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Magnetic skyrmioniums—with a composite structure comprising two skyrmions with opposite topological charges, exhibit unique dynamic behaviors that are crucial for technological advancements and have application potential for high-density and nonvolatile memory. This study explores the impact of periodic perpendicular magnetic anisotropy (PMA) and damping gradients on skyrmioniums. Utilizing the object oriented micromagnetic framework for detailed simulations, the effective control and enhancement of the skyrmionium stability and mobility through the periodic modulation of PMA and damping gradients is demonstrated. The results demonstrate the dynamic behavior and stability control of skyrmioniums in periodic PMA/damping gradient nanowires. Moreover, the critical influence of the periodic gradient on the skyrmionium motion and stability is highlighted. The results present new avenues for developing advanced memory technologies, leveraging skyrmionium's unique nonlinear behaviors to improve the device performance and reliability. [ABSTRACT FROM AUTHOR]

Strain can significantly affect the electronic structure and functional properties of dilute magnetic semiconductors. As a wide bandgap transparent semiconductor, doped In2O3 has also received extensive attention for the modulation of physical properties by lattice strain due to its excellent functional properties. Here, we epitaxially grew the Cr:In2O3 thin film on the (111)-oriented 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN–PT) ferroelectric single-crystal substrate. By applying an electric field to PMN–PT, multiple reversible and nonvolatile resistance states can be achieved at room temperature. Utilizing in situ XRD, different strain states corresponding to different resistance states induced by the ferroelastic domain switching of the PMN–PT were characterized. Based on first-principles calculations, the influence of lattice strain on the resistivity of the Cr:In2O3 was discussed. These results offer a route for the design of multiple-valued nonvolatile memory devices and multiple functional magneto-electric devices based on dilute magnetic semiconductors. [ABSTRACT FROM AUTHOR]

While magnetoresistive random-access memory (MRAM) stands out as a leading candidate for embedded nonvolatile memory and last-level cache applications, its endurance is compromised by substantial self-heating due to the high programming current density. The effect of self-heating on the endurance of the magnetic tunnel junction (MTJ) has primarily been studied in spin-transfer torque (STT)-MRAM. Here, we analyze the transient temperature response of two-terminal spin–orbit torque (SOT)-MRAM with a 1 ns switching current pulse using electro-thermal simulations. We estimate a peak temperature range of 350–450 °C in 40 nm diameter MTJs, underscoring the critical need for thermal management to improve endurance. We suggest several thermal engineering strategies to reduce the peak temperature by up to 120 °C in such devices, which could improve their endurance by at least a factor of 1000× at 0.75 V operating voltage. These results suggest that two-terminal SOT-MRAM could significantly outperform conventional STT-MRAM in terms of endurance, substantially benefiting from thermal engineering. These insights are pivotal for thermal optimization strategies in the development of MRAM technologies. [ABSTRACT FROM AUTHOR]

Nonvolatile memory using intersubband transitions and quantum-well electron accumulation in GaN/AlN resonant tunneling diodes (RTDs) is a promising candidate for high-speed nonvolatile memory operating on a picosecond timescale. This memory has been fabricated on sapphire(0001) substrates to date because of the high affinity between the nitride materials and the substrate. However, the fabrication of this memory on Si(111) substrates is attractive to realize hybrid integration with Si devices and nonvolatile memory and three-dimensional integration such as chip-on-wafer and wafer-on-wafer. In this study, GaN/AlN RTDs are fabricated on a Si(111) substrate using metal-organic vapor phase epitaxy. The large strain caused by the differences in the thermal expansion coefficients and lattice constants between the Si(111) substrate and nitride materials are suppressed by a growth technique based on the insertion of low-temperature-grown AlGaN and thin AlN layers. The GaN/AlN RTDs fabricated on Si(111) substrates show clear GaN/AlN heterointerfaces and a high ON/OFF ratio of >220, which are equivalent to those for devices fabricated on sapphire(0001) substrates. However, the nonvolatile memory characteristics fluctuate by repeated write/erase memory operations. Evaluation of the ON/OFF switching time and endurance characteristics indicates that the instability of the nonvolatile memory characteristics is caused by electron leakage through deep levels in the quantum-well structure. Possible methods for suppressing this are discussed with an aim of realizing high-speed and high-endurance nonvolatile memory. [ABSTRACT FROM AUTHOR]

Better techniques for imaging ferroelectric polarization would aid the development of new ferroelectrics and the refinement of old ones. Here we show how scanning transmission electron microscope (STEM) electron beam-induced current (EBIC) imaging reveals ferroelectric polarization with obvious, simply interpretable contrast. Planar imaging of an entire ferroelectric hafnium zirconium oxide (Hf0.5Zr0.5O2, HZO) capacitor shows an EBIC response that is linearly related to the polarization determined in situ with the positive-up, negative-down (PUND) method. The contrast is easily calibrated in MV/cm. The underlying mechanism is magnification-independent, operating equally well on micrometer-sized devices and individual nanoscale domains. Coercive-field mapping reveals that individual domains are biased positive and negative, as opposed to being easy and hard to switch. The remanent background E-fields generating this bias can be isolated and mapped. Coupled with STEMs native capabilities for structural identification, STEM EBIC imaging provides a revolutionary tool for characterizing ferroelectric materials and devices.

Ferroelectric tunnel junctions (FTJs) utilizing hafnium zirconium oxide (HZO) have attracted interest as non-volatile memory for microelectronics due to ease of integration into back-end-of-line (BEOL) complementary metal oxide semiconductor fabrication. This work examines asymmetric electrode NbN/HZO/Nb devices with 7 nm thick HZO as FTJs in a memory structure, with an output resistance that can be controlled by read and write voltages. The individual FTJs are measured to have a tunneling electroresistance of 10 during the read state without significant filament conduction formation and reasonable ferroelectric performance. Endurance and remanent polarizations of up to 105 cycles and 20 μC/cm2, respectively, are measured and are shown to be dependent on the cycling voltage. Electrical measurements demonstrate how magnitude of the write pulse can modulate the high state resistance and the read pulse influences both resistance values as well as separation of resistance states. Then, by using two opposite switching FTJ devices in series, a programmable nonvolatile resistor divider is demonstrated. Measurements of these two FTJ unit memory cells show wide applicability to a BEOL microfabrication process for a re-readable, rewritable, and nonvolatile memory cell. [ABSTRACT FROM AUTHOR]

