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1.
《Current Applied Physics》2020,20(2):288-292
In this study, a nickel oxide (NiO) nanocrystal (NC) based flexible resistive memory device is demonstrated at temperature as low as 180 °C by ligand exchange process. The fabricated device for flexible application with structure Ni/NiO/Ni on PI substrate exhibits excellent switching characteristics with low set/reset voltages and stable resistance values in both ON and OFF states for over 100 switching cycles of memory operation. Also, this flexible memory device shows stable resistive switching properties under compressive stress with bending radius to 10 mm and consecutive bending cycles. The ReRAM fabricated by a low-temperature solution-process shows potential for next generation flexible electronics.  相似文献   

2.
In this study, the unipolar resistive switching(URS) and bipolar resistive switching(BRS) are demonstrated to be coexistent in the Ag/Zn O/Pt memory device, and both modes are observed to strongly depend on the polarity of forming voltage. The mechanisms of the URS and BRS behaviors could be attributed to the electric-field-induced migration of oxygen vacancies(VO) and metal-Ag conducting filaments(CFs) respectively, which are confirmed by investigating the temperature dependences of low resistance states in both modes. Furthermore, we compare the resistive switching(RS)characteristics(e.g., forming and switching voltages, reset current and resistance states) between these two modes based on VO- and Ag-CFs. The BRS mode shows better switching uniformity and lower power than the URS mode. Both of these modes exhibit good RS performances, including good retention, reliable cycling and high-speed switching. The result indicates that the coexistence of URS and BRS behaviors in a single device has great potential applications in future nonvolatile multi-level memory.  相似文献   

3.
蒋然  杜翔浩  韩祖银  孙维登 《物理学报》2015,64(20):207302-207302
为了研究阻变存储器导电细丝的形成位置和分布规律, 使用X射线光电子能谱研究了Ti/HfO2/Pt阻变存储器件单元中Hf 4f的空间分布, 得到了阻变层的微结构信息. 通过I-V测试, 得到该器件单元具有典型的阻变特性; 通过针对Hf 4f的不同深度测试, 发现处于低阻态时, 随着深度的增加, Hf4+化学组分单调地减小; 而处于高阻态和未施加电压前, 该组分呈现波动分布; 通过Hf4+在高阻态和低阻态下组分含量以及电子能损失谱分析, 得到高阻态下Hf4+组分的平均含量要高于低阻态; 另外, 高阻态和低阻态下的O 1s谱随深度的演变也验证了Hf4+的变化规律. 根据实验结果, 提出了局域分布的氧空位聚簇可能是造成这一现象的原因. 空位簇间的链接和断裂决定了导电细丝的形成和消失. 由于导电细丝容易在氧空位缺陷聚簇的地方首先形成, 这一研究为导电细丝的发生位置提供了参考.  相似文献   

4.
《Current Applied Physics》2019,19(9):987-991
Orthorhombic Bi2SiO5 thin films with dense surface were synthesized by using a chemical solution deposition method. The crystallized films were first utilized to implement resistive memory cells with Pt/Bi2SiO5/Pt sandwich architecture. It exhibited outstanding switching parameters including concentrated distributions of low and high resistance states, uniform switching voltages, cycling endurance, and long retention. Furthermore, the model of formation and rupture of conductive filaments consisted of oxygen vacancies was used to well explain resistive switching behavior. The results revealed that the solution-processed Bi2SiO5 thin film devices have great potential for forefront application in nonvolatile memory.  相似文献   

5.
Coexistence of nonvolatile unipolar and volatile threshold resistive switching is observed in the Pt/LaMnO3 (LMO)/Pt heterostructures. The nonvolatile unipolar memory is achieved by applying a negative bias, while the volatile threshold resistive switching is obtained under a positive bias. Additionally, the pristine low resistance state (LRS) could be switched to high resistance state (HRS) by the positive voltage sweeping, which is attributed to the conduction mechanism of Schottky emission. Subsequently, the insulator-to-metal transition in the LMO film due to formation of ferromagnetic metallic phase domain contributes to the volatile threshold resistive switching. However, the nonvolatile unipolar switching under the negative bias is ascribed to the formation/rupture of oxygen-vacancy conducting filaments. The simultaneously controllable transition between nonvolatile and volatile resistance switching by the polarity of the applied voltage exhibits great significance in the applications of in-memory computing technology.  相似文献   

