【作者】 张凯；

【导师】 陈建彪；

【作者基本信息】 西北师范大学 ， 凝聚态物理， 2021， 硕士

【摘要】 随着数据的爆炸式增长,手机、电脑等电子产品对集成电路芯片的信息处理和存储能力提出了更高的要求。因此,开发出能够满足存储和处理大量数据的非易失性存储器迫在眉睫。忆阻器以结构简单、能耗低、响应时间快和集成度高等特点被认为是最有竞争力的下一代信息处理单元之一。已有研究人员通过开发新忆阻材料、新结构、施加电、光和其他刺激信号等途径,在非易失性存储器、逻辑运算和神经突触模拟等领域取得了令人瞩目的进展,然而距离大规模集成应用还面临诸多亟待解决的问题。目前,材料的选择以及相应的制备工艺尚未成熟,不同材料的阻变机制更是不够明确。鉴于以上考虑,本论文以“Cu_xS薄膜的制备及其忆阻性能研究”为题开展相关研究。主要包括以下两个方面的内容:（1）为优化Al/Cu_xS/Cu结构忆阻器介质层中的离子迁移路径,采用阳极氧化法,制备出垂直于基底的Cu_xS纳米片薄膜,以利于电导丝的有序形成。结果表明:Al/Cu_xS/Cu系列忆阻器件呈现出阻变行为（RS）与负微分电阻（NDR）共存现象,工作电压小于0.3 V,阻变性能稳定,保留时间大于10⁴s,在120次循环后依然稳定。在此基础上,详细探讨了RS效应与NDR现象可重复共存的机理。分析表明,Cu_xS介电层中,空间电荷限制电流（SCLC）机制和铜离子迁移形成电导丝机制协同主导忆阻器阻值转变,与此同时,Cu_xS与铜的界面处的肖特基势垒是NDR出现的原因。这项工作为未来具有多种物理属性的非易失性存储器的性能优化提供了新的途径。（2）采用脉冲激光沉积和化学气相沉积两步法制备Cu₂S薄膜,最终形成Cu/Cu₂S/p-Si纳米结构忆阻器。通过扫描电子显微镜、X-射线光电子能谱和紫外可见近红外分光光度计等表征了Cu₂S薄膜的形貌、成分和光学性能。结果发现,两步法制备的Cu₂S薄膜由多晶纳米颗粒构成,大面积均匀分布。I-V循环测试显示,忆阻器工作电压为3 V。在氙灯光源辐照下,器件的电流比黑暗条件时增大5倍左右,即光生载流子会减小肖特基势垒从而导致器件的阻变机制转变,这对探究基于Cu₂S忆阻器的多通道响应有参考价值。更多还原

【Abstract】 With the explosive growth of data,mobile phones,computers and other electronic products have put forward higher requirements on the information processing and storage capacity of integrated circuit chips.Therefore,it is urgent to develop a nonvolatile memory which can store and process a large amount of data.Memristor is considered to be one of the most competitive next generation information processing units due to its simple structure,low energy consumption,fast response time and high integration.Researchers have made remarkable progress in the fields of nonvolatile memory,logic operations,and synaptic simulation by developing new memristor materials,new structures,and applying electrical,optical and other stimulus signals.However,there are still many problems to be solved before large-scale integrated applications.At present,the selection of materials and the corresponding preparation process are not yet mature,and the resistance mechanism of different materials is not clear enough.In view of the above considerations,this paper focuses on the topic of"preparation of Cu_xS films and their memristor properties".It mainly includes the following two aspects:Firstly,in order to optimize the ion migration path in the Al/Cu_xS/Cu memristor dielectric layer,Cu_xS nanosheet films perpendicular to the substrate were prepared by anodic oxidation to facilitate the orderly formation of conductive wires.The results show that the Al/Cu_xS/Cu series memristor exhibits the coexistence of resistance behavior（RS）and negative differential resistance（NDR）.The operating voltage is less than 0.3 V,the resistance performance is stable,the retention time is more than 10⁴s,and the device is still stable after 120 cycles.On this basis,the mechanism of the repeatable coexistence of RS effect and NDR phenomenon is discussed in detail.The results show that the space charge limited current（SCLC）mechanism and the conduction wire mechanism formed by the migration of copper ions co-dominate the change of memristor resistance value in the dielectric layer of Cu_xS.Meanwhile,the Schottky potential barrier at the interface between Cu_xS and copper is the cause of NDR.This work provides a new way to optimize the performance of nonvolatile memory with various physical properties in the future.Secondly,Cu₂S thin films were prepared by pulsed laser deposition and chemical vapor deposition,and finally the Cu/Cu₂S/p-Si nanostructured memristor was formed.The morphology,composition and optical properties of Cu₂S films were characterized by scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）and UV-Vis NIR spectrophotometer.The results show that the Cu₂S films prepared by the two-step method are composed of polycrystalline nanoparticles and distributed uniformly in a large area.I-V cycle test shows that the memristor operating voltage is 3V.Under the irradiation of xenon lamp,the current of the device increases about 5 times compared with that in the dark condition,that is,the photogenerated carriers will reduce the Schottky barrier and lead to the change of the resistance mechanism of the device,which is of reference value for exploring the multi-channel response of the Cu₂S-based memristor.更多还原