Neural-PIM: Efficient Processing-In-Memory with Neural Approximation of Peripherals

Resistive random access memory (ReRAM) devices are considered to be one of the most promising candidates for the next generation of nonvolatile memory devices because of their superior properties such as low power consumption, simple structure, high integration density, and fast operation speed. In this study, we used zinc oxide (ZnO) thin films to fabricate ReRAM devices comprising Au/ZnO/Al and Al/Au/ZnO/Al structures. We observed that the operating stability of the device containing the Al/Au/ZnO/Al structure improved. The devices displayed effective and stable operational characteristics. The operational voltage of the ZnO ReRAM devices was less than 3 V, and the reset operational voltage was less than −1.5 V.

In this study, 10-nm rare-earth metal-oxide (REMO) films, namely, pure HoScO x (HSO) and HoScO x doped with Nb (HSO-Nb) and Zn (HSO-Zn), were deposited to build resistive random access memory (RRAM) devices with a Pt/REMO/Pt structure using radio frequency magnetron sputtering. The results of x-ray diffraction and transmission electron microscopy showed that all as-deposited REMO films are featureless microstructures lacking long-range order. In all RRAM devices, layer structures were well adhered to each other with relatively smooth interfaces and no cracks or holes were observed. Hall measurements demonstrated n-type conduction in the as-deposited films. The addition of Nb and Zn increased carrier concentration and mobility of the HSO films and reduced electrical resistivity. The former was possibly caused by the electronic compensation of NbSc ··, thereby triggering the formation of polarons, and the latter was probably due to the increase in concentration of oxygen vacancies associated with acceptor doping. The RRAM devices revealed unipolar switching behavior characterized by a resistance ratio of more than three orders of magnitude, good endurance, and a long retention time. The switching behavior of the RRAM with amorphous HSO films was altered by the doping species. Doping with Nb and Zn decreased the forming voltage, facilitated the use of a smaller switching voltage, and increased the resistance ratio of high- and low-resistance states. The conduction mechanisms for the low resistive state and high resistive state were dominated by Ohmic conduction and trap-controlled space-charge-limited current mechanisms, respectively.

Modulation of the electrical characteristics on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)-based resistive random access memory device by the impact of top electrode materials

Resistance switching characteristics, observed in metal oxide thin films, has recently attracted a great deal of attention to develop next generation low power, low cost, high speed, rugged and nonvolatile resistive random access memory (RRAM) devices. The memory effect in these materials is realized through the switching of the resistance of their thin films between two states of high and low resistances. Amongst the known metal oxides currently being explored for the development of RRAM, ZnO has been demonstrated to be a potential candidate. ZnO is an n‐type wide bandgap semiconductor and is highly transparent in the visible spectral region. Moreover its conductivity can be tailored in a broad range from metal like to insulator like by suitable impurity doping. Therefore it is possible to develop a fully transparent RRAM entirely based on ZnO. In this paper we report growth of a novel transparent RRAM devices based on ZnO and its variants. We studied the resistive switching characteristics of these devices and associated conduction mechanisms responsible for the switching. The details of this study will be presented in the paper (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The transition from idealized memristor models to physical implementations, such as resistive random access memory (RRAM) devices, is pivotal for advancing neuromorphic circuits in hardware. However, real‐world RRAM devices face challenges due to inherent variability and fabrication tolerances, which hinder their adoption. This study presents the variability intensity model (VIM), a statistical framework designed to assess variability in RRAM devices. The VIM is employed to evaluate the resilience of a memristor‐based Hindmarsh–Rose circuit, which models neuronal behavior in biological systems. The results indicate that the circuit exhibits heightened sensitivity to variability in high‐conductance states, while demonstrating increased tolerance in low‐conductance states. This observation is consistent with RRAM characteristics, where conductance variability decreases as conductance increases. Furthermore, robust spiking dynamics are observed, though the bursting behavior remains sensitive, leading to critical parameter constraints for RRAM devices. By employing a variability model based on real‐world measurements, this work establishes a crucial foundation for the implementation of memristor‐based Hindmarsh–Rose circuits in hardware, where variability is a paramount consideration.

The power consumption (PC), window margin (WM), thermal stability (TS), and reliability [i.e., endurance (EN) and retention-time (RT)] of aluminum nitride (AlN) resistive random access memory (RRAM) devices with different film orientations [i.e., amorphous, (100)- and (002)-oriented] are investigated. It is shown that the charge carrier transport mechanism of the three devices is dominated by Ohmic behavior under low electric fields and the trap-controlled space charge limited current (TC-SCLC) model under high electric fields. Among the three devices, the (002)-oriented AlN sample provides the best overall PC, WM, TS, EN, and RT performance due to its ${c}$ -axis orientation, which is favorable for the formation and rupture of the vertically arranged conductive filaments (CFs) in the AlN film.

The morphological evolution of the conducting filament (CF) predominantly controls the electric response of the resistive random access memory (ReRAM) devices. However, the parameters—in terms of the material and the processing—which control the growth of such CF are plenty. Extending the phase field technique for ReRAM systems presented by Roy and Cha [J. Appl. Phys. 128, 205102 (2020)], we could successfully model the complete SET (to attain low resistance state) and RESET (to attain high resistance state) processes due to the application of sweeping voltage. The key parameters that influence the stability of the multi-cycle I-V response or the endurance behavior are identified. The computational findings of the presented model ReRAM system are practical in correlating the multi-parametric influence with the stability, variability, and reliability of the endurance cycle that affect the device performance and also lead to the device failure. We believe that our computational approach of connecting the morphological changes of the CF with the electrical response has the potential to further understand and optimize the performance of the ReRAM devices.

