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Christophe Muller - One of the best experts on this subject based on the ideXlab platform.
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Role of Ti and Pt electrodes on resistance switching variability of HfO$_2$-based Resistive Random Access Memory
2012Co-Authors: T. Cabout, Carlo Cagli, Marc Bocquet, J. Buckley, Vincent Jousseaume, J. F. Nodin, Barbara De Salvo, Christophe MullerAbstract:This paper deals with the role of platinum or titanium–titanium nitride electrodes on variability of resistive switching characteristics and electrical performances of HfO2-based memory elements. Capacitor-like Pt/HfO2 (10 nm)/Pt and Ti/HfO2 (10 nm)/TiN structures were fabricated on top of a tungsten pillar bottom electrode and integrated in-between two interconnect metal lines. First, quasi-static measurements were performed to apprehend the role of electrodes on electroforming, set and Reset Operations and their corresponding switching parameters. Memory elements with Pt as top and bottom electrodes exhibited a non-polar behavior with sharp decrease of current during Reset Operation while Ti/HfO2/TiN capacitors showed a bipolar switching behavior, with a gradual Reset. In a second step, statistical distributions of switching parameters (voltage and resistance) were extracted from data obtained on few hundreds of capacitors. Even if the resistance in low resistive state and Reset voltage was found to be comparable for both types of electrodes, the progressive Reset Operation observed on samples with Ti/TiN electrodes led to a lower variability of resistance in high resistive state and concomitantly of set voltage. In addition Ti–TiN electrodes enabled gaining: (i) lower forming and set voltages with significantly narrower capacitor-to-capacitor distributions; (ii) a better data retention capability (10 years at 65 °C instead of 10 years at 50 °C for Pt electrodes); (iii) satisfactory dynamic performances with lower set and Reset voltages for ramp speed ranging from 10− 2 to 107 V/s. The significant improvement of switching behavior with Ti–TiN electrodes is mainly attributed to the formation of a native interface layer between HfO2 oxide and Ti top electrode.
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Resistance switching variability in HfO2-based memory structures with different electrodes
2012Co-Authors: T. Cabout, Carlo Cagli, J. Buckley, Vincent Jousseaume, J. F. Nodin, Barbara De Salvo, M. Bocquet, Christophe MullerAbstract:This paper deals with the effect of platinum or titanium-based electrodes on resistive switching characteristics and electrical performances of HfO2-based memory elements. Capacitor-like Pt/HfO2(10nm)/Pt and Ti/HfO2(10nm)/TiN structures were fabricated on top of a tungsten pillar bottom electrode and integrated in-between two interconnect metal lines. Initially, quasi-static measurements were performed to study the influence of electrode nature on forming, set and Reset Operations and their corresponding switching parameters. Memory elements with top and bottom Pt electrodes exhibited a non-polar behavior with sharp decrease of current during Reset Operation while cells integrating Ti-based electrodes showed a bipolar switching behavior, with a progressive Reset. Then, statistical distribution of switching parameters (voltage and resistance) were extracted from data obtained on hundreds of memory devices. Even if the resistance in the low resistive state (LRS) and the Reset voltage were found to be comparable for both kinds of electrodes. On the other hand, the progressive Reset Operation observed on samples with Ti-based electrodes led to a lower variability of resistance in high resistive state (HRS) and subsequently of set voltage. In addition Ti-based electrodes enabled gaining: (i) lower forming and set voltages with significantly narrower cell-to-cell distributions; (ii) a better data retention (10 years at 65°C instead of 10 years at 50°C for Pt electrodes); (iii) satisfactory dynamic performances with lower set and Reset voltages for ramp speed ranging from 10-2 to 107 V/s.
