An innovative and reliable RF setup based on sine wave stress is proposed, revealing for the first time that TDDB follows a kind of power law with frequency up to 15 GHz. A physical model based on dielectric relaxation is then proposed to explain the increase in TDDB with frequency. Finally, by using an effective duty factor for RF, AC and RF sine waves can be matched to derive a universal TDDB frequency behavior that is independent of the signal waveform.

This article discusses the effect of polarization relaxation on dielectric breakdown. We establish analytical statistical Weibull distributions, taking into account the changing local electric field instead of the usual static field in acceleration models. The time dependence of the local field is expressed using the universal Curie–Von Schweidler law. The derived distribution fits well with various observations on time-to-breakdown statistical distributions. In the case of voltage square pulse alternative stress, the calculated time to breakdown follows a power law with stress frequency, regardless of the field dependence of the acceleration model, consistent with observations. The dielectric lifetime is longer compared to continuous voltage stress, as observed in transistors and integrated capacitors. The analytical expression of the power law exponent depends on the field acceleration model and polarization current. It matches well with the measured values for metal–oxide–semiconductor and metal insulator metal capacitors with different dielectrics. The power law exponent increases with the static dielectric constant. The Weibull shape factor is shown to be lower in the AC mode than in the DC mode, as observed. The AC signal duty factor effect decreases the lifetime in the AC mode. Finally, we demonstrate that the consequence of polarization relaxation also affects the lifetime in the DC mode. The acceleration factor and lifetime projections are close to power laws with the field, regardless of the static field dependence of the acceleration model.

Neuromorphic computing has recently emerged as a potential alternative to the conventional von Neumann computer paradigm, which is inherently limited due to its architectural bottleneck. Thus, new artificial components and architectures for brain-inspired computing hardware implementation are required. Bipolar analog memristive devices, whose resistance (or conductance) can be continuously tuned (as a synaptic weight), are potential candidates for artificial synapse applications. In this work, lanthanum nickelate (La 2 NiO 4+ δ , L2NO4), a mixed ionic electronic conducting oxide, is used in combination with TiN and Pt electrodes. The TiN/L2NO4/Pt devices show bipolar resistive switching with gradual transitions both for the SET and RESET processes. The resistance (conductance) can be gradually modulated by the pulse amplitude and duration, showing good data retention characteristics. A linear relationship between the resistance change and total applied pulse duration is experimentally measured. Moreover, synaptic depression and potentiation characteristics, one of the important functions of bio-synapses, are artificially reproduced for these devices, then modeled and successfully tested in a spiking neural network environment. These results indicate the suitability of using TiN/L2NO4/Pt memristive devices as long-term artificial synapses in neuromorphic computing.

Recently, the development of zero-dimensional (0D) materials has experienced significant growth. Among them, PbS colloidal quantum dots (CQDs) have received special attention due to their outstanding properties, including tunable optical absorption ranging from 600 to 2600 nm (size dependent bandgap) and easy solution synthesis. PbS CQDs are considered as one of the most promising materials for the next generation of infrared sensors. Hence, there is a growing interest in their use in industrial spheres. One of the major keys to obtaining high-performance devices is the realization of efficient charge extraction contacts on PbS CQDs films. In this work, we have demonstrated an efficient hole extraction layer (HEL) using NiOx ultra-thin film on infrared p-i-n photodiode based on only n-type PbS nanocrystals (CQDs). We compared the performance with the standard optimized MoOx. We obtained a significant gain in external quantum efficiency (EQE), a decrease of the operating bias, while keeping the same dark current level.

This paper deals with the set and reset time measurements of a resistive memory consisting of a Ti/TiN/HfO2 layer stack contacted with the tip of a conductive atomic force microscope in ultra high vacuum. We present measurements of the set and reset switching times in voltage pulse regime for different voltages and compliance currents. The experimental results are well reproduced by simulation. We derive analytical expressions for the set and reset times as function of experimental conditions. The effect of voltage and current on reset and set switching times is then discussed with the help of their analytical expressions, which are also applied on standard devices characteristics.

In this work, a new model of the time-dependent dielectric breakdown is proposed as a function of frequency. This is an analytical model based on an experimental observations of gate oxide breakdown at high frequencies on 28nm FDSOI technology in NMOS. This model considers two significant conditions: at first, the defect generation rate in the gate oxide is not constant over time, secondly, the recovery time is negligible. Following the experimental evidences, we found it possible to model four important characteristics of AC breakdown: frequency dependence, voltage acceleration factor (VAF), activation energy Ea, and the change of Weibull slope from DC to AC.