6.
《Current Applied Physics》2018,18(1):102-106
The present study reports the resistive switching behaviour in Titanium Dioxide (TiO2) material, with possible implementations in non volatile memory device. The Cu/TiO2/Pt memory device exhibit uniform and stable bipolar resistive switching behaviour. The current-voltage (I-V) analysis shows two discrete resistance states, the High Resistance State (HRS) and the Low Resistance State (LRS). The effect of an additional AlN layer in the resistive memory cell is also investigated. The Cu/TiO2/AlN/Pt device shows a multilevel (tri-state) resistive switching. Multilevel switching is facilitated by ionic and metallic filament formation, and the nature of the formed filaments is confirmed by performing a resistance vs. temperature measurement. The bilayer device shows improved reliability over the single layer device. The formation of high thermal conductive interfacial oxy-nitride (AlON) layer is the main reasons for the enhancement of resistive switching properties in Cu/TiO2/AlN/Pt cell. The performance of device was measured in terms of endurance and retention, which exhibits good endurance over 105 cycles and long retention time of 105 s at 125 °C. The above result suggests the feasibility of Cu/TiO2/AlN/Pt devices for multilevel non volatile ReRAM application.  相似文献   

7.
赵晶  董静雨  任书霞  张礼勇  赵旭  陈伟 《中国物理 B》2014,23(12):127301-127301
Oxygen vacancy plays a crucial role in resistive switching. To date, a quantitative study about the distribution of the oxygen vacancies and its effect on the resistive switching has not yet been reported. In this study, we report our first-principles calculations in ZnO-based resistive switching memory grown on a Pt substrate. We show that the oxygen vacancies prefer to be located in the ZnO (0001) plane, i.e. in the direction parallel to the film surface in the preparation process. These oxygen vacancies drift easily in the film when a voltage is applied in the SET process and prefer to form a line defect perpendicular to the film surface. An isolated oxygen vacancy makes little contribution to the conductivity of ZnO, whereas the ordering of oxygen vacancies in the direction perpendicular to the film surface leads to a dramatic enhancement of the conductivity and thus forms conductive filaments. The semiconducting characteristics of the conductive filaments are confirmed experimentally.  相似文献   

8.
《Current Applied Physics》2015,15(9):1005-1009
Forming-free and self-compliant bipolar resistive switching is observed in Cu/TaOx/TiN conductive bridge random access memory. Generally, Pt has been investigated as an inert electrode. However, Pt is not desirable material in current semiconductor industry for mass production. In this study, all electrodes are adapted to complementary metal-oxide-semiconductor compatible materials. The self-compliant resistive switching is achieved via usage of TiN bottom electrode. Also, dissolved Cu ions in TaOx lead to forming-free resistive switching behavior. The resistive switching mechanism is formation and rupture of combined oxygen vacancy/metallic copper conductive filament. We propose that Cu/TaOx/TiN is a promising candidate for a conductive bridge random access memory structure.  相似文献   

9.
张志超  王芳  吴仕剑  李毅  弭伟  赵金石  张楷亮 《物理学报》2018,67(5):57301-057301
采用射频磁控溅射的方法,基于不同氧分压制备的氧化铪构建了Ni/HfO_x/TiN结构阻变存储单元.研究发现,随着氧分压的增加,薄膜表面粗糙度略有降低;另一方面,阻变单元功耗降低,循环耐受性能可达10~3次,且转变电压分布的一致性得到改善.结合电流-电压曲线线性拟合结果及外加温度测试探究了器件的转变机理,得出在低阻态的传导机理为欧姆传导机理,在高阻态的传导机理为肖特基发射机理,并根据氧空位导电细丝理论,对高低阻态的阻变机理进行了详细的理论分析.  相似文献   

10.
Zinc Oxide (ZnO) thin films have been addressed as promising candidates for the fabrication of Resistive Random Access Memory devices, which are alternative to conventional charge-based flash memories. According to the filamentary conducting model and charge trapping/detrapping theory developed in the last decade, the memristive behavior of ZnO thin films is explained in terms of conducting filaments formed by metallic ions and/or oxygen vacancies, and their breaking through electrochemical redox reactions and/or recombination of oxygen vacancies/ions. A comparative review of the memristive properties of ZnO thin films grown by sputtering, atomic layer deposition (ALD), pulsed laser deposition (PLD), and sol-gel methods is here proposed. Sputtered ZnO thin films show promising resistive switching behaviors, showing high on/off ratios (10–104), good endurance, and low operating voltages. ALD is also indicated to be useful for growing conformal ZnO layers with atomic thickness control, resulting in important resistive switching characteristics, such as relatively high on/off ratios and low operating voltages. High insulating epitaxial ZnO thin films can be obtained by PLD, showing reliable switching properties at low voltages and with good retention. On the contrary, the sol-gel approach generally results in ZnO thin films with poor resistive switching behaviors. Nevertheless, thin films derived from ZnO NPs show improved switching performances, with higher on/off ratios and lower operating voltages. Independently of the synthetic approach, doped ZnO thin films exhibit better resistive switching behaviors than pristine ones, coupling a strong increase of the on/off ratio with a more stable switching response.  相似文献   

