Research on the Teaching Model of Experimental Virtualization in Digital Logic and Digital System Design Course

By stating the problems faced by the experiment of digital logic design course in traditional laboratory, the necessity of hardware experiment virtualization is analyzed, and then two virtual experiment methods are introduced. The pilot implementation of remote virtual experimental platform and virtual component library shows that the virtualization of hardware experiment can effectively break the time and space limitation of traditional hardware experiment, and improves the learning enthusiasm and autonomy of students, which is worth further promoted.

Exploration of C Language Practical Teaching Method Based on Project Learning

This paper proposes a practical teaching approach in C programing language based on project learning.Having performing experimental teaching in class,this approach obtains pretty good teaching results,although it presents some flaws.This paper briefs the process of teaching,analyses the problems which are found during teaching and provides the solutions accordingly.

用于低能耗人工视觉系统的具有互补光调制和低功耗的双极突触有机/无机异质结晶体管

光电突触晶体管将光传感和突触功能集成到单个器件中,在视觉信息采集、识别、记忆和处理的神经形态计算具有显著的优势.然而,现有光电突触的权重更新主要是基于光刺激和电刺激分别调节突触的兴奋和抑制.这种方式严重限制了器件的处理速度和应用场景.在这项工作中,我们提出了双极突触有机/无机异质结晶体管(BSOIHT),可以有效地模拟光刺激下的双向(兴奋/抑制)突触行为.此外,通过优化电极接触位置以及电极材料,晶体管的载流子注入得到了显著改善,使得突触事件功耗降至2.4 fJ.此外,采用BSOIHT构建的神经形态视觉系统,有效地促进了图像预处理,将识别准确率从44.93%大幅提高到87.01%.这为构建低能耗的人工视觉系统提供了新的途径.

基于肖特基势垒调控的低能耗高识别精度的有机突触晶体管

为了构建类脑神经形态计算网络,单一的人工突触器件应该表现出极低的能量消耗,达到飞焦耳级别.然而,大多数现有的基于欧姆接触的低能耗突触器件实施方案,要么结构复杂,要么需要特定材料,这些因素都阻碍了人工神经网络的进一步发展.本文报告了一种肖特基势垒调控的有机突触晶体管(SBROST).通过在源电极和半导体之间的接触界面引入肖特基势垒,显著降低了单个突触事件的能耗,与使用欧姆接触的传统有机突触晶体管相比,SBROST的性能得到了改善.SBROST不仅可在低工作电压和电流下运行,还具有可适用于不同有机突触器件的简单结构.此外,SBROST可以实现低能耗下的高识别精度.经过100个周期,基于SBROST的手写人工神经网络表现出卓越的识别精度(93.53%),接近理想精度(95.62%).将肖特基势垒引入突触晶体管的方案为构建类脑神经计算网络提供了新的视角.

Temperature-controlled multisensory neuromorphic devices for artificial visual dynamic capture enhancement

Multi-sensory neuromorphic devices(MND)have broad potential in overcoming the structural bottleneck of von Neumann in the era of big data.However,the current multisensory artificial neuromorphic system is mainly based on unitary nonvolatile memory or volatile synaptic devices without intrinsic thermal sensitivity,which limits the range of biological multisensory perception and the flexibility and computational efficiency of the neural morphological computing system.Here,a temperature-dependent memory/synaptic hybrid artificial neuromorphic device based on floating gate phototransistors(FGT)is fabricated.The CsPbBr_(3)/TiO_(2)core–shell nanocrystals(NCs)prepared by in-situ pre-protection low-temperature solvothermal method were used as the photosensitive layer.The device exhibits remarkable multi-level visual memory with a large memory window of 59.6 V at room temperature.Surprisingly,when the temperature varies from 20 to 120℃back and forth,the device can switch between nonvolatile memory and volatile synaptic device with reconfigurable and reversible behaviors,which contributes to the efficient visual/thermal fusion perception.This work expands the sensory range of multisensory devices and promotes the development of memory and neuromorphic devices based on organic field-effect transistors(OFET).

All optical artificial synapses based on long-afterglow material for optical neural network

Artificial neural network with broad application prospect has attracted particular attention due to the promise of solving the memory wall bottleneck.The neural devices that mix light and electricity provide more degrees of freedom for the design of artificial neural network,but they still do not get rid of the shackles that the response signal needs circuit to transmission.The exploration of all-optical neural devices(optical signal input and output)is expected to solve this problem.Here,an all-optical synaptic device simply based on a long-afterglow material is reported.The optical properties of the all-optical synaptic device are similar to the responses in biological synapses.Unique image displays and memory functions can be achieved by combining alloptical synaptic arrays with synaptic memory behavior.Furthermore,the optical summation of all-optical synaptic array pixels can be completed by combining the focusing characteristics of convex lens,which realizes the photon transmission after preprocessing multiple input signals.Particularly,the simple single-layer structure of all-optical synapses with polydimethylsiloxane(PDMS)as the carrier has high plasticity and is expected to achieve large-scale preparation.This work enriches the diversity of artificial synapses and shows the huge development potential of photoelectric artificial neural networks.