Due to the growing demand for miniaturization and energy efficiency in modern electronic devices, there is a renewed interest for optoelectronic memories and sensors based on 2D materials. In particular, the molybdenum ditelluride (MoTe 2) is one of the most promising materials for applications in nonvolatile phase-change memory devices, as its properties can be controlled by visible-light illumination. Among the several ways to synthesize MoTe 2 , the molybdenum oxide tellurization through isothermal close space sublimation (CSS) annealing in gas atmosphere is a simple and low-cost effective method for large-scale production of devices based on this layered material. Therefore, the understanding of the physical properties of MoTe 2 thin films produced by this technique is crucial for future applications. Surprisingly, our results indicate that there is a photoinduced growth of the crystalline phase of tellurium on the 1T ′ -MoTe 2 matrix even when the power density of the laser is low. From Raman spectroscopy investigations, we were able to show that nanometer-sized tellurium crystallites work as seed sites for the photocrystallization of tellurium. By assuming that the overall crystallization process is described by a kinetic approach that is based on the Kolmogorov–Johnson–Mehl–Avrami theory, our results indicate that the process is governed by an anisotropic organization of the tellurium atoms in helical structures during the crystal growth. [ABSTRACT FROM AUTHOR]

Sneak current issues in crossbar arrays of non-volatile memories can be effectively alleviated using threshold switching (TS)-based selectors. However, 1-selector–1-resistor integration requires coherence between the constituent materials and operational parameters of the two components. Here, we propose a highly coherent selector via in-depth investigation of the operation process of a fab-friendly As-SiO2 selector unit. The structural and electrical characteristics of an As-embedded SiO2 selector are analyzed, and the TS-on and -off operational mechanism is presented. Further, the critical control elements governing the selector operation are identified, including the electron charging into the oxygen vacancies in the SiO2 matrix and energy band alignment between the As cluster and charged oxygen vacancies in SiO2. Consequently, practical control strategies for the TS behavior are proposed with a pulse scheme applicable to actual device operation. The proposed TS operational mechanism and analytical methodology can contribute to interpreting and integrating various memory/selector components, thereby advancing their operational and integrative research. [ABSTRACT FROM AUTHOR]

The emerging logic-in-memory (LIM) technology is a promising strategy to overcome the von Neumann bottleneck in modern computers. For LIM circuits, the complementary structure is desirable for low-power consumption. To date, there have been rare reports on the n-channel organic thin-film transistor nonvolatile memories (OTFT-NVMs), which is indispensable for building the complementary LIM circuits. In this Letter, we demonstrate a route to achieve the low-voltage operatable n-channel OTFT-NVMs, by blade-coating an ultrathin tetratetracontane buffer layer on the oxygen plasma treated ferroelectric terpolymer insulator with a low coercive field. The n-channel OTFT-NVMs exhibit good performances, with a high electron mobility over 0.1 cm2/V s, highly reliable endurance over 1000 cycles, and highly stable retention over 10 000 s. The mechanism for improving device performances is discussed. Moreover, the mechanism and the route for improving performances are also suitable for p-channel OTFT-NVMs. Furthermore, the LIM architecture-based complementary organic inverters are constructed by integrating the n-channel and p-channel OTFT-NVMs, which can well perform logic and memory operations at the low voltage of 10 V. The work laid the foundation for the development of the LIM circuits. [ABSTRACT FROM AUTHOR]

Ferroelectric tunnel junction (FTJ) with tunable tunnel electroresistance is promising for emerging nonvolatile memory applications. In this work, 6 nm-thick Hf-doped ZrO2 ferroelectrics with Zr : Hf = 3 : 1 (ZHO), exhibiting a high remanent polarization of 30 μC/cm2, was prepared and further used to build Pt/ZHO/Al2O3/W FTJ devices with adding 1 nm-thick Al2O3 dielectric layer to reduce the leakage. The FTJ delivered superior performance with a tunneling electroresistance ratio of over 7000, outperforming previously reported other FTJ devices based on hafnia/zirconia ferroelectrics. Under 100 ns single-pulse writing, the FTJ exhibited multiple stable states, good retention over 104 s, and switching endurance exceeding 5 × 104 cycles. Additionally, it delivered a relatively high read current density of 8 A/cm2 at 0.2 V. The results demonstrate that the ZHO/Al2O3 composite structure can effectively alter the tunneling barrier height and increase tunneling current, resulting in a large ON/OFF ratio. The results underscore a great potential of ZHO ferroelectrics in the future development of high-performance nonvolatile memory technologies. [ABSTRACT FROM AUTHOR]

Voltage-controlled magnetoresistive random access memory (VC-MRAM) is an emerging nonvolatile memory based on the voltage-controlled magnetic anisotropy (VCMA) effect. It has been garnering considerable attention because of its fast and low-power operation. However, two major issues must be addressed for practical applications. First, the voltage-induced switching of the free layer magnetization is sensitive to ultrashort voltage pulse duration. Second, the write error rate (WER) of the voltage-induced switching is high. To address these issues, a magnetic tunnel junction (MTJ) structure with an exchange coupled free layer, consisting of a precession layer with the VCMA effect and an anchor layer without the VCMA effect, is proposed. The anchor layer prevents the precession layer from returning to its initial direction, thereby reducing the WER without requiring the voltage pulse duration to be precisely controlled. The write operation of the proposed MTJ with an exchange coupled free layer was analyzed using the macrospin model. Using optimized MTJ parameters, a low WER of approximately 10−6 was obtained for an 80 nm MTJ without requiring the pulse duration to be precisely controlled. These results facilitate the reduction of the WER for VC-MRAM and improve its usability, thereby expanding its range of applications. [ABSTRACT FROM AUTHOR]

Perovskite oxides have a wide variety of physical properties that make them promising candidates for versatile technological applications including nonvolatile memory and logic devices. Chemical tuning of those properties has been achieved, to the greatest extent, by cation-site substitution, while anion substitution is much less explored due to the difficulty in synthesizing high-quality, mixed-anion compounds. Here, nitrogen-incorporated BaTiO3 thin films have been synthesized by reactive pulsed-laser deposition in a nitrogen growth atmosphere. The enhanced hybridization between titanium and nitrogen induces a large ferroelectric polarization of 70 μC/cm² and high Curie temperature of ~1213 K, which are ~2.8 times larger and ~810 K higher than in bulk BaTiO3, respectively. These results suggest great potential for anion-substituted perovskite oxides in producing emergent functionalities and device applications. [ABSTRACT FROM AUTHOR]