The resistive random access memory (RRAM) device has been widely studied due to its excellent memory characteristics and great application potential in different fields. In this paper, resistive switching materials, switching mechanism, and memory characteristics of RRAM are discussed. Recent research progress of RRAM in high-density storage and nonvolatile logic application are addressed. Technological trends are also discussed.

This article focuses on the relevance of the effect of ambient temperature and annealing in the context of compact modeling of metal oxide resistive random access memory (RRAM) devices. The ambient temperature affects the conduction characteristic of resistive switching memories, so it becomes an essential factor to include when adjusting the experimental data. Reported the fabricated results and memory switching parameters with the defined set (Vset) and reset (Vreset) transition voltages for the fabricated annealed HfO2-based RRAM. Additionally, to illustrate the importance of this characteristic in the form of the I-V curve, the Stanford model (SFM) for RRAM devices is enhanced by incorporating the annealing temperature as an additional parameter in the script of the Verilog-A model. Stanford and modified Stanford model (MSFM) are analyzed at the device level using cadence circuit simulator and implemented in the nonvolatile memory circuit (3 *3 memory arrays). Results confirmed that the experimental switching voltages, Vset, Vreset are 1.7 V, −0.8 V. These values are well suited along the simulated MSFM switching voltages of, Vset, Vreset (1.8 V, −0.7 V). The mean error percentage of the MSF is 18.42%.

Resistive Random Access Memory (ReRAM) devices have gathered significant attention recently for high-density non-volatile data storage applications. However, there are several challenges that need to be addressed to take complete benefit of this enabling technology. This paper discusses the role of intentional doping in transition metal oxide dielectrics, particularly HfO2, and its implications on the device performance. Our studies indicate that Mg doped HfO2 based ReRAM devices require lower electroforming voltage compared to undoped HfO2 based ReRAM devices. The reduction in set/reset voltages was also achieved in ReRAM devices with Mg doped HfO2. Excellent bipolar switching and endurance characteristics were achieved demonstrating doping in HfO2 as a viable route for achieving the desired ReRAM characteristics.

In this study, multilevel switching at low-power in Ti/TiN/Ga2O3/Ti/Pt resistive random-access memory (RRAM) devices has been systematically studied. The fabricated RRAM device exhibits an excellent non-overlapping window between set and reset voltages of ∼1.1 V with a maximum R off/R on ratio of ∼103. Moreover, to the best of our knowledge, the multi-bit storage capability of these RRAM devices with a reasonably high R off/R on ratio is experimentally demonstrated, for the first time, for lower compliance currents at 10 μA, 20 μA and 50 μA. The multi-bit resistive switching behavior of the Ga2O3 RRAM device at a low compliance current paves the way for low-power and high-density data storage applications.

We report a study of light-activated resistance switching in silicon oxide (SiOx) resistive random access memory (RRAM) devices. Our devices had an indium tin oxide/SiOx/p-Si Metal/Oxide/Semiconductor structure, with resistance switching taking place in a 35 nm thick SiOx layer. The optical activity of the devices was investigated by characterising them in a range of voltage and light conditions. Devices respond to illumination at wavelengths in the range of 410–650 nm but are unresponsive at 1152 nm, suggesting that photons are absorbed by the bottom p-type silicon electrode and that generation of free carriers underpins optical activity. Applied light causes charging of devices in the high resistance state (HRS), photocurrent in the low resistance state (LRS), and lowering of the set voltage (required to go from the HRS to LRS) and can be used in conjunction with a voltage bias to trigger switching from the HRS to the LRS. We demonstrate negative correlation between set voltage and applied laser power using a 632.8 nm laser source. We propose that, under illumination, increased electron injection and hence a higher rate of creation of Frenkel pairs in the oxide—precursors for the formation of conductive oxygen vacancy filaments—reduce switching voltages. Our results open up the possibility of light-triggered RRAM devices.

Design of wafer-scale uniform Au nanotip array by ion irradiation for enhanced single conductive filament resistive switching

Resistive switching mechanism of zirconium oxide-based resistive random access memory (RRAM) devices composed of Cu-doped ZrO2 film sandwiched between an oxidizable electrode and an inert electrode was investigated. The Ag/ZrO2:Cu/Pt RRAM devices with crosspoint structure fabricated by e-beam evaporation and e-beam lithography show reproducible bipolar resistive switching. The linear I–V relationship of low resistance state (LRS) and the dependence of LRS resistance (RON) and reset current (Ireset) on the set current compliance (Icomp) indicate that the observed resistive switching characteristics of the Ag/ZrO2:Cu/Pt device should be ascribed to the formation and annihilation of localized conductive filaments (CFs). The physical origin of CF was further analyzed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). CFs were directly observed by cross-sectional TEM. According to EDS and elemental mapping analysis, the main chemical composition of CF is determined by Ag atoms, coming from the Ag top electrode. On the basis of these experiments, we propose that the set and reset process of the device stem from the electrochemical reactions in the zirconium oxide under different external electrical stimuli.

Stable switching behavior of low-temperature ZrO2 RRAM devices realized by combustion synthesis-assisted photopatterning