Low voltage resistive switching behavior of Al/HfO x /Au structure on ultra-flexible polyimide substrate
01 Dec 2016-pp 1-4
TL;DR: In this paper, bipolar resistive switching behavior in Al/HfO x /Au resistive random access memory (RRAM) devices fabricated on ultra-flexible polyimide substrates is demonstrated.
Abstract: Flexible resistive switching memory device is an excellent option for future high density memory and flexible electronics applications. Here, bipolar resistive switching behavior in Al/HfO x /Au resistive random access memory (RRAM) devices fabricated on ultra-flexible polyimide substrates is demonstrated. These devices can be programmed at read-write voltages as low as 0.18 V with on-off current ratios (I on /I off ) of 18, resistance ratio of ∼41 in high and low resistance states (HRS & LRS) and stable set and reset voltages over 16 cycles of operation. The mechanism of resistive switching in these devices is explained with help of filament formation and rupture process due to oxygen vacancy and oxygen ions migration. Ohmic conduction prevails in HRS and LRS whereas conduction mechanism is dominated by space charge limited conduction (SCLC). These flexible RRAM devices could be an excellent option for future high density memory applications.
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27 Nov 2002
TL;DR: Inference procedures for Log-Location-Scale Distributions as discussed by the authors have been used for estimating likelihood and estimating function methods. But they have not yet been applied to the estimation of likelihood.
Abstract: Basic Concepts and Models. Observation Schemes, Censoring and Likelihood. Some Nonparametric and Graphical Procedures. Inference Procedures for Parametric Models. Inference procedures for Log-Location-Scale Distributions. Parametric Regression Models. Semiparametric Multiplicative Hazards Regression Models. Rank-Type and Other Semiparametric Procedures for Log-Location-Scale Models. Multiple Modes of Failure. Goodness of Fit Tests. Beyond Univariate Survival Analysis. Appendix A. Glossary of Notation and Abbreviations. Appendix B. Asymptotic Variance Formulas, Gamma Functions and Order Statistics. Appendix C. Large Sample Theory for Likelihood and Estimating Function Methods. Appendix D. Computational Methods and Simulation. Appendix E. Inference in Location-Scale Parameter Models. Appendix F. Martingales and Counting Processes. Appendix G. Data Sets. References.
4,151 citations
TL;DR: A comprehensive review of the recent progress in the so-called resistive random access memories (RRAMs) can be found in this article, where a brief introduction is presented to describe the construction and development of RRAMs, their potential for broad applications in the fields of nonvolatile memory, unconventional computing and logic devices, and the focus of research concerning RRAMS over the past decade.
Abstract: This review article attempts to provide a comprehensive review of the recent progress in the so-called resistive random access memories (RRAMs) First, a brief introduction is presented to describe the construction and development of RRAMs, their potential for broad applications in the fields of nonvolatile memory, unconventional computing and logic devices, and the focus of research concerning RRAMs over the past decade Second, both inorganic and organic materials used in RRAMs are summarized, and their respective advantages and shortcomings are discussed Third, the important switching mechanisms are discussed in depth and are classified into ion migration, charge trapping/de-trapping, thermochemical reaction, exclusive mechanisms in inorganics, and exclusive mechanisms in organics Fourth, attention is given to the application of RRAMs for data storage, including their current performance, methods for performance enhancement, sneak-path issue and possible solutions, and demonstrations of 2-D and 3-D crossbar arrays Fifth, prospective applications of RRAMs in unconventional computing, as well as logic devices and multi-functionalization of RRAMs, are comprehensively summarized and thoroughly discussed The present review article ends with a short discussion concerning the challenges and future prospects of the RRAMs
1,129 citations
"Low voltage resistive switching beh..." refers background in this paper
...vacancy migration, and direct tunneling of charge carriers across thin insulating layers [18, 19]....
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TL;DR: The review ends with the current status of RRAMs in terms of stability, scalability and switching speed, which are three important aspects of integration onto semiconductors.
