封面图片说明

正封面图片出自论文"阳离子迁移型阻变存储材料与器件研究进展".是清华大学材料学院潘峰教授研究团队提供的阳离子迁移型阻变存储器的器件结构及选材和阻变特性及机理示意图.阳离子迁移型阻变存储器的存储单元为"活性电极/存储介质/惰性电极"三层膜结构,通过外加电压作用下活性电极原子发生氧化还原反应和定向迁移过程而实现信息存储,其中逻辑"1"对应于低阻     

重点实验室研究进展

中国科学院磁性材料与器件重点实验室在阻变材料探索与机理研究方面取得进展基于电致电阻效应的电阻型随机存储器(RRAM)是一种极具发展潜力的新兴存储技术,具有非易失性、低功耗、超高密度、快速读写等优势。目前开展稳定的新型电致电阻材料的探索以及阻变机理研究非常重要,也是当前的一个研究热点。     

阳离子基阻变存储器的研究进展

基于电荷存储的传统非易失存储技术越来越难以满足大数据时代对海量信息的存储需求,亟需发展基于新材料、新原理的非易失存储技术。基于阳离子电化学效应的阻变存储器具有结构简单、速度快、功耗低、可缩小性好、易于三维集成等优点,被认为是下一代非易失存储器的有力竞争者。然而,器件参数离散性大以及阻变机制不清晰严重阻碍了该类器件的快速发展。近几年,国内外学者通过材料和结构的优化设计显著提高了器件的性能,借助先进的表征技术阐明了器件电阻转变的微观机制,为阳离子基阻变存储器的大规模生产和应用奠定了科学基础。从材料改性、器件结构设计和微观机制表征三个方面综述了阳离子基阻变存储器的研究进展,并对其未来的研究方向和发展趋势进行了展望。     

柔性阻变存储器材料研究进展EI北大核心CSCD

本文简述了阻变存储器的基本结构、工作原理、发展历程和研究现状,归纳总结了柔性阻变存储器的材料体系,包括介质材料、电极材料和基底材料,以及柔性阻变存储器材料体系的总体趋势和最新研究进展;分析了柔性阻变存储器的性能特点,包括存储性能和力学性能。阐述了发展柔性阻变存储器的重要意义与面临的挑战,提出了该领域现在研究中存在的不足和未来需要进一步研究的方向。得出力学性能稳定的高电导可拉伸电极和存储性能稳定的可拉伸介质是柔性阻变存储器材料今后发展的主要方向。     

基于相变存储器的相变存储材料的研究进展

相变存储器具有非易失性、循环寿命长、元件尺寸小、功耗低、多级存储、与现有集成电路工艺相兼容等诸多优点,被认为是最具潜力的下一代存储器.简要介绍了相变存储材料的工作原理和对相变存储材料的性能要求,综述了近年来国内外在相变材料存储性能的优化、存储机理以及面临的关键问题等方面的最新研究成果,最后展望了相变存储材料的研究和发展趋势.     

柔性阻变存储材料与器件研究进展

物联网技术的飞速发展对柔性可穿戴电子设备提出了迫切需求,而作为电子设备不可或缺的部分,存储器势必也需要向柔性化的方向发展。阻变存储器具有高速、低功耗、非易失、结构简单、选材广泛等特性,被视为未来柔性存储器的重要候选器件之一。在应变条件下,阻变存储器的薄膜开裂无疑会导致器件性能失效。因此,近年来除研究应变对材料性质和器件性能的影响外,研究人员主要从选择合适的阻变材料和优化器件制备工艺方面不断尝试,取得了丰硕的成果,大幅提升了器件的柔韧性。为构建高性能的柔性阻变存储器,许多材料已被开发作为存储介质,包括无机、有机、有机-无机复合或杂化材料等。同时,金属、金属合金、碳/硅材料、氮化物、导电氧化物等已被尝试用作电极材料,聚酰亚胺(PI)、聚萘二甲酸乙二醇酯(PEN)、聚对苯二甲酸乙二醇酯(PET)、聚二甲基硅氧烷(PDMS)等也已被尝试用作柔性衬底。此外,器件的制备起初主要采用全气相法,条件相对苛刻,通常需要高真空甚至高温环境。近年来的研究工作将气相-液相混合甚至是全液相法引入到柔性阻变存储器的制备工艺中,初步实现了器件的简单、低温和快速制备。本文归纳了柔性阻变存储器的研究进展,分别对器件材料(存储介质、电极和衬底)和制备工艺及性能进行了全面介绍,分析了器件的失效机理,并对本领域当前存在的挑战与未来发展前景进行了讨论。     

