely high linearity with correlation coefficients of 0.999 and 0.976 in parts of potentiation and depression.Further investigations also go insight to mechanisms of Ru doping according to thorough microstructure characterization,revealing that Ru dopant is able to enter GST lattices thus changing and stabilizing atomic arrangement of GST.This leads to the short-term plasticity realized by RuGST PCRAM.Eventually,the proposed RuGST electronic synapses performs a high accuracy of94.1%in a task of image recognition of CIFAR-100 database using ResNet 101.This work promotes the development of PCRAM platforms for large-scale neuromorphic systems.展开更多
Crystallization speed of phase change material is one of the main obstaclesfor the application of phase change memory(PCM)as storage classmemory in computing systems,which requires the combination ofnonvolatility with...Crystallization speed of phase change material is one of the main obstaclesfor the application of phase change memory(PCM)as storage classmemory in computing systems,which requires the combination ofnonvolatility with ultra-fast operation speed in nanoseconds.Here,wepropose a novel approach to speed up crystallization process of the onlycommercial phase change chalcogenide Ge_(2)Sb_(2)Te_(5)(GST).By employingTiO_(2)as the dielectric layer in phase change device,operation speed of650 ps has been achieved,which is the fastest among existing representativePCM,and is comparable to the programing speed of commercialdynamic random access memory(DRAM).Because of its octahedralatomic configuration,TiO_(2)can provide nucleation interfaces for GST,thus facilitating the crystal growth at the determinate interface area.Ti–O–Ti–O four-fold rings on the(110)plane of tetragonal TiO_(2)is critical forthe fast-atomic rearrangement in the amorphous matrix of GST thatenables ultra-fast operation speed.The significant improvement of operationspeed in PCM through incorporating standard dielectric materialTiO_(2)in DRAM paves the way for the application of phase change memoryin high performance cache-type data storage.展开更多
Dynamically tunable metasurfaces employing chalcogenide phase-change materials(PCMs)such as Ge_(2)Sb_(2)Te_(5)alloys have garnered significant attention and research efforts.However,the utilization of chalcogenide PCM...Dynamically tunable metasurfaces employing chalcogenide phase-change materials(PCMs)such as Ge_(2)Sb_(2)Te_(5)alloys have garnered significant attention and research efforts.However,the utilization of chalcogenide PCMs in dynamic metasurface devices necessitates protection,owing to their susceptibility to volatilization and oxidation.Conventional protective layer materials such as Al_(2)O_(3),TiO_(2),and SiO_(2)present potential drawbacks including diffusion,oxidation,or thermal expansion coefficient mismatch with chalcogenide PCMs during high-temperature phase transition,severely limiting the durability of chalcogenide PCM-based devices.In this paper,we propose,for the first time to our knowledge,the utilization of chalcogenide glass characterized by high thermal stability as a protective material for chalcogenide PCM.This approach addresses the durability challenge of current dynamic photonic devices based on chalcogenide PCM by virtue of their closely matched optical and thermal properties.Building upon this innovation,we introduce an all-chalcogenide dynamic tunable metasurface filter and comprehensively simulate and analyze its characteristics.This pioneering work paves the way for the design and practical implementation of optically dynamically tunable metasurface devices leveraging chalcogenide PCMs,ushering in new opportunities in the field.展开更多
Hardware electronic synapse and neuro-inspired computing system based on phase change random access memory(PCRAM)have attracted an extensive investigation.However,due to the intrinsic asymmetric reversible phase trans...Hardware electronic synapse and neuro-inspired computing system based on phase change random access memory(PCRAM)have attracted an extensive investigation.However,due to the intrinsic asymmetric reversible phase transition,the defective weight update of PCRAM synapses in aspects of tuning range,linearity and continuity has long required a system-level complexity of circuits and al-gorithms.The cell-level improvements to a great extent may slim the system thus achieving efficient computing.We report in this work the great enhancement of Ge_(2)Sb_(2)Te_(5)(GST)based PCRAM synapses by combining materials engineering and pulse programming.It is found that carbon doping in GST retards the rate of phase changing thus increasing the controllability of the conductance,while non-linear programmable pulse excitations can eventually lead to a reliable synaptic potentiation and depression.A set of improved programmable pulse schemes for spike-timing dependent plasticity was then demonstrated,suggesting its potential superiority in flexible programming and reliable data collection.Our methods and results are of great significance for implementing PCRAM electronic synapses and high-performance neuro-inspired computing.展开更多
