Enhancing simulation feasibility for multi-layer 2D MoS RRAM devices: reliability performance learnings from a passive network model.

While two-dimensional (2D) MoS has recently shown promise as a material for resistive random-access memory (RRAM) devices due to its demonstrated resistive switching (RS) characteristics, its practical application faces a significant challenge in industry regarding its limited yield and endurance. Our earlier work introduced an effective switching layer model to understand RS behavior in both mono- and multi-layered MoS. However, functioning as a phenomenological percolation modeling tool, it lacks the capability to accurately simulate the intricate current-voltage (-) characteristics of the device, thereby hindering its practical applicability in 2D RRAM research.

Programmable Retention Characteristics in MoS-Based Atomristors for Neuromorphic and Reservoir Computing Systems.

In this study, we investigate the coexistence of short- and long-term memory effects owing to the programmable retention characteristics of a two-dimensional Au/MoS/Au atomristor device and determine the impact of these effects on synaptic properties. This device is constructed using bilayer MoS in a crossbar structure. The presence of both short- and long-term memory characteristics is proposed by using a filament model within the bilayer transition-metal dichalcogenide.

Editorial for the Special Issue on the Progress of Emerging Hardware Development for Post-Moore's Computing.

The potential of machine learning and novel computing architecture can be exploited in the immediate future if more efficient hardware is developed that meets the special requirements of bio-inspired computing or unconventional computing schemes [...

A feasibility investigation of a pilot-scale bioelectrochemical coupled anaerobic digestion system with centric electrode module for real membrane manufacturing wastewater treatment.

The large-scale application of bioelectrochemical coupled anaerobic digestion (BES-AD) is limited by the matching of electrode configuration and the applicability of real wastewater. In this study, a pilot-scale BES-AD system with an effective system volume of 5 m and a 1 m volume of a carbon fiber brush electrode module was constructed and tested for treatment of the membrane manufacturing wastewater. The results showed that the BOD/COD of the wastewater was increased from 0.

The microbial synergy and response mechanisms of hydrolysis-acidification combined microbial electrolysis cell system with stainless-steel cathode for textile-dyeing wastewater treatment.

Microbial electrolysis cell (MEC) has been existing problems such as poor applicability to real wastewater and lack of cost-effective electrode materials in the practical application of refractory wastewater. A hydrolysis-acidification combined MEC system (HAR-MECs) with four inexpensive stainless-steel and conventional carbon cloth cathodes for the treatment of real textile-dyeing wastewater, which was fully evaluated the technical feasibility in terms of parameter optimization, spectral analysis, succession and cooperative/competition effect of microbial. Results showed that the optimum performance was achieved with a 12 h hydraulic retention time (HRT) and an applied voltage of 0.

Deciphering physicochemical properties and enhanced microbial electron transfer capacity by magnetic biochar.

Magnetic biochar is important for improving the electron transfer capacity (ETC) of microorganisms in wastewater treatment. In this study, three magnetic biochar under different pyrolysis temperatures (300, 500 and 700 °C) were prepared by co-precipitation, and their characteristics and impacts on mediating microbial ETC were investigated. Results indicated that magnetic biochar had a higher capacitance and conductivity than pyrolytic biochar, with the largest specific capacitance of 14.

Small biochar addition enhanced anammox granular sludge system for practical wastewater treatment: Performance and microbial community.

Anaerobic ammonium oxidation (Anammox) granular sludge (AnGS) has poor strength and is prone to disintegration under complex environmental conditions, especially in the presence of complex organic carbon, which renders the Anammox process instable. Herein, with a mixture of landfill leachate and domestic sewage as wastewater, the effect on the properties of AnGS with two small particle size (0.1-0.

Bioelectrochemical systems with a cathode of stainless-steel electrode for treatment of refractory wastewater: Influence of electrode material on system performance and microbial community.

The large-scale application of the bioelectrochemical system (BES) is limited by the cost-effective electrode materials. In this study, five kinds of stainless-steel materials were used as the cathode of the BES coupled with anaerobic digestion (BES-AD) for the treatment of diluted N, N-dimethylacetamide (DMAC) wastewater. Compared with a carbon-cloth cathode, BES-AD with a stainless-steel cathode had more engineering due to its low cost, although the operating efficiencies were slightly inferior.

