The intrinsic variability of memristor switching behavior can be used as a natural source of randomness,this variability is valuable for safe applications in hardware,such as the true random number generator(TRNG).How...The intrinsic variability of memristor switching behavior can be used as a natural source of randomness,this variability is valuable for safe applications in hardware,such as the true random number generator(TRNG).However,the speed of TRNG is still be further improved.Here,we propose a reliable Ag/SiNx/n-Si volatile memristor,which exhibits a typical threshold switching device with stable repeat ability and fast switching speed.This volatile-memristor-based TRNG is combined with nonlinear feedback shift register(NFSR)to form a new type of high-speed dual output TRNG.Interestingly,the bit generation rate reaches a high speed of 112 kb/s.In addition,this new TRNG passed all 15 National Institute of Standards and Technology(NIST)randomness tests without post-processing steps,proving its performance as a hardware security application.This work shows that the SiNx-based volatile memristor can realize TRNG and has great potential in hardware network security.展开更多
An autonomous altitude adjustment system for a stratospheric satellite(StratoSat)platform is proposed.This platform consists of a helium balloon,a ballonet,and a two-way blower.The helium balloon generates lift to bal...An autonomous altitude adjustment system for a stratospheric satellite(StratoSat)platform is proposed.This platform consists of a helium balloon,a ballonet,and a two-way blower.The helium balloon generates lift to balance the platform gravity.The two-way blower inflates and deflates the ballonet to regulate the buoyancy.Altitude adjustment is achieved by tracking the differential pressure difference(DPD),and a threshold switching strategy is used to achieve blower flow control.The vertical acceleration regulation ability is decided not only by the blower flow rate,but also by the designed margin of pressure difference(MPD).Pressure difference is a slow-varying variable compared with altitude,and it is adopted as the control variable.The response speed of the actuator to disturbance can be delayed,and the overshoot caused by the large inertia of the platform is inhibited.This method can maintain a high tracking accuracy and reduce the complexity of model calculation,thus improving the robustness of controller design.展开更多
The use of electrochemical-metallization-based volatile threshold switching selectors in cross-point arrays has been widely explored owing to their high on-off ratios and simple structure.However,these devices are uns...The use of electrochemical-metallization-based volatile threshold switching selectors in cross-point arrays has been widely explored owing to their high on-off ratios and simple structure.However,these devices are unsuitable for cross-point architectures because of the difficulty in controlling the random filament formation that results in large fluctuations in the threshold voltage during operation.In this study,we investigated the unidirectional threshold transition characteristics associated with an Ag/GST/HfO_(x)/Pt-based bilayer selector and demonstrated the occurrence of a low leakage current(<1×10^(-11) A) and low distribution of the threshold voltage(Δ0.11 V).The bilayer structure could control the filament formation in the intermediate state through the insertion of an HfO_(x) tunneling barrier.By stacking a bilayer selector with NiO_(x)based resistive random-access memory,the leakage and programming currents of the device could be significantly decreased.For the crossbar array configuration,we performed equivalent circuit analysis of a one-selector oneresistor(1S1R) devices and estimated the optimal array size to demonstrate the applicability of the proposed structure.The maximum acceptable crossbar array size of the 1S1R device with the Ag/GST/HfO_(x)/Pt/Ti/NiO_(x)/Pt structure was 5.29×10^(14)(N^(2),N=2.3×10^(7)).展开更多
The recent development of three-dimensional semiconductor integration technology demands a key component-the ovonic threshold switching(OTS)selector to suppress the current leakage in the high-density memory chips.Yet...The recent development of three-dimensional semiconductor integration technology demands a key component-the ovonic threshold switching(OTS)selector to suppress the current leakage in the high-density memory chips.Yet,the unsatisfactory performance of existing OTS materials becomes the bottleneck of the industrial advancement.The sluggish development of OTS materials,which are usually made from chalcogenide glass,should be largely attributed to the insufficient understanding of the electronic structure in these materials,despite of intensive research in the past decade.Due to the heavy first-principles computation on disordered systems,a universal theory to explain the origin of mid-gap states(MGS),which are the key feature leading to the OTS behavior,is still lacking.To avoid the formidable computational tasks,we adopt machine learning method to understand and predict MGS in typical OTS materials.We build hundreds of chalcogenide glass models and collect major structural features from both short-range order(SRO)and medium-range order(MRO)of the amorphous cells.After training the artificial neural network using these features,the accuracy has reached~95%when it recognizes MGS in new glass.By analyzing the synaptic weights of the input structural features,we discover that the bonding and coordination environments from SRO and particularly MRO are closely related to MGS.The trained model could be used in many other OTS chalcogenides after minor modification.The intelligent machine learning allows us to understand the OTS mechanism from vast amount of structural data without heavy computational tasks,providing a new strategy to design functional amorphous materials from first principles.展开更多