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Ge2Sb2Te5 layer used as solid electrolyte in conductive-bridge memory devices fabricated on flexible substrate
Solid-State Electronics, 2012Co-Authors: D. Deleruyelle, Marc Bocquet, Magali Putero, T. Ouled-khachroum, M.v. Coulet, Xavier Boddaert, C. Calmes, Christophe MullerAbstract:This paper shows that the well-know chalcogenide Ge2Sb2Te5 (GST) in its amorphous state may be advantageously used as solid electrolyte material to fabricate Conductive-Bridge Random Access Memory (CBRAM) devices. GST layer was sputtered on preliminary inkjet-printed silver lines acting as active electrode on either silicon or plastic substrates. Whatever the substrate, the resistance switching is unambiguously attested at a nanoscale by means of conductive-atomic force microscopy (C-AFM) using a Pt-Ir coated tip on the GST surface acting as a passive electrode. The resistance change is correlated to the appearance or disappearance of concomitant hillocks and current spots at the surface of the GST layer. This feature is attributed to the formation/dissolution of a silver-rich protrusion beneath the AFM tip during set/Reset Operation. Beside, this paper constitutes a step toward the elaboration of crossbar memory arrays on flexible substrates since CBRAM Operations were demonstrated on W/GST/Ag crossbar memory cells obtained from an heterogeneous fabrication process combining physical deposition and inkjet-printing.
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Self-consistent physical modeling of set/Reset Operations in unipolar resistive-switching memories
Applied Physics Letters, 2011Co-Authors: Marc Bocquet, Damien Deleruyelle, Christophe Muller, Jean-michel PortalAbstract:This Letter deals with a self-consistent physical model for set/Reset Operations involved in unipolar resistive switching memories integrating a transition metal oxide. In this model, set Operation is described in terms of a local electrochemical reduction of the oxide leading to the formation of metallic conductive filaments. Beside, Reset Operation relies on the thermally assisted destruction of the formed metallic filaments by Joule heating effect. An excellent agreement is demonstrated with numerous published experimental data suggesting that this model can be confidently implemented into circuit simulators for design purpose.
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Self-consistent physical modeling of set/Reset Operations in unipolar resistive-switching memories
Applied Physics Letters, 2011Co-Authors: Marc Bocquet, Damien Deleruyelle, Christophe Muller, Jean-michel PortalAbstract:This letter deals with a self-consistent physical model for set/Reset Operations involved in unipolar resistive switching memories integrating a transition metal oxide. In this model, set Operation is described in terms of a local electrochemical reduction of the oxide leading to the formation of metallic conductive filaments. Beside, Reset Operation relies on the thermally-assisted destruction of the formed metallic filaments by Joule heating effect. An excellent agreement is demonstrated with numerous published experimental data suggesting that this model can be confidently implemented into circuit simulators for design purpose. Memory devices based on resistive switching materials are currently pointed out as promising candidates to replace conventional non-volatile memory devices based on charge-storage beyond 2x nm-technological nodes. 1 In particular, devices integrating a transition metal oxide (so-called TMO) such as NiO, TiO 2 , ZnO or Cu x O, are of growing interest due to their simple Metal/Insulator/Metal (MIM) structure, oxides compatible with complementary metal-oxide-semiconductor technology and low process temperature. 2 So far, in TMO-based memory devices, the unipolar switching between low resistance state (LRS) and high resistance state (HRS) is explained in terms of creation/destruction of conductive filaments within the oxide. 3,4 Waser et al. 5 explained that set, i.e. the transition from HRS to LRS, originates from a local reduction reaction leading to the creation of metallic conductive filaments (CF). During Reset, local dissipation of Joule power enhances the thermally activated diffusion of defects and/or of different atomic species constituting the CF combined with a local oxidation process. 6,7 Based on this phenomenological description , several models for Reset were reported in Refs. 8–10 but very few offer a model for set. 11 Furthermore, it has to be stressed that there is currently no complete model taking into account both set and Reset Operations that could be easily implemented in circuit simulators for design purpose. In this context, this paper proposes a self-consistent physical model accounting for both set/Reset Operations in NiO-based unipolar resistive switching devices. After uncovering the theoretical background and the set of relevant physical parameters, the model is confronted to quasi-static and dynamic experimental data from literature. Fig.
