scholarly journals Multi-Level Control of Resistive RAM (RRAM) Using a Write Termination to Achieve 4 Bits/Cell in High Resistance State

Electronics ◽  
2021 ◽  
Vol 10 (18) ◽  
pp. 2222
Author(s):  
Hassan Aziza ◽  
Said Hamdioui ◽  
Moritz Fieback ◽  
Mottaqiallah Taouil ◽  
Mathieu Moreau ◽  
...  
Keyword(s):  
High Capacity ◽  
Average Energy ◽  
High Resistance State ◽  
Level Control ◽  
Power Efficient ◽  
Analog Resistance ◽  
Resistance State ◽  
Multi Level ◽  
Average Energy Consumption ◽  
First Time

RRAM density enhancement is essential not only to gain market share in the highly competitive emerging memory sector but also to enable future high-capacity and power-efficient brain-inspired systems, beyond the capabilities of today’s hardware. In this paper, a novel design scheme is proposed to realize reliable and uniform multi-level cell (MLC) RRAM operation without the need of any read verification. RRAM quad-level cell (QLC) capability with 4 bits/cell is demonstrated for the first time. QLC is implemented based on a strict control of the cell programming current of 1T-1R HfO2-based RRAM cells. From a design standpoint, a self-adaptive write termination circuit is proposed to control the RESET operation and provide an accurate tuning of the analog resistance value of each cell of a memory array. The different resistance levels are obtained by varying the compliance current in the RESET direction. Impact of variability on resistance margins is simulated and analyzed quantitatively at the circuit level to guarantee the robustness of the proposed MLC scheme. The minimal resistance margin reported between two consecutive states is 2.1 kΩ along with an average energy consumption and latency of 25 pJ/cell and 1.65 μs, respectively.

Vanadium Oxide Based RRAM Device

MRS Advances ◽  
2017 ◽  
Vol 2 (52) ◽  
pp. 3019-3024
Author(s):  
Zhenni Wan ◽  
Robert B. Darling ◽  
M. P. Anantram
Keyword(s):  
Electric Field ◽  
Vanadium Oxide ◽  
Sandwich Structure ◽  
Common Ground ◽  
High Resistance State ◽  
Conducting Layer ◽  
Bipolar Resistive Switching ◽  
Resistance State ◽  
Switching Characteristics ◽  
First Time

ABSTRACTForming-free bipolar resistive switching characteristics in a Vanadium oxide based sandwich structure is observed for the first time. The bottom conducting layer is the common ground electrode for all devices. The top conducting layer acts as an active element with an additional Cr/Al/Cr electrode patterned on its top for making contact. Different from the typical metal/transition metal oxide/metal sandwich structure based resistive memories, our device exhibits a low resistance state (LRS) in its virgin state, and can be switched to a high resistance state (HRS) when a positive bias of +2.5V is applied to the top electrode. Following this, the device can be reset to a LRS when a negative bias of approximately 2.5V is applied. A significant decrease of switching voltages is observed when the diameter of the top contact decreases, indicating an electric field enhanced switching mechanism. Simulation using TCAD confirms that electric field beneath the top metal contact increases due to fringing. The results suggest future applications in low power integrated non-volatile memories.

scholarly journals Nano-Graphitic based Non-Volatile Memories Fabricated by the Dynamic Spray-Gun Deposition Method

Micromachines ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 95 ◽  
Author(s):  
Paolo Bondavalli ◽  
Marie Martin ◽  
Louiza Hamidouche ◽  
Alberto Montanaro ◽  
Aikaterini-Flora Trompeta ◽  
...  
Keyword(s):  
Random Access ◽  
High Resistance State ◽  
Resistive Random Access Memory ◽  
Deposition Method ◽  
Metal Insulator Metal ◽  
Oxidized Carbon ◽  
Resistance State ◽  
Scientific Group ◽  
First Time ◽  
Spray Gun

This paper deals with the fabrication of Resistive Random Access Memory (ReRAM) based on oxidized carbon nanofibers (CNFs). Stable suspensions of oxidized CNFs have been prepared in water and sprayed on an appropriate substrate, using the dynamic spray-gun deposition method, developed at Thales Research and Technology. This technique allows extremely uniform mats to be produced while heating the substrate at the boiling point of the solvent used for the suspensions. A thickness of around 150 nm of CNFs sandwiched between two metal layers (the metalized substrate and the top contacts) has been achieved, creating a Metal-Insulator-Metal (MIM) structure typical of ReRAM. After applying a bias, we were able to change the resistance of the oxidized layer between a low (LRS) and a high resistance state (HRS) in a completely reversible way. This is the first time that a scientific group has produced this kind of device using CNFs and these results pave the way for the further implementation of this kind of memory on flexible substrates.