柔性阻变存储器材料研究进展

本文简述了阻变存储器的基本结构、工作原理、发展历程和研究现状,归纳总结了柔性阻变存储器的材料体系,包括介质材料、电极材料和基底材料,以及柔性阻变存储器材料体系的总体趋势和最新研究进展;分析了柔性阻变存储器的性能特点,包括存储性能和力学性能。阐述了发展柔性阻变存储器的重要意义与面临的挑战,提出了该领域现在研究中存在的不足和未来需要进一步研究的方向。得出力学性能稳定的高电导可拉伸电极和存储性能稳定的可拉伸介质是柔性阻变存储器材料今后发展的主要方向。     

氧化铁忆阻器中缺陷态诱导的模拟型阻变及突触双脉冲易化特性

模拟型阻变突触特性能够为神经形态计算提供高的计算精度并避免计算过程中带来的电导卡滞、跃变以及失效等问题。模拟生物突触在刺激脉冲下的行为,能够更好地揭示电子器件的仿生特性机理并为高性能神经形态计算提供支撑。突触双脉冲易化是生物突触的重要特性,反映了在外界刺激作用下的易化和适应性过程,对揭示神经元的工作机制至关重要。为了构建突触双脉冲易化的模拟型忆阻器件,本研究通过器件的能带结构设计及氧空位缺陷态的调控,利用射频磁控溅射法制备了一种结构为Ag/FeOx/ITO的忆阻器。电学测试结果表明,该器件具有优异的渐进递增的非线性阻变特性,即模拟型阻变特性。在I-V循环扫描3000次范围内,这种器件均表现出模拟型阻变特性,可提供稳定的、可分离的16个电导状态,且在104 s内维持良好,说明这些电导状态是非易失性的,这主要归功于电子在氧空位缺陷态中的捕获与去捕获以及在势垒间隧穿行为。但是,在低电场强度情况下,捕获的热电子有可能会跃迁出浅陷阱能级,而呈现出易失性。根据这种器件的易失性和非易失性共存特性,通过调制电压脉冲宽度、幅度,器件能够表现出很好的突触双脉冲易化特性,显示出该类型器件在神经形态计算中的潜...     

石墨烯∶聚合物复合薄膜的图形化制备与非易失性存储性能研究

采用旋涂技术、光刻技术、蒸发镀膜技术制备以图形化石墨烯∶聚合物复合薄膜为活性层,具有氧化铟锡/石墨烯∶聚合物/铝交叉型夹层结构的阻变器件。采用光刻胶为有机基体,实现阻变层的可图形化;通过优化石墨烯浓度,获得具有优良性能的可擦写非易失性阻变存储器件,讨论其阻变机制。实验表明,当石墨烯浓度为0.01%(质量分数)时,器件具有最佳的阻变特性,其开关比达8.9×103,且表现出良好的数据维持能力。     

Hf/HfO_2基双极阻变存储器研究

本文制备了纳米级的Hf/Hf O2基阻变存储器,阻变存储器上电极金属和下电极金属交叉,形成交叉点型的金属-氧化物-金属结构。系统地对其电学特性进行表征,包括forming过程、SET过程和RESET过程。详细研究了该阻变存储器SET电压与RESET电压,高阻态阻值与低阻态阻值间的关联性。该阻变存储器的电学参数与SET过程的电流限制值强相关,因此需要折中优化。利用量子点接触模型对Hf/Hf O2基阻变存储器的开关物理机制进行了分析。     

Analysis of the Bipolar Resistive Switching Behavior of a Biocompatible Glucose Film for Resistive Random Access Memory

Resistive random access memory (RRAM) devices are fabricated through a simple solution process using glucose, which is a natural biomaterial for the switching layer of RRAM. The fabricated glucose‐based RRAM device shows nonvolatile bipolar resistive switching behavior, with a switching window of 10³. In addition, the endurance and data retention capability of glucose‐based RRAM exhibit stable characteristics up to 100 consecutive cycles and 10⁴ s under constant voltage stress at 0.3 V. The interface between the top electrode and the glucose film is carefully investigated to demonstrate the bipolar switching mechanism of the glucose‐based RRAM device. The glucose based‐RRAM is also evaluated on a polyimide film to verify the possibility of a flexible platform. Additionally, a cross‐bar array structure with a magnesium electrode is prepared on various substrates to assess the degradability and biocompatibility for the implantable bioelectronic devices, which are harmless and nontoxic to the human body. It is expected that this research can provide meaningful insights for developing the future bioelectronic devices.     