Start-up of Anammox systems with different biochar amendment: Process characteristics and microbial community.

As the 'go-to' process when it comes to biological nitrogen removal from wastewaters in recent years, the Anammox process has undergone lots of investigations in order to optimize its performance. In evaluating the effect of distinct biochar types at different concentrations on the Anammox startup process, as well as analyze their corresponding influence on the microbial community structure, three additives (coconut, peach, and bamboo) at either 5%, 10%, or 15% respectively were amended in various Anammox EGSB setups. (i).

Post-Moore Memory Technology: Sneak Path Current (SPC) Phenomena on RRAM Crossbar Array and Solutions.

The sneak path current (SPC) is the inevitable issue in crossbar memory array while implementing high-density storage configuration. The crosstalks are attracting much attention, and the read accuracy in the crossbar architecture is deteriorated by the SPC. In this work, the sneak path current problem is observed and investigated by the electrical experimental measurements in the crossbar array structure with the half-read scheme.

[Characteristics of ANAMMOX Granular Sludge and Differences in Microbial Community Structure Under Different Culture Conditions].

Anaerobic ammonium oxidation (ANAMMOX) granular sludge was cultured during different operating conditions by an expanded granular sludge bed (EGSB) reactor and up-flow anaerobic sludge bed (UASB) reactors, and the characteristics of the granular sludge and microbial community were compared. The results showed that the flocculent ANAMMOX sludge can be granulated after being operated for 384 days by the EGSB and UASB reactors. The average particle size reached 1.

Neuronal dynamics in HfO/AlO-based homeothermic synaptic memristors with low-power and homogeneous resistive switching.

We studied the pseudo-homeothermic synaptic behaviors by integrating complimentary metal-oxide-semiconductor-compatible materials (hafnium oxide, aluminum oxide, and silicon substrate). A wide range of temperatures, from 25 °C up to 145 °C, in neuronal dynamics was achieved owing to the homeothermic properties and the possibility of spike-induced synaptic behaviors was demonstrated, both presenting critical milestones for the use of emerging memristor-type neuromorphic computing systems in the near future. Biological synaptic behaviors, such as long-term potentiation, long-term depression, and spike-timing-dependent plasticity, are developed systematically, and comprehensive neural network analysis is used for temperature changes and to conform spike-induced neuronal dynamics, providing a new research regime of neurocomputing for potentially harsh environments to overcome the self-heating issue in neuromorphic chips.

Dual Functions of V/SiO/AlO/pSi Device as Selector and Memory.

This letter presents dual functions including selector and memory switching in a V/SiO/AlO/pSi resistive memory device by simply controlling compliance current limit (CCL). Unidirectional threshold switching is observed after a positive forming with low CCL of 1 μA. The shifts to the V-electrode side of the oxygen form the VO layer, where the threshold switching can be explained by the metal-insulation-transition phenomenon.

Graphite-based selectorless RRAM: improvable intrinsic nonlinearity for array applications.

Selectorless graphite-based resistive random-access memory (RRAM) has been demonstrated by utilizing the intrinsic nonlinear resistive switching (RS) characteristics, without an additional selector or transistor for low-power RRAM array application. The low effective dielectric constant value (k) layer of graphite or graphite oxide is utilized, which is beneficial in suppressing sneak-path currents in the crossbar RRAM array. The tail-bits with low nonlinearity can be manipulated by the positive voltage pulse, which in turn can alleviate variability and reliability issues.

Scaling Effect on Silicon Nitride Memristor with Highly Doped Si Substrate.

A feasible approach is reported to reduce the switching current and increase the nonlinearity in a complementary metal-oxide-semiconductor (CMOS)-compatible Ti/SiN /p -Si memristor by simply reducing the cell size down to sub-100 nm. Even though the switching voltages gradually increase with decreasing device size, the reset current is reduced because of the reduced current overshoot effect. The scaled devices (sub-100 nm) exhibit gradual reset switching driven by the electric field, whereas that of the large devices (≥1 µm) is driven by Joule heating.

Analog Synaptic Behavior of a Silicon Nitride Memristor.