Data for publication: La2NiO4+δ-Based Memristive Devices Integrated on Si-Based Substrates

Valence change memories, in which internal redox reactions control the change in resistance are promising candidates for resistive random access memories (ReRAMs) and neuromorphic computing elements. In this context, La 2 NiO 4+ δ (L2NO4), a mixed ionic‐electronic conducting oxide, well known for its highly mobile oxygen interstitial ions, emerges as a potential switching material for novel L2NO4‐based memristive devices. However, their integration in complementary metal oxide semiconductor (CMOS) technology still has to be demonstrated, as the major focus of previous studies has been carried out on epitaxial films grown on single crystals. In this work, the optimization of the deposition temperature and precursor solution composition is presented, allowing to obtain high‐quality polycrystalline L2NO4 thin films grown by metal organic chemical vapor deposition on a platinized silicon substrate, and to use these films to build memristive devices in vertical configuration with Ti top electrodes. A bipolar analog‐type transition in resistance can be achieved in Ti/L2NO4/Pt memristive devices. While the “forming” process required for the devices based on nonoptimized L2NO4 thin films is considered as a drawback, the Ti/optimized L2NO4/Pt devices are forming‐free and exhibit a good cyclability. These results prove the switching response of L2NO4‐based devices in a vertical configuration for the first time.

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.

Metal oxide-based resistive random access memory devices are highly attractive candidates for next-generation nonvolatile memories, but the resistive switching phenomena remain poorly understood. This article focuses on the microscopic understanding of the initial forming step, which is decisive for the switching process. The integrated resistive switching memory effect in Ti/HfO2/TiWN metal insulator metal structures is studied. After forming, transmission electron microscopy investigations pointed out the presence of a funnel-shaped region, in the ON state of the cell, where slightly oxidized Ti (TiOx) was present within HfO2 dielectric. Modeling of the measured ON state conductance of the cell with the semi-classical approximation is consistent with a conductive nanometric TiOx filament (or a sum of sub-nanometric TiOx filaments) present in the funnel-shaped region. The conductive area is likely formed by diffusion after the dielectric breakdown.

In this work we report on the integration of indium oxide (In2O3) nanoparticles (NPs) for Resistive Random Access Memory (RRAM) applications. This low-temperature integration process is fully compatible CMOS Back-End integration given a carefull selection of materials deposited by MOCVD and ALD. A detailed description of the process is provided together with AFM analysis performed on the indium oxide nanoparticles and TEM cross-sections on the whole stack. It is shown that the introduction of In2O3 NPs provides bipolar switching behavior together with promising electrical performances in terms of large OFF/ON resistance ratio (106) and retention time at room temperature.

The ternary alloy GeSbTe is widely used as material for phase-change memories. Thanks to an optimized Ge-rich GeSbTe alloy, the crystallizion temperature of the alloy is increased and the stability requirements of high working temperature required for automotive applications are fullfilled, but the crystallization of the Ge-rich alloy proceeds with a composition change and a phase separation. We have developed a multi-phase-field model for the crystallization of the Ge-rich GeSbTe alloy and we have coupled it to an electro-thermal solver. This model is able to capture both the emergence of a two-phase polycristalline structure starting from an initially amorphous material, and the melting and recrystallization during the device operations.

The ternary alloy of germanium, antimony, and tellurium (GST) is widely used as a material for phase-change memories. In particular, the stoichiometric compound Ge2Sb2Te5 exhibits a rapid congruent crystallization. To increase the temperature at which spontaneous crystallization erases the stored information, alloys that are enriched in germanium have been investigated. Their crystallization is accompanied by segregation and eventually the nucleation of a new, germanium-rich phase. In order to model the redistribution of alloy components and the time evolution of the microstructure during device operations, we develop a multi-phase-field model for the crystallization of GST that includes segregation and couple it with orientation fields that describe the grain structure. We demonstrate that this model is capable to capture both the emergence of a two-phase polycrystalline structure starting from an initially amorphous material, and the melting and recrystallization during the SET and RESET operations in a memory cell of the “wall” type.

In this work, we propose a novel integration in order to significantly reduce the High Resistance State vari-ability and to improve thermal stability in Oxide-based Resistive Random Access Memory (OxRRAM) devices. A novel device featuring a metallic liner, acting as a parallel resistance, is presented. To assess the effect of this solution, we compare the results with a standard OxRRAM cell structure. A very good stability of the resistive states, both in endurance and temperature, is highlighted and explained thanks to a conductive fila-ment based model.