Symmetric Ultrafast Writing and Erasing Speeds in Quasi‐Nonvolatile Memory via van der Waals Heterostructures

Due to the large gap in timescale between volatile memory and nonvolatile memory technologies, quasi‐nonvolatile memory based on 2D materials has become a viable technology for filling the gap. By exploiting the elaborate energy band structure of 2D materials, a quasi‐nonvolatile memory with symmetric ultrafast write‐1 and erase‐0 speeds and long refresh time is reported. Featuring the 2D semifloating gate architecture, an extrinsic p–n junction is used to charge or discharge the floating gate. Owing to the direct injection or recombination of charges from the floating gate electrode, the erasing speed is greatly enhanced to nanosecond timescale. Combined with the ultrafast write‐1 speed, symmetric ultrafast operations on the nanosecond timescale are achieved, which are ≈10⁶ times faster than other memories based on 2D materials. In addition, the refresh time after a write‐1 operation is 219 times longer than that of dynamic random access memory. This performance suggests that quasi‐nonvolatile memory has great potential to decrease power consumption originating from frequent refresh operations, and usher in the next generation of high‐speed and low‐power memory technology.     

Hybrid Flexible Resistive Random Access Memory‐Gated Transistor for Novel Nonvolatile Data Storage

Here, a single‐device demonstration of novel hybrid architecture is reported to achieve programmable transistor nodes which have analogies to flash memory by incorporating a resistive switching random access memory (RRAM) device as a resistive switch gate for field effect transistor (FET) on a flexible substrate. A high performance flexible RRAM with a three‐layered structure is fabricated by utilizing solution‐processed MoS₂ nanosheets sandwiched between poly(methyl methacrylate) polymer layers. Gate coupling with the pentacene‐based transistor can be controlled by the RRAM memory state to produce a nonprogrammed state (inactive) and a programmed state (active) with a well‐defined memory window. Compared to the reference flash memory device based on the MoS₂ floating gate, the hybrid device presents robust access speed and retention ability. Furthermore, the hybrid RRAM‐gated FET is used to build an integrated logic circuit and a wide logic window in inverter logic is achieved. The controllable, well‐defined memory window, long retention time, and fast access speed of this novel hybrid device may open up new possibilities of realizing fully functional nonvolatile memory for high‐performance flexible electronics.     

Resistive-switching crossbar memory based on Ni-NiO core-shell nanowires

Resistive-switching memory (RRAM) is an emerging nanoscale device based on the localized metal-insulator transition within a few-nanometer-sized metal oxide region. RRAM is one of the most promising memory technologies for the ultimate downscaling of nonvolatile memory. However, to develop memory arrays with densities approaching 1 Tb cm(-2) , bottom-up schemes based on synthesis and assembly of metal oxide nanowires (NWs) must be demonstrated. A RRAM memory device based on core-shell Ni-NiO NWs is presented, in which the Ni core plays the role of the metallic interconnect, while the NiO shell serves as the active switching layer. A resistance change of at least two orders of magnitude is shown on electrical operation of the device, and the metal-insulator switching is unequivocally demonstrated to take place in the NiO shell at the crossing between two NWs or between a NW and a gold electrode strip. Since the fabrication of the NW crossbar device is not limited by lithography, this approach may provide a basis for high-density, low-cost crossbar memory with long-term storage stability.     

Recent Advances of Flexible Data Storage Devices Based on Organic Nanoscaled Materials

Following the trend of miniaturization as per Moore's law, and facing the strong demand of next‐generation electronic devices that should be highly portable, wearable, transplantable, and lightweight, growing endeavors have been made to develop novel flexible data storage devices possessing nonvolatile ability, high‐density storage, high‐switching speed, and reliable endurance properties. Nonvolatile organic data storage devices including memory devices on the basis of floating‐gate, charge‐trapping, and ferroelectric architectures, as well as organic resistive memory are believed to be favorable candidates for future data storage applications. In this Review, typical information on device structure, memory characteristics, device operation mechanisms, mechanical properties, challenges, and recent progress of the above categories of flexible data storage devices based on organic nanoscaled materials is summarized.     

