High-temperature Retention Research Articles

Decomposition of Charge Loss Mechanisms in 3-D Nand Flash Memory: Impact of Cell Dimension via High-Temperature Long-Term Retention Characteristics

Decomposition of Charge Loss Mechanisms in 3-D Nand Flash Memory: Impact of Cell Dimension via High-Temperature Long-Term Retention Characteristics

High-Temperature Retention Stability of Multibit Ferroelectric HfZrO₂ FinFET With SiGe/Si Superlattice Channel for Enhanced Speed and Memory Window

High-Temperature Retention Stability of Multibit Ferroelectric HfZrO₂ FinFET With SiGe/Si Superlattice Channel for Enhanced Speed and Memory Window

Stabilized Nickel-Rich oxide cathode by the confining effect of Nb lattice anchoring and epitaxial shielding layer

Ni-rich LiNixCoyMn1−x−yO2 cathodes attract growing attention for high energy density but still face great challenges in terms of cyclic lifespan and thermal stability issues. The structural degradation is primarily caused by the increased oxygen vacancy and lattice oxygen loss, especially at high temperatures. Here, we develop an anchoring-confining strategy to rivet lattice oxygen and inhibit the formation and migration of oxygen vacancy by constructing LiNbO3 & LiF epitaxial layer and Nb5+ lattice doping within LiNi0.92Co0.055Mn0.025O2 (NCM92) cathode. The optimized NCM-FN material exhibits excellent stability with retenion of 93 % after 200 cycles at 1C supassing the pristine one (68.7 %), conspicuous high-temperature capacity retention rate (81.6 % vs. 49.5 %) and superior reversible capacity of 165 mAh/g at 5C. In particular, it even possessed superior thermal safety pushing thermal runaway temperature to 223.65 °C. In-situ X-ray diffraction (XRD) result indicates that Nb5+ lattice substitution coupled with LiNbO3 & LiF epitaxial layer alleviates the irreversibility of H2-H3 phase transition, thus stabilizing the layered structure. Furthermore, the LiNbO3 & LiF epitaxial layer, as both a physical shielding layer and ionic conductive layer, protects interface structural integrity and simultaneously promotes Li+ diffusion. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) results demonstrate that the formation and propagation of oxygen vacancy within NCM-FN material is significantly inhibited. DFT calculation results reveal that Nb5+ introduction can increase the formation energy of oxygen vacancies and inhibit outward migration of active oxygen Oα- (α < 2) to stabilize layer structure by tuning the breaking energy barrier of nearby metal-O bonds. This work not only demonstrates the design of advanced Ni-rich layered cathodes but also underscores the importance of stabilized lattice oxygen for advanced Ni-rich cathodes.

Enhancing strength and ductility in high Nb-containing TiAl alloy additively manufactured via directed energy deposition

Intermetallic TiAl alloys have found applications in the aerospace and automotive fields. Nevertheless, to satisfy the increasingly complex environmental requirements, these lightweight alloys must be improved particularly in strength and ductility. Additive manufacturing (AM) exhibits a rapid solidification rate and may strengthen intermetallic TiAl alloys. In this study, an additively manufactured (AMed) Ti-48Al-8 Nb alloy with fine formability was successfully fabricated by optimizing the power used during directed energy deposition. The preferential crystal plane for the obtained alloy is {111}γ due to its lowest surface energy, and the presence of the thermal gradient during the AM process results in the alloy growing along the building direction. The TiAl alloy AMed at 500 W delivers an excellent tensile strength of 880 MPa that is 1.71 times higher than that of its as-cast counterpart, as well as elongation of 0.7% at room temperature. The superior properties of this alloy are due to the formation of numerous deformation twins during tensile deformation at room temperature that enables twin intersections to produce high-density nano-twins while contributing to stress release. Moreover, the AMed TiAl alloy exhibits outstanding high-temperature strength retention performance.

