Complementary Resistive Switching Devices Research Articles

Implication Logic Circuit Based on a Graphene Oxide Complementary Resistive Switching Device

AbstractThe logic circuit is the main component of an integrated circuit chip that dictates the operation and performance of the chip. The logic circuit based on a memristor can improve the integration and operation speed of the existing integrated circuit and reduce the chip size and the number of devices used by a single logic circuit. However, most of the research on logic circuits based on memristors has focused only on simulations, and research on the realization of logic circuits by hardware using actual memristors is limited. In this paper, a memristor based on graphene oxide with stable complementary resistive switching characteristics is fabricated, a logic circuit is built by using this device, and the logic functions of “IMP,” “AND,” and “NOR” are successfully realized. The complementary resistive switching device can alleviate the severe power loss caused by the memory separation of the von Neumann architecture. Moreover, its unique structure enables it to realize material logic independently without the use of multiple memristors and resistors, providing a new scheme for the physical realization of logic circuits. It also opens up a new path for integrated chips to break through von Neumann architecture.

Understanding the complementary resistive switching in egg albumen-based single sandwich structure with non-inert Al electrode

The concept of complementary resistive switching (CRS) has been proposed as a potential solution for mitigating the unwanted sneak path current intrinsic to large-scale crossbar memory arrays. In this study, CRS devices based on egg albumen are fabricated using non-inert Al layers as the top electrodes (TE). The Al/Albumen/indium tin oxide (ITO) single sandwich structure achieves stable and reproducible CRS behavior without requiring a forming process. The application of a compliance current leads to an evolution from CRS to bipolar resistive switching (BRS). Furthermore, the BRS analog switching feature enables the emulation of synaptic functions, like paired-pulse facilitation (PPF) and paired-pulse depression (PPD). Our systematic and in-depth analyses demonstrate that the CRS is due to the interfacial Schottky barriers originating from the Al electrode oxidation. Consequently, the resistance switching behavior in the albumen-based cells with inert Pt top electrodes can further validate this model. These findings provide significant insight into the role of non-inert electrodes and contribute to a comprehensive understanding of the CRS mechanism, which may facilitate the development of high-performance CRS biodevices.

SPICE model for complementary resistive switching devices based on anti-serially connected quasi-static memdiodes

This paper reports the use of the Quasi-static Memdiode Model (QMM) for simulating Complementary Resistive Switching (CRS) devices. CRS arises from the anti-serial connection of two memristors and it is used for generating low and high-resistance regions in the I-V characteristic with the aim of mitigating the sneak-path conduction problem in crossbar arrays. Here, the use of the QMM for CRS in the form of a six terminal subcircuit is explored. While two terminals of the subcircuit correspond to the conventional input and output pins of the CRS structure, the rest provide information about the voltage at the central node, the low-voltage conductance of each device, and the low-voltage conductance of the whole structure. Special attention is paid to the simulation of the so-called table with legs hysteresis loop (resistance at fixed bias vs. write voltage), which is often invoked in connection with devices that exhibit switching activity at the two interfaces of a single dielectric layer. Because of the internal potential drop distribution, the switching process takes place alternately at one side of the structure or the other giving rise to a pseudo-CRS behavior. The flexibility of the proposed approach is demonstrated through a series of fitting exercises that involve experimental data reported in the literature. The model script for the SPICE simulator is also provided.

Tunability Properties and Compact Modeling of HfO2-Based Complementary Resistive Switches Using a Three-Terminal Subcircuit

Complementary resistive switching (CRS) arises when two bipolar-mode memristive devices are antiserially connected, forming a single functional structure. The combined effect of both memristors leads to the appearance of high (HRS) and low (LRS) resistance windows in the current–voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> ) characteristic that finds application in fields such as neuromorphic computing and logic circuits. In this work, the electric behavior of HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based CRS devices intentionally fabricated with a common central electrode is investigated both from experimental and modeling viewpoints. Experiments reveal that the maximum voltage applied to the structure allows tuning the amplitude of the resistance window following a self-balance dynamics. The origin of the abrupt (digital) and gradual (analog) transitions between the HRS and LRS states is elucidated through the inclusion of the snapback and snapforward effects in the switching dynamics. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}$ </tex-math></inline-formula> characteristics of the CRS devices are compact modeled with two opposite-biased memdiodes and simulated in LTSpice using an equivalent three-terminal subcircuit. It is shown that the proposed model is able to reproduce with a high degree of accuracy not only the observed CRS behavior for HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> but also the main features exhibited by devices with a wide variety of oxide/electrode materials.

Recent Progress in Selector and Self‐Rectifying Devices for Resistive Random‐Access Memory Application

The recent progress of selector and self‐rectifying devices for resistive random‐access memory applications is reviewed. In particular, the performance of crossbar arrays based on resistive switching (RS) devices, the sneak‐path current issue, and possible solutions is discussed. The parameters and requirements of selector devices are elucidated here, and several types of selector devices, such as a transistor‐assisted transistor‐one resistor, unipolar one diode‐one resistor, bipolar one selector‐one resistor, and threshold switching selectors, are comprehensively discussed. In the case of self‐rectifying devices, the recent progress in complementary RS devices, vacancy‐modulated conductive oxide‐based devices, and tunneling barrier‐based RS devices is reviewed. The switching mechanisms and the geometrical configuration of the selector and self‐rectifying RS devices are emphasized. Furthermore, comparative assessments of the different devices are evaluated. Finally, an overview of the gaps in previously reported devices is presented and some key improvements for future research direction suggested.