Two‐Terminal Multibit Optical Memory via van der Waals Heterostructure

2D van der Waals (vdWs) heterostructures exhibit intriguing optoelectronic properties in photodetectors, solar cells, and light‐emitting diodes. In addition, these materials have the potential to be further extended to optical memories with promising broadband applications for image sensing, logic gates, and synaptic devices for neuromorphic computing. In particular, high programming voltage, high off‐power consumption, and circuital complexity in integration are primary concerns in the development of three‐terminal optical memory devices. This study describes a multilevel nonvolatile optical memory device with a two‐terminal floating‐gate field‐effect transistor with a MoS₂/hexagonal boron nitride/graphene heterostructure. The device exhibits an extremely low off‐current of ≈10^?14 A and high optical switching on/off current ratio of over ≈10⁶, allowing 18 distinct current levels corresponding to more than four‐bit information storage. Furthermore, it demonstrates an extended endurance of over ≈10⁴ program–erase cycles and a long retention time exceeding 3.6 × 10⁴ s with a low programming voltage of ?10 V. This device paves the way for miniaturization and high‐density integration of future optical memories with vdWs heterostructures.     

Tubular 3D Resistive Random Access Memory Based on Rolled‐Up h‐BN Tube

Due to their advantages compared with planar structures, rolled‐up tubes have been applied in many fields, such as field‐effect transistors, compact capacitors, inductors, and integrative sensors. On the other hand, because of its perfect insulating nature, ultrahigh mechanical strength and atomic thickness property, 2D hexagonal boron nitride (h‐BN) is a very suitable material for rolled‐up memory applications. In this work, a tubular 3D resistive random access memory (RRAM) device based on rolled‐up h‐BN tube is realized, which is achieved by self‐rolled‐up technology. The tubular RRAM device exhibits bipolar resistive switching behavior, nonvolatile data storage ability, and satisfactorily low programming current compared with other 2D material‐based RRAM devices. Moreover, by releasing from the substrate, the footprint area of the tubular device is reduced by six times. This tubular RRAM device has great potential for increasing the data storage density, lowering the power consumption, and may be applied in the fields of rolled‐up systems and sensing‐storage integration.     

Development of ferroelectric oxides based resistive switching materials

Resistive random access memory (RRAM) is one of the most promising candidates that satisfies the requirements of new generation non-volatile memories, as a consequence of its high density, outstanding scalability, and low power consumption. The review is based on a summary of recent studies in ferroelectric oxides based resistive switching (RS) materials and devices. It highlights the various ferroelectric oxide materials with RS behaviour and the underlying mechanisms including filament-type and interface-type mechanism. In the end, the challenge in current RRAM for future high-density data storage applications is addressed.     

Resistive Switching Behavior in Ferroelectric Heterostructures

Resistive random‐access memory (RRAM) is a promising candidate for next‐generation nonvolatile random‐access memory protocols. The information storage in RRAM is realized by the resistive switching (RS) effect. The RS behavior of ferroelectric heterostructures is mainly controlled by polarization‐dominated and defect‐dominated mechanisms. Under certain conditions, these two mechanisms can have synergistic effects on RS behavior. Therefore, RS performance can be effectively improved by optimizing ferroelectricity, conductivity, and interfacial structures. Many methods have been studied to improve the RS performance of ferroelectric heterostructures. Typical approaches include doping elements into the ferroelectric layer, controlling the oxygen vacancy concentration and optimizing the thickness of the ferroelectric layer, and constructing an insertion layer at the interface. Here, the mechanism of RS behavior in ferroelectric heterostructures is briefly introduced, and the methods used to improve RS performance in recent years are summarized. Finally, existing problems in this field are identified, and future development trends are highlighted.     

Towards the Development of Flexible Non‐Volatile Memories

Flexible non‐volatile memories have attracted tremendous attentions for data storage for future electronics application. From device perspective, the advantages of flexible memory devices include thin, lightweight, printable, foldable and stretchable. The flash memories, resistive random access memories (RRAM) and ferroelectric random access memory/ferroelectric field‐effect transistor memories (FeRAM/FeFET) are considered as promising candidates for next generation non‐volatile memory device. Here, we review the general background knowledge on device structure, working principle, materials, challenges and recent progress with the emphasis on the flexibility of above three categories of non‐volatile memories.