To develop low-power, miniature, nonvolatile memory resistor integrated devices for in-memory computing technologies, the exploration of atomic-scale ferroelectric channel semiconductor devices is necessary. We theoretically designed tunnel junction devices based on two-dimensional ferroelectric semiconductors, with two-dimensional metal TaSe2 used as the top electrode and van der Waals bilayer boron arsenide (BAs) as the ferroelectric semiconductor channel, aiming to achieve high-performance, low-power, two-dimensional ferroelectric memory resistors. Our findings demonstrate that the bilayer BAs, upon contact with metal electrodes, can achieve two stable and switchable ferroelectric states. Interlayer relative sliding enables stable and alternating two-dimensional ferroelectric domains, altering the types of triple potential barriers at interfaces from Schottky contacts to Ohmic contacts. Thus, under the modulation of the "triple barrier" mechanism, control over channel carrier switching is achieved, resulting in a tunneling electroresistance of 104%. Additionally, non-equilibrium Green's function results indicate nonlinear changes in the I–V curve when switching between the two stable ferroelectric states, highlighting the multi-resistive state nature of channel resistance. Our research underscores the potential of sliding ferroelectric tunnel junctions in integrating nonvolatile storage and computing units, emphasizing their innovative applications in in-memory computing technologies. [ABSTRACT FROM AUTHOR]

2D ferroelectrics open a new realm of nonvolatile memory and computing devices, while metal–organic frameworks (MOF) offer tremendous possibilities to design and optimize ferroelectric performance. Integrating a MOF ferroelectric gate with a semiconducting channel provides new strategy toward ultralow power ferroelectric field effect transistors (FeFETs), yet no 2D MOF is experimentally demonstrated to be ferroelectric yet. Here, the study successfully develops 2D ferroelectric MOF nanosheets, {CuL2(H2O)2(NO3)2(H2O)1.5·(CH3OH)}∞ wherein L denotes PhPO(NH4Py)2, abbreviated as {CuIIL2}n‐MOF, and confirm its ferroelectricity down to 7 nm thickness. A large polarization of ≈14.2 µC cm−2, small coercive field of ≈33.3 V µm−1, and excellent endurability >106 cycles are found in 2D {CuIIL2}n‐MOF nanosheets. This enables to fabricate FeFETs using 2D {CuIIL2}n‐MOF as the gate and MoS2 as the channel, achieving an on/off ratio of 107 with ultralow off‐state current of 100 fA and tunable memory window, making it exceptional among known FeFETs and very promising for next‐generation ultralow power memories and computing devices [ABSTRACT FROM AUTHOR]

The Exascale Computing Project (ECP)'s Simplified Interface to Complex Memories (SICM) effort focuses on developing universal interfaces for discovering, managing, and sharing data across complex memory hierarchies. These facilitate the exploitation of emerging memory technologies and support precise control over their various trade-offs such as high-bandwidth versus low-latency, persistent versus ephemeral, high-capacity versus low-capacity, and near-CPU versus near-GPU. SICM comprises three interrelated components: a low-level interface, a high-level interface, and a persistent-heap interface. The low-level SICM interface is intended for system and run-time developers as well as expert application developers who prefer full control of the memory objects used within their application. The high-level SICM interface builds upon the low-level interface, employing application-level profiling and analysis to optimize data management for complex memory hierarchies. The persistent-heap interface provides applications with a persistent memory allocator that can allocate custom C++ data structures in both block-storage and byte-addressable persistent memories. [ABSTRACT FROM AUTHOR]

Ferroelectric semiconductors have the advantages of switchable polarization ferroelectric field regulation and semiconductor transport characteristics, which are highly promising in ferroelectric transistors and nonvolatile memory. However, it is difficult to prepare a Sn-based perovskite film with both robust ferroelectric and semiconductor properties. Here, by doping with 2-methylbenzimidazole, Sn-based perovskite [93.3 mol% (FA0.86Cs0.14)SnI3 and 6.7 mol% PEA2SnI4] semiconductor films are transformed into ferroelectric semiconductor films, owing to molecular reconfiguration. The reconfigured ferroelectric semiconductors exhibit a high remanent polarization (Pr) of 23.2 μC/cm2. The emergence of ferroelectricity can be ascribed to the hydrogen bond enhancement after imidazole molecular doping, and then the spatial symmetry breaks causing the positive and negative charge centers to become non-coincident. Remarkably, the transistors based on perovskite ferroelectric semiconductors have a low subthreshold swing of 67 mv/dec, which further substantiates the superiority of introducing ferroelectricity. This work has developed a method to realize Sn-based ferroelectric semiconductor films for electronic device applications. The authors observe the emergence of ferroelectricity in Sn-based perovskite [93.3 mol% (FA0.86Cs0.14)SnI3 and 6.7 mol% PEA2SnI4] semiconductor films doped with 2-methylbenzimidazole, ascribing to the hydrogen bond enhancement after imidazole molecular doping. [ABSTRACT FROM AUTHOR]

Extending ferroelectric materials to two-dimensional limit provides versatile applications for the development of next-generation nonvolatile devices. Conventional ferroelectricity requires materials consisting of at least two constituent elements associated with polar crystalline structures. Monolayer graphene as an elementary two-dimensional material unlikely exhibits ferroelectric order due to its highly centrosymmetric hexagonal lattices. Here, we report the observations of electronic ferroelectricity in monolayer graphene by introducing asymmetric moiré superlattice at the graphene/h-BN interface, in which the electric polarization stems from electron-hole dipoles. The polarization switching is probed through the measurements of itinerant Hall carrier density up to room temperature, manifesting as standard polarization-electric field hysteresis loops. We find ferroelectricity in graphene moiré systems exhibits generally similar characteristics in monolayer, bilayer, and trilayer graphene, which indicates layer polarization is not essential to observe the ferroelectricity. Furthermore, we demonstrate the applications of this ferroelectric moiré structures in multi-state nonvolatile data storage with high retention and the emulation of versatile synaptic behaviors. Our work not only provides insights into the fundamental understanding of ferroelectricity, but also demonstrates the potential of graphene for high-speed and multi-state nonvolatile memory applications. Monolayer graphene, with its highly centrosymmetric hexagonal lattice, is typically not considered ferroelectric. Here, the authors observe ferroelectricity in monolayer graphene by introducing asymmetric moiré superlattices, where polarization arises from electron-hole dipoles. [ABSTRACT FROM AUTHOR]

