A5055599683- Advanced Memory and Neural Computing
- Ferroelectric and Negative Capacitance Devices
- Neuroscience and Neural Engineering
- Semiconductor materials and devices
- Transition Metal Oxide Nanomaterials
- Electronic and Structural Properties of Oxides
- Photoreceptor and optogenetics research
- Conducting polymers and applications
- Perovskite Materials and Applications
- Neural dynamics and brain function
- Advanced Battery Materials and Technologies
- Advanced battery technologies research
- Neural Networks and Reservoir Computing
- Nonlinear Dynamics and Pattern Formation
Nanyang Technological University
2018-2025
Nanyang Polytechnic
2023
The commercial implementation of aqueous Zn-ion batteries is being impeded by the rampant dendrite growth and exacerbated side reactions on Zn metal anodes. Herein, a 60 nm artificial protective layer with spatial dielectric–metallic gradient composition (denoted as GZH) developed via HfO2 cosputtering. In this design, top high permittivity low electronic conductivity effectively suppresses hydrogen evolution. intermediate Zn-rich oxide region promotes dendrite-free deposition reinforces...
Pyridinium-templated one-dimensional (1D) halide perovskites are studied as crossbar memristive materials for artificial neural networks with higher on–off ratios, enhanced endurance, and superior retention characteristics.
We report on the conduction mechanisms of novel Ru/MgO/Cu and Ru/MgO/Ta resistive switching memory (RSM) devices. Current-voltage (I-V) measurements revealed Schottky emission (SE) as dominant mechanism in high resistance state (HRS), which was validated by varying temperatures transmission electron microscopy (TEM) results. Retention more than 10 years at 85 °C obtained for both RSM In addition, annealing processes greatly improved consistency HRS LRS paths from cycle to cycle, exhibiting...
Emerging technologies, i.e., spintronics, 2D materials, and memristive devices, have been widely investigated as the building block of neuromorphic computing systems. Three-terminal memristor (3TM) is specifically designed to mitigate challenges encountered by its two-terminal counterpart it can concurrently execute signal transmission memory operations. In this work, we present a complementary metal-oxide-semiconductor-compatible 3TM with highly linear weight update characteristics dynamic...
This work introduces a scalable CMOS-integrated memristive device designed to demonstrate dual-mode functionality encompassing both localized (digital) and interfacial (analog) switching mechanisms.
We report a switching model that directly explains the change in activation energy (EAC) at different RESET stop voltages (Vstop) HfO2-based resistive random access memory devices. The dependence of oxygen vacancy-driven conductive filaments (Vo2+) density (nD) on Vstop was validated by kinetic Monte Carlo (kMC) simulation and hopping conduction mechanism. A wide operating range temperatures from −40 to 175 °C is achieved with stable endurance 100 ns short pulses high retention more than 10...
Short-term plasticity (STP) is an important synaptic characteristic in the hardware implementation of artificial neural networks (ANN), as it enables temporal information processing (TIP) capability. However, STP feature rather challenging to reproduce from a single nonvolatile resistive random-access memory (RRAM) element, requires certain degree volatility. In this work, Pt/TiOx/Pt exponential selector introduced not only suppress sneak current but also enable TIP one selector-one RRAM...
Due to their significant resemblance the biological brain, spiking neural networks (SNNs) show promise in handling spatiotemporal information with high time and energy efficiency. Two-terminal memristors have capability achieve both synaptic neuronal functions; however, such face asynchronous programming/reading operation issues. Here, a three-terminal memristor (3TM) based on oxygen ion migration is developed function as synapse neuron. We demonstrate short-term plasticity pair-pulse...
A gradual electroforming process was implemented on the pristine Pt/HfOx/Cu/Pt structure to realize volatile threshold switching characteristics of a diffusive memristor. The reported devices exhibit stable unidirectional properties with high selectivity >107 and ultralow OFF current ∼100 fA for over 104 endurance cycles. Nucleation theory spheroidal-shaped metallic filament growth is used extensively discuss structural changes device after forming treatments by analyzing applied bias...