In this paper, we present a synapse function using analog resistive-switching behaviors in a SiN-based memristor with a complementary metal-oxide-semiconductor compatibility and expandability to three-dimensional crossbar array architecture. A progressive conductance change is attainable as a result of the gradual growth and dissolution of the conducting path, and the series resistance of the AlO layer in the Ni/SiN/AlO/TiN memristor device enhances analog switching performance by reducing current overshoot. A continuous and smooth gradual reset switching transition can be observed with a compliance current limit (>100 μA), and is highly suitable for demonstrating synaptic characteristics.

Self-Compliant Bipolar Resistive Switching in SiN-Based Resistive Switching Memory.

Here, we present evidence of self-compliant and self-rectifying bipolar resistive switching behavior in Ni/SiN/n⁺ Si and Ni/SiN/n Si resistive-switching random access memory devices. The Ni/SiN/n Si device's Si bottom electrode had a higher dopant concentration (As ion > 10 cm) than the Ni/SiN/n⁺ Si device; both unipolar and bipolar resistive switching behaviors were observed for the higher dopant concentration device owing to a large current overshoot. Conversely, for the device with the lower dopant concentration (As ion < 10 cm), self-rectification and self-compliance were achieved owing to the series resistance of the Si bottom electrode.

Ultralow power switching in a silicon-rich SiN/SiN double-layer resistive memory device.

Here we demonstrate low-power resistive switching in a Ni/SiN/SiN/p-Si device by proposing a double-layered structure (SiN/SiN), where the two SiN layers have different trap densities. The LRS was measured to be as low as 1 nA at a voltage of 1 V, because the SiN layer maintains insulating properties for the LRS. The single-layered device suffers from uncontrollability of the conducting path, accompanied by the inherent randomness of switching parameters, weak immunity to breakdown during the reset process, and a high operating current.

Attaining resistive switching characteristics and selector properties by varying forming polarities in a single HfO-based RRAM device with a vanadium electrode.

This study proposes a method for a HfO-based device to exhibit both resistive switching (RS) characteristics as resistive random access memory (RRAM) and selector characteristics by introducing vanadium (V) as the top electrode. This simple V/HfO/TiN structure can demonstrate these two different properties depending on forming polarities. The RS mechanism is activated by a positive forming bias.

Demonstration of Synaptic Behaviors and Resistive Switching Characterizations by Proton Exchange Reactions in Silicon Oxide.

We realize a device with biological synaptic behaviors by integrating silicon oxide (SiO(x)) resistive switching memory with Si diodes. Minimal synaptic power consumption due to sneak-path current is achieved and the capability for spike-induced synaptic behaviors is demonstrated, representing critical milestones for the use of SiO2-based materials in future neuromorphic computing applications. Biological synaptic behaviors such as long-term potentiation (LTP), long-term depression (LTD) and spike-timing dependent plasticity (STDP) are demonstrated systematically using a comprehensive analysis of spike-induced waveforms, and represent interesting potential applications for SiO(x)-based resistive switching materials.

A study of the interfacial resistive switching mechanism by proton exchange reactions on the SiO(x) layer.

In this work, we investigated SiO(x)-based interfacial resistive switching in planar metal-insulator-metal structures using physical/chemical/electrical analyses. This work helps clarify the interfacial reaction process and mechanism in SiO(x), and also shows the potential for high temperature operation in future nonvolatile memory applications.

"Cut-and-Paste" Manufacture of Multiparametric Epidermal Sensor Systems.

Multifunctional epidermal sensor systems (ESS) are manufactured with a highly cost and time effective, benchtop, and large-area "cut-and-paste" method. The ESS made out of thin and stretchable metal and conductive polymer ribbons can be noninvasively laminated onto the skin surface to sense electrophysiological signals, skin temperature, skin hydration, and respiratory rate.

Physical and chemical mechanisms in oxide-based resistance random access memory.

In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition.

Integrated one diode-one resistor architecture in nanopillar SiOx resistive switching memory by nanosphere lithography.

We report on a highly compact, one diode-one resistor (1D-1R) nanopillar device architecture for SiOx-based ReRAM fabricated using nanosphere lithography (NSL). The intrinsic SiOx-based resistive switching element and Si diode are self-aligned on an epitaxial silicon wafer using NSL and a deep-Si-etch process without conventional photolithography. AC-pulse response in 50 ns regime, multibit operation, and good reliability are demonstrated.