Jean-michel Portal - One of the best experts on this subject based on the ideXlab platform.
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Self-consistent physical modeling of set/Reset Operations in unipolar resistive-switching memories
Applied Physics Letters, 2011Co-Authors: Marc Bocquet, Damien Deleruyelle, Christophe Muller, Jean-michel PortalAbstract:This Letter deals with a self-consistent physical model for set/Reset Operations involved in unipolar resistive switching memories integrating a transition metal oxide. In this model, set Operation is described in terms of a local electrochemical reduction of the oxide leading to the formation of metallic conductive filaments. Beside, Reset Operation relies on the thermally assisted destruction of the formed metallic filaments by Joule heating effect. An excellent agreement is demonstrated with numerous published experimental data suggesting that this model can be confidently implemented into circuit simulators for design purpose.
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Self-consistent physical modeling of set/Reset Operations in unipolar resistive-switching memories
Applied Physics Letters, 2011Co-Authors: Marc Bocquet, Damien Deleruyelle, Christophe Muller, Jean-michel PortalAbstract:This letter deals with a self-consistent physical model for set/Reset Operations involved in unipolar resistive switching memories integrating a transition metal oxide. In this model, set Operation is described in terms of a local electrochemical reduction of the oxide leading to the formation of metallic conductive filaments. Beside, Reset Operation relies on the thermally-assisted destruction of the formed metallic filaments by Joule heating effect. An excellent agreement is demonstrated with numerous published experimental data suggesting that this model can be confidently implemented into circuit simulators for design purpose. Memory devices based on resistive switching materials are currently pointed out as promising candidates to replace conventional non-volatile memory devices based on charge-storage beyond 2x nm-technological nodes. 1 In particular, devices integrating a transition metal oxide (so-called TMO) such as NiO, TiO 2 , ZnO or Cu x O, are of growing interest due to their simple Metal/Insulator/Metal (MIM) structure, oxides compatible with complementary metal-oxide-semiconductor technology and low process temperature. 2 So far, in TMO-based memory devices, the unipolar switching between low resistance state (LRS) and high resistance state (HRS) is explained in terms of creation/destruction of conductive filaments within the oxide. 3,4 Waser et al. 5 explained that set, i.e. the transition from HRS to LRS, originates from a local reduction reaction leading to the creation of metallic conductive filaments (CF). During Reset, local dissipation of Joule power enhances the thermally activated diffusion of defects and/or of different atomic species constituting the CF combined with a local oxidation process. 6,7 Based on this phenomenological description , several models for Reset were reported in Refs. 8–10 but very few offer a model for set. 11 Furthermore, it has to be stressed that there is currently no complete model taking into account both set and Reset Operations that could be easily implemented in circuit simulators for design purpose. In this context, this paper proposes a self-consistent physical model accounting for both set/Reset Operations in NiO-based unipolar resistive switching devices. After uncovering the theoretical background and the set of relevant physical parameters, the model is confronted to quasi-static and dynamic experimental data from literature. Fig.
Marc Bocquet - One of the best experts on this subject based on the ideXlab platform.