Further improvement of storage density is a key challenge for the application of phase-change memory(PCM)in storage-class memory.However,for PCM,storage density improvements include feature size scaling down and multi...Further improvement of storage density is a key challenge for the application of phase-change memory(PCM)in storage-class memory.However,for PCM,storage density improvements include feature size scaling down and multilevel cell(MLC)operation,potentially causing thermal crosstalk issues and phase separation issues,respectively.To address these challenges,we propose a high-aspect-ratio(25:1)lateral nanowire(NW)PCM device with conventional chalcogenide Ge_(2)Sb_(2)Te_(5)(GST-225)to realize stable MLC operations,i.e.,low intra-and inter-cell variability and low resistance drift(coefficient=0.009).The improved MLC performance is attributed to the high aspect ratio,which enables precise control of the amorphous region because of sidewall confinement,as confirmed by transmission electron microscopy analysis.In summary,the NW devices provide guidance for the design of future high-aspect-ratio threedimensional PCM devices with MLC capability.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62205231 and 22002102)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX223271)Jiangsu Key Laboratory for Environment Functional Materials。
文摘Multilevel phase-change memory is an attractive technology to increase storage capacity and density owing to its high-speed,scalable and non-volatile characteristics.However,the contradiction between thermal stability and operation speed is one of key factors to restrain the development of phase-change memory.Here,N-doped Ge_(2)Sb_(2)Te_(5)-based optoelectronic hybrid memory is proposed to simultaneously implement high thermal stability and ultrafast operation speed.The picosecond laser is adopted to write/erase information based on reversible phase transition characteristics whereas the resistance is detected to perform information readout.Results show that when N content is 27.4 at.%,N-doped Ge_(2)Sb_(2)Te_(5)film possesses high ten-year data retention temperature of 175℃and low resistance drift coefficient of 0.00024 at 85℃,0.00170 at 120℃,and 0.00249 at 150℃,respectively,owing to the formation of Ge–N,Sb–N,and Te–N bonds.The SET/RESET operation speeds of the film reach 520 ps/13 ps.In parallel,the reversible switching cycle of the corresponding device is realized with the resistance ratio of three orders of magnitude.Four-level reversible resistance states induced by various crystallization degrees are also obtained together with low resistance drift coefficients.Therefore,the N-doped Ge_(2)Sb_(2)Te_(5)thin film is a promising phase-change material for ultrafast multilevel optoelectronic hybrid storage.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61804079 and 61964012)the open research fund of the National and Local Joint Engineering Laboratory of RF Integration and Micro-Assembly Technology (Grant No.KFJJ20200102)+2 种基金the Natural Science Foundation of Jiangsu Province of China (Grant Nos.BK20211273 and BZ2021031)the Nanjing University of Posts and Telecommunications (Grant No.NY220112)the Foundation of Jiangxi Science and Technology Department (Grant No.20202ACBL21200)。
文摘Threshold switching(TS) memristors can be used as artificial neurons in neuromorphic systems due to their continuous conductance modulation, scalable and energy-efficient properties. In this paper, we propose a low power artificial neuron based on the Ag/MXene/GST/Pt device with excellent TS characteristics, including a low set voltage(0.38 V)and current(200 nA), an extremely steep slope(< 0.1 m V/dec), and a relatively large off/on ratio(> 10^(3)). Besides, the characteristics of integrate and fire neurons that are indispensable for spiking neural networks have been experimentally demonstrated. Finally, its memristive mechanism is interpreted through the first-principles calculation depending on the electrochemical metallization effect.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFB0701703 and 2017YFA0206101)the National Natural Science Foundation of China(Grant No.61874151)the Science and Technology Council of Shanghai,China(Grant Nos.19JC1416801 and 19JC1416802).
文摘Mo,as a dopant,is doped into SbTe to improve its thermal stability.It is shown in this paper that the Mo-doped Sb_(2)Te_(3)(Mo_(0.26)Sb_(2)Te_(3),MST)material possesses phase change memory(PCM)applications.MST has better thermal stability than Sb_(2)Te_(3)(ST)and will crystallize only when the annealing temperature is higher than 250℃.With the good thermal stability,MST-based PCM cells have a fast crystallization time of 6 ns.Furthermore,endurance up to 4×10^(5) cycles with a resistance ratio of more than one order of magnitude makes MST a promising candidate for PCM applications.