With rapid advancement and deep integration of artificial intelligence and the internet-of-things,artificial intelligence of things has emerged as a promising technology changing people’s daily life.Massive growth of...With rapid advancement and deep integration of artificial intelligence and the internet-of-things,artificial intelligence of things has emerged as a promising technology changing people’s daily life.Massive growth of data generated from the devices challenges the AIoT systems from information collection,storage,processing and communication.In the review,we introduce volatile threshold switching memristors,which can be roughly classified into three types:metallic conductive filament-based TS devices,amorphous chalcogenide-based ovonic threshold switching devices,and metal-insulator transition based TS devices.They play important roles in high-density storage,energy efficient computing and hardware security for AIoT systems.Firstly,a brief introduction is exhibited to describe the categories(materials and characteristics)of volatile TS devices.And then,switching mechanisms of the three types of TS devices are discussed and systematically summarized.After that,attention is focused on the applications in 3D cross-point memory technology with high storage-density,efficient neuromorphic computing,hardware security(true random number generators and physical unclonable functions),and others(steep subthreshold slope transistor,logic devices,etc.).Finally,the major challenges and future outlook of volatile threshold switching memristors are presented.展开更多
为了设计一款300 V IGBT,从理论分析了IGBT各工艺参数与器件主要性能之间的关系.并利用Tsuprem4和Medici软件,重点研究了器件工艺参数对器件击穿电压、阈值电压的影响,同时分析了IGBT器件的开关特性及其影响因素,最终得到了兼容CMOS工艺...为了设计一款300 V IGBT,从理论分析了IGBT各工艺参数与器件主要性能之间的关系.并利用Tsuprem4和Medici软件,重点研究了器件工艺参数对器件击穿电压、阈值电压的影响,同时分析了IGBT器件的开关特性及其影响因素,最终得到了兼容CMOS工艺的300 V IGBT的最佳结构、工艺参数.通过计算机模拟得知,该器件的关态和开态的击穿电压都达到了要求,阈值电压为2V,而且兼容目前国内的CMOS工艺,可以很好地应用于各种高压功率集成电路.展开更多
The impact of the variations of threshold voltage(V_(th))and hold voltage(V_(hold))of threshold switching(TS)selector in1 S1 R crossbar array is investigated.Based on ON/OFF state I–V curves measurements from a large...The impact of the variations of threshold voltage(V_(th))and hold voltage(V_(hold))of threshold switching(TS)selector in1 S1 R crossbar array is investigated.Based on ON/OFF state I–V curves measurements from a large number of Ag-filament TS selectors,V_(th)and V_(hold)are extracted and their variations distribution expressions are obtained,which are then employed to evaluate the impact on read process and write process in 32×321 S1 R crossbar array under different bias schemes.The results indicate that V_(th)and V_(hold)variations of TS selector can lead to degradation of 1 S1 R array performance parameters,such as minimum read/write voltage,bit error rate(BER),and power consumption.For the read process,a small V_(hold)variation not only results in the minimum read voltage increasing but it also leads to serious degradation of BER.As the standard deviation of V_(hold)and V_(th)increases,the BER and the power consumption of 1 S1 R crossbar array under 1/2 bias,1/3 bias,and floating scheme degrade,and the case under 1/2 bias tends to be more serious compared with other two schemes.For the write process,the minimum write voltage also increases with the variation of V_(hold)from small to large value.A slight increase of V_(th)standard deviation not only decreases write power efficiency markedly but also increases write power consumption.These results have reference significance to understand the voltage variation impacts and design of selector properly.展开更多
基金supported by the National Key R&D Plan“Nano Frontier”Key Special Project(Grant No.2021YFA1200502)Cultivation Projects of National Major R&D Project(Grant No.92164109)+12 种基金the National Natural Science Foundation of China(Grant Nos.61874158,62004056,and 62104058)the Special Project of Strategic Leading Science and Technology of Chinese Academy of Sciences(Grant No.XDB44000000-7)Key R&D Plan Projects in Hebei Province(Grant No.22311101D)Hebei Basic Research Special Key Project(Grant No.F2021201045)the Support Program for the Top Young Talents of Hebei Province(Grant No.70280011807)the Supporting Plan for 100 Excellent Innovative Talents in Colleges and Universities of Hebei Province(Grant No.SLRC2019018)the Interdisciplinary Research Program of Natural Science of Hebei University(No.DXK202101)the Institute of Life Sciences and Green Development(No.521100311)the Natural Science Foundation of Hebei Province(Nos.F2022201054 and F2021201022)the Outstanding Young Scientific Research and Innovation Team of Hebei University(Grant No.605020521001)the Special Support Funds for National High Level Talents(Grant No.041500120001)the Advanced Talents Incubation Program of the Hebei University(Grant Nos.521000981426,521100221071,and 521000981363)the Science and Technology Project of Hebei Education Department(Grant Nos.QN2020178 and QN2021026).