Understanding microscopic mechanisms of polarization retention characteristics in ferroelectric thin films is of great significance for exploring unusual physical phenomena inaccessible in the bulk counterparts and for realizing thin‐film‐based functional electronic devices. Perovskite (K,Na)NbO3 is an excellent class of lead‐free ferroelectric oxides attracting tremendous interest thanks to its potential applications to nonvolatile memory and eco‐friendly energy harvester/storage. Nonetheless, in‐depth investigation of ferroelectric properties of (K,Na)NbO3 films and the following developments of nano‐devices are limited due to challenging thin‐film fabrication associated with nonstoichiometry by volatile K and Na atoms. Herein, ferroelectric (K,Na)NbO3 films of which the atomic‐level geometrical structures strongly depend on thickness‐dependent strain relaxation are epitaxially grown. Nanopillar crystal structures are identified in fully relaxed (K,Na)NbO3 films to the bulk states representing a continuous reduction of switchable polarization under air environments, that is, polarization retention failures. Protonation by water dissociation is responsible for the humidity‐induced retention loss in nano‐columnar (K,Na)NbO3 films. The protonation‐driven polarization retention failure originates from domain wall pinning by the accumulation of mobile hydrogen ions at charged domain walls for effective screening of polarization‐bound charges. Conceptually, the results will be utilized for rational design to advanced energy materials such as photo‐catalysts enabling ferroelectric tuning of water splitting. [ABSTRACT FROM AUTHOR]

Perovskite thin‐film transistors (TFTs) simultaneously possessing exceptional carrier transport capabilities, nonvolatile memory effects, and photosensitivity have recently attracted attention in fields of both complementary circuits and neuromorphic computing. Despite continuous performance improvements through additive and composition engineering of the channel materials, the equally crucial dielectric/channel interfaces of perovskite TFTs have remained underexplored. Here, it is demonstrated that engineering the dielectric/channel interface in 2D tin perovskite TFTs not only enhances the performance and operational stability for their utilization in complementary circuits but also enables efficient synaptic behaviors (optical information sensing and storage) under an extremely low operating voltage of −1 mV at the same time. The interface‐engineered TFT arrays operating at −1 mV are then demonstrated as the preprocessing hardware for neuromorphic visions with pattern recognition accuracy of 92.2% and long‐term memory capability. Such a low operating voltage provides operational feasibility to the design of large‐scale‐integrated and wearable/implantable neuromorphic hardware. [ABSTRACT FROM AUTHOR]

Miniaturizing van der Waals (vdW) ferroelectric materials to atomic scales is essential for modern devices like nonvolatile memory and sensors. To unlock their full potential, their growth mechanisms, interface effects, and stabilization are preferably investigated, particularly for ultrathin 2D nanosheets with single‐unit cell thickness. This study focuses on Bi2TeO5 (BTO) and utilizes precise control over growth kinetics at the nucleation temperature to create specific interfacial reconfiguration layers. Ultrathin BTO nanosheets with planar ferroelectricity at a single‐unit cell thickness are successfully grown. Atomic‐scale characterization reveals a disordered distribution of elements in the interfacial layer, which buffers strain from lattice mismatch. The theoretical calculations support these observations. Furthermore, this strategy also can be extended to the growth of a variety of 2D ternary oxide nanosheets. This work contributes to a better understanding of growth and stability mechanisms in 2D ultrathin nanosheets. [ABSTRACT FROM AUTHOR]

With the growing need for extensive data storage, enhancing the storage density of nonvolatile memory technologies presents a significant challenge for commercial applications. This study explores the use of monatomic antimony (Sb) in multi-level phase-change storage, leveraging its thickness-dependent crystallization behavior. We optimized nanoscale Sb films capped with a 4-nm SiO2 layer, which exhibit excellent amorphous thermal stability. The crystallization temperature ranges from 165 to 245 °C as the film thickness decreases from 5 to 3 nm. These optimized films were then assembled into a multilayer structure to achieve multi-level phase-change storage. A typical multilayer film consisting of three Sb layers was fabricated as phase-change random access memory (PCRAM), demonstrating four distinct resistance states with a large on/off ratio (∼102) and significant variation in operation voltage (∼0.5 V). This rapid, reversible, and low-energy multi-level storage was achieved using an electrical pulse as short as 20 ns at low voltages of 1.0, 2.1, 3.0, and 3.6 V for the first, second, and third SET operation, and RESET operation, respectively. The multi-level storage capability, enabled by segregation-free Sb with enhanced thermal stability through nano-confinement effects, offers a promising pathway toward high-density PCRAM suitable for large-scale neuromorphic computing. [ABSTRACT FROM AUTHOR]

Among the transition metal oxides, hematite (α-Fe2O3) has been widely used in the preparation of memristors because of its excellent physical and chemical properties. In this paper, α-Fe2O3 nanowire arrays with a preferred orientation along the [110] direction were prepared by a facile hydrothermal method and annealing treatment on the FTO substrate, and then α-Fe2O3 nanowire array-based Au/α-Fe2O3/FTO memristors were obtained by plating the Au electrodes on the as-prepared α-Fe2O3 nanowire arrays. The as-prepared α-Fe2O3 nanowire array-based Au/α-Fe2O3/FTO memristors have demonstrated stable nonvolatile bipolar resistive switching behaviors with a high resistive switching ratio of about two orders of magnitude, good resistance retention (up to 103 s), and ultralow set voltage (Vset = +2.63 V) and reset voltage (Vreset = −2 V). In addition, the space charge-limited conduction (SCLC) mechanism has been proposed to be in the high resistance state, and the formation and destruction of the conductive channels modulated by oxygen vacancies have been suggested to be responsible for the nonvolatile resistive switching behaviors of the Au/α-Fe2O3/FTO memristors. Our results show the potential of the Au/α-Fe2O3/FTO memristors in nonvolatile memory applications. [ABSTRACT FROM AUTHOR]