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Role of Ti and Pt electrodes on resistance switching variability of HfO$_2$-based Resistive Random Access Memory
2012Co-Authors: T. Cabout, Carlo Cagli, Marc Bocquet, J. Buckley, Vincent Jousseaume, J. F. Nodin, Barbara De Salvo, Christophe MullerAbstract:This paper deals with the role of platinum or titanium–titanium nitride electrodes on variability of resistive switching characteristics and electrical performances of HfO2-based memory elements. Capacitor-like Pt/HfO2 (10 nm)/Pt and Ti/HfO2 (10 nm)/TiN structures were fabricated on top of a tungsten pillar bottom electrode and integrated in-between two interconnect metal lines. First, quasi-static measurements were performed to apprehend the role of electrodes on electroforming, set and Reset Operations and their corresponding switching parameters. Memory elements with Pt as top and bottom electrodes exhibited a non-polar behavior with sharp decrease of current during Reset Operation while Ti/HfO2/TiN capacitors showed a bipolar switching behavior, with a gradual Reset. In a second step, statistical distributions of switching parameters (voltage and resistance) were extracted from data obtained on few hundreds of capacitors. Even if the resistance in low resistive state and Reset voltage was found to be comparable for both types of electrodes, the progressive Reset Operation observed on samples with Ti/TiN electrodes led to a lower variability of resistance in high resistive state and concomitantly of set voltage. In addition Ti–TiN electrodes enabled gaining: (i) lower forming and set voltages with significantly narrower capacitor-to-capacitor distributions; (ii) a better data retention capability (10 years at 65 °C instead of 10 years at 50 °C for Pt electrodes); (iii) satisfactory dynamic performances with lower set and Reset voltages for ramp speed ranging from 10− 2 to 107 V/s. The significant improvement of switching behavior with Ti–TiN electrodes is mainly attributed to the formation of a native interface layer between HfO2 oxide and Ti top electrode.
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Ge2Sb2Te5 layer used as solid electrolyte in conductive-bridge memory devices fabricated on flexible substrate
Solid-State Electronics, 2012Co-Authors: D. Deleruyelle, Marc Bocquet, Magali Putero, T. Ouled-khachroum, M.v. Coulet, Xavier Boddaert, C. Calmes, Christophe MullerAbstract:This paper shows that the well-know chalcogenide Ge2Sb2Te5 (GST) in its amorphous state may be advantageously used as solid electrolyte material to fabricate Conductive-Bridge Random Access Memory (CBRAM) devices. GST layer was sputtered on preliminary inkjet-printed silver lines acting as active electrode on either silicon or plastic substrates. Whatever the substrate, the resistance switching is unambiguously attested at a nanoscale by means of conductive-atomic force microscopy (C-AFM) using a Pt-Ir coated tip on the GST surface acting as a passive electrode. The resistance change is correlated to the appearance or disappearance of concomitant hillocks and current spots at the surface of the GST layer. This feature is attributed to the formation/dissolution of a silver-rich protrusion beneath the AFM tip during set/Reset Operation. Beside, this paper constitutes a step toward the elaboration of crossbar memory arrays on flexible substrates since CBRAM Operations were demonstrated on W/GST/Ag crossbar memory cells obtained from an heterogeneous fabrication process combining physical deposition and inkjet-printing.
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Self-consistent physical modeling of set/Reset Operations in unipolar resistive-switching memories
Applied Physics Letters, 2011Co-Authors: Marc Bocquet, Damien Deleruyelle, Christophe Muller, Jean-michel PortalAbstract:This Letter deals with a self-consistent physical model for set/Reset Operations involved in unipolar resistive switching memories integrating a transition metal oxide. In this model, set Operation is described in terms of a local electrochemical reduction of the oxide leading to the formation of metallic conductive filaments. Beside, Reset Operation relies on the thermally assisted destruction of the formed metallic filaments by Joule heating effect. An excellent agreement is demonstrated with numerous published experimental data suggesting that this model can be confidently implemented into circuit simulators for design purpose.
