With recent progress in material science, resistive random access memory (RRAM) devices have attracted interest for nonvolatile, low-power, nondestructive readout, and high-density memories. Relevant performance param...With recent progress in material science, resistive random access memory (RRAM) devices have attracted interest for nonvolatile, low-power, nondestructive readout, and high-density memories. Relevant performance parameters of RRAM devices include operating voltage, operation speed, resistance ratio, endurance, retention time, device yield, and multilevel storage. Numerous resistive-switching mechanisms, such as conductive filament, space-charge-limited conduction, trap charging and discharging, Schottky Emission, and Pool-Frenkel emission, have been proposed to explain the resistive switching of RRAM devices. In addition to a discussion of these mechanisms, the effects of electrode materials, doped oxide materials, and different configuration devices on the resistive-switching characteristics in nonvolatile memory applications, are reviewed. Finally, suggestions for future research, as well as the challenges awaiting RRAM devices, are given.展开更多
脉冲神经网络(spiking neural network,SNN)作为第三代神经网络,其计算效率更高、资源开销更少,且仿生能力更强,展示出了对于语音、图像处理的优秀潜能.传统的脉冲神经网络硬件加速器通常使用加法器模拟神经元对突触权重的累加.这种设...脉冲神经网络(spiking neural network,SNN)作为第三代神经网络,其计算效率更高、资源开销更少,且仿生能力更强,展示出了对于语音、图像处理的优秀潜能.传统的脉冲神经网络硬件加速器通常使用加法器模拟神经元对突触权重的累加.这种设计对于硬件资源消耗较大、神经元/突触集成度不高、加速效果一般.因此,本工作开展了对拥有更高集成度、更高计算效率的脉冲神经网络推理加速器的研究.阻变式存储器(resi-stive random access memory,RRAM)又称忆阻器(memristor),作为一种新兴的存储技术,其阻值随电压变化而变化,可用于构建crossbar架构模拟矩阵运算,已经在被广泛应用于存算一体(processing in memory,PIM)、神经网络计算等领域.因此,本次工作基于忆阻器阵列,设计了权值存储矩阵,并结合外围电路模拟了LIF(leaky integrate and fire)神经元计算过程.之后,基于LIF神经元模型实现了脉冲神经网络硬件推理加速器设计.该加速器消耗了0.75k忆阻器,集成了24k神经元和192M突触.仿真结果显示,在50 MHz的工作频率下,该加速器通过部署三层的全连接脉冲神经网络对MNIST(mixed national institute of standards and techno-logy)数据集进行推理加速,其最高计算速度可达148.2 frames/s,推理准确率为96.4%.展开更多
For Pt(Ag)/ZnO single-layer/Pt structure,random 10 formation and rupture of conductive filaments composed by oxygen vacancies or metallic ions often cause dispersion problems of resistive switching(RS)parameters,which...For Pt(Ag)/ZnO single-layer/Pt structure,random 10 formation and rupture of conductive filaments composed by oxygen vacancies or metallic ions often cause dispersion problems of resistive switching(RS)parameters,which is disadvantageous to devices application.In this study,ZnO/CoOx/ZnO(ZCZ)tri-layers were utilized as the switching layers to investigate their RS properties as compared with ZnO-based single-layer devices.It is interestingly noted that Pt/ZCZ/Pt devices show quite stable bipolar RS behaviors with little resistance value fluctuations compared to Ag/ZCZ/Pt devices and Pt(Ag)/ZnO/Pt devices,which minimize the dispersion of the resistances of RS.This highly stable RS effect of Pt/ZCZ/Pt structure would be promising for high density memory devices.展开更多
阻变存储器(resistive random access memory, RRAM)以其结构简单、操作速度快、可缩小性好、易三维(3D)集成、与互补金属氧化物半导体(complementary metal oxide semiconductor, CMOS)工艺兼容等优势成为下一代非挥发性存储器的有力...阻变存储器(resistive random access memory, RRAM)以其结构简单、操作速度快、可缩小性好、易三维(3D)集成、与互补金属氧化物半导体(complementary metal oxide semiconductor, CMOS)工艺兼容等优势成为下一代非挥发性存储器的有力竞争者之一,但基于阻变存储器无源交叉阵列中的交叉串扰问题影响了其实现高密度存储的应用和发展.本文简单介绍了阻变存储器交叉阵列中的串扰现象,详细综述了避免无源交叉阵列串扰的1D1R(one diode one resistor)结构、1S1R(one selector one resistor)结构、背靠背(back to back)结构及具有自整流效应的1R(one resistor)结构.同时,对基于阻变存储器无源交叉阵列实现高密度存储的研究发展趋势以及面临的挑战进行了展望.展开更多
文摘With recent progress in material science, resistive random access memory (RRAM) devices have attracted interest for nonvolatile, low-power, nondestructive readout, and high-density memories. Relevant performance parameters of RRAM devices include operating voltage, operation speed, resistance ratio, endurance, retention time, device yield, and multilevel storage. Numerous resistive-switching mechanisms, such as conductive filament, space-charge-limited conduction, trap charging and discharging, Schottky Emission, and Pool-Frenkel emission, have been proposed to explain the resistive switching of RRAM devices. In addition to a discussion of these mechanisms, the effects of electrode materials, doped oxide materials, and different configuration devices on the resistive-switching characteristics in nonvolatile memory applications, are reviewed. Finally, suggestions for future research, as well as the challenges awaiting RRAM devices, are given.