This work demonstrates oscillation frequency modulation in a NbO2-based relaxation oscillator device, which the increases with operating temperature and source voltage, decreases load resistance. An annealing-induced oxygen diffusion at 373 K was carried out to optimize stoichiometry of bulk NbO2to achieve consistent shift device temperature. The exhibits stable self-sustained can be modulated between 2 33 MHz, wider voltage range obtained. additional surface treatment step employed during...
One of the main challenges in development conductive bridging random access memory (CBRAM) is large stochastic nature ion movement that ultimately leads to parameter variability. In this study, resistive switching variability CBRAM devices significantly improved by employing Co–Cu alloy as active electrode. By comparing with Pt/Ta2O5/Co devices, Co70Cu30 exhibited lower forming voltage (<2 V), SET (<0.70 and faster response time (∼70 ns). The filament stability indicated...
In this work, we explore the use of resistive random access memory (RRAM) device as a synapse for mimicking trained weights linking neurons in deep learning neural network (DNN) (AlexNet). The RRAM devices were fabricated in-house and subjected to 1000 bipolar read-write cycles measure resistances recorded Logic-0 Logic-1 (we demonstrate feasibility achieving eight discrete resistance states same depending on RESET stop voltage). DNN simulations have been performed compare relative error...
The readout margin of the one selector-one RRAM crossbar array architecture is strongly dependent on nonlinearity selector device. In this work, we demonstrated that Pt/TiO2/Pt exponential selectors increases with decreasing oxygen vacancy defect density. density controlled by modulating sputtering pressure in oxide deposition process. Our results reveal dominant conduction mechanisms structure transit from Schottky emission to Poole-Frenkel increase pressure. Such transition attributed rise...
A scalable (<130 nm) resistive switching memristor that features both filamentary and interfacial aimed at neuromorphic computing is developed in this study. The typically perceived noise or volatility was effectively harnessed as a controlled mechanism for switching. multilayer structure the proposed enhances stability by curbing ionic overmigration mitigating leakage paths. Furthermore, memristors showcased their reliability demonstrating more than 15 M cycles mode 1 pulses mode....
Conductive filaments (CFs) play a critical role in the mechanism of resistive random-access memory (ReRAM) devices. However, situ detection and visualization precise location CFs are still key challenges. We demonstrate for first time use π-conjugated molecule which can transform between its twisted planar states upon localized Joule heating generated within filament regions, thus reflecting locations underlying CFs. Customized patterns were induced observed by layer, confirmed hypothesis....
In this paper, study on the thermal annealing effect is done nanoscale W/TaO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> /Pt resistive random access memory (RRAM) structure. Electrical characterization shows that device performance improved after undergoing annealing, with cycle-to-cycle and device-to-device variability showing less variation lower operating voltage. The also undergoes CMOS BEoL compatible budget.
Resistive RAM (RRAM) has emerged as a promising candidate for the next generation of non-volatile memories (NVMs) due to its low write voltage and compact area that is compatible with CMOS technology. In this work, we propose 1Mb macro consisting two 512Kb sub-arrays, reduced by implementing common source-line (SL) structure. A voltage-mode sense amplifier (VSA) designed overcome challenge ratio between high-resistance low-resistance states (R-ratio). Two columns replica cells situated in...
We report hopping conduction in Pt/MgO/Cu resistive switching memory (RSM) devices predominantly the low resistance state. Current-voltage measurements of RSM exhibited good cycle-to-cycle variability. Promising DC endurance exceeding 2000 cycles and retention 10 years at 125°C were obtained <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> -10 xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> ON/OFF ratio within a consistent range SET...
We investigate the functionality of NbOx-based selector devices on a flexible substrate. It was observed that failure mechanism cyclic tensile strain is from disruption atom arrangements, which essentially led to crack formation film. When under compressive strain, buckling delamination film occurs as compressed films have debonded their neighboring layers. By implementing an annealing process after strain-induced degradation, recovery device with reduced threshold and hold voltages. The...
Abstract Resistive random-access memory (RRAM) is promising for various low-power applications, including Internet of Things (IOTs), neuromorphic and data-centric computing. However, the poor reliability, mainly variability in switching, one biggest challenges RRAM. Here, a novel geometry electrochemical metallization (ECM)-based RRAM proposed with lower switching voltage less variability. From COMSOL Multiphysics simulation, intensity distribution electric field can be tuned by design...