11.
The anti-clockwise bipolar resistive switching in Ag/NiO/ITO (Indium–Tin–Oxide) heterojunctional thin film assembly is investigated. A sequential voltage sweep in 0 → V max → 0 → ?V min → 0 order shows intrinsic hysteresis behaviour and resistive switching in current density (J)–voltage (V) measurements at room temperature. Switching is induced by possible rupture and recovery of the conducting filaments in NiO layer mediated by oxygen ion migration and interfacial effects at NiO/ITO junction. In the high-resistance OFF-state space charge limited current passes through the filamentary path created by oxygen ion vacancies. In OFF-state, the resistive switching behaviour is attributed to trapping and detrapping processes in shallow trap states mostly consisting of oxygen vacancies. The slope of Log I vs Log V plots, in shallow trap region of space charge limited conduction is ~2 (I ∝ V 2) followed by trap-filled and trap-free conduction. In the low-resistance ON-state, the observed electrical features are governed by the ohmic conduction.  相似文献   

12.
Experimental verification of the microscopic origin of resistance switching in metal/oxide/metal heterostructures is needed for applications in non‐volatile memory and neuromorphic computing. Numerous reports suggest that resistance switching in NiO is caused by local reduction of the oxide layer into nanoscale conducting filaments, but few reports have shown experimental evidence correlating electroforming with site‐specific changes in composition. We have investigated the mechanisms of reversible and irreversible electroforming in 250–500 nm wide pillars patterned from a single Ta/Ti/Pt/Ti‐doped NiO/Pt/Ta heterostructure and have shown that these can coexist within a single sample. We performed in situ transmission electron microscopy (TEM) electroform‐ ing and switching on each pillar to correlate the local electron transport behavior with microstructure and composition in each pillar. DFT calculations fitted to electron energy loss spectroscopy data showed that the Ti‐doped NiO layer is partially reduced after reversible electroforming, with the formation of oxygen vacancies ordered into lines in the 〈110〉 direction. However, under the same probing conditions, adjacent pillars show irreversible electroforming caused by electromigration of metallic Ta to form a single bridge across the oxide layer. We propose that the different electroforming behaviors are related to microstructural variations across the sample and may lead to switching variability. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)  相似文献   

13.
《Current Applied Physics》2015,15(4):441-445
In this study, the resistive switching performance of amorphous indium–gallium–zinc oxide (a-IGZO) resistive switching random-access memory (ReRAM) was improved by inserting a thin silicon oxide layer between silver (Ag) top electrode and a-IGZO resistive switching layer. Compared with the single a-IGZO layer structure, the SiO2/a-IGZO bi-layer structure exhibits the higher On/Off resistance ratio larger than 103, and the lower operation power using a smaller SET compliance current. In addition, good endurance and excellent retention characteristics were achieved. Furthermore, multilevel resistance states are obtained through adjusting SET compliance current and RESET stop voltage, which shows a promise for high-performance nonvolatile multilevel memory application.  相似文献   

14.
采用氧化硅材料构建了Cu/SiOx/Al的三明治结构阻变存储器件.用半导体参数分析仪对其阻变特性进行测量,结果表明其具有明显的阻变特性,并且通过调节限制电流,得到了四个稳定的阻态,各相邻阻态的电阻比大于10,并且具有良好的数据保持能力.在不同温度条件下对各个阻态进行电学测试及拟合,明确了不同阻态的电子传输机理不尽相同:阻态1和阻态2为欧姆传导机制,阻态3为P-F(Pool-Frenkel)发射机制,阻态4为肖特基发射机制.根据电子传输机制,建立了铜细丝导电模型并对Cu/SiOx/Al阻变存储器件各个阻态的电致阻变机制进行解释.  相似文献   

