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[IEEE 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Hiroshima (2018.5.27-2018.6.1)] 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Control of Leakage Current through BaTiO<inf>3</inf> Film by Cumulative Cycle of Applied Voltage Scanning for ReRAM or Neuromorphic Application
摘要： We found a new phenomenon that shows a large change in leakage current through BaTiO3 (BTO) film with the maximum ratio of 107 to 109 observed in this work by changing cumulative cycle of voltage scan applied on the film capacitor. These leakage phenomena are thought to depend on several factors such as BTO film thickness, concentration of Vo+, bias voltage, its sweep rate and so on, because trapping/detrapping of carrier electron into/from oxygen vacancy would be a competition dependent on their rates and concentrations. These results imply that the leakage current can be controlled by some sequences or protocols of applied voltage scan, leading to use for ReRAM or neuromorphic applications.
关键词： ReRAM,leakage current,resistive switching,BaTiO3,oxygen vacancy
更新于2025-09-23 15:23:52
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New Uses of Micro and Nanomaterials || The Atomic Layer Deposition Technique for the Fabrication of Memristive Devices: Impact of the Precursor on Pre-deposited Stack Materials
摘要： Atomic layer deposition (ALD) is a standard technique employed to grow thin-film oxides for a variety of applications. We describe the technique and demonstrate its use for obtaining memristive devices. The metal/insulator/metal stack is fabricated by means of ALD-grown HfO2, deposited on top of a highly doped Si substrate with an SiO2 film and a Ti electrode. Enhanced device capabilities (forming free, self-limiting current, non-crossing hysteretic current-voltage features) are presented and discussed. Careful analysis of the stack structure by means of X-ray reflectometry, atomic force microscopy, and secondary ion mass spectroscopy revealed a modification of the device stack from the intended sequence, HfO2/Ti/SiO2/Si. Analytical studies unravel an oxidation of the Ti layer which is addressed for the use of the ozone precursor in the HfO2 ALD process. A new deposition process and the model deduced from impedance measurements support our hypothesis: the role played by ozone on the previously deposited Ti layer is found to determine the overall features of the device. Besides, these ALD-tailored multifunctional devices exhibit rectification capability and long enough retention time to deserve their use as memory cells in a crossbar architecture and multibit approach, envisaging other potential applications.
关键词： ReRAM,nonvolatile memory,complementary resistive switching cell,forming free memristive device,atomic layer deposition,redox-based resistive random access memory
更新于2025-09-23 15:21:21
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Optical properties of HfO <sub/>x</sub> ( <i>x</i> < 2) films grown by ion beam sputtering-deposition method
摘要： The optical properties of the HfOx films of different chemical composition (x < 2) deposited by ion beam sputtering-deposition (IBSD) method were studied. Spectral dependencies of refractive index n(λ) and extinction coefficient k(λ) were determined with ellipsometry in λ = 250–1100 nm wavelength region. The x values (i.e. [O]/[Hf] ratio) for the films were derived from x-ray photoelectron spectroscopy (XPS) data. The spectral dependences of optical constants n(λ) and k(λ) were found to undergo radical changes with x = 1.78–1.82. The films with x < 1.78 demonstrated high extinction coefficient k > 1 with the metallic-like behavior of optical constants spectral dependences. The films with x > 1.82 were found to be transparent, with k = 0 and n(λ) being well approximated by a Cauchy polynomial dependence for dielectrics. Using a sample with a gradient of x, it was established that the transition from the metallic to the dielectric-like behavior of the optical constants occurs not smoothly, but is discontinuous. A sharp jump in the optical constants is observed at x ≈ 1.8. According to XPS data, the transparent films were found to consist of two components only: HfO2 and Hf4O7 suboxide. Cauchy polynomial coefficients for Hf4O7 suboxide and HfO2 were found by using the Bruggeman effective medium approximation.
关键词： IBSD,ReRAM,spectroscopic ellipsometry,HfOx
更新于2025-09-23 15:21:01
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Comparison of spin-on-glass and WO <sub/>3</sub> as an insulating layer for printed resistive memory devices
摘要： Resistive Random Access Memory (ReRAM) is a highly promising technology for various future memory applications. In this work, spin-on-glass (SOG) and WO3 nanoparticles are used as an insulating layer for completely inkjet-printed ReRAM cells. The direct comparison shows that the di?erence in switching parameters can be used to serve di?erent device requirements for various applications. While local ?lament formation with conductive atomic force microscopy con?rms the same switching mechanism for both compounds, the current–voltage characteristics di?er from each other. SOG as excellent insulator shows an OFF resistance in the range of GΩ and is therefore highly suitable for multi-bit data storage to increase memory density. ReRAM cells with WO3 face larger leakage currents and show a low degree of multi-bit data storage. However, WO3 can be used to fabricate completely sinter-free memory devices for applications which do not allow high temperatures in the fabrication process.