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Self-consistent physical modeling of set/Reset Operations in unipolar resistive-switching memories
Applied Physics Letters, 2011Co-Authors: Marc Bocquet, Damien Deleruyelle, Christophe Muller, Jean-michel PortalAbstract:This letter deals with a self-consistent physical model for set/Reset Operations involved in unipolar resistive switching memories integrating a transition metal oxide. In this model, set Operation is described in terms of a local electrochemical reduction of the oxide leading to the formation of metallic conductive filaments. Beside, Reset Operation relies on the thermally-assisted destruction of the formed metallic filaments by Joule heating effect. An excellent agreement is demonstrated with numerous published experimental data suggesting that this model can be confidently implemented into circuit simulators for design purpose. Memory devices based on resistive switching materials are currently pointed out as promising candidates to replace conventional non-volatile memory devices based on charge-storage beyond 2x nm-technological nodes. 1 In particular, devices integrating a transition metal oxide (so-called TMO) such as NiO, TiO 2 , ZnO or Cu x O, are of growing interest due to their simple Metal/Insulator/Metal (MIM) structure, oxides compatible with complementary metal-oxide-semiconductor technology and low process temperature. 2 So far, in TMO-based memory devices, the unipolar switching between low resistance state (LRS) and high resistance state (HRS) is explained in terms of creation/destruction of conductive filaments within the oxide. 3,4 Waser et al. 5 explained that set, i.e. the transition from HRS to LRS, originates from a local reduction reaction leading to the creation of metallic conductive filaments (CF). During Reset, local dissipation of Joule power enhances the thermally activated diffusion of defects and/or of different atomic species constituting the CF combined with a local oxidation process. 6,7 Based on this phenomenological description , several models for Reset were reported in Refs. 8–10 but very few offer a model for set. 11 Furthermore, it has to be stressed that there is currently no complete model taking into account both set and Reset Operations that could be easily implemented in circuit simulators for design purpose. In this context, this paper proposes a self-consistent physical model accounting for both set/Reset Operations in NiO-based unipolar resistive switching devices. After uncovering the theoretical background and the set of relevant physical parameters, the model is confronted to quasi-static and dynamic experimental data from literature. Fig.
Antoine Petit - One of the best experts on this subject based on the ideXlab platform.
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CAV - Are Timed Automata Updatable
Computer Aided Verification, 2000Co-Authors: Patricia Bouyer, Catherine Dufourd, Emmanuel Fleury, Antoine PetitAbstract:In classical timed automata, as defined by Alur and Dill [AD90,AD94] and since widely studied, the only Operation allowed to modify the clocks is the Reset Operation. For instance, a clock can neither be set to a non-null constant value, nor be set to the value of another clock nor, in a non-deterministic way, to some value lower or higher than a given constant. In this paper we study in details such updates.
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Expressiveness of Updatable Timed Automata
2000Co-Authors: Patricia Bouyer, Catherine Dufourd, Emmanuel Fleury, Antoine PetitAbstract:Since their introduction by Alur and Dill, timed automata have been one of the most widely studied models for real-time systems. The syntactic extension of so-called updatable timed automata allows more powerful updates of clocks than the Reset Operation proposed in the original model. We prove that any language accepted by an updatable timed automaton (from classes where emptiness is decidable) is also accepted by a “classical” timed automaton. We propose even more precise results on bisimilarity between updatable and classical timed automata.
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Are Timed Automata Updatable ?
2000Co-Authors: Patricia Bouyer, Catherine Dufourd, Emmanuel Fleury, Antoine PetitAbstract:In classical timed automata, as dened by Alur and Dill [AD90,AD94] and since widely studied, the only Operation allowed to modify the clocks is the Reset Operation. For instance, a clock can neither be set to a non-null constant value, nor be set to the value of another clock nor, in a non-deterministic way, to some value lower or higher than a given constant. In this paper we study in details such updates. We characterize in a thin way the frontier between decidability and undecidability. Our main contributions are the following:- We exhibit many classes of updates for which emptiness is undecidable. These classes depend on the clock constraints that are used diagonal-free or not whereas it is well known that these two kinds of constraints are equivalent for classical timed automata.- We propose a generalization of the region automaton proposed by Alur and Dill, allowing to handle larger classes of updates. The complexity of the decision procedure remains Pspace-complete.