基金The work was financially supported by W.M.Keck Foundation.
文摘Flexible tactile sensor has been extensively investigated as a key component for emerging electronics applications such as robotics,wearable devices,computer hardware,and security systems.Tactile sensors based on various one-dimensional materials have been widely explored.However,precise control of the direction and distribution of these nanomaterials remains a great challenge,and it has been difficult to scale down the device.Here,we introduce highly sensitive integrated flexible tactile sensors based on uniform phase-change Ge_(2)Sb_(2)Te_(5)(GST)thin films that can scale device size down,at least,to micrometer range.Significant piezoresistive effect has been observed in GST-based sensors,showing a giant gauge factor of 338.A proof of concept 5×5 sensor array functioning as a touch panel has been demonstrated.Also,the flexible GST tactile sensor has been utilized for monitoring of radial artery pulse.In addition to the well-known tunable electrical and optical properties,the piezoresistive GST films provide a versatile platform for the integration of sensing,recording,and displaying functions.
基金National Natural Science Foundation of China,Grant/Award Numbers:M0441,61634008,91964204111 Project of China,Grant/Award Number:B14040+3 种基金Open Project of National Key Laboratory of Materials for Integrated Circuits,Grant/Award Number:SKL202207Shanghai Research and Innovation Functional Program,Grant/Award Number:17DZ2260900National Key Projects of China,Grant/Award Number:2021XJTU0016Natural Sciences and Engineering Research Council of Canada,Grant/Award Numbers:RGPIN-2017-06915,RGPIN-2023-04416。
文摘In order to fulfill the complex cognitive behaviors in neuromorphic systems with reduced peripheral circuits,the reliable electronic synapses mimicked by single device that achieves diverse long-term and short-term plasticity are essential.Phase change random access memory(PCRAM)is of great potential for artificial synapses,which faces,however,difficulty to realize short-term plasticity due to the long-lasting resistance drift.This work reports the ruthenium-doped Ge_(2)Sb_(2)Te_(5)(RuGST)based PCRAM,demonstrating a series of synaptic behaviors of short-term potentiation,pair-pulse facilitation,longterm depression,and short-term plasticity in the same single device.The optimized RuGST electronic synapse with the high transformation temperature of hexagonal phase>380C,the outstanding endurance>108 cycles,the low resistance drift factor of 0.092,as well as the extremely high linearity with correlation coefficients of 0.999 and 0.976 in parts of potentiation and depression.Further investigations also go insight to mechanisms of Ru doping according to thorough microstructure characterization,revealing that Ru dopant is able to enter GST lattices thus changing and stabilizing atomic arrangement of GST.This leads to the short-term plasticity realized by RuGST PCRAM.Eventually,the proposed RuGST electronic synapses performs a high accuracy of94.1%in a task of image recognition of CIFAR-100 database using ResNet 101.This work promotes the development of PCRAM platforms for large-scale neuromorphic systems.
基金the National Key Research andDevelopment Program of China,Grant/Award Number:2021YFA1202804the National Natural Science Foundationof China,Grant/Award Number:62174065the Hubei Provincial NaturalScience Foundation of China,Grant/Award Number:2021CFA038。
文摘Crystallization speed of phase change material is one of the main obstaclesfor the application of phase change memory(PCM)as storage classmemory in computing systems,which requires the combination ofnonvolatility with ultra-fast operation speed in nanoseconds.Here,wepropose a novel approach to speed up crystallization process of the onlycommercial phase change chalcogenide Ge_(2)Sb_(2)Te_(5)(GST).By employingTiO_(2)as the dielectric layer in phase change device,operation speed of650 ps has been achieved,which is the fastest among existing representativePCM,and is comparable to the programing speed of commercialdynamic random access memory(DRAM).Because of its octahedralatomic configuration,TiO_(2)can provide nucleation interfaces for GST,thus facilitating the crystal growth at the determinate interface area.Ti–O–Ti–O four-fold rings on the(110)plane of tetragonal TiO_(2)is critical forthe fast-atomic rearrangement in the amorphous matrix of GST thatenables ultra-fast operation speed.The significant improvement of operationspeed in PCM through incorporating standard dielectric materialTiO_(2)in DRAM paves the way for the application of phase change memoryin high performance cache-type data storage.