15.
郭家俊  董静雨  康鑫  陈伟  赵旭 《物理学报》2018,67(6):63101-063101
实验表明掺杂是一种改善阻变存储器性能的有效手段,但其物理机理鲜有研究.本文采用第一性原理方法系统研究了过渡金属元素X(X=Mn,Fe,Co,Ni)掺杂对ZnO基阻变存储器中氧空位迁移势垒和形成能的影响.计算结果表明Ni掺杂可同时有效降低+1和+2价氧空位在掺杂原子附近的迁移势垒,X掺杂均减小了氧空位的形成能,特别是掺杂Ni时氧空位的形成能减小最为显著(比未掺杂时减少了64%).基于该结果制备了未掺杂和Ni掺杂ZnO阻变存储器,研究表明通过掺杂控制体系中氧空位的迁移势垒和形成能,可以有效改善器件的初始化过程、操作电压、保持性等阻变性能.研究结果有助于理解探究影响阻变的微观机制,并可为掺杂提高阻变存储器性能提供一定的理论指导.  相似文献   

16.
Asymmetric resistive switching processes were observed in W:Al O x/WO y bilayer RRAM devices. During pulse programming measurements, the RESET speed is in the range of hundreds of microseconds under-1.1 V bias, while the SET speed is in the range of tens of nanoseconds under 1.2 V bias. Electrical measurements with different pulse conditions and different temperatures were carried out to understand these significant differences in switching time. A redox reaction model in the W:Al O x/WO y device structure is proposed to explain this switching time difference.  相似文献   

17.
The flexible Ag/TiO2/ITO/PET resistive switching memory is prepared by low-temperature sol-gel method with UV irradiation, and the simple method that combined the advantages of sol-gel method and low temperature can be applied to fabricate high-quality film. The flexible Ag/TiO2/ITO/PET memory device displays good resistive behavior, for instance, the narrow distributions of switching voltages, good cycle endurance, and long retention time. Meanwhile, the multilevel resistance states of the device can be realized by controlling the compliance current or reset voltages, showing the potential of applications in neural networks and high-density storge. In addition, flexibility of the Ag/TiO2/ITO/PET is studied, which exhibit good endurance and retention properties under bending condition. The I–V curves are replotted and fitted for analyzing the conductive mechanism of the device. The fitting results show that SCLC and Ohmic mechanism are main mechanisms of high resistance state and low resistance state respectively. The electrochemical and thermochemical modes are adopted to explain resistive switching behavior. Our results indicate the Ag/TiO2/ITO/PET memory has potential application in wearable and foldable electronics.  相似文献   

18.
The bipolar resistive switching mechanisms of a p-type NiO film and n-type TiO2 film were examined using local probe-based measurements. Scanning probe-based current–voltage (IV) sweeps and surface potential/current maps obtained after the application of dc bias suggested that resistive switching is caused mainly by the surface redox reactions involving oxygen ions at the tip/oxide interface. This explanation can be applied generally to both p-type and n-type conducting resistive switching films. The contribution of oxygen migration to resistive switching was also observed indirectly, but only in the cases where the tip was in (quasi-) Ohmic contact with the oxide.  相似文献   

19.
张培健  孟洋  刘紫玉  潘新宇  梁学锦  陈东敏  赵宏武 《物理学报》2012,61(10):107703-107703
通过改变制备条件,研究了Ag-SiO2薄膜中的缺陷对电阻翻转效应的影响.对比不同的热处理实验条件, 发现在120 ℃退火的样品经forming过程后具有稳定的电阻转变特性;另一方面, 在Ar/O2混合气氛下生长的SiO2具有比在纯Ar下生长的样品更加稳定、重复的电阻转变特性. 通过实验分析,表明热处理、电场作用和样品制备气氛可以改变、调节样品中的缺陷分布 (Ag填隙原子和氧空位缺陷),从而导致Ag-SiO2中基于缺陷的导电通道结构的形成和湮灭, 提出了提高电阻翻转稳定性的必要条件.  相似文献   

20.
We demonstrate the polarization of resistive switching for a Cu/VOx/Cu memory cell.The switching behaviors of Cu/VOx/Cu cell are tested by using a semiconductor device analyzer(Agilent B1500A),and the relative micro-analysis of I-V characteristics of VOx/Cu is characterized by using a conductive atomic force microscope(CAFM).The I-V test results indicate that both the forming and the reversible resistive switching between low resistance state(LRS) and high resistance state(HRS) can be observed under either positive or negative sweep.The CAFM images for LRS and HRS directly exhibit evidence for the formation and rupture of filaments based on positive or negative voltage.The Cu/VOx/Cu sandwiched structure exhibits reversible resistive switching behavior and shows potential applications in the next generation of nonvolatile memory.  相似文献   

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