文摘The intrinsic variability of memristor switching behavior can be used as a natural source of randomness,this variability is valuable for safe applications in hardware,such as the true random number generator(TRNG).However,the speed of TRNG is still be further improved.Here,we propose a reliable Ag/SiNx/n-Si volatile memristor,which exhibits a typical threshold switching device with stable repeat ability and fast switching speed.This volatile-memristor-based TRNG is combined with nonlinear feedback shift register(NFSR)to form a new type of high-speed dual output TRNG.Interestingly,the bit generation rate reaches a high speed of 112 kb/s.In addition,this new TRNG passed all 15 National Institute of Standards and Technology(NIST)randomness tests without post-processing steps,proving its performance as a hardware security application.This work shows that the SiNx-based volatile memristor can realize TRNG and has great potential in hardware network security.
基金the National Natural Science Foundation of China(No.52175103)。
文摘An autonomous altitude adjustment system for a stratospheric satellite(StratoSat)platform is proposed.This platform consists of a helium balloon,a ballonet,and a two-way blower.The helium balloon generates lift to balance the platform gravity.The two-way blower inflates and deflates the ballonet to regulate the buoyancy.Altitude adjustment is achieved by tracking the differential pressure difference(DPD),and a threshold switching strategy is used to achieve blower flow control.The vertical acceleration regulation ability is decided not only by the blower flow rate,but also by the designed margin of pressure difference(MPD).Pressure difference is a slow-varying variable compared with altitude,and it is adopted as the control variable.The response speed of the actuator to disturbance can be delayed,and the overshoot caused by the large inertia of the platform is inhibited.This method can maintain a high tracking accuracy and reduce the complexity of model calculation,thus improving the robustness of controller design.
基金financially supported by the National Research Foundation of Korea (NRF)(No.2016R1A3B1908249)。
文摘The use of electrochemical-metallization-based volatile threshold switching selectors in cross-point arrays has been widely explored owing to their high on-off ratios and simple structure.However,these devices are unsuitable for cross-point architectures because of the difficulty in controlling the random filament formation that results in large fluctuations in the threshold voltage during operation.In this study,we investigated the unidirectional threshold transition characteristics associated with an Ag/GST/HfO_(x)/Pt-based bilayer selector and demonstrated the occurrence of a low leakage current(<1×10^(-11) A) and low distribution of the threshold voltage(Δ0.11 V).The bilayer structure could control the filament formation in the intermediate state through the insertion of an HfO_(x) tunneling barrier.By stacking a bilayer selector with NiO_(x)based resistive random-access memory,the leakage and programming currents of the device could be significantly decreased.For the crossbar array configuration,we performed equivalent circuit analysis of a one-selector oneresistor(1S1R) devices and estimated the optimal array size to demonstrate the applicability of the proposed structure.The maximum acceptable crossbar array size of the 1S1R device with the Ag/GST/HfO_(x)/Pt/Ti/NiO_(x)/Pt structure was 5.29×10^(14)(N^(2),N=2.3×10^(7)).
基金National Key R&D Plan of China(Grant No.2019YFB2205100,2017YFB0701700)National Science and Technology Major Project of China(Grant No.2017ZX02301007-002)+2 种基金National Natural Science Foundation of China(Grant No.62174060)Fundamental Research Funds for the Central Universities,HUST(No.2021GCRC051)Hubei Key Laboratory of Advanced Memories.