Damien Deleruyelle - One of the best experts on this subject based on the ideXlab platform.
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Self-consistent physical modeling of set/Reset Operations in unipolar resistive-switching memories
Applied Physics Letters, 2011Co-Authors: Marc Bocquet, Damien Deleruyelle, Christophe Muller, Jean-michel PortalAbstract:This Letter deals with a self-consistent physical model for set/Reset Operations involved in unipolar resistive switching memories integrating a transition metal oxide. In this model, set Operation is described in terms of a local electrochemical reduction of the oxide leading to the formation of metallic conductive filaments. Beside, Reset Operation relies on the thermally assisted destruction of the formed metallic filaments by Joule heating effect. An excellent agreement is demonstrated with numerous published experimental data suggesting that this model can be confidently implemented into circuit simulators for design purpose.
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Self-consistent physical modeling of set/Reset Operations in unipolar resistive-switching memories
Applied Physics Letters, 2011Co-Authors: Marc Bocquet, Damien Deleruyelle, Christophe Muller, Jean-michel PortalAbstract:This letter deals with a self-consistent physical model for set/Reset Operations involved in unipolar resistive switching memories integrating a transition metal oxide. In this model, set Operation is described in terms of a local electrochemical reduction of the oxide leading to the formation of metallic conductive filaments. Beside, Reset Operation relies on the thermally-assisted destruction of the formed metallic filaments by Joule heating effect. An excellent agreement is demonstrated with numerous published experimental data suggesting that this model can be confidently implemented into circuit simulators for design purpose. Memory devices based on resistive switching materials are currently pointed out as promising candidates to replace conventional non-volatile memory devices based on charge-storage beyond 2x nm-technological nodes. 1 In particular, devices integrating a transition metal oxide (so-called TMO) such as NiO, TiO 2 , ZnO or Cu x O, are of growing interest due to their simple Metal/Insulator/Metal (MIM) structure, oxides compatible with complementary metal-oxide-semiconductor technology and low process temperature. 2 So far, in TMO-based memory devices, the unipolar switching between low resistance state (LRS) and high resistance state (HRS) is explained in terms of creation/destruction of conductive filaments within the oxide. 3,4 Waser et al. 5 explained that set, i.e. the transition from HRS to LRS, originates from a local reduction reaction leading to the creation of metallic conductive filaments (CF). During Reset, local dissipation of Joule power enhances the thermally activated diffusion of defects and/or of different atomic species constituting the CF combined with a local oxidation process. 6,7 Based on this phenomenological description , several models for Reset were reported in Refs. 8–10 but very few offer a model for set. 11 Furthermore, it has to be stressed that there is currently no complete model taking into account both set and Reset Operations that could be easily implemented in circuit simulators for design purpose. In this context, this paper proposes a self-consistent physical model accounting for both set/Reset Operations in NiO-based unipolar resistive switching devices. After uncovering the theoretical background and the set of relevant physical parameters, the model is confronted to quasi-static and dynamic experimental data from literature. Fig.
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Direct Observation at Nanoscale of Resistance Switching in NiO Layers by Conductive-Atomic Force Microscopy
Applied Physics Express, 2011Co-Authors: Damien Deleruyelle, Christophe Muller, Carine Dumas, Marion Carmona, Sabina Spiga, Marco FanciulliAbstract:This paper reports a direct observation of resistive switching occurring on the nanoscale within NiO layers deposited on top of a tungsten pillar bottom electrode. Filamentary conduction was evidenced by atomic force microscopy using a conductive tip that enabled performing electroforming and Reset Operations at nanoscale. In the low resistive state, it is shown that the current is driven by multiple conductive nanometric regions in agreement with the filamentary conduction models. In the high resistive state, conduction originates from weak residual conductive regions remaining after Reset Operation. Finally, retention measurements performed at the nanoscale demonstrated the persistence of localized conductive regions after more than 30 days.