基金supported by the Program of Marine Economy Development Special Fund under Department of Natural Resources of Guangdong Province(Grant No.GDNRC[2023]23)the National Natural Science Foundation of China(Grant Nos.62005098 and 61935013)+1 种基金the General Items of Guangzhou Science and Technology Plan Project(PhD Young Scientists and Technologists category)(Grant No.202201010320)the Fundamental Research Funds for the Central University(Grant No.11623415).
文摘Dynamically tunable metasurfaces employing chalcogenide phase-change materials(PCMs)such as Ge_(2)Sb_(2)Te_(5)alloys have garnered significant attention and research efforts.However,the utilization of chalcogenide PCMs in dynamic metasurface devices necessitates protection,owing to their susceptibility to volatilization and oxidation.Conventional protective layer materials such as Al_(2)O_(3),TiO_(2),and SiO_(2)present potential drawbacks including diffusion,oxidation,or thermal expansion coefficient mismatch with chalcogenide PCMs during high-temperature phase transition,severely limiting the durability of chalcogenide PCM-based devices.In this paper,we propose,for the first time to our knowledge,the utilization of chalcogenide glass characterized by high thermal stability as a protective material for chalcogenide PCM.This approach addresses the durability challenge of current dynamic photonic devices based on chalcogenide PCM by virtue of their closely matched optical and thermal properties.Building upon this innovation,we introduce an all-chalcogenide dynamic tunable metasurface filter and comprehensively simulate and analyze its characteristics.This pioneering work paves the way for the design and practical implementation of optically dynamically tunable metasurface devices leveraging chalcogenide PCMs,ushering in new opportunities in the field.
基金This work was supported by Key R&D Program of Shaanxi Province of China(2020GY-271 and 2018ZDXM-GY-150)the Fundamental Research Funds for the Central Universities(xjj2018016)+3 种基金the“111 Project”of China(B14040),the Open Project of State Key Laboratory of Electronic Thin Films and Integrated Devices(KFJJ201902)the Open Project of State Key Laboratory of Information Functional Materials(SKL-201908)the Natural Sci-ences and Engineering Research Council of Canada(NSERC,Dis-covery Grant No.RGPIN-2017-06915)the National Natural Science Foundation of China(91964204 and 61634008).
文摘Hardware electronic synapse and neuro-inspired computing system based on phase change random access memory(PCRAM)have attracted an extensive investigation.However,due to the intrinsic asymmetric reversible phase transition,the defective weight update of PCRAM synapses in aspects of tuning range,linearity and continuity has long required a system-level complexity of circuits and al-gorithms.The cell-level improvements to a great extent may slim the system thus achieving efficient computing.We report in this work the great enhancement of Ge_(2)Sb_(2)Te_(5)(GST)based PCRAM synapses by combining materials engineering and pulse programming.It is found that carbon doping in GST retards the rate of phase changing thus increasing the controllability of the conductance,while non-linear programmable pulse excitations can eventually lead to a reliable synaptic potentiation and depression.A set of improved programmable pulse schemes for spike-timing dependent plasticity was then demonstrated,suggesting its potential superiority in flexible programming and reliable data collection.Our methods and results are of great significance for implementing PCRAM electronic synapses and high-performance neuro-inspired computing.
基金supported by the National Natural Science Foundation of China(62174065)the Key Research and Development Plan of Hubei Province(2020BAB007)+1 种基金Hubei Provincial Natural Science Foundation(2021CFA038)the support from Hubei Key Laboratory of Advanced Memories&Hubei Engineering Research Center on Microelectronics。
文摘Further improvement of storage density is a key challenge for the application of phase-change memory(PCM)in storage-class memory.However,for PCM,storage density improvements include feature size scaling down and multilevel cell(MLC)operation,potentially causing thermal crosstalk issues and phase separation issues,respectively.To address these challenges,we propose a high-aspect-ratio(25:1)lateral nanowire(NW)PCM device with conventional chalcogenide Ge_(2)Sb_(2)Te_(5)(GST-225)to realize stable MLC operations,i.e.,low intra-and inter-cell variability and low resistance drift(coefficient=0.009).The improved MLC performance is attributed to the high aspect ratio,which enables precise control of the amorphous region because of sidewall confinement,as confirmed by transmission electron microscopy analysis.In summary,the NW devices provide guidance for the design of future high-aspect-ratio threedimensional PCM devices with MLC capability.