Influence of the special behavior of interpass retention-relaxation on the softening mechanism of precipitation strengthened GH99 alloy during multi-pass hot deformation

This study investigates the hot deformation behavior of the GH99 alloy for hypersonic missile airfoils at 1020–1170 °C and 0.001–1 s−1 by single-pass hot compression experiments. Based on the establishment of the constitutive equation, thermal processing map, and dynamic recrystallization kinetic model, it elucidates the influence of the second phase strengthening on dynamic recrystallization (DRX). It determines the optimal hot deformation parameters of the GH99 alloy. Moreover, through designing different multi-pass hot compression experiments, we investigated the relaxation characteristics of the organization properties during the water quenching-cooling-holding process in the interpass and the influence of the interpass retention-relaxation behavior on the DRX mechanism. The results show that the water quenching process increases the rheological stress of the second pass compression, and the nucleation of discontinuously dominates the organization dynamically recrystallized (DDRX), supplemented by continuously dynamically recrystallized (CDRX); the static recrystallization (SRX) occurring in the high-temperature retention stage of the interpass can effectively reduce the rheological stress. The organization is characterized by the growth of recrystallized grains during the subsequent deformation process. With the prolongation of the high-temperature retention time, the number of recrystallized grains and the dislocation density increase.

Tunable defect engineering of Mo/TiON electrode in angstrom-laminated HfO2/ZrO2ferroelectric capacitors towards long endurance and high temperature retention.

A novel defect control approach based on laminated HfO2/ZrO2with multifunctional TiN/Mo/TiOxNyelectrode is proposed to significantly improve the endurance and data retention in HZO-based ferroelectric capacitor. The O-rich interface reduces leakage current and prolong the endurance up to 1011cycles while retaining a 2Pr value of 34 (μC cm-2) at 3.4 MV cm-1. Using first-principles calculations and experiments, we demonstrate that the enhancement of endurance is ascribed to the higher migration barrier of oxygen vacancies within the laminated HZO film and higher work function of MoOx/TiOxNybetween top electrode and the insulating oxide. This 2.5 nm thick TiOxNybarrier further increase the grain size of HZO, lowering the activation field and thus improving polarization reversal speed. This interfacial layer further decreases the overall capacitance, increases the depolarization field, thereby enhancing the data retention. By fitting the data using the Arrhenius equation, we demonstrate a 10 years data retention is achieved at 109.6 °C, surpassing traditional SS-HZO of 78.2 °C with a 450 °C rapid thermal annealing (required by backend-of-the-line). This work elucidates that interfacial engineering serves as a crucial technology capable of resolving the endurance, storage capability, and high-temperature data retention issues for ferroelectric memory.

High-temperature load retention behavior of general-purpose wrought magnesium alloys

High-temperature load retention behavior of general-purpose wrought magnesium alloys

High-temperature tolerant TaOX/HfO2 self-rectifying memristor array with robust retention and ultra-low switching energy

Due to the heat generation during operations in high-density three-dimensional (3D) integrated chips, a high-temperature tolerant and high-performance self-rectifying memristor (SRM) is a promising candidate for 3D integration. Here, we investigated the high-temperature characteristics of Ta/TaOX/HfO2/Pt SRMs with a 250 nm feature size in an 8 × 8 crossbar array (CBA). The SRMs exhibit high uniformity and can be operated repeatedly at Set (4 V/2 μs) and Reset (-2 V/1 μs) pulses for more than 104 cycles resulting in ultra-low switching energy (5.86 aJ for Set and 77.2 aJ for Reset). High yield of the array indicates the reliable preparation processes. Remarkably, the CBA is capable of stably resistive switching at high temperatures from 300 to 475 K. At 300 K, the SRM shows large nonlinearity (NL, ∼1.4 × 104) and rectification ratio (RR, ∼8.8 × 103) as well as high scalability (330 Mbit); at 475 K, the NL and RR of the SRM can still maintain above 400, and the scalability still reaches 71 Kbit. Moreover, our SRM passed a high-temperature retention test of over 5 × 104 s at 438 K. Segmented fittings of the I–V curves of the SRM at different temperatures were performed, concluding that large NL and RR attributed to the Schottky barriers at TaOX/HfO2 and Pt/HfO2 interfaces, respectively. Our work furnishes a feasible solution for high-density 3D integrated memristors in high-temperature application scenarios represented by automotive-grade chips.