Low density parity check code (LDPC) is the most popular error correction code (ECC) for current nand flash memory controllers. Next generation flash memory, such as triple-level cell (TLC) and quad-level cell (QLC) with a higher bit error rate, bring up the demand for superior ECC algorithms providing excellent performance and acceptable hardware overhead. This letter proposes turbo product code (TPC) as an alternative to LDPC by exploring embedding of a TPC engine into a solid-state drive (SSD) controller architecture. The implementation of this TPC engine uses 2-D error coding and applies the Bose-Chaudhuri–Hocquenghem (BCH) code in each dimension. The algorithm is further improved by flipping the dedicated bit matrix when the basic TPC decoding algorithm terminates with uncorrectable conditions. This bit-flipping enhanced TPC (BFE-TPC) module is finally integrated into a nonvolatile memory express (NVMe) SSD controller driving eight flash memory channels. This BFE-TPC module illustrates the potential of 2D-TPCs as a replacement for LDPCs due to its high throughput and low hardware overhead. [ABSTRACT FROM AUTHOR]

Memristors are utilized in nonvolatile memory and artificial synaptic devices. However, the industrial application of memristors has been restricted by the occurrence of fatigue, the mechanism of which is still under debate. In this paper, we systematically investigated the mechanism of defect generation created by Joule heating in Cu-doped TiO2 memristive device. The results also demonstrated that the Joule heat for artificial synaptic emulation was less severe than that for digital data storage. [ABSTRACT FROM AUTHOR]

Compensation has been a common while unacknowledged strategy in the design of computing‐in‐memory (CIM) schemes. It enables efficient CIM designs by intentionally letting the sum of capacitances or conductances of two or more rows or columns in the memory array equal, thus resulting in a concise mathematical formula regarding the memory cell data and the input data, which constitute computing primitives. Here, the capacitance and conductance compensation methods are reviewed that have been used for CIM designs based on static random‐access memory (SRAM) in combination with capacitors and nonvolatile resistive memory, respectively, and uncover the underlying principles and their application to CIM. It is hoped this effort will help recognize the compensation methods as a building block for CIM designs, and will be an inspiration to developing more CIM schemes that are more compact in area, more efficient in energy consumption, and capable of solving more complicated problems. [ABSTRACT FROM AUTHOR]

The chemical solution-deposited zinc ferrite (ZFO; ZnFe2O4) RRAM devices on Pt/Ti/SiO2/Si substrate are being reported. Fabricated devices show the positive as well as negative unipolar switching memory properties. Thickness of ZFO thin films in Au/ZFO/Pt structure was varied to explore the resistive switching behavior. It is reported that forming voltage and resistance of the device increase by increasing the number of ZFO layers. Our results reveal that ZFO thin film deposited by eight times spin coating with a thickness of eight layers illustrates stable resistive switching with the most steady Set (2 V) and Reset voltages (0.5 V) as compared to the devices with two, four, and six layers. It also demonstrates the enhanced endurance of greater than 300 switching cycles and stable time-dependent resistance greater than 104 s. The current transport mechanism is Ohmic at low-resistance state, while it leads to Schottky emission at high-resistance state. The possible switching mechanism is also discussed for the possible application of ZFO-based memory for nonvolatile RRAM devices. [ABSTRACT FROM AUTHOR]

The chemical solution-deposited zinc ferrite (ZFO; ZnFe2O4) RRAM devices on Pt/Ti/SiO2/Si substrate are being reported. Fabricated devices show the positive as well as negative unipolar switching memory properties. Thickness of ZFO thin films in Au/ZFO/Pt structure was varied to explore the resistive switching behavior. It is reported that forming voltage and resistance of the device increase by increasing the number of ZFO layers. Our results reveal that ZFO thin film deposited by eight times spin coating with a thickness of eight layers illustrates stable resistive switching with the most steady Set (2 V) and Reset voltages (0.5 V) as compared to the devices with two, four, and six layers. It also demonstrates the enhanced endurance of greater than 300 switching cycles and stable time-dependent resistance greater than 104 s. The current transport mechanism is Ohmic at low-resistance state, while it leads to Schottky emission at high-resistance state. The possible switching mechanism is also discussed for the possible application of ZFO-based memory for nonvolatile RRAM devices. [ABSTRACT FROM AUTHOR]

As one of the most promising candidates for next-generation nonvolatile memory, phase change memory is still facing the problem of high power consumption required to reset the device. The melt-quench process during amorphization leads to thermal crosstalk between devices as well. In this work, a paired pulses (P.P.) RESET operation scheme has been demonstrated to reduce the maximum temperature during the amorphization process, which in turn significantly reduces the power consumption. Experiments show that both the minimum RESET programming voltage and power consumption have decreased by up to 0.4 V and 60%, respectively. This proposed programming strategy is promising to optimize the device endurance and stability without sacrificing operating speed. [ABSTRACT FROM AUTHOR]

In the study presented in this article, the impact of proton doping on the structural and electronic properties of hafnium oxide nanoclusters is investigated, with a focus on their potential for use in resistive and polar switching devices. In the results, it is shown that the incorporation of protons can stabilize the cage‐like crystalline structures of Hf6Ox clusters, leading to reversible changes in electronic properties by varying oxygen stoichiometry. However, the full coverage of hafnia atoms by hydrogen removes in‐gap states, highlighting the importance of controlled moisture content in redox‐based memristive devices and neuromorphic units. In addition, in this study, the polar properties of these clusters are explored, illustrating possible polar switching in metastable pure Hf6O9, low‐barrier antiferroelectric‐like switching in carbon‐stabilized Hf6O9:C, and low‐barrier polar switching in Hf10O15:C. In these findings, the potential of HfOx clusters is revealed as active components for next‐generation high‐capacity nonvolatile electronic memory and beyond von Neumann computing in sub‐nanometer scale. [ABSTRACT FROM AUTHOR]