文摘脉冲神经网络(spiking neural network,SNN)作为第三代神经网络,其计算效率更高、资源开销更少,且仿生能力更强,展示出了对于语音、图像处理的优秀潜能.传统的脉冲神经网络硬件加速器通常使用加法器模拟神经元对突触权重的累加.这种设计对于硬件资源消耗较大、神经元/突触集成度不高、加速效果一般.因此,本工作开展了对拥有更高集成度、更高计算效率的脉冲神经网络推理加速器的研究.阻变式存储器(resi-stive random access memory,RRAM)又称忆阻器(memristor),作为一种新兴的存储技术,其阻值随电压变化而变化,可用于构建crossbar架构模拟矩阵运算,已经在被广泛应用于存算一体(processing in memory,PIM)、神经网络计算等领域.因此,本次工作基于忆阻器阵列,设计了权值存储矩阵,并结合外围电路模拟了LIF(leaky integrate and fire)神经元计算过程.之后,基于LIF神经元模型实现了脉冲神经网络硬件推理加速器设计.该加速器消耗了0.75k忆阻器,集成了24k神经元和192M突触.仿真结果显示,在50 MHz的工作频率下,该加速器通过部署三层的全连接脉冲神经网络对MNIST(mixed national institute of standards and techno-logy)数据集进行推理加速,其最高计算速度可达148.2 frames/s,推理准确率为96.4%.
基金supported by the National Natural Science Foundation of China (Nos.51231004 and 51202125)National Basic Research Program of China (No.2010CB832905)
文摘For Pt(Ag)/ZnO single-layer/Pt structure,random 10 formation and rupture of conductive filaments composed by oxygen vacancies or metallic ions often cause dispersion problems of resistive switching(RS)parameters,which is disadvantageous to devices application.In this study,ZnO/CoOx/ZnO(ZCZ)tri-layers were utilized as the switching layers to investigate their RS properties as compared with ZnO-based single-layer devices.It is interestingly noted that Pt/ZCZ/Pt devices show quite stable bipolar RS behaviors with little resistance value fluctuations compared to Ag/ZCZ/Pt devices and Pt(Ag)/ZnO/Pt devices,which minimize the dispersion of the resistances of RS.This highly stable RS effect of Pt/ZCZ/Pt structure would be promising for high density memory devices.
文摘阻变存储器(resistive random access memory, RRAM)以其结构简单、操作速度快、可缩小性好、易三维(3D)集成、与互补金属氧化物半导体(complementary metal oxide semiconductor, CMOS)工艺兼容等优势成为下一代非挥发性存储器的有力竞争者之一,但基于阻变存储器无源交叉阵列中的交叉串扰问题影响了其实现高密度存储的应用和发展.本文简单介绍了阻变存储器交叉阵列中的串扰现象,详细综述了避免无源交叉阵列串扰的1D1R(one diode one resistor)结构、1S1R(one selector one resistor)结构、背靠背(back to back)结构及具有自整流效应的1R(one resistor)结构.同时,对基于阻变存储器无源交叉阵列实现高密度存储的研究发展趋势以及面临的挑战进行了展望.