Modeling current and voltage peaks generation in complementary resistive switching devices

We propose a physical model of complementary resistive switching (CRS) based on the disruption and reformation process of a metallic filament inside each Oxyde Resistive Random Access Memory (OxRRAM) composing the CRS. The driving forces involved in this process are electromigration forces, electron phonon coupling and joule heating. The model accounts well for the experimental CRS current voltage characteristics. The stability of the CRS states and the CRS operation in pulse regime, including the current and voltage peaks generation are discussed.

A simple, robust, and accurate compact model for a wide variety of complementary resistive switching devices

Complementary Resistive Switching (CRS) using memristive devices has been intensively investigated in the last decade. The objective of CRS is to generate low and high resistance windows in the I-V characteristic of the selector device with the aim of reducing the sneak-path conduction problem in crossbar arrays. Though a wide variety of compact models for CRS have been proposed, the one presented here stands out for its simplicity, robustness, and accuracy. The flexibility of the memdiode model is demonstrated through a series of fitting exercises using experimental data found in the literature. The model script for the LTSpice XVII simulator is also provided.

Control of the set and reset voltage polarity in anti-series and anti-parallel resistive switching structures

In the attempt to control the polarity of the set and reset voltages in bipolar resistive switching capacitors, we have studied the switching properties of structures consisting of either two anti-series or two anti-parallel metal-insulator-metal capacitors. The capacitors were based on hafnium oxide, and W and TiN/Ti were used as bottom and top electrodes respectively. MIM capacitors showed bipolar resistive switching behavior, with very good repetitiveness and endurance properties. Both anti-series and anti-parallel structures showed again bipolar resistive switching behavior, being the polarity of the set and reset voltages controllable by applying higher biases. In the case of anti-series configuration, there is a stretch-out in the current-voltage characteristic because the bias is applied across two different devices. Changing the polarity is equivalent to the process of write and erase of complementary resistive switching devices in crossbar arrays. In the case of anti-parallel configuration, the resistance window between both resistivity states is reduced. The control of the switching polarity has also been observed when applying a small ac signal, and measuring the conductance of the structures.

Compact Modeling of Complementary Resistive Switching Devices Using Memdiodes

In spite of the apparent simplicity of the system under study, compact modeling of complementary resistive switching (CRS) devices, i.e., two antiserially connected memristive structures, is by no means straightforward. This requires a deep understanding of the voltage drops occurring across the circuit elements and correct treatment of the so-called snapback (SB) effect typical of the breakdown process of a thin dielectric film in an MIS or a MIM structure. The SB effect fundamentally consists in a sudden reduction of the device resistance caused by the formation of a filamentary path spanning the insulator. Beyond this point, the filament widens keeping the voltage drop across its extremes constant. The consequence of disregarding this effect is clearly distinguishable in the simulated curves: progressive openings of the on-state windows for both positive and negative voltages instead of abrupt ones. In this paper, a modification is introduced in the original memdiode model for memristive devices in order to account for this remarkable feature. Ta2O5-based CRS devices are considered to demonstrate the suitability of our approach.

Voltage-amplitude-controlled complementary and self-compliance bipolar resistive switching of slender filaments in Pt/HfO2/HfOx/Pt memory devices

Complementary resistive switching (CRS) in single devices without internal electrodes is attractive in high-density memory applications because it simplifies fabrication and avoids the complicated controlling and matching needed when using two resistive switching (RS) devices, as in conventional CRS devices. To improve the performance of such devices, however, the CRS mechanism must be understood further. Here, the authors report on voltage-amplitude-controlled CRS and self-compliance opposite-polarity bipolar RS in Pt/HfO2/HfOx/Pt memory devices. In these devices, CRS showed an almost symmetrical current–voltage hysteresis loop. Both the set voltages and hopping conduction mechanism of the high resistance states in both the bipolar RS were consistent with those of the CRS. An excess current beyond Ohmic conduction appeared before the reset switching in the bipolar RS. To interpret the characteristics of the CRS and bipolar RS, the authors propose a slender conductive filament model. According to this model, a limited oxygen vacancy (Vo) source, high Vo diffusion barrier, small film thickness, and concentrated electric field all contribute to the formation of slender filaments and to CRS operations. The model also suggests that a slender filament might form in a layer of multilayer junctions, which allows for different layers to play specific roles and improve device performance.

