【作者】 张磊；

【导师】 闫小兵；

【作者基本信息】 河北大学 ， 微电子学与固体电子学， 2019， 硕士

【摘要】 忆阻器（Memristor）是蔡绍棠提出的第四种基本电子元器件,其电阻可以根据流经它的电荷量而发生改变。由于忆阻器的独特性,对它的研究延伸到诸多方面,阻变存储器（resistance random access memory,RRAM）就是忆阻器在存储器领域的一个重要应用。阻变存储器由于具有结构简单,速度快,功耗低,制备工艺与现有的超大规模集成电路芯片生产工艺相兼容等突出优势,成为下一代存储器的可能选择之一。然而阻变存储器在走向产业化过程中时也面临着很多障碍,其中阻变存储器的开关阈值电压（Set和Reset）具有较大的弥散性是最突出的问题,因此研究制备出性能更加优异,开关阈值电压均一性较高的新型阻变器件是阻变领域的研究重点。忆阻器的另一个应用是神经突触仿生研究,即运用忆阻器模仿人类大脑的神经突触行为,如记忆,遗忘以及突触可塑性等功能,研究神经突触仿生器件对于类脑计算具有重要意义。针对阻变存储及神经突触仿生器件领域的研究需要,本论文做了以下三项研究工作。一.使用石墨烯氧化物量子点（graphene oxide quantum dots,GOQDs）,结合传统的阻变功能层材料Zr_0.5Hf_0.5O₂（ZHO）,将GOQDs嵌入到ZHO薄膜中间,首次制备出Ag/ZHO/GOQDs/ZHO/Pt这种堆叠结构的新型阻变器件。相比于传统的Ag/ZHO/Pt阻变器件,制备的新型器件在直流扫描电压下表现出可逆的双极电阻开关（Resistive switch,RS）行为,该器件的Set/Reset电压显著降低、并且Set/Reset电压数值分布更加集中,均一性大大增强,除此之外,该器件的数据保持能力、开关速度等性能也被进一步改善。同时本论文也研究了致使器件性能改善的物理机制,认为嵌入的GOQDs增强局域电场是导致性能大幅度改善的原因。二.在使用GOQDs导致阻变器件性能大幅度提升的研究基础上,创新性地改变器件结构,制备出Ag/Zr_0.5Hf_0.5O₂:GOQDs/Ag结构的新型忆阻器件,使该器件能够在幅值0.6V,宽度30ns的脉冲作用下成功进行电导的双向渐进调控,发现该器件在低能量的脉冲作用下可以实现近似线性电导调控的突出优势。在电导双向渐进调控的基础上,使用该新型忆阻器模拟出时间依赖可塑性（spiking-timing-dependent plasticity,STDP）、双脉冲异化（paired-pulse facilitation,PPF）等突触功能。通过研究器件电导变化的微观机制,揭示出隧穿机制和电化学金属化效应的共同作用是导致该忆阻器的电导能够连续渐进调控的重要因素。该项工作提供了一种在低能耗下能够进行快速电导调控的新型忆阻器制备方法。三.针对SiC材料宽禁带,稳定性好的优势,本论文首次将SiC引入阻变研究领域,制备出以SiC为衬底的Al/ZrO₂/SiC新型阻变器件,该器件工作电压较大,适合大功率应用场景,有良好的多阻值存储能力,而且由于该器件有独特的整流效应,可以有效减少寄生电流对于器件的不利影响,提高阻变存储的稳定性,有利于大规模集成。同时本论文发现将石墨烯氧化物量子点嵌入该器件之后,其开关电压也进一步降低。更多还原

【Abstract】 Memristor is the fourth basic electronic component proposed by Cai Shaotang.Its resistance can be changed according to the amount of charge flowing through it.Because of the unique characteristics of memristors,the research on them extends to many aspects.Resistance random access memory（RRAM）is an important application of memristors in memory field.Because of its simple structure,fast speed,low power consumption,and compatibility of fabrication process with the existing VLSI chip production process,RRAM has become a prominent advantage as one of the possible choices of next-generation memory.However,there are many obstacles in the process of industrialization of resistance memory.Among them,the most prominent problem is that the switching threshold voltage（Set and Reset）of resistance memory has greater dispersion.Therefore,the research and preparation of new resistance devices with better performance and higher uniformity of switching threshold voltage is the focus in the field of RRAM.Another application of memristors is the study of synaptic bionics,which imitates the synaptic behavior of human brain,such as memory,forgetting and synaptic plasticity.The study of synaptic bionic devices is of great significance for brain-like computing.In order to meet the research needs in the field of rheological storage and synaptic bionic devices,the following three research works have been done in this paper.Firstly,using graphene oxide quantum dots（GOQDs）,combined with the traditional resistance functional layer material Zr_0.5Hf_0.5O₂（ZHO）,GOQDs were embedded in ZHO thin films,and a new type of resistance devices with Ag/ZHO/GOQDs/ZHO/Pt stacking structure was prepared for the first time.Compared with the traditional Ag/ZHO/Pt device,the new device exhibits reversible bipolar resistive switch（RS）behavior under direcr current（DC）scanning voltage.The Set/Reset voltage of the device is significantly lower,and the numerical distribution of Set/Reset voltage is more centralized,and the uniformity is greatly enhanced.In addition,the data retention ability and switching speed of the device are further improved.At the same time,the physical mechanism of the device performance improvement is also studied in this paper.The performance improvement is due to the local enhanced electric field by the embedded GOQDs.Secondly,based on the research that GOQDs can lead to a great improvement in the performance of RRAM devices,a novel memristor with Ag/Zr_0.5Hf_0.5O₂:GOQDs/Ag structure was fabricated by innovatively changing the device structure,which enables the device to successfully conduct bi-directional progressive control of conductance under the action of pulses with amplitude of 0.6V and width of 30ns.It is found that the device can be regulated approximately linearly under the action of low-energy pulses.The prominent advantages of linear conductivity regulation are presented.On the basis of the bi-directional progressive regulation of the memristor conductance,the synaptic functions such as spiking-timing-dependent plasticity（STDP）and paired-pulse facilitation（PPF）are simulated using the new memristor.By studying the microcosmic mechanism of device conductance change,it is revealed that the interaction of tunneling mechanism and electrochemical metallization effect is an important factor leading to the continuous and progressive regulation of the conductance of the memristor.This work provides a new method for fabricating memristors with fast conductivity regulation under low energy consumption.Thirdly,in view of the advantages of wide bandgap and good stability of SiC materials,this paper introduces SiC into the field of RRAM research for the first time,and fabricates a new type of Al/ZrO₂/SiC resistor device based on SiC.It is found that the device has a large working voltage and is suitable for high-power application scenarios.It also has good multi-resistance storage capability.Moreover,because of its unique rectification effect,the device can effectively reduce the adverse effects of parasitic current on the device.The stability of high resistivity storage is conducive to large-scale integration.At the same time,it is found that the switching voltage after the GOQDs was embedded in the device is further reduced.更多还原