Time Voltage Dependency in Resistance Switching TiO2

2012 ◽  
Vol 1430 ◽  
Author(s):  
Christian Nauenheim ◽  
Dominique Drouin ◽  
Rainer Waser ◽  
Andreas Ruediger
Keyword(s):  
Operation Time ◽  
Memory Cell ◽  
High Resistance State ◽  
Memory Systems ◽  
Resistance Switching ◽  
Additional Insight ◽  
Metal Insulator Metal ◽  
Resistance State ◽  
Multi Level ◽  
Insight Into

ABSTRACTResistively switching TiO2 thin films show a multitude of resistance states, which are achieved during the programming and erasing of a memory cell. These resistance states depend on the applied voltage and the allowed current. Additionally, the operation time has a relevant influence on the adjusted resistance. This parameterization points out a potential application in future multi-level cell memory systems, but also determines the persistence of the non-volatile nature and provides an additional insight into the physics of the resistance switching. Our devices consist of metal-insulator-metal stacks made of Pt/TiO2/Ti/Pt, which are built up in crosspoint junctions. The maximum programming current and the maximum erase voltage amplitude were used to tune in the low resistance and high resistance state, respectively, in combination with the operation time. The corresponding dependencies were determined by quasi-static voltage sweeps, pulse bursts and single pulses of up to 4 V and down to 10 ns.

Functional Gradient Transparent Conducting Oxide Nanowire Arrays as Monophasic Schottky-Barrier Free Memristors for Bipolar Linear Switching

2020 ◽  
Author(s):  
Thomas Herzog ◽  
Naomi Weitzel ◽  
Sebastian Polarz
Keyword(s):  
Schottky Barrier ◽  
Data Storage ◽  
Tin Oxide ◽  
Transparent Conducting Oxide ◽  
Electrical Potential ◽  
High Resistance State ◽  
Nanowire Arrays ◽  
Metal Metal ◽  
Resistance State ◽  
Barrier Free

<div><div><div><p>One of the fascinating properties of metal-semiconductor Schottky-barriers, which has been observed for some material combinations, is memristive behavior. Memristors are smart, since they can reversibly switch between a low resistance state and a high resistance state. The devices offer a great potential for advanced computing and data storage, including neuromorphic networks and resistive random-access memory. However, as for many other cases, the presence of a real interface (metal - metal oxide) has numerous disadvantages. The realization of interface-free, respectively Schottky-barrier free memristors is highly desirable. The aim of the current paper is the generation of nanowire arrays with each nanorod possessing the same crystal phase (Rutile) and segments only differing in composition. The electric conductivity is realized by segments made of highly-doped antimony tin oxide (ATO) transitioning into pure tin oxide (TO). Complex nanoarchitectures are presented, which include ATO-TO, ATO-TO-ATO nanowires either with a stepwise distribution of antimony or as a graded functional material. The electrical characterization of the materials reveals that the introduction of memristive properties in such structures is possible. The special features observed in voltage-current (IV) curves are correlated to the behavior of mobile oxygen vacancies (VO..) at different values of applied electrical potential.</p></div></div></div>

Influence of Metal Substitution on the Pressure-Induced Phase Change in Flexible Zeolitic Imidazolate Frameworks

2018 ◽  
Author(s):  
C. Michael McGuirk ◽  
Tomče Runčevski ◽  
Julia Oktawiec ◽  
Ari Turkiewicz ◽  
mercedes K. taylor ◽  
...  
Keyword(s):  
Phase Change ◽  
Single Crystal ◽  
Gas Adsorption ◽  
High Capacity ◽  
Phase Changes ◽  
Zeolitic Imidazolate Frameworks ◽  
Metal Substitution ◽  
Heat Management ◽  
Metal Organic ◽  
First Time