Electret has been extensively utilized as a charge‐trapping layer in organic phototransistor memory applications; nevertheless, the intricate nature of the unique structural configuration posed challenges regarding manipulating device characteristics and performance. Research on understanding material‐driven electronic performance in single‐component phototransistor memory is insufficient. This study highlights the morphology‐dependent characteristics of phototransistor memory composed of a single‐component only, followed by the expansion of optical manipulability by introducing heterojunction. A combined approach involving crystallographic and the intrinsic transistor field‐effect is employed to illustrate the intricate balance that exists between intermolecular, intercrystalline, as well as the charge transfer at the conjugated core and the carriers confinement at the non‐conjugated region. Ultimately, a novel concept of single‐component phototransistor memory is introduced. Given the performance stability of the devices, the emphasis is placed on fully optical programming. The mechanisms of charge transfer and charge trapping effect at heterojunctions under illumination remain challenging to explain. Consequently, a simplified stacking design utilizing molecular systems has been created. A P‐N junction configuration is designed in the studied N‐type phototransistor memory, demonstrating enriched minority carriers to modulate the content of trapped charges and thus leading its memory state switching without applying additional gate bias. [ABSTRACT FROM AUTHOR]

Recent advancements in phase‐change memory (PCM) technology have predominantly stemmed from material‐level designs, which have led to fast and durable device performances. However, there remains a pressing need to address the enormous energy consumption through device‐level electrothermal solutions. Thus, the concept of a 3D heater‐all‐around (HAA) PCM fabricated along the vertical nanoscale hole of dielectric/metal/dielectric stacks is proposed. The embedded thin metallic heater completely encircles the phase‐change material, so it promotes highly localized Joule heating with minimal loss. Hence, a low RESET current density of 6–8 MA cm−2 and operation energy of 150–200 pJ are achieved even for a sizable hole diameter of 300 nm. Beyond the conventional 2D scaling of the bottom electrode contact, it accordingly enhances ≈80% of operational energy efficiency compared to planar PCM with an identical contact area. In addition, reliable memory operations of ≈105 cycles and the 3‐bits‐per‐cell multilevel storage despite ultrathin (<10 nm) sidewall deposition of Ge2Sb2Te5 are optimized. The proposed 3D‐scaled HAA‐PCM architecture holds promise as a universally applicable backbone for emerging phase‐change chalcogenides toward high‐density, ultralow‐power computing units. [ABSTRACT FROM AUTHOR]

Ferroelectric HfO2‐based films incorporated in nonvolatile memory devices offer a low‐energy, high‐speed alternative to conventional memory systems. Oxygen vacancies have been rigorously cited in literature to be pivotal in stabilizing the polar noncentrosymmetric phase responsible for ferroelectricity in HfO2‐based films. Thus, the ability to regulate and control oxygen vacancy migration in operando in such materials would potentially offer step changing new functionalities, tunable electrical properties, and enhanced device lifespan. Herein, a novel in‐ operando approach to control both wake‐up and fatigue device dynamics is reported. Via clever design of short ad hoc square electrical pulses, both wake‐up can be sped up and both fatigue and leakage inside the film can be reduced, key factors for enhancing the performance of memory devices. Using plasmon‐enhanced photoluminescence and dark‐field spectroscopy (sensitive to <1% vacancy variation), evidence that the electrical pulses give rise to oxygen vacancy redistribution is provided and it is shown that pulse engineering effectively delays wake‐up and reduces fatigue characteristics of the HfO2‐based films. Comprehensive analysis also includes impedance spectroscopy measurements, which exclude any influence of polarization reversal or domain wall movement in interpretation of results. [ABSTRACT FROM AUTHOR]

In this study, Y2O3-based resistive random-access memory (RRAM) devices with a mono-ethanolamine (MEA) stabilizer fabricated using the sol–gel process on indium tin oxide/glass substrates were investigated. The effects of MEA content on the structural, optical, chemical, and electrical characteristics were determined. As the MEA content increased, film thickness and crystallite size decreased. In particular, the increase in MEA content slightly decreased the oxygen vacancy concentration. The decreased film thickness decreased the physical distance for conductive filament formation, generating a strong electric field. However, owing to the lowest oxygen vacancy concentration, a large electrical field is required. To ensure data reliability, the endurance cycles across several devices were measured and presented statistically. Additionally, endurance performance improved with the increase in MEA content. Reduced oxygen vacancy concentration can successfully suppress the excess formation of the Ag conductive filament. This simplifies the transition from the high- to the low-resistance state and vice versa, thereby improving the endurance cycles of the RRAM devices. [ABSTRACT FROM AUTHOR]

Crystalline metal halide perovskites (MHPs) have ushered in remarkable advancements across diverse fields, including materials, electronics, and photonics. While the advantages of crystallinity are well‐established, the ability to transition to a glassy state with unique properties presents unprecedented opportunities to expand the structure‐property relationship and broaden the application scope for 2D MHPs. Up until now, the exploration of amorphous analogs for MHPs is confined to high‐pressure conditions, limiting in‐depth studies and practical applications. In this context, a new type of 2D MHPs is synthesized by incorporating halogen substituted organic cations, resulting in a remarkable combination of low melting temperature and inhibited crystallization. This new type of 2D MHPs can be effectively melt‐quenched into a glassy state except for (DMIEA)3Pb2I7 (DMIEA = N, N‐dimethyl iodoethylammonium) counterpart. Analysis of the crystallization activation energy for (DMIPA)4Pb3I10 (DMIPA = N, N‐dimethyl iodopropylammonium) reveals a low crystallization activation energy of 60.7 ± 4.0 kJ mol−1, which indicates a fast glass‐crystal transition. The type of atypical 2D MHP showcases facile and reversible switching between glassy and crystalline states and opens up novel possibilities for applications, such as nonvolatile memory, optical communication, and neuromorphic computing. [ABSTRACT FROM AUTHOR]

Spin Orbit Torque Magnetic Random Access Memory (SOT–)MRAM is gaining interest as it eradicates several limitations posed by its predecessor Spin Transfer Torque (STT-)MRAM, yet inherits all its advantages. This work explores in detail, the suitability of SOT–MRAM implemented caches in different levels of memory hierarchy in comparison to conventional SRAM technology, over several performance parameters like area, energy consumption and execution time for an embedded benchmark suite. Our circuit-level analysis shows that SOT–MRAM outperforms SRAM for caches (>128 KB), and only lags in area and read-access energy for smaller caches. A typical 512 KB SOT–MRAM cache improves area by 1%, read/write latency by 33/38%, and leakage by over 99% than that of SRAM memory technology. The architecture-level analysis confirms that on average SOT–MRAM is energy efficient by 74% in L1, 97.2% in L2 and 89.3% in both (i.e., L1 + L2) implementations against SRAM, for a 22nm technology node. We also estimate that SOT–MRAM only solution offers ∼68.8% energy savings and ∼79.5% better EDP than Hybrid (L1-SRAM and L2-SOT) memory hierarchy for multi-core ARM processors. [ABSTRACT FROM AUTHOR]