文摘The recent development of three-dimensional semiconductor integration technology demands a key component-the ovonic threshold switching(OTS)selector to suppress the current leakage in the high-density memory chips.Yet,the unsatisfactory performance of existing OTS materials becomes the bottleneck of the industrial advancement.The sluggish development of OTS materials,which are usually made from chalcogenide glass,should be largely attributed to the insufficient understanding of the electronic structure in these materials,despite of intensive research in the past decade.Due to the heavy first-principles computation on disordered systems,a universal theory to explain the origin of mid-gap states(MGS),which are the key feature leading to the OTS behavior,is still lacking.To avoid the formidable computational tasks,we adopt machine learning method to understand and predict MGS in typical OTS materials.We build hundreds of chalcogenide glass models and collect major structural features from both short-range order(SRO)and medium-range order(MRO)of the amorphous cells.After training the artificial neural network using these features,the accuracy has reached~95%when it recognizes MGS in new glass.By analyzing the synaptic weights of the input structural features,we discover that the bonding and coordination environments from SRO and particularly MRO are closely related to MGS.The trained model could be used in many other OTS chalcogenides after minor modification.The intelligent machine learning allows us to understand the OTS mechanism from vast amount of structural data without heavy computational tasks,providing a new strategy to design functional amorphous materials from first principles.
基金supported by the STI 2030—Major Projects(Grant No.2021ZD0201201)National Natural Science Foundation of China(Grant No.92064012)Hubei Province Postdoctoral Innovation Research Program(Grant No.0106182103)。
文摘With rapid advancement and deep integration of artificial intelligence and the internet-of-things,artificial intelligence of things has emerged as a promising technology changing people’s daily life.Massive growth of data generated from the devices challenges the AIoT systems from information collection,storage,processing and communication.In the review,we introduce volatile threshold switching memristors,which can be roughly classified into three types:metallic conductive filament-based TS devices,amorphous chalcogenide-based ovonic threshold switching devices,and metal-insulator transition based TS devices.They play important roles in high-density storage,energy efficient computing and hardware security for AIoT systems.Firstly,a brief introduction is exhibited to describe the categories(materials and characteristics)of volatile TS devices.And then,switching mechanisms of the three types of TS devices are discussed and systematically summarized.After that,attention is focused on the applications in 3D cross-point memory technology with high storage-density,efficient neuromorphic computing,hardware security(true random number generators and physical unclonable functions),and others(steep subthreshold slope transistor,logic devices,etc.).Finally,the major challenges and future outlook of volatile threshold switching memristors are presented.
基金financially supported by the National Natural Science Foundation of China(62188102 and 12035019)the Natural Science Basic Research Program of Shaanxi(2022JQ-582)the National Key Research and Development Program(2018YFB2202900)。
文摘为了设计一款300 V IGBT,从理论分析了IGBT各工艺参数与器件主要性能之间的关系.并利用Tsuprem4和Medici软件,重点研究了器件工艺参数对器件击穿电压、阈值电压的影响,同时分析了IGBT器件的开关特性及其影响因素,最终得到了兼容CMOS工艺的300 V IGBT的最佳结构、工艺参数.通过计算机模拟得知,该器件的关态和开态的击穿电压都达到了要求,阈值电压为2V,而且兼容目前国内的CMOS工艺,可以很好地应用于各种高压功率集成电路.
基金Project supported by the MOST of China(Grant No.2016YFA0201801)the Beijing Advanced Innovation Center for Future Chip(ICFC)+2 种基金Beijing Municipal Science and Technology Project(Grant No.D161100001716002)the National Natural Science Foundation of China(Grant Nos.61674089,61674087,61674092,61076115,and 61774012)the Research Fund from Beijing Innovation Center for Future Chip(Grant No.KYJJ2016008)
文摘The impact of the variations of threshold voltage(V_(th))and hold voltage(V_(hold))of threshold switching(TS)selector in1 S1 R crossbar array is investigated.Based on ON/OFF state I–V curves measurements from a large number of Ag-filament TS selectors,V_(th)and V_(hold)are extracted and their variations distribution expressions are obtained,which are then employed to evaluate the impact on read process and write process in 32×321 S1 R crossbar array under different bias schemes.The results indicate that V_(th)and V_(hold)variations of TS selector can lead to degradation of 1 S1 R array performance parameters,such as minimum read/write voltage,bit error rate(BER),and power consumption.For the read process,a small V_(hold)variation not only results in the minimum read voltage increasing but it also leads to serious degradation of BER.As the standard deviation of V_(hold)and V_(th)increases,the BER and the power consumption of 1 S1 R crossbar array under 1/2 bias,1/3 bias,and floating scheme degrade,and the case under 1/2 bias tends to be more serious compared with other two schemes.For the write process,the minimum write voltage also increases with the variation of V_(hold)from small to large value.A slight increase of V_(th)standard deviation not only decreases write power efficiency markedly but also increases write power consumption.These results have reference significance to understand the voltage variation impacts and design of selector properly.