制造具有高机械稳定性的柔性突触晶体管的一般策略

柔性有机突触晶体管(FOSTs)由于其灵活性、生物相容性、易于加工和低复杂性而引起了广泛关注.然而,FOSTs很难在满足装置变形要求的同时保持其突触性质的机械稳定性.在此,我们通过实验发现,弯曲变形对FOSTs的突触性能(即兴奋性突触后电流(EPSC)值)的影响大于对导通电流的影响.此外,通过公式推导,我们证明了通道附近产生的弯曲诱导缺陷状态的密度显著影响突触性能.我们提出了一种使用封装层调整器件稳定段的通用方法.无调节稳定段的普通FOSTs的EPSC值在弯曲后下降了近1.5-2个数量级.相比之下,设计的柔性突触装置表现出相对稳定的EPSC.此外,设计的FOSTs表现出稳定的成对脉冲促进、长期增强和光学突触性能.此外,使用手写人工神经网络在500次弯曲循环前后基于我们的设备进行神经形态计算模拟,该设备在50个学习周期后显示出稳定的识别精度(初始状态下91.55%,500个弯曲周期后90.43%).稳定段在柔性突触晶体管中的成功应用为制造具有机械稳定性的柔性神经形态电子器件提供了一个方便和简单的思路.

Recent advances in fabrication and functions of neuromorphic system based on organic field effect transistor

The development of various artificial electronics and machines would explosively increase the amount of information and data,which need to be processed via in-situ remediation.Bioinspired synapse devices can store and process signals in a parallel way,thus improving fault tolerance and decreasing the power consumption of artificial systems.The organic field effect transistor(OFET)is a promising component for bioinspired neuromorphic systems because it is suitable for large-scale integrated circuits and flexible devices.In this review,the organic semiconductor materials,structures and fabrication,and different artificial sensory perception systems functions based on neuromorphic OFET devices are summarized.Subsequently,a summary and challenges of neuromorphic OFET devices are provided.This review presents a detailed introduction to the recent progress of neuromorphic OFET devices from semiconductor materials to perception systems,which would serve as a reference for the development of neuromorphic systems in future bioinspired electronics.

Band-tailored van der Waals heterostructure for multilevel memory and artificial synapse

Two-dimensional(2D)van der Waals heterostructure(vdWH)-based floating gate devices show great potential for next-generation nonvolatile and multilevel data storage memory.However,high program voltage induced substantial energy consumption,which is one of the primary concerns,hinders their applications in lowenergy-consumption artificial synapses for neuromorphic computing.In this study,we demonstrate a three-terminal floating gate device based on the vdWH of tin disulfide(SnS2),hexagonal boron nitride(h-BN),and few-layer graphene.The large electron affinity of SnS2 facilitates a significant reduction in the program voltage of the device by lowering the hole-injection barrier across h-BN.Our floating gate device,as a nonvolatile multilevel electronic memory,exhibits large on/off current ratio(105),good retention(over 104 s),and robust endurance(over 1000 cycles).Moreover,it can function as an artificial synapse to emulate basic synaptic functions.Further,low energy consumption down to7 picojoule(pJ)can be achieved owing to the small program voltage.High linearity(<1)and conductance ratio(80)in long-term potentiation and depression(LTP/LTD)further contribute to the high pattern recognition accuracy(90%)in artificial neural network simulation.The proposed device with attentive band engineering can promote the future development of energy-efficient memory and neuromorphic devices.

基于CsPbBr_(3)量子点/PDVT-10共轭聚合物杂化薄膜的光突触晶体管用于高效的神经形态计算

光突触晶体管被视为有潜力的神经形态计算系统,有望克服基于冯诺依曼架构运算的固有限制.然而,具备简单制备工艺和高效信息处理能力的光突触晶体管的设计和构建面临着巨大的挑战.本文报道了一种通过旋涂CsPbBr_(3)钙钛矿量子点(QDs)和PDVT-10共轭聚合物共混物来制备光突触晶体管的新方法.由CsPbBr_(3)QDs和PDVT-10组成的杂化薄膜具有平坦的表面、优异的光吸收和良好的电荷传输性能,有助于此类钙钛矿基突触实现高效的光电转换.因此,基于CsPbBr_(3)QDs和PDVT-10杂化薄膜的光突触晶体管表现出了优异的器件性能,并具有基本的突触功能,包括兴奋性突触后电流、双脉冲促进和长程记忆.通过利用光增强和电抑制特性,基于钙钛矿的光突触晶体管被成功应用于神经形态计算,其模式识别精度高达89.98%,这是迄今为止用于模式识别的突触晶体管的最高值之一.这项工作为制备高模式识别精度的钙钛矿基神经形态系统提供了一条有效且方便的途径.