The tunable molecular scaffold of organic moieties in metallopolymers generates variation in their properties, but what could be the minimal change that can produce variation in the properties of these macromolecules is still untouched. This research has meticulously explored the trivial change in the molecular scaffold of the ligand capable of making a mammoth difference in the nonvolatile memory and coordination pattern in two metallopolymers. The significance of this research lies in the fact that it demonstrates how a slight change in the organic building block can significantly alter the memristive and fluorescence properties of iron(II) metallopolymers, opening up new possibilities for their design and synthesis. Two novel positional isomeric ligands and their corresponding iron(II)-polymers were synthesized and thoroughly characterized using NMR, XRD, ATR-IR, FESEM, AFM and other techniques. Bright orange solid and solution state fluorescence was observed both in the solid and solution states for ligand L2 (3,3′-bis((E)-(pyridin-3-ylimino)methyl)-[1,1′-biphenyl]-4,4′-diol), while ligand L1 (3,3′-bis((E)-(pyridin-2-ylimino)methyl)-[1,1′-biphenyl]-4,4′-diol) showed blue fluorescence in the solution state only. A robust memristive property for Fe(II)-L1-poly with a high current ON/OFF ratio of 104, remarkable random access behaviour, and a long retention time greater than 35 000 seconds was observed while its counterpart was entirely silent. Both polymers showed solution-state electrochromism. These synthesised metallopolymers also showed good specific capacitance in the range of 50–60 F g−1 with a remarkable retention of 98% of the initial value even after 5000 charge–discharge cycles. The AFM and FESEM micrographs revealed the formation of long polymer nano-rods, which correlates with the NMR, ATR-IR, and XRD results. The difference in the properties of polymers generated by such a slight change in the organic building block forces different coordination patterns of these two ligands around the same central metal ion, and this is also evident in all the characterization methods. [ABSTRACT FROM AUTHOR]

Biodegradable electronic devices play a crucial role in addressing the escalating issue of electronic waste accumulation, which poses significant environmental threats. In this study, we explore the utilization of a methanol-based extract of the Elaeodendron buchananii plant blended with a carboxymethyl cellulose biopolymer to produce a biodegradable and environmentally friendly functional material for a resistive switching memory system using silver and tungsten electrodes. Our analyses revealed that these two materials chemically interact to generate a perfect composite with near semiconducting optical bandgap (4.01 eV). The resultant device exhibits O-type memory behavior, with a low ON/OFF ratio, strong endurance (≥ 10 3 write/erase cycles), and satisfactory (≥ 10 3 ) data retention. Furthermore, through a comprehensive transport mechanism analysis, we observed the formation of traps in the composite that significantly improved conduction in the device. In addition, we established that altering the voltage amplitude modifies the concentration of traps, leading to voltage amplitude-driven multiple resistance states. Overall, our findings underscore the potential of functionalizing polymers that can be functionalized by incorporating plant extracts, resulting in biodegradable and nonvolatile memory devices with promising performance metrics. [ABSTRACT FROM AUTHOR]

Low‐band gap semiconductor polymer materials play a crucial role in the field of organic optoelectronics. In this context, a series of low‐band gap polymers containing thienopyrazine as the acceptor and cyclofluorene–bithiophene as the donor were synthesized and utilized in resistive random access memory (RRAM) devices. These memory devices consistently exhibit nonvolatile flash memory behavior. Remarkably, all three polymers demonstrate stability even after 1000 cycles without significant fluctuations. Notably, the three polymer‐based devices also exhibit excellent ternary memory performance, with current ratios of 1:102.8:104, 1:101.3:103.9, and 1:101.8:103.6. Furthermore, the photoelectric properties of the three polymers and the conduction mechanisms of the memory devices were thoroughly discussed. [ABSTRACT FROM AUTHOR]

Recently, metal–organic frameworks (MOFs) have gained attention in the field of electronics owing to their capability to tune their electrical characteristics. However, conventional methods for synthesizing MOFs pose challenges for their integration into electronic devices because of their long synthesis times and complex transfer steps. In this study, for the first time, lasing‐assisted synthesis (LAS) is used to rapidly and directly synthesize MOFs. These are applied to resistive random access memory (RRAM) devices. Using the LAS method, Cu(BDC) and Cu(BTC) are synthesized in a remarkably short time (≈5 min) and formed directly on metal substrates as thin films. This simplified their integration into RRAMs. The Cu(BDC)‐ and Cu(BTC)‐based RRAMs are evaluated for their potential in memory and neuromorphic applications. Both devices demonstrated nonvolatile memory capabilities with a remarkable data retention time of 104 s and long‐term plasticity (LTP) in response to voltage stimuli. However, the suitability of each device for a specific application varies depending on the type of MOFs used. The Cu(BTC)‐based RRAM is more suitable for memory applications because of its higher on/off ratio, longer endurance, and more data storage capacity. Conversely, Cu(BDC)‐based RRAM is highly effective in neural network simulation, achieving higher classification accuracy. [ABSTRACT FROM AUTHOR]

Ge‐rich GeSbTe chalcogenide alloys have gained significant attention in the field of phase‐change materials due to their remarkable thermal stability and thus their suitability for integration in nonvolatile memories targeting embedded automotive applications. Herein, the effects of different encapsulating materials on the evolution and on the crystallization kinetic of N‐doped Ge‐rich GeSbTe films are focused on. These films are annealed with temperatures compatible with the back‐end‐of‐line of the complementary metal‐oxide‐semiconductor (CMOS) fabrication. First, it shows how the encapsulation layer thickness should be tuned in order to protect the layer from oxidation and at the same time to avoid delamination phenomena. TaN, C, TiN, SiC, and SiN used as encapsulating layers are compared. The segregation and crystallization of Ge‐rich GeSbTe alloys appear more homogeneous in the case of C, TiN, and SiC. On the contrary, the effects of an interfacial heterogeneous nucleation in the case of TaN and SiN are observed. It results in a different final morphology of the chalcogenide layer after annealing depending on the encapsulation, with different grain sizes and kinetic of phase separation. [ABSTRACT FROM AUTHOR]

Flexible electronics which are easy to manufacture and integrate into everyday items require suitable memory technology that can function on flexible surfaces. Herein, the properties of Ge‐rich GeSbTe (GST) and Se‐substituted GeSbSeTe (GSST) phase‐change alloys are investigated for application as nonvolatile write‐once and rewritable memories in flexible electronics. These materials have a higher crystallization temperature than the archetypal composition of Ge2Sb2Te5 and hence better data retention properties. Moreover, their high crystallization temperature provides for a particularly straightforward implementation of a write‐once memory configuration. Material properties of Ge‐rich GST and GSST are measured as a function of temperature using four‐point probe electrical testing, Raman spectroscopy, and X‐ray diffraction. Following this, the switching of flexible memory devices is investigated through both simulation and experiment. More specifically, crossbar memory devices fabricated using Ge‐rich GST are experimentally fabricated and tested, while the operation of GSST pore cell structures suitable for flexible memory applications is demonstrated through simulation. [ABSTRACT FROM AUTHOR]

Phase‐change materials have long been employed for rewriteable optical data storage at the industrial scale and are hailed as one of the most mature technologies for their applications in emerging nonvolatile memories. Memristors based on these materials have the potential to circumvent the long‐standing von Neumann bottleneck and offer significant computational advantage through neuromorphic computing. A very core fundamental concept that lies at the crux for such realization is their ability to offer multilevel cell (MLC) storage, in contrast to the binary counterpart. Yet, numerous challenges still remain to be tackled for their successful implementation in this regard. This work is a finite element analysis that particularly reports the polarity dependence of such MLC operation in the conventional mushroom geometry of devices employing this technology. The mechanism lying underneath is discussed and a perspective combining thermoelectric effects with the energy band diagrams resulting from metal–semiconductor contact formation is additionally put forth. [ABSTRACT FROM AUTHOR]

The power saving in mobile systems is a big concern. It has attracted the attention of most of the researchers. In addition to this, process variation plays an important role in device performance, especially at lower technology nodes and low supply voltages. The application of non-volatile memory (NVM) devices with SRAM cell is found as an effective solution for power consumption. Also, the Schmitt Trigger (ST) action helps in maintaining the device performance under process variations. To attain both the features, a non-volatile SRAM (nvSRAM) cell using eleven transistor and one memristor (11T1M) is presented in this work. In addition to this, Schmitt Trigger (ST) action is used to improve the stability of the proposed design. From simulations, it is observed that the proposed 11T1M nvSRAM cell offer minimum deviation in delay performance and better stability in comparison to considered cells. The leakage power consumption of proposed design is also minimum. [ABSTRACT FROM AUTHOR]

Herein, a prototype nonvolatile bent ferroelastic domain wall (DW) memory based on extension–retraction of DWs in a top electrode/bent ferroelastic DWs/bottom electrode architecture is demonstrated and the effects of mechanical condition, electrical condition, and the material parameter on ferroelastic DWs in PbTiO3 ferroelectric thin films are studied by phase field modeling. Misfit strain can be used to drive the bend of DWs in PbTiO3 thin film, resulting in a change of ferroelastic domain size, bending degree, and conductivity. Stable and reversible switching of DWs between the extendible state with high conductivity and the retractile state with low conductivity can be realized, resulting in an apparent resistance change with a large ON/OFF ratio of >102 and an excellent retention characteristic. The extension and retraction speed, corresponding to data writing speed, can be adjusted by the electric field magnitude and distributions. The memory speed increases by 5% under a homogeneous electric field and 6% under an inhomogeneous probing electric field, after the buildup of space charges in a ferroelectric thin film, and the fastest memory speed is obtained at tip potential φ = 1.8. Moreover, polarization orientations of a and c domains separated by bent ferroelastic DWs do not affect memory performance. This paper can guide the development of new ferroelectric domain wall memory. [ABSTRACT FROM AUTHOR]

Phase-change memory (PCM) is one of the leading candidates for the next generation nonvolatile memory. As a growth-dominated crystalline material, Sb2Te3 is of rapid crystallization speed while its poor thermal stability limits its application. Doping Ti can significantly enhance its amorphous stability but inevitably slows down its crystallization speed. How to balance the contradiction between thermal stability and operation speed remains challenging. In this work, we proposed a gradient Ti-doped Sb2Te3 phase-change material and device. This gradient doping strategy compensates for the negative effect of Ti doping on the crystallization rate of Sb2Te3 via the template effect of the lower doping concentration layer. Very small lattice mismatch between the Sb2Te3 layers with different Ti doping concentrations is verified by x-ray diffraction characterization. The crystallization temperature of a gradient Ti-doped Sb2Te3 thin film is raised up to 172.6 °C and the same 50 ns operation speed as a pure Sb2Te3 device is achieved in the corresponding PCM device. Furthermore, the gradient distribution of Ti elements and the corresponding progressive crystallization phenomenon are verified by transmission electron microscopy revealing the microscopic origin of rapid crystallization speed. Therefore, with our gradient doping strategy, the amorphous stability is improved without sacrificing the crystallization speed in PCM. [ABSTRACT FROM AUTHOR]

Thin-film ferroelectric doped hafnia has emerged as a promising candidate for non-volatile computer memory devices due to its CMOS compatibility. The ferroelectricity in thin-film HfO2 is defined by the polar orthorhombic phase, whose stabilization depends on various parameters, such as doping species, stress, thickness, crystallization annealing temperature, etc. The concentration of oxygen vacancies is yet another parameter affecting the stabilization of the ferroelectric phase in HfO2 thin films. Here, we report on the effect of oxygen vacancies introduced in Y-doped HfO2 (HYO) films during reactive pulsed laser deposition on their ferroelectric properties, which we systematically study by correlating structural and electrical properties. Among different techniques, near-edge x-ray absorption fine structure analysis is successfully employed to distinguish between structurally similar ferroelectric orthorhombic and paraelectric tetragonal phases. It is shown that oxygen vacancies introduced at a certain concentration in HYO films can be used as a tool to control the phase composition as well as to decrease the formation energy (crystallization temperature) of the ferroelectric phase. Based on these results, we demonstrate a back-end-of-line compatible ferroelectric HYO capacitor device with competitive functional properties. [ABSTRACT FROM AUTHOR]