Exceptional high temperature retention in Al0.93B0.07N films

This paper reports the retention behavior for Al0.93B0.07N thin films, a member of the novel family of wurtzite ferroelectrics. Our experiments suggest that bipolar cycling of metal (Pt/W)/Al0.93B0.07N/W/Al2O3 film stacks first induced wake-up and then a region of constant switchable polarization. The films showed excellent retention of the stored polarization state. As expected, data retention was slightly inferior in the opposite state (OS) measurements. However, it is noted that even after 3.6 × 106 s (1000 h) at 200 °C, the OS signal margin still exceeded 200 μC/cm2. The predicted OS retention is 82% after 10 yr baking at 200 °C.

Structure-modified polymeric carbon-dots with lowered retention and enhanced colloidal stability in porous media for tracer application at extreme reservoir condition

Tracer technology has been increasingly used in inter-well tests to investigate reservoir performance, reservoir connectivity and residual oil saturation for providing useful information to improve decision making in reservoir management. Stable nanoparticle tracers with high-sensitive real-time detectability are highly desired, and as one of the nanoparticles tracers, carbon dots (C-dots) have been studied and tested in field trial for reservoir monitoring. In this research, we report a modified method to synthesize fluorescent C-dots which fluorinated, sulfonated or zwitterionic functional groups were incorporated into the C-dots. The synthesis reactions occurred at hydrothermal conditions with inexpensive starting materials and are readily to scale up for industrial application. The synthesized C-dots are readily dispersible in brines and exhibit improved colloidal stability in high salinity and at high temperature and lowered retention in reservoir rock. Optical properties of the synthesized colloidal C-dots were studied by UV–visible and fluorescence spectroscopies, and the difference in fluorescence between the C-dots hydrothermally treated at different temperatures enables them to be used as multicolor tracers with fluorescence barcodes. Retentions of the C-dots in porous rocks were evaluated by adsorption in crushed calcite and core flooding tests with limestone, and near zero retention of the modified C-dots in reservoir rock were revealed. In molecular dynamics (MD) simulations, results show the C-dot adhesions on calcite surface follow the decreasing order: plain > sulfonated > zwitterionic > fluorinated C-dots, consistent well with experiments that the functionalized C-dots all have lowered adsorption on limestone. In comparison with those C-dots reported in literature, our results suggest that the synthesized C-dots using the modified procedure have excellent fluorescence properties, improved thermal stability, photostability, and water dispersibility, enabling their use as optically detectable nano-agent tracers for oilfield application.

Design of all-phase-change-memory spiking neural network enabled by Ge-Ga-Sb compound

The implementation of artificial spiking neural network (SNN) usually takes advantage of multiple heterogeneous circuits to mimic either neurons which generate spiking pulses, or synapses which store the weights of event correlations. Here, we design a homogeneous device using Ge-Ga-Sb (GGS) as a phase-change-memory (PCM) material which can do both jobs. The GGS compound shows high stability when used in data storage, such as high working temperature (281°C) and high 10-years data retention temperature (230°C), as well as low resistance drift. Interestingly, when the as-fabricated GGS device is set by iterative narrow-width electric pulses, it first experiences an abrupt resistance drop by two orders of magnitude, followed by a continuous resistance decrease. This unique abrupt-to-progressive transition can be used to mimic both neuronal and synaptic functions, mechanistically enabled by the formation of conductive channels and the continuous growth with the phase separation of crystalline areas. To this end, we propose an all-PCM SNN, which is emulated to have high accuracy (90%) in the standard pattern recognition.

Engineering commercial polycrystalline precursors to single crystal Ni-rich cathodes with outstanding long-cycle performance

Single crystal cathode materials were prepared through crystal construction, purification, and restoration processes, demonstrating outstanding high-temperature capacity retention.

Enhanced Synaptic Features of ZnO/TaOx Bilayer Invisible Memristor for Brain-Inspired Computing

In this letter, we present a transparent bilayer ZnO/TaOx memristive synapse for brain-inspired computing. The device shows excellent AC endurance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{9}}$ </tex-math></inline-formula> cycles) and high-temperature retention ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{4}}$ </tex-math></inline-formula> s) without any degradation at 100 °C. The device exhibits highly stable repetitive 5130 potentiation (P) and depression (D) epochs with 1.026 M pulses. The multilevel characteristics (MLC) of the device are achieved by changing the pulse height from 0.7 to 1.1 V for long-term potentiation (LTP) and from −0.9 to −1.3 V for long-term depression (LTD) having gradual conductance change for both P and D cases. The synaptic features such as paired-pulse facilitation (PPF) and spike time-dependent plasticity (STDP) are measured using consecutive AC pulses. These unique features confirm that the synaptic device has excellent capability for the application in the brain-inspired computing systems.