<p>Metal–organic frameworks that display step-shaped adsorption profiles arising from discrete pressure-induced phase changes are promising materials for applications in both high-capacity gas storage and energy-efficient gas separations. The thorough investigation of such materials through chemical diversification, gas adsorption measurements, and <i>in situ </i>structural characterization is therefore crucial for broadening their utility. We examine a series of isoreticular, flexible zeolitic imidazolate frameworks (ZIFs) of the type M(bim)<sub>2</sub> (SOD; M = Zn<sup> </sup>(ZIF-7), Co (ZIF-9), Cd (CdIF-13); bim<sup>–</sup> = benzimidazolate), and elucidate the effects of metal substitution on the pressure-responsive phase changes and the resulting CO<sub>2</sub> and CH<sub>4</sub> step positions, pre-step uptakes, and step capacities. Using ZIF-7 as a benchmark, we reexamine the poorly understood structural transition responsible for its adsorption steps and, through high-pressure adsorption measurements, verify that it displays a step in its CH<sub>4 </sub>adsorption isotherms. The ZIF-9 material is shown to undergo an analogous phase change, yielding adsorption steps for CO<sub>2</sub> and CH<sub>4</sub> with similar profiles and capacities to ZIF-7, but with shifted threshold pressures. Further, the Cd<sup>2+</sup> analogue CdIF-13 is reported here for the first time, and shown to display adsorption behavior distinct from both ZIF-7 and ZIF-9, with negligible pre-step adsorption, a ~50% increase in CO<sub>2</sub> and CH<sub>4</sub> capacity, and dramatically higher threshold adsorption pressures. Remarkably, a single-crystal-to-single-crystal phase change to a pore-gated phase is also achieved with CdIF-13, providing insight into the phase change that yields step-shaped adsorption in these flexible ZIFs. Finally, we show that the endothermic phase change of these frameworks provides intrinsic heat management during gas adsorption. </p>

scholarly journals Gradually Modified Conductance in the Self-Compliance Region of an Atomic-Layer-Deposited Pt/TiO2/HfAlOx/TiN RRAM Device

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1199
Author(s):  
Hojeong Ryu ◽  
Sungjun Kim
Keyword(s):  
Photoelectron Spectroscopy ◽  
Depth Profiling ◽  
Atomic Layer ◽  
High Resistance State ◽  
Long Term Potentiation ◽  
Memory Device ◽  
Bipolar Resistive Switching ◽  
Term Potentiation ◽  
Resistance State ◽  
Neuromorphic System

This study presents conductance modulation in a Pt/TiO2/HfAlOx/TiN resistive memory device in the compliance region for neuromorphic system applications. First, the chemical and material characteristics of the atomic-layer-deposited films were verified by X-ray photoelectron spectroscopy depth profiling. The low-resistance state was effectively controlled by the compliance current, and the high-resistance state was adjusted by the reset stop voltage. Stable endurance and retention in bipolar resistive switching were achieved. When a compliance current of 1 mA was imposed, only gradual switching was observed in the reset process. Self-compliance was used after an abrupt set transition to achieve a gradual set process. Finally, 10 cycles of long-term potentiation and depression were obtained in the compliance current region for neuromorphic system applications.

scholarly journals Nanostructured intermetallic InSb as a high-capacity and high-performance negative electrode for sodium-ion batteries

2021 ◽  
Author(s):  
Irshad Mohammad ◽  
Lucie Blondeau ◽  
Eddy Foy ◽  
Jocelyne Leroy ◽  
Eric Leroy ◽  
...  
Keyword(s):  
Intermetallic Compound ◽  
High Performance ◽  
High Capacity ◽  
Negative Electrode ◽  
Sodium Ion ◽  
Sodium Ion Batteries ◽  
Negative Electrodes ◽  
First Time

Following the trends of alloys as negative electrodes for Na-ion batteries, the sodiation of the InSb intermetallic compound was investigated for the first time. The benefit of coupling Sb with...

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