Complementary resistive switching in single sandwich structure for crossbar memory arrays

Cu2O film based single sandwich structure with complementary resistive switching characteristics is demonstrated. Unlike the conventional complementary resistive switching devices, the Pt/Cu2O/fluorine doped tin oxide sandwich structure is fabricated without anti-serially bipolar resistive switching cells or interfacial layer. In addition, the forming-step is unnecessary to turn on the device, which makes the complementary resistive switching process easy to control. With high resistance ratio, stable retention and reproducible switching properties, this complementary resistive switching device can be used in three dimensional stacked crossbar memory arrays. The switching mechanism is also discussed by developing a conductive path model.

Self-electroforming and high-performance complementary memristor based on ferroelectric tunnel junctions

Complementary resistive switching (CRS) has potential applications in ultra-high density three-dimensional crossbar arrays for resistive random access memories and Logic-in-Memories. For real applications, the good stability and electroforming-free character have become essential pre-requisites. In this work, we investigate the resistance switching behaviors of a CRS device based on two anti-serial Au/BaTiO3/Nb:SrTiO3 ferroelectric tunnel junctions (FTJs). This FTJ-based CRS device shows a stable butterfly-like resistance-voltage hysteresis, as well as self-electroforming, multi-switching, and good performance complementary switching behaviors. The present work presents a convincing demonstration of the complementary multi-switching states modulated by remnant ferroelectric polarization, making the FTJ structure good potentials for high-performance CRS memristors.

Complementary Floating Gate Transistors With Memristive Operation Mode

A two-terminal complementary floating gate transistor architecture with a memristive operation mode is proposed. Therefore, a diode configuration wiring scheme is assumed for n-channel metal–oxide–semiconductor and p-channel metal–oxide–semiconductor-based floating gate transistors (MemFlash), which enables the persistent device resistance to be varied according to the history of the charge flow. By means of a capacitive device model, we show that the n-channelMemFlash cells exhibits bipolar resistive switching from high-to-low resistance state, while the p-channel MemFlash cells switches complementary to the n-channel type under drain–source voltage application. By combining both memristive cells to a single two-terminal device structure, a complementary resistive switching device is obtained (C-MemFlash) with a bipolar, symmetric switching characteristics, and an increased number of end-resistant states. This allows realizing a rich variety of memory and logic functionalities for new nanoelectronic concepts.

Evolution of complementary resistive switching characteristics using IrOx/GdOx/Al2O3/TiN structure

The complementary resistive switching (CRS) characteristics using an IrOx/GdOx/Al2O3/TiN single cell are observed whereas the bipolar resistive switching (BRS) characteristics are observed for the IrOx/GdOx/TiN structure. Transmission electron microscope and energy dispersive X-ray spectroscopy depth profile show crystalline GdOx film and the presence of higher amount of oxygen at both IrOx/GdOx interface and Al2O3 layer. Inserting thin Al2O3 layer, the BRS is changed to CRS. This CRS has hopping distance of 0.58 nm and Poole-Frenkel current conductions for the “0” and “1” states, respectively. A schematic model using oxygen vacancy filament formation/rupture at the TE/GdOx interface and Al2O3 layer has been illustrated. This CRS device has good endurance of 1000 cycles with a pulse width of 1 μs, which is very useful for future crossbar architecture.

Tunable multilevel storage of complementary resistive switching on single-step formation of ZnO/ZnWO(x) bilayer structure via interfacial engineering.

Tunable multilevel storage of complementary resistive switching (CRS) on single-step formation of ZnO/ZnWOx bilayer structure via interfacial engineering was demonstrated for the first time. In addition, the performance of the ZnO/ZnWOx-based CRS device with the voltage- and current-sweep modes was demonstrated and investigated in detail. The resistance switching behaviors of the ZnO/ZnWOx bilayer ReRAM with adjustable RESET-stop voltages was explained using an electrochemical redox reaction model whose electron-hopping activation energies of 28, 40, and 133 meV can be obtained from Arrhenius equation at RESET-stop voltages of 1.0, 1.3, and 1.5 V, respectively. In the case of the voltage-sweep operation on the ZnO-based CRS device, the maximum array numbers (N) of 9, 15, and 31 at RESET-stop voltages of 1.4, 1.5, and 1.6 V were estimated, while the maximum array numbers increase into 47, 63, and 105 at RESET-stop voltages of 2.0, 2.2, and 2.4 V, operated by the current-sweep mode, respectively. In addition, the endurance tests show a very stable multilevel operation at each RESET-stop voltage under the current-sweep mode.

Electric-field induced transition of resistive switching behaviors in BaTiO3/Co:BaTiO3/BaTiO3 trilayers

Electric-field induced transition of resistive switching behaviors has been demonstrated in BaTiO3/Co:BaTiO3/BaTiO3 trilayers. At low applied bias, the Au/BaTiO3/Co:BaTiO3/BaTiO3/Pt device shows bipolar resistive switching (BRS) behavior, whereas it converts to complementary resistive switching (CRS) at high applied bias due to the depletion of oxygen vacancies in BaTiO3 layer. The Schottky-like emission accompanied by trapping/detrapping process at the interfaces is likely responsible for the BRS and CRS effects in the trilayers. Furthermore, the operating current of the CRS devices can be reduced significantly by decreasing the doped layer.