Abstract: The resistance switching behaviour of several materials has recently attracted considerable attention for its application in non-volatile memory (NVM) devices, popularly described as resistive random access memories (RRAMs). RRAM is a type of NVM that uses a material(s) that changes the resistance when a voltage is applied. Resistive switching phenomena have been observed in many oxides: (i) binary transition metal oxides (TMOs), e.g. TiO(2), Cr(2)O(3), FeO(x) and NiO; (ii) perovskite-type complex TMOs that are variously functional, paraelectric, ferroelectric, multiferroic and magnetic, e.g. (Ba,Sr)TiO(3), Pb(Zr(x) Ti(1-x))O(3), BiFeO(3) and Pr(x)Ca(1-x)MnO(3); (iii) large band gap high-k dielectrics, e.g. Al(2)O(3) and Gd(2)O(3); (iv) graphene oxides. In the non-oxide category, higher chalcogenides are front runners, e.g. In(2)Se(3) and In(2)Te(3). Hence, the number of materials showing this technologically interesting behaviour for information storage is enormous. Resistive switching in these materials can form the basis for the next generation of NVM, i.e. RRAM, when current semiconductor memory technology reaches its limit in terms of density. RRAMs may be the high-density and low-cost NVMs of the future. A review on this topic is of importance to focus concentration on the most promising materials to accelerate application into the semiconductor industry. This review is a small effort to realize the ambitious goal of RRAMs. Its basic focus is on resistive switching in various materials with particular emphasis on binary TMOs. It also addresses the current understanding of resistive switching behaviour. Moreover, a brief comparison between RRAMs and memristors is included. The review ends with the current status of RRAMs in terms of stability, scalability and switching speed, which are three important aspects of integration onto semiconductors.
950 citations
"Low voltage resistive switching beh..." refers background in this paper
...Since the evolution of computers, the main focus of microelectronics research was on metal oxide semiconductor field effect transistor (MOSFET) based flash memories [1], which have captured a big market of secondary memory devices due to its low cost and high density [1-3]....
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TL;DR: New non-volatile memory devices store information using different physical mechanisms from those employed in today's memories and could achieve substantial improvements in computing performance and energy efficiency.
Abstract: New non-volatile memory devices store information using different physical mechanisms from those employed in today's memories and could achieve substantial improvements in computing performance and energy efficiency.
677 citations
Additional excerpts
...magnetic RAM (MRAM), phase-change RAM (PCRAM) and resistive RAM (RRAM) [2, 6-8]....
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TL;DR: In this paper, the authors provide an overview of the underlying physics behind connectivity changes in highly conductive regions under an electric field, and discuss percolation model approaches and the theory for the scaling behaviors of numerous transport properties observed in RS.
Abstract: Resistive switching (RS) phenomena are reversible changes in the metastable resistance state induced by external electric fields. After discovery ∼50 years ago, RS phenomena have attracted great attention due to their potential application in next-generation electrical devices. Considerable research has been performed to understand the physical mechanisms of RS and explore the feasibility and limits of such devices. There have also been several reviews on RS that attempt to explain the microscopic origins of how regions that were originally insulators can change into conductors. However, little attention has been paid to the most important factor in determining resistance: how conducting local regions are interconnected. Here, we provide an overview of the underlying physics behind connectivity changes in highly conductive regions under an electric field. We first classify RS phenomena according to their characteristic current–voltage curves: unipolar, bipolar, and threshold switchings. Second, we outline the microscopic origins of RS in oxides, focusing on the roles of oxygen vacancies: the effect of concentration, the mechanisms of channel formation and rupture, and the driving forces of oxygen vacancies. Third, we review RS studies from the perspective of statistical physics to understand connectivity change in RS phenomena. We discuss percolation model approaches and the theory for the scaling behaviors of numerous transport properties observed in RS. Fourth, we review various switching-type conversion phenomena in RS: bipolar-unipolar, memory-threshold, figure-of-eight, and counter-figure-of-eight conversions. Finally, we review several related technological issues, such as improvement in high resistance fluctuations, sneak-path problems, and multilevel switching problems.
341 citations
"Low voltage resistive switching beh..." refers background in this paper
...magnetic RAM (MRAM), phase-change RAM (PCRAM) and resistive RAM (RRAM) [2, 6-8]....
[...]
...Since the evolution of computers, the main focus of microelectronics research was on metal oxide semiconductor field effect transistor (MOSFET) based flash memories [1], which have captured a big market of secondary memory devices due to its low cost and high density [1-3]....
[...]