关键词： spin-on-glass,?exible electronics,printed electronics,organic electronics,inkjet printing,ReRAM
更新于2025-09-19 17:15:36
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Halide perovskites for resistive random-access memories
摘要： Halide perovskite based resistive random-access memory (ReRAM) devices are emerging as a new class of revolutionary data storage devices because their switching material—halide perovskite—has received considerable attention in recent years. Among the electrical characteristics of the material, its current–voltage (I–V) hysteresis, which may occur due to defect formation and migration, means that ReRAM can employ halide perovskites as a resistive switching material. Many studies have been conducted on resistive switching materials; however, the investigation of halide perovskites for ReRAM devices is still in the early research stages; therefore, the application of halide perovskites in ReRAM devices is a topic worth studying. Herein, we introduce halide perovskites and their operating mechanism within a ReRAM device. Moreover, recent notable achievements along with future challenges have been reviewed.
关键词： Halide perovskites,ion migration,hysteresis,resistive random-access memories,switching materials,ReRAM
更新于2025-09-19 17:15:36
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<i>Operando</i> observation of resistive switching in a resistive random-access memoryby laser-excited photoemission electron microscope
摘要： We developed a laser-excited photoemission electron microscope (Laser-PEEM) that enables us to perform a non-destructive operando observation for elucidating the changes in the physical properties of electronic devices. By utilizing the Laser-PEEM, the non-volatile resistance change in the resistive random-access memory (ReRAM) was clearly visualized, even though the resistance change occurred under the electrode of the ReRAM, thanks to the deep probing depth. The operando observation of the Laser-PEEM is very promising as an observation method for various kinds of devices because the observation simultaneously provides us with morphological and electrical properties in real time.
关键词： ReRAM,Laser-PEEM,operando observation,photoemission electron microscope,resistive switching
更新于2025-09-16 10:30:52
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[IEEE 48th European Solid-State Device Research Conference (ESSDERC 2018) - Dresden (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Observation and Analysis of Bit-by-Bit Cell Current Variation During Data-Retention of TaO<inf>x</inf>-based ReRAM
摘要： This work analyzes the bit-by-bit memory cell current variation during the data-retention to study the long time data-retention behavior of TaOx-based resistive random access memory (ReRAM). For the first time, the current variation during data-retention is observed and analyzed for each memory cell of ReRAM. Cell current of low resistance state (LRS) cells shows complicated characteristics, that is, decreasing in the long term and fluctuating in the short term due to oxygen vacancy diffusion. On the other hand, high resistance state cell hardly shifts during the data-retention. A physical model for LRS cell current fluctuation is proposed in this study, based on the numerical calculation.
关键词： ReRAM,Data-retention characteristics
更新于2025-09-10 09:29:36
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Aspects of the a-TiO <sub/>x</sub> memristor active medium technology
摘要： New physical approaches make fast-response non-volatile resistive memory (ReRAM) very attractive for digital, neuromorphic, and other data processing systems considered in many previous publications. Even though the effect of resistance and memory switching in metal-dielectric-metal structures is well known, the physical mechanisms underlying these phenomena are still vague. Considerable instability and insufficient reproducibility of electrical characteristics are the major factors that hold back the practical use of memristors. This problem can be solved by combining the theory of filaments and physics of amorphous wide-bandgap semiconductors which make up the majority of active memristor media currently being investigated. The properties of amorphous and crystalline nanostructures are radically different. Being rather specific, the characteristics of amorphous nanostructures are much dependent on the manufacturing technique. The methods of controlling the amorphous state and its stability are the subject of this paper. The conventional technique of electron-beam induced deposition is used to make the samples. Well-studied TiO2 is taken as a base material for active memristor media. The amorphous state of resultant coats is modified by varying the deposition temperature at an unvaried deposition rate, a residual vacuum-chamber pressure, and coat thicknesses. Sensitive surface plasmon resonance method, spectral technique, and total-external-reflection X-ray diffractometry are the tools to control the stability of the coats. In the experiment, we have observed the long and distinct relaxation of the optical parameters of amorphous layers and the manifestation of the development of an inhomogeneous amorphous layer.
关键词： ReRAM,amorphous,memristor,SPR,TiO2,HRXRD
更新于2025-09-10 09:29:36
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Improvement in Resistance Switching of SiC-Based Nonvolatile Memory by Solution-Deposited HfO <sub/><i>x</i> </sub> Thin Film
摘要： In this study, we implemented a resistance change memory (ReRAM) device using a SiC layer with excellent physical properties. We fabricated devices composed of Ti/SiC/Pt and Ti/HfOx/SiC/Pt structures and investigated their memory characteristics. The Ti/SiC/Pt ReRAM devices exhibited stable bipolar resistive switching characteristics but had a relatively small memory window, whereas the Ti/HfOx/SiC/Pt ReRAM devices had a large memory window and low operating voltage. In addition, the Ti/HfOx/SiC/Pt ReRAM devices exhibited stable endurance characteristics over 500 cycles and excellent retention characteristics at room temperature and high temperatures for 1 × 104 s. Further, the Ti/HfOx/SiC/Pt ReRAM devices exhibited multi-level conduction states by modulating the reset stop voltage, and each resistance level had excellent endurance characteristics. The average transmittance of the HfOx/SiC bilayer in visible light was 87%. Such a high value indicates that the HfOx/SiC bilayer fabricated by the stacking method is expected to be a suitable material for highly reliable nonvolatile memory and transparent electronic devices, even in harsh environments.
关键词： Bilayer,ReRAM,BRS,Silicon Carbide,Multi-Level Cell (MLC)
更新于2025-09-04 15:30:14