用于神经机器翻译的浮栅型PN共混光电突触晶体管

具有编码器-解码器框架的神经机器翻译被认为是未来机器翻译的一种主要框架.然而,由于多种语言融合和新词不断涌现,目前大多数基于冯诺依曼架构的神经机器翻译系统的解码器设备数量大幅增加,导致系统功耗过高.本研究首先展示了具有两种不同捕获机制的多级光敏混合半导体光电突触晶体管(MOST),它在480–800 nm波长范围的光照下表现出8种稳定且易于区分的状态和突触行为,且均具备兴奋性突触后电流、短期记忆和长期记忆等突触性能.此外,本研究首次将神经形态器件应用在神经机器翻译领域,成功制作了基于MOST的光解码器模型,显著简化了传统神经机器翻译系统的结构.并且作为一种多级突触器件, MOST可以进一步减少器件数量,在光照下简化编解码模型的结构.这项研究首先将神经形态器件应用于神经机器翻译,并提出了一种多级突触晶体管作为解码模块的基础单元,为打破机器翻译的瓶颈奠定了坚实的基础.

Flexible multi-level quasi-volatile memory based on organic vertical transistor

Driven by important megatrends such as cloud computing,artificial intelligence,and the Internet of Things,as a device used to store programs and data in computing systems,memory is struggling to catch up with the explosive growth of data and bandwidth requirements in the system.However,the storage wair between non-volatile memory and volatile memory retards the further improvement of modern memory computing systems.Herein,a quasi-volatile transistor memory based on organic polymer/perovskite quantum dot blend was fabricated using the vertical transistor configuration.Contributing to vertical structure and appropriate doping ratio of blend film,the quasi-volatile memory device displayed 1,560 times longer data retention time(>100 s)with respect to the dynamic random access memory and fast data programming speed(20 ps)in which was far more quickly than that of other organic non-volatile memories to fill the gap between volatile and non-volatile memories.Moreover,the device retention characteristics could be further promoted under the photoelectric synergistic stimulation,which also provided the possibility to reduce electric writing condition.Furthermore,the quasi-volatile memory device showed good electrical performance under bending conditions.This work provides a simple solution to fabricate multi-level quasi-volatile memory,which opens up a whole new avenue of"universal memory"and lays a solid foundation for low power and flexible random access memory devices.

基于增强电子传输的双层MXene/半导体高性能n型薄膜晶体管

电介质/半导体的界面工程是制备高性能有机场效应晶体管的关键.本工作提出采用MXene/半导体双层结构制备高性能n型晶体管,其中载流子的形成和调控发生在二氧化硅/半导体界面,同时高迁移率和长横向尺寸的MXene纳米片作为主要的电荷传输通道.通过调节MXene纳米片的互连度,优化了器件的电学性能.与单层N2200晶体管相比,MXene/N2200晶体管表现出显著增强的n型特性,包括提升100倍的场效应迁移率、10^(4)电流开关比以及0.64 V dec^(-1)亚阈值摆幅.MXene/N2200晶体管的高性能归因于MXene纳米沟道的电负性和高迁移率.电负性显著增强了电子从N2200向MXene沟道的转移,而高迁移率使得电子有效传输至电极.MXene/p型半导体晶体管却表现出受抑制的p型性能,这是因为MXene纳米片具有高度电负性.此外,本文提出的双层MXene/n型半导体结构也具有良好的结构普适性和高性能优势.这些结果表明双层MXene/半导体结构有望应用于高性能n型晶体管的制备.

具有光电信号双输出的发光电化学人工突触

尽管近年来多种突触器件的研究已取得了显著进展,但寻找具有新功能的人工突触器件仍是构建人工神经网络的重要任务.片上光电互连技术的成熟使得人工神经网络中的权重更新能以光和电的形式进行,作为权重控制端的人工突触器件中光电信号的并行输出便成为一个有趣和值得拥有的功能.在大规模神经网络的设计中,光电信号双输出能够提供额外的输出自由度并降低电子引线密度.因此,本研究首次开发了基于聚[2-甲氧基-5-(2-乙基己氧基)-1,4-苯乙炔]/聚(环氧乙烷)/锂盐共混的具有光电信号双输出的发光电化学人工突触(LEEAS).LEEAS中的电化学氧化还原反应使该器件能够实现生物学中的突触可塑性,并模拟了记忆增强过程、高通滤波特性和经典的巴甫洛夫条件反射实验.此外,在连续相同的电脉冲刺激下,LEEAS的瞬态发光强度表现出类似突触可塑性的增强行为.由于结合了电致发光和突触记忆行为,LEEAS阵列展现了独特的图像显示和存储功能,可以记忆显示过的图像.本研究提出的LEEAS丰富了人工突触器件的种类,促进了下一代光电混合人工神经网络的多样化设计与发展.