【作者】 李小平；

【导师】 陈鹏；

【作者基本信息】 西南大学 ， 凝聚态物理学， 2018， 硕士

【摘要】 当今,随着信息化时代的全面普及和快速发展,人们对存储器的读写速率和存储容量也随之有了更高的要求,所以发展性能更加优异的新型高密度快速存储器迫在眉睫。目前主流的存储器包括磁存储器、铁电存储器、相变存储器、阻变存储器,其中要数阻变存储器是最具有前景成为下一代的新型存储器。阻变存储器主要归因于电阻开关效应,电阻开关效应分为双极电阻开关和单极电阻开关,他们的区别在于电阻态开关状态切换依赖于电极的极性还是电压的振幅,依赖于电压极性的是双极电阻开关,依赖于电压振幅的是单极电阻开关,两种电阻开关效应都可以应用于阻变存储器。衡量阻变存储器品质优劣有三个比较重要的参数,一是I-V扫描循环圈数;二是高低电阻态之比;三是保持时间。保持一定的开关比时间越长,并且I-V扫描圈数越多,说明其电阻开关效应的性能更优异,也就更适合应用于存取器的研发。阻变存储器的电阻开关效应受到多种情形调控,分为内在和外在两种情形。内在情形主要包括器件的结构设计、材料本身的属性以及样品的制作工艺。外在情形包括外加偏压、退火处理、光照强度、测试温度、磁场强度。为了研究单层、两层和三层薄膜构建的忆阻器单元所具备的电阻开关效应及其机理,并试图探究部分器件光照对其忆阻的影响,本篇文章主要研究光照强度对BiFeO₃/Carbon/BaTiO₃和BiFeO₃/BaTiO₃两种结构电阻开关效应的影响以及Carbon薄膜电阻开关效应的机理。BiFeO₃、Carbon、BaTiO₃这三种材料有相关研究表明其有显著的电阻开关效应。我们通过设计新型结构制备非易失存储器件,研究其阻变特性及其机理,这有助于探索多功能材料在非易失性存储器件中应用。本实验采用磁控溅射镀膜技术制备了Ta/BiFeO₃/C/BaTiO₃/Si、Ta/BiFeO₃/BaTiO₃/Si和Ag/C/Si三种结构的阻变存储器件,通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）等设备进行相关表征,进一步应用Keithley2400或者电化学分析仪对其进行阻变性能测试。测试结果显示出几种结构的样品表现出优异的电阻开关效应,包括开关比、抗疲劳性和保持时间。根据电学测试得到的I-V曲线,可以得出三种结构的电阻开关效应都属于双极性的,并且都可以利用材料内部的陷阱对载流子的俘获和释放模型来解释所得到的双极电阻开关效应。最后,我们改变外部条件,研究光照强度对Ta/BiFeO₃/C/BaTiO₃/Si和Ta/BiFeO₃/BaTiO₃/Si的电阻开关效应的影响,研究发现光照强度可以很好的调控这两种结构的电阻开关效应,并且具有较好的品质参数。更多还原

【Abstract】 With the rapid development of information age,people’s demand for memory read and write speed and storage density is higher and higher.So developing the next generation of high-density fast memory is imminent.At present,the mainstream memory includes magnetic memory,ferroelectric memory,phase change memory and resistive variable memory.Resistive memory is the most promising way to become the next generation of new memory.RRAM is committed to the resistance switching effect,resistance switching effect for bipolar resistive switching and unipolar resistive switching,the difference between them is that the amplitude of resistance switching state switch depends on the electrode polarity or voltage,depending on the polarity of the voltage switch is bipolar resistance,dependent on the amplitude of voltage is unipolar resistive switching two,the resistance switching effect can be applied to variable resistance memory.There are three important parameters to measure the quality of the resistive memory,the first is the I-V scanning loop number;and second is the ratio of the high and low resistance states;the third is to maintain time and maintain a longer switch time than I-V.The more the number of scan cycles,the better the resistance switch effect is.It is more suitable for the research and development of access devices.The resistance switching effect of the resistive memory is regulated by a variety of situations,which are divided into two internal and external situations.The internal situation mainly includes the structure design of the device,the properties of the material itself and the manufacturing process of the sample.External conditions include external bias,annealing,light intensity,test temperature,and magnetic field strength.In order to study the resistance switching effect and the mechanism of the memristor unit of single layer,two layer and three layer thin film,and the effect of light on the memory resistance of some devices is explored,this paper mainly studies the influence of light intensity on two kinds of structure resistance switch effect of BiFeO₃/Carbon/BaTiO₃ and BiFeO₃/BaTiO₃,and the mechanism of resistance switch effect of Carbon film.BiFeO₃,Carbon,BaTiO₃ of the three kinds of materials have a lot of research showed that the resistance switching effect is significant.By designing a new type of nonvolatile memory devices,we study the resistive switching phenomenon and mechanism of the devices,which is helpful to explore the application of multi-functional materials in non-volatile memory parts.This experiment adopts magnetron sputtering technology for Ta/BiFeO₃/C/BaTiO₃/Si,Ta/BiFeO₃/BaTiO₃/Si and Ag/C/Si three kinds of resistive memory devices.The related characterization was performed by X ray diffractometer（XRD）,scanning electron microscope（SEM）and other equipment.The test results show that the samples of several structures exhibit excellent resistance switching effects,including high switching ratio,excellent fatigue resistance,and longer holding time.According to the I-V curve obtained from electrical test,we can conclude that the resistance switch effects of all three structures are bipolar,and all the resistive switching effects can be explained by using the trap and release model of carriers in the material.Finally,we study the change of external conditions,the influence of light intensity on the resistive switching effect of Ta/BiFeO₃/C/BaTiO₃/Si and Ta/BiFeO₃/BaTiO₃/Si,it is found that the light intensity can well regulate the resistance switching effects of the two structures and have good quality parameters.更多还原