Cr-doped Sb2Te materials promising for high performance phase-change random access memory

Transition metal doping is an effective strategy to improve the properties of phase-change random access memory (PCRAM), while the underlying mechanism remains to be sufficiently investigated. Herein, a Cr-doped Sb2Te film is fabricated by co-sputtering and the enhancement mechanism of Cr-doping is deeply investigated by experiments and first-principles calculations. The CrxSb2Te film exhibits excellent performances involving high crystallization temperature (238.9 °C) and good data retention (10 years @161.7 °C) for Cr0.56Sb2Te, low density change rate (3.8%) and high reversible switching speed (5 ns) for Cr0.29Sb2Te, providing a variety of options for different applications. The calculated results show that Cr atoms preferentially substitute the Sb1 site and the CrTe bonds display a stronger ionic bond character in contrast to the covalent bonded SbTe, thus improving the crystalline phase stability and crystallization temperature. Moreover, ab initio molecular dynamics simulations demonstrate that in the amorphous phase Cr atoms locate in defective octahedral coordination. Meanwhile, the homopolar SbSb wrong bond increased with Cr doping and the Cr atoms tend to form tight cluster in the amorphous phase which could benefit for the fast phase-change speed. Our present findings of Cr0.29Sb2Te PCRAM device clearly reveal the enhancement mechanism by Cr doping which provides guidance for developing high-performance PCRAM devices.

Embedded sensors in additively manufactured silicon carbide

Silicon carbide (SiC) components are being considered for a wide range of nuclear applications due to their high-temperature strength retention, low neutron absorption, chemical inertness, and dimensional stability under neutron irradiation. However, machining and joining of SiC components have traditionally limited its application to relatively simple geometries. Recent work has demonstrated additive manufacturing of complex, high-purity, crystalline SiC components using a combination of binder jet printing and densification via chemical vapor infiltration (CVI). The process lends itself to embedding of fuel, absorbers, moderators, and sensors at strategic locations within a component. The latter could allow for enhanced in situ performance monitoring of limiting fuel temperatures, self-shielded neutron flux, and potentially spatially distributed strain within complex SiC components if sensors can be successfully embedded during CVI. This work describes (1) methods for embedding sensors; (2) thermodynamic analyses and material compatibility testing for identifying sensors capable of surviving high temperatures and exposure to hydrogen and hydrogen chloride during CVI; and (3) nuclear applications for embedded sensors, including potential failure modes during fabrication and during reactor operation. Molybdenum-sheathed thermocouples were successfully embedded in a complex SiC component, whereas niobium-sheathed high-temperature irradiation-resistant thermocouples started to drift as soon as the reactant gases were introduced and ultimately failed during CVI due to severe constrained expansion, potentially resulting from niobium hydride formation in the low-temperature region of the CVI system. Optical fibers were successfully embedded in SiC, but further work is needed to protect the fragile fiber leads after their protective coatings are removed during CVI.

Microstructure evolution and high-temperature mechanical properties of porous Si3N4 ceramics prepared by SHS with a small amount of Y2O3 addition

Porous Si3N4 ceramics with well-developed microstructure and high flexural strength were successfully prepared by self-propagating high temperature synthesis (SHS) using a small amount of Y2O3 as sintering additive. Influences of Y2O3 content on the phase composition, microstructure evolution, flexural strength at both room temperature and elevated temperature of ~1400 °C and their fracture behavior of the obtained porous Si3N4 ceramics were investigated. Porous Si3N4 ceramic with high average aspect ratio of 4.03 and excellent flexural strength of 101 MPa was obtained by 0.4 wt% Y2O3 addition. It also shows good strength retention of 76.6% and evidently elastic fracture behavior at 1400 °C because of its rather low amorphous intergranular phase content. With the increase of Y2O3 content, the creep resistance of sample degraded owning to the softening of amorphous intergranular thus resulting in the degradation of high-temperature strength retention.

Simplistic approach to reduce thermal issues in 3D IC integration technology

Abstract A practical exhibition of the consequences of the 3D IC in heat management by adding the fin and heat spreaders to thermal through silicon via (TTSV) and IC respectively is proposed in this paper. Thermal cooling and its distribution of burnt potentials at various conditions are the different possessions which can be simulated using FEM simulator. This paper illustrate materials like Silicon nitride (Si3N4), Aluminium oxide (Al2O3), Silicon dioxide (SiO2) as they have the high thermal conductivity and high temperature capabilities which leads to the thermal management in the 3D IC design. Currently, semiconductor industries has cognizance of the metrics such as low density, high thermal strength, good facture of toughness, excellent wear resistance of Silicon nitride and it also shows better capabilities of high temperature, oxidation resistance and high retention strength compared to other metals. Besides silicon nitride has good resistance to thermal shock due to low coefficient of thermal expansion. Aluminium oxide is known for an better electrical insulator but has high thermal conductivity and which can be utilized as the substrate for integrated circuits. The high temperature furnace insulations and electrical insulations are designed by using the aluminium oxides as it has high boiling points and melting points. This makes the rapid use of alumina films in manufacture of IC industry. The other uses of alumina films include spark plug insulators, micro-electric substrates and insulating heat sinks. Silicon dioxide has the properties which helps to use them as the insulator material in IC technology as it has high thermal stability and making it useful for device integration and has high dielectric strength and thermal expansion coefficient is very low and in this paper we have taken these three materials and these materials have been implemented in our model and advertence the outcomes that which material is working efficiently and preciously.

Microstructure and properties of a high temperature Al–Ce–Mn alloy produced by additive manufacturing

An Al–10Ce-8Mn (wt%) alloy was designed and fabricated by laser powder bed fusion additive manufacturing (AM). The rapid cooling rates of the AM process produced a refined microstructure with a large fraction of reinforcing intermetallic phases. The tensile properties of the alloy were characterized in the as-fabricated state and following thermal exposure. The properties of the as-fabricated microstructure showed exceptional high-temperature performance and strength retention at elevated temperatures up to 400 °C relative to benchmark wrought Al and AM Al alloy properties. Characterization of the microstructure and thermodynamic modeling of the ternary Al–Ce–Mn system rationalized the solidification and solid-state phase transformations. Analysis of the relevant strengthening mechanisms for both the as-fabricated and thermally exposed conditions was performed.

Surface characterization and mechanical behavior of aluminum based metal matrix composite reinforced with nano Al2O3, SiC, TiO2 particles

Aluminum based metal matrix composites (AMMCs) have the potential for replacing conventional monolithic materials due to excellent fatigue, creep and wear resistance, high temperature retention, and high strength to weight ratio. Thus Aluminum based metal matrix composites have several applications in different industries including Aerospace and Automotive. This study revealed that Al 6063 based metal matrix composites reinforced with Al2O3, SiC, TiO2 have higher hardness, tensile strength, and yield strength as compared to the pure Al 6063. This study shows that hardness, tensile strength, and yield strength are increasing as increasing SiC particles content. Microstructure and surface morphological studies have been carried out to see their surface and particles distribution. Energy Dispersive X-ray Spectroscopy (EDS) and XRD analysis have been conducted to identify elements content. Fourier Transform Infrared Spectroscopy (FTIR) analysis is carried out to identify chemical functional group of the Al6063 metal matrix composites.

Effects of Charge Quantity Induced by Different Forming Methods in Solid Electrolyte GeSO-Based Resistance Switching Device With Copper Electrode

In this article, two different resistance switching (RS) behaviors are demonstrated after using dc and constant bias stressed (CBS) forming methods in GeSO-based resistive random access memory (RRAM) with a copper top electrode. Electrical measurements show that the amount of charge during the forming process significantly affects their RS behaviors. Large memory windows appear when applying CBS forming, while traditional dc forming did not exhibit such characteristics. Both current–voltage ( $I-V$ ) fitting and high temperature retention test are used to further investigate the RS property and verify the stability. Finally, conduction models for devices using these different forming methods are also proposed to better illustrate their different conducting behaviors in